Micom P740: Numerical Busbar Protection

MiCOM P740
Numerical Busbar Protection
Technical Manual
P740/EN T/D11
SAFETY SECTION Px4xx/EN SS/A11
SAFETY SECTION
Page 1/8
CONTENTS
1. HANDLING OF ELECTRONIC EQUIPMENT 3
2. SAFETY SECTION 4
3. INSTALLING, COMMISSIONING AND SERVICING 5
4. EQUIPMENT OPERATING CONDITIONS 6

4.1. Current transformer circuits 6
4.2. External resistors 6
4.3. Battery replacement 6
4.4. Insulation and dielectric strength testing 6
4.5. Insertion of modules and pcb cards 6
4.6. Fibre optic communication 6
5. DECOMMISSIONING AND DISPOSAL 7
6. TECHNICAL SPECIFICATIONS 7
Px4xx/EN SS/A11 SAFETY SECTION
Page 2/8
BLANK PAGE
Page 3/8
1. HANDLING OF ELECTRONIC EQUIPMENT

A person's normal movements can easily generate electrostatic potentials of several
thousand volts. Discharge of these voltages into semiconductor devices when
handling electronic circuits can cause serious damage, which often may not be
immediately apparent but the reliability of the circuit will have been reduced.
The electronic circuits of AREVA T&D products are immune to the relevant levels
of electrostatic discharge when housed in their cases. Do not expose them to the risk
of damage by withdrawing modules unnecessarily.
Each module incorporates the highest practicable protection for its semiconductor
devices. However, if it becomes necessary to withdraw a module, the following
precautions should be taken to preserve the high reliability and long life for which the
equipment has been designed and manufactured.
1. Before removing a module, ensure that you are at the same electrostatic
potential as the equipment by touching the case.
2. Handle the module by its front-plate, frame, or edges of the printed circuit
board. Avoid touching the electronic components, printed circuit track or
connectors.
3. Do not pass the module to any person without first ensuring that you are both
at the same electrostatic potential. Shaking hands achieves equipotential.
4. Place the module on an antistatic surface, or on a conducting surface which is
at the same potential as yourself.
5. Store or transport the module in a conductive bag.
More information on safe working procedures for all electronic equipment can be
found in BS5783 and IEC 60147-0F.
If you are making measurements on the internat electronic circuitry of an equipment
in service, it is preferable that you are earthed to the case with a conductive wrist
strap.
Wrist straps should have a resistance to ground between 500k - 10M ohms. If a wrist
strap is not available, you should maintain regular contact with the case to prevent
the build up of static. Instrumentation which may be used for making measurements
should be earthed to the case whenever possible.
AREVA T&D strongly recommends that detailed investigations on the electronic
circuitry, or modification work, should be carried out in a Special Handling Area such
as described in BS5783 or IEC 60147-0F.
Page 4/8
2. SAFETY SECTION
This Safety Section should be read before commencing any work on the
equipment.
Health and safety
The information in the Safety Section of the product documentation is intended to
ensure that products are properly installed and handled in order to maintain them in
a safe condition. It is assumed that everyone who will be associated with the
equipment will be familiar with the contents of the Safety Section.
Explanation of symbols and labels
The meaning of symbols and labels which may be used on the equipment or in the
product documentation, is given below.
!
Important: Important:
refer to the product documentation risk of electrocution
Protective/safety earth * Functional earth terminal*
NOTE: This symbol can also be used for a

protective/safety earth terminal if that
terminal is part of a terminal block or sub-
assembly eg. power supply.
*NOTE: The term earth used throughout the product documentation is

the direct equivalent of the North American term ground.
Page 5/8
3. INSTALLING, COMMISSIONING AND SERVICING

Equipment connections
Personnel undertaking installation, commissioning or servicing work on this
equipment should be aware of the correct working procedures to ensure safety. The
! product documentation should be consulted before installing, commissioning or

servicing the equipment.
Terminals exposed during installation, commissioning and maintenance may present
a hazardous voltage unless the equipment is electrically isolated.
If there is unlocked access to the rear of the equipment, care should be taken by all
personnel to avoid electric shock or energy hazards.
Voltage and current connections should be made using insulated crimp terminations
to ensure that terminal block insulation requirements are maintained for safety. To
ensure that wires are correctly terminated, the correct crimp terminal and tool for the
wire size should be used.
Before energising the equipment it must be earthed using the protective earth
terminal, or the appropriate termination of the supply plug in the case of plug
connected equipment. Omitting or disconnecting the equipment earth may cause a
safety hazard.
The recommended minimum earth wire size is 2.5 mm2, unless otherwise stated in
the technical data section of the product documentation.
Before energising the equipment, the following should be checked:
− Voltage rating and polarity;
− CT circuit rating and integrity of connections;
− Protective fuse rating;
− Integrity of earth connection (where applicable)
Page 6/8
4. EQUIPMENT OPERATING CONDITIONS

The equipment should be operated within the specified electrical and
environmental limits.
4.1. Current transformer circuits
Do not open the secondary circuit of a live CT since the high voltage produced may
be lethal to personnel and could damage insulation.
4.2. External resistors
Where external resistors are fitted to relays, these may present a risk of electric shock
or burns, if touched.
4.3. Battery replacement
Where internal batteries are fitted they should be replaced with the recommended
type and be installed with the correct polarity, to avoid possible damage to the
equipment.
4.4. Insulation and dielectric strength testing
Insulation testing may leave capacitors charged up to a hazardous voltage. At the
end of each part of the test, the voltage should be gradually reduced to zero, to
discharge capacitors, before the test leads are disconnected.
4.5. Insertion of modules and pcb cards
These must not be inserted into or withdrawn from equipment whilst it is energised,
since this may result in damage.
4.6. Fibre optic communication
Where fibre optic communication devices are fitted, these should not be viewed
directly. Optical power meters should be used to determine the operation or signal
level of the device.
Page 7/8
5. DECOMMISSIONING AND DISPOSAL

Decommissioning: The auxiliary supply circuit in the relay may include capacitors
across the supply or to earth. To avoid electric shock or
energy hazards, after completely isolating the supplies to the
relay (both poles of any do supply), the capacitors should be
safely discharged via the external terminals prior to
decommissioning.
Disposal: It is recommended that incineration and disposal to water
courses is avoided. The product should be disposed of in a
safe manner. Any products containing batteries should have
them removed before disposal, taking precautions to avoid
short circuits. Particular regulations within the country of
operation, may apply to the disposal of lithium batteries.
6. TECHNICAL SPECIFICATIONS
Protective fuse rating
The recommended maximum rating of the external protective fuse for this equipment
is 16A, Red Spot type or equivalent, unless otherwise stated in the technical data
section of the product documentation.
Insulation class: IEC 601010-1: 1990/A2: 1995 This equipment requires a

Class I protective (safety) earth
EN 61010-1: 1993/A2: 1995 connection to ensure user
Class I safety.
Installation IEC 601010-1: 1990/A2: 1995 Distribution level, fixed
Category Category III installation. Equipment in this
(Overvoltage): EN 61010-1: 1993/A2: 1995 category is qualification tested
Category III at 5kV peak, 1.2/50µs,
500Ω, 0.5J, between all
supply circuits and earth and
also between independent
circuits.
Environment: IEC 601010-1: 1990/A2: 1995 Compliance is demonstrated
Pollution degree 2 by reference to generic safety
EN 61010-1: 1993/A2: 1995 standards.
Pollution degree 2
Product safety: 73/23/EEC Compliance with the
European Commission Low
Voltage Directive.
EN 61010-1: 1993/A2: 1995 Compliance is demonstrated
EN 60950: 1992/A11: 1997 by reference to generic safety
standards.
Page 8/8
BLANK PAGE
Introduction P740/EN IT/D11
MiCOM P740
INTRODUCTION
P740/EN IT/D11 Introduction
MiCOM P740
MiCOM P740 Page 1/18
CONTENTS
1. INTRODUCTION TO MiCOM 3
2. INTRODUCTION TO MiCOM GUIDES 4
3. USER INTERFACES AND MENU STRUCTURE 6

3.1 Introduction to the relay 6
3.1.1 Front panel 6
3.1.2 Relay rear panel 7
3.2 Introduction to the user interfaces and settings options 10

3.3 Menu structure 11
3.3.1 Central Unit settings 12
3.3.2 Peripheral Units settings 12
3.4 Password protection 13

3.5 Relay configuration 13
3.6 Front panel user interface (keypad and LCD) 14
3.6.1 Default display and menu time-out 15
3.6.2 Menu navigation and setting browsing 15
3.6.3 Password entry 15
3.6.4 Reading and clearing of alarm messages and fault records 16
3.6.5 Setting changes 16
3.7 Front communication port user interface 17

Page 2/18 MiCOM P740

1. INTRODUCTION TO MiCOM
MiCOM is a comprehensive solution capable of meeting all electricity supply

requirements. It comprises a range of components, systems and services from
AREVA.
Central to the MiCOM concept is flexibility.
MiCOM provides the ability to define an application solution and, through extensive
communication capabilities, to integrate it with your power supply control system.
The components within MiCOM are:
• P range protection relays;
• C range control products;
• M range measurement products for accurate metering and monitoring;
• S range versatile PC support and substation control packages.
MiCOM products include extensive facilities for recording information on the state
and behaviour of the power system using disturbance and fault records. They can
also provide measurements of the system at regular intervals to a control centre
enabling remote monitoring and control to take place.
For up-to-date information on any MiCOM product, visit our website:
www.areva-td.com
2. INTRODUCTION TO MiCOM GUIDES
The guides provide a functional and technical description of the MiCOM protection
relay and a comprehensive set of instructions for the relay’s use and application.
The Technical Manual is composed as follows:
Technical Guide, includes information on the application of the relay and a technical
description of its features. It is mainly intended for protection engineers concerned
with the selection and application of the relay for the protection of the power system.
Operation Guide, contains information on the installation and commissioning of the
relay, and also a section on fault finding. This volume is intended for site engineers
who are responsible for the installation, commissioning and maintenance of the
relay.
The chapter content within the Technical Manual is summarised below:
Technical Guide
Handling of Electronic Equipment
Safety Section
P740/EN IT Introduction
A guide to the different user interfaces of the protection relay describing how to
start using the relay.
P740/EN AP Application Notes (includes a copy of publication P740/EN BR)
Comprehensive and detailed description of the features of the relay including
both the protection and non-protection element of the P740 scheme including
circuit breaker fail element. Description of the other functions such as event and
disturbance recording, fault location, programmable scheme logic and specific
topology. This chapter includes a description of the current transformer
requirements (saturation detection) and how to apply the settings to the relay.
P740/EN HW Hardware Description
Overview of the operation of the relay’s hardware. This chapter includes
information on the self-checking features and diagnostics of the relay.
P740/EN FT Functional Description
Overview of the operation of the relay’s software.
P740/EN TD Technical Data
Technical data including setting ranges, accuracy limits, recommended
operating conditions, ratings and performance data. Compliance with technical
standards is quoted where appropriate.
P740/EN IN Installation (includes a copy of publication P740/EN BR)

Recommendations on unpacking, handling, inspection and storage of the relay.
A guide to the mechanical and electrical installation of the relay is provided
incorporating earthing recommendations.
P740/EN CM Commissioning and Maintenance
Instructions on how to commission the relay, comprising checks on the
calibration and functionality of the relay. A general maintenance policy for the
relay is outlined.
P740/EN PR Problem Analysis:
P740/EN GC Configuration / Mapping:

Listing of all of the settings contained within the relay together with a brief
description of each.
P740/EN CO External Connection Diagrams
All external wiring connections to the relay.
P740/EN HI HMI/User Interface (menu content tables)
P740/EN VC Version compatibility
Hardware / Software Version History and Compatibility
Repair Form
3. USER INTERFACES AND MENU STRUCTURE
The settings and functions of the MiCOM protection relay can be accessed both from
the front panel keypad and LCD, and via the front and rear communication ports.
Information on each of these methods is given in this section to describe how to get
started using the relay.
3.1 Introduction to the relay
3.1.1 Front panel
The front panel of the relay is shown in Figure 1, with the hinged covers at the top
and bottom of the relay shown open. Extra physical protection for the front panel can
be provided by an optional transparent front cover. With the cover in place read only
access to the user interface is possible. Removal of the cover does not compromise
the environmental withstand capability of the product, but allows access to the relay
settings. When full access to the relay keypad is required, for editing the settings, the
transparent cover can be unclipped and removed when the top and bottom covers
are open. If the lower cover is secured with a wire seal, this will need to be removed.
Using the side flanges of the transparent cover, pull the bottom edge away from the
relay front panel until it is clear of the seal tab.
The cover can then be moved vertically down to release the two fixing lugs from their
recesses in the front panel.
Serial N° and I*, V Ratings Top cover
Zn 1/5 A 50/60 Hz
SER N o Vx V
DIAG N o Vn V
LCD
TRIP
Fixed ALARM
function
OUT OF SERVICE
LEDs
HEALTHY
User programable
= CLEAR function LEDs
= READ
= ENTER
Keypad
SK 1 SK 2
Bottom
cover
Battery compartment Front comms port Download/monitor port
P0103ENa
FIGURE 1: RELAY FRONT VIEW (example for MiCOM P742 – 40 TE)

The front panel of the relay includes the following, as indicated in Figure 1:
• a 16-character by 2-line alphanumeric liquid crystal display (LCD).
• a 7-key keypad comprising 4 arrow keys ( !, ", # and $ ),
an enter key ( %), a clear key ( & ), and a read key ( ' ).
• 12 LEDs; 4 fixed function LEDs on the left hand side of the front panel and 8
programmable function LEDs on the right hand side.
Under the top hinged cover:
• the relay serial number, and the relay’s current and voltage rating information*.
Under the bottom hinged cover:
• battery compartment to hold the 1/2 AA size battery which is used for memory
back-up for the real time clock, event, fault and disturbance records.
• a 9-pin female D-type front port for communication with a PC locally to the relay
(up to 15m distance) via an RS232 serial data connection.
• a 25-pin female D-type port providing internal signal monitoring and high speed
local downloading of software and language text via a parallel data connection.
The fixed function LEDs on the left hand side of the front panel are used to indicate
the following conditions:
Trip (Red) indicates that the relay has issued a trip signal. It is reset when the
associated fault record is cleared from the front display. (Alternatively the trip LED
can be configured to be self-resetting)*.
Alarm (Yellow) flashes to indicate that the relay has registered an alarm. This may be
triggered by a fault, event or maintenance record. The LED will flash until the alarms
have been accepted (read), after which the LED will change to constant illumination,
and will extinguish when the alarms have been cleared.
Out of service (Yellow) indicates that the relay’s protection is unavailable.
Healthy (Green) indicates that the relay is in correct working order, and should be on
at all times. It will be extinguished if the relay’s self-test facilities indicate that there is
an error with the relay’s hardware or software. The state of the healthy LED is
reflected by the watchdog contact at the back of the relay.
3.1.2 Relay rear panel
The rear panel of the relay is shown in Figure 2. All current and voltage signals,
digital logic input signals and output contacts are connected at the rear of the relay.
Also connected at the rear is the twisted pair wiring for the rear RS485
communication port, the IRIG-B time synchronising input and the optical fibre rear
communication port which are both optional.
A B C D E
F
1 2 3 19
2 2 2 2
1 1 1 1
4 4 4 4
3 4 5 6 20 3 3 3
6 6 6 6
5 5 5 5
8 8 8 8
7 8 9 21
7 7 7 7
10 10 10 10
9 9 9 9
12 12 12 12
10 11 12 22
11 11 11 11
14 14 14 14
13 13 13 13
16 16 16 16
13 14 15 23
15 15 15 15
18 18 18 18
17 17 17 17
16 17 18 24
ANALOG INPUT MODULE 8 LOGICAL OUTPUTS
16 LOGICAL INPUTS
POWER SUPPLY
COPROCESSOR BOARD
(Connexion to CU via optical fibre)
P3710ENa
Figure 2a: P742 - Relay rear view 40TE case
A B C D E F G H
I
1 2 3 19
2 2 2 2 2 2 2
1 1 1 1 1 1 1
4 4 4 4 4 4 4
4 5 6 20 3 3 3 3 3 3 3
6 6 6 6 6 6 6
5 5 5 5 5 5 5
8 8 8 8 8 8 8
7 8 9 21
7 7 7 7 7 7 7
10 10 10 10 10 10 10
9 9 9 9 9 9 9
12 12 12 12 12 12 12
10 11 12 22
11 11 11 11 11 11 11
14 14 14 14 14 14 14
13 13 13 13 13 13 13
16 16 16 16 16 16 16
13 14 15 23
15 15 15 15 15 15 15
18 18 18 18 18 18 18
17 17 17 17 17 17 17
16 17 18 24
COPROCESSOR BOARD
(connexion to CU via optic fibre)
24 LOGICAL INPUTS 21 LOGICAL OUTPUTS
ANALOG INPUT POWER SUPPLY

P3711ENa
Figure 2b: P743 - Relay rear view 60 TE

J K L
A B C D E F G H M N
2 2 2
1 1 1
4 4 4
TX TX TX TX TX TX TX TX 3 3 3 TX
6 6 6
IRIG-B
CH1 RX CH1 RX CH1 RX CH1 RX CH1 RX CH1 RX CH1 RX CH1 RX 5 5 5 CH1 RX
8 8 8
7 7 7
9 9 9
11 11 11
RX
13 13 13
16 16 16
CH3 RX CH3 RX CH3 RX CH3 RX CH3 RX CH3 RX CH3 RX CH3 RX
15 15 15
TX TX TX TX TX TX TX TX 18 18 18
17 17 17
1 TO 8 COMMUNICATION BOARDS
LOGICAL OUTPUT CONTACT BOARD
LOGICAL INPUT CONTACT BOARD
POWER SUPPLY MODULE
CO-PROCESSOR BOARD
OPTIONAL IRIG-B BOARD

P3712ENa
Figure 2c: P741 - Relay rear view 80 TE
Refer to the wiring diagram in ‘Connection Diagrams Chapter’ (P740/EN CO) for
complete connection details.
3.2 Introduction to the user interfaces and settings options
The relay has three user interfaces:

• the front panel user interface via the LCD and keypad.
• the front port which supports Courier communication.
The measurement information and relay settings which can be accessed from the
three interfaces are summarised in Table 1.
Keypad/ Courier
LCD
Display & modification of all settings • •
Digital I/O signal status • •
Display/extraction of measurements • •
Display/extraction of fault records • •
Extraction of disturbance records •
Programmable scheme logic settings •
Reset of fault & alarm records • •
Clear event & fault records • •
Time synchronisation •
Control commands • •
TABLE 1
3.3 Menu structure

The relay’s menu is arranged in a tabular structure. Each setting in the menu is
referred to as a cell, and each cell in the menu may be accessed by reference to a
row and column address. The settings are arranged so that each column contains
related settings, for example all of the disturbance recorder settings are contained
within the same column. As shown in Figure 3, the top row of each column contains
the heading which describes the settings contained within that column. Movement
between the columns of the menu can only be made at the column heading level. A
complete list of all of the menu settings is given in ‘Configuration / Mapping Chapter’
of the manual.
Column header
Up to 4 protection setting groups
System data View records Overcurrent Earth fault Overcurrent Earth fault Overcurrent Earth fault Overcurrent Earth fault
Column
data
settings
Control & support Group 1 Group 2 Group 3 Group 4 P0106ENa
FIGURE 3: Px40 SERIES - MENU STRUCTURE

The menu content tables for P740 are fully described in ‘HMI/User Interface Chapter’.
All of the settings in the menu fall into one of three categories: protection settings,
disturbance recorder settings, or control and support (C&S) settings. One of two
different methods is used to change a setting depending on which category the
setting falls into. Control and support settings are stored and used by the relay
immediately after they are entered. For either protection settings or disturbance
recorder settings, the relay stores the new setting values in a temporary ‘scratchpad’.
It activates all the new settings together, but only after it has been confirmed that the
new settings are to be adopted. This technique is employed to provide extra security,
and so that several setting changes that are made within a group of protection
settings will all take effect at the same time.
3.3.1 Central Unit settings

The central Unit settings include the following items:
• system data
• view records
• measurements (1 & 2)
• topology
• PU configuration & status
• date & time
• configuration
• record control
• disturbance recorder
• measurement setup
• commission tests
• opto setup
• protection element settings*
• busbar element
• input labels
• output labels
3.3.2 Peripheral Units settings

The central Unit settings include the following items:
• system data
• view records
• measurements
• topology
• CB condition
• CB control
• date & time
• configuration
• CT & VT ratios
• record control
• disturbance recorder
• measurement setup
• commission tests
• CB monitor
• opto setup
• protection element settings*
• busbar element
• backup phase O/C
• backup earth O/C
• CB fail
• supervision
• input labels
• output labels
* There are four groups of protection settings, with each group containing the same
setting cells. One group of protection settings is selected as the active group, and is
used by the protection elements.
3.4 Password protection
The menu structure contains three levels of access. The level of access that is enabled
determines which of the relay’s settings can be changed and is
controlled by entry of two different passwords. The levels of access are summarised
in Table 2.
Access level Operations enabled

Level 0 No password required Read access to all settings, alarms, event
records and fault records
Level 1 Password 1 or 2 As level 0 plus:
Control commands, e.g.
circuit breaker open/close.
Reset of fault and alarm conditions.
Reset LEDs.
Clearing of event and fault records.
Level 2 Password 2 required
As level 1 plus: All other settings.
TABLE 2
Each of the two passwords are 4 characters of upper case text. The factory default for
both passwords is AAAA. Each password is user-changeable once it has been
correctly entered. Entry of the password is achieved either by a prompt when a
setting change is attempted, or by moving to the ‘Password’ cell in the ‘System data’
column of the menu. The level of access is independently enabled for each interface,
that is to say if level 2 access is enabled for the rear communication port, the front
panel access will remain at level 0 unless the relevant password is entered at the
front panel. The access level enabled by the password entry will time-out
independently for each interface after a period of inactivity and revert to the default
level. If the passwords are lost an emergency password can be supplied - contact
AREVA with the relay’s serial number. The current level of access enabled for an
interface can be determined by examining the 'Access level' cell in the 'System data'
column, the access level for the front panel User Interface (UI), can also be found as
one of the default display options.
The relay is supplied with a default access level of 2, such that no password is
required to change any of the relay settings. It is also possible to set the default menu
access level to either level 0 or level1, preventing write access to the relay settings
without the correct password. The default menu access level is set in the ‘Password
control’ cell which is found in the ‘System data’ column of the menu (note that this
setting can only be changed when level 2 access is enabled).
3.5 Relay configuration
The relay is a multi-function device which supports numerous different protection,

control and communication features. In order to simplify the setting of the relay,
there is a configuration settings column which can be used to enable or disable
many of the functions of the relay. The settings associated with any function that is
disabled are made invisible, i.e. they are not shown in the menu. To disable a
function change the relevant cell in the ‘Configuration’ column from ‘Enabled’ to
‘Disabled’.
The configuration column controls which of the four protection settings groups is
selected as active through the ‘Active settings’ cell. A protection setting group can
also be disabled in the configuration column, provided it is not the present active
group. Similarly, a disabled setting group cannot be set as the active group.
The column also allows all of the setting values in one group of protection settings to
be copied to another group.
To do this firstly set the ‘Copy from’ cell to the protection setting group to be copied,
then set the ‘Copy to’ cell to the protection group where the copy is to be placed. The
copied settings are initially placed in the temporary scratchpad, and will only be used
by the relay following confirmation.
To restore the default values to the settings in any protection settings group, set the
‘Restore defaults’ cell to the relevant group number. Alternatively it is possible to set
the ‘Restore defaults’ cell to ‘All settings’ to restore the default values to all of the
relay’s settings, not just the protection groups’ settings. The default settings will
initially be placed in the scratchpad and will only be used by the relay after they have
been confirmed. Note that restoring defaults to all settings includes the rear
communication port settings, which may result in communication via the rear port
being disrupted if the new (default) settings do not match those of the master station.
3.6 Front panel user interface (keypad and LCD)
When the keypad is exposed it provides full access to the menu options of the relay,
with the information displayed on the LCD.
The !, ", # and $ keys which are used for menu navigation and setting value
changes include an auto-repeat function that comes into operation if any of these
keys are held continually pressed. This can be used to speed up both setting value
changes and menu navigation; the longer the key is held depressed, the faster the
rate of change or movement becomes.
System Other default displays

3-phase voltage
frequency
Alarm messages
Date and time

C
C
Column 1 Column 2 Column n

System data View records Group 4
Other column headings Overcurrent
Data 1.1 Data 2.1 Data n.1

Language Last record
C I>1 function
Note:C key will return

The
to column header
Data 1.2 Data 2.2 from any menu cell Data n.2
Password Time and date I>1 directional
Other setting Other setting Other setting

cells in cells in cells in
column 1 column 2 column n
Data 1.n Data 2.n Data n.n

Password
level 2
C - A voltage I> char angle
P0105ENa
FIGURE 4: Px40 SERIES - FRONT PANEL USER INTERFACE

3.6.1 Default display and menu time-out
The front panel menu has a selectable default display. The relay will time-out and
return to the default display and turn the LCD backlight off after 15 minutes of
keypad inactivity. If this happens any setting changes which have not been confirmed
will be lost and the original setting values maintained.
The contents of the default display can be selected from the following options:
3-phase and neutral current, 3-phase voltage, power, system frequency, date and
time, relay description, or a user-defined plant reference*. The default display is
selected with the ‘Default display’ cell of the ‘Measure’t setup’ column. Also, from the
default display the different default display options can be scrolled through using the
!and " keys. However the menu selected default display will be restored following
the menu time-out elapsing. Whenever there is an uncleared alarm present in the
relay (e.g. fault record, protection alarm, control alarm etc.) the default display will
be replaced by:
Alarms/Faults
Present
Entry to the menu structure of the relay is made from the default display and is not
affected if the display is showing the ‘Alarms/Faults present’ message.
3.6.2 Menu navigation and setting browsing
The menu can be browsed using the four arrow keys, following the structure shown
in Figure 4. Thus, starting at the default display the # key will display the first
column heading. To select the required column heading use the !and " keys. The
setting data contained in the column can then be viewed by using the
$ and # keys. It is possible to return to the column header either by holding the
[up arrow symbol] key down or by a single press of the clear key &. It is only
possible to move across columns at the column heading level. To return to the
default display press the # key or the clear key & from any of the column
headings. It is not possible to go straight to the default display from within one of the
column cells using the auto-repeat facility of the # key, as the auto-repeat will stop
at the column heading. To move to the default display, the # key must be released
and pressed again.
3.6.3 Password entry
When entry of a password is required the following prompt will appear:
Enter password
**** Level 1
Note: The password required to edit the setting is the prompt as shown above
A flashing cursor will indicate which character field of the password may be
changed. Press the # and $ keys to vary each character between A and Z.
To move between the character fields of the password, use the ( and " keys.
The password is confirmed by pressing the enter key %. The display will revert to
‘Enter Password’ if an incorrect password is entered. At this point a message will be
displayed indicating whether a correct password has been entered and if so what
level of access has been unlocked. If this level is sufficient to edit the selected setting
then the display will return to the setting page to allow the edit to continue. If the
correct level of password has not been entered then the password prompt page will
be returned to. To escape from this prompt press the clear key &. Alternatively, the
password can be entered using the ‘Password’ cell of the ‘System data’ column.
For the front panel user interface the password protected access will revert to the
default access level after a keypad inactivity time-out of 15 minutes. It is possible to
manually reset the password protection to the default level by moving to the
‘Password’ menu cell in the ‘System data’ column and pressing the clear key &
instead of entering a password.
3.6.4 Reading and clearing of alarm messages and fault records
The presence of one or more alarm messages will be indicated by the default display
and by the yellow alarm LED flashing. The alarm messages can either be self-
resetting or latched, in which case they must be cleared manually. To view the alarm
messages press the read key '. When all alarms have been viewed, but not
cleared, the alarm LED will change from flashing to constant illumination and the
latest fault record will be displayed (if there is one). To scroll through the pages of
this use the ' key. When all pages of the fault record have been viewed, the
following prompt will appear:
Press clear to
reset alarms
To clear all alarm messages press &; to return to the alarms/faults present display
and leave the alarms uncleared, press '. Depending on the password
configuration settings, it may be necessary to enter a password before the alarm
messages can be cleared (see section on password entry). When the alarms have
been cleared the yellow alarm LED will extinguish, as will the red trip LED if it was
illuminated following a trip.
Alternatively it is possible to accelerate the procedure, once the alarm viewer has
been entered using the ' key, the & key can be pressed, this will move the display
straight to the fault record. Pressing & again will move straight to the alarm reset
prompt where pressing & once more will clear all alarms.
3.6.5 Setting changes
To change the value of a setting, first navigate the menu to display the relevant cell.
To change the cell value press the enter key %, which will bring up a flashing cursor
on the LCD to indicate that the value can be changed. This will only happen if the
appropriate password has been entered, otherwise the prompt to enter a password
will appear. The setting value can then be changed by pressing the or " keys. If the
setting to be changed is a binary value or a text string, the required bit or character
to be changed must first be selected using the !and " keys. When the desired new
value has been reached it is confirmed as the new setting value by pressing %.
Alternatively, the new value will be discarded either if the clear button & is pressed
or if the menu time-out occurs.
For protection group settings and disturbance recorder settings, the changes must be
confirmed before they are used by the relay. To do this, when all required changes
have been entered, return to the column heading level and press the key. Prior to
returning to the default display the following prompt will be given:
Update settings?
Enter or clear
Pressing % will result in the new settings being adopted, pressing & will cause the
relay to discard the newly entered values. It should be noted that, the setting values
will also be discarded if the menu time out occurs before the setting changes have
been confirmed. Control and support settings will be updated immediately after they
are entered, without ‘Update settings?’ prompt.
3.7 Front communication port user interface
The front communication port is provided by a 9-pin female D-type connector

located under the bottom hinged cover. It provides RS232 serial data communication
and is intended for use with a PC locally to the relay (up to 15m distance) as shown
in Figure 5. This port supports the Courier communication protocol only. Courier is
the communication language developed by AREVA to allow communication with its
range of protection relays. The front port is particularly designed for use with the
relay settings program MiCOM S1 which is a Windows 95/NT based software
package.
MiCOM relay
Laptop
SK 2
25 pin
download/monitor port
9 pin
Battery front comms port Serial communication port
(COM 1 or COM 2)
Serial data connector
(up to 15m) P0107ENb
FIGURE 5: FRONT PORT CONNECTION
The relay is a Data Communication Equipment (DCE) device. Thus the pin
connections of the relay’s 9-pin front port are as follows:
Pin no. 2 Tx Transmit data
Pin no. 3 Rx Receive data
Pin no. 5 0V Zero volts common
None of the other pins are connected in the relay. The relay should be connected to
the serial port of a PC, usually called COM1 or COM2. PCs are normally Data
Terminal Equipment (DTE) devices which have a serial port pin connection as below
(if in doubt check your PC manual):
25 Way 9 Way
Pin no. 3 2 Rx Receive data
Pin no. 2 3 Tx Transmit data
Pin no. 7 5 0V Zero volts common
For successful data communication, the Tx pin on the relay must be connected to the
Rx pin on the PC, and the Rx pin on the relay must be connected to the Tx pin on the
PC, as shown in Figure 6. Therefore, providing that the PC is a DTE with pin
connections as given above, a ‘straight through’ serial connector is required, i.e. one
that connects pin 2 to pin 2, pin 3 to pin 3, and pin 5 to pin 5. Note that a common
cause of difficulty with serial data communication is connecting Tx to Tx and Rx to Rx.
This could happen if a ‘cross-over’ serial connector is used, i.e. one that connects pin
2 to pin 3, and pin 3 to pin 2, or if the PC has the same pin configuration as the
relay.
PC
MiCOM relay
DCE Serial data connector DTE

Pin 2 Tx Pin 2 Tx
Pin 3 Rx Pin 3 Rx
Pin 5 0V Pin 5 0V
Note: PC connection shown assuming 9 Way serial port

P0108ENb
FIGURE 6: PC – RELAY SIGNAL CONNECTION
Having made the physical connection from the relay to the PC, the PC’s
communication settings must be configured to match those of the relay. The relay’s
communication settings for the front port are fixed as shown in the table below:
Protocol Courier
Baud rate 19,200 bits/s
Courier address 1
Message format 11 bit - 1 start bit, 8 data bits, 1 parity bit
(even parity), 1 stop bit
The inactivity timer for the front port is set at 15 minutes. This controls how long the
relay will maintain its level of password access on the front port. If no messages are
received on the front port for 15 minutes then any password access level that has
been enabled will be revoked.
Hardware Description P740/EN HW/D11
MiCOM P740
HARDWARE DESCRIPTION
P740/EN HW/D11 Hardware Description
MiCOM P740
CONTENTS
1. HARDWARE OVERVIEW 5
1.1 Power supply module 5
1.2 Main board 5
1.3 Co-processor board 5
1.4 Internal Communication board 5
1.5 Input module 5
1.6 Input and output boards 6
1.7 IRIG-B board 6
2. HARDWARE MODULES 8
2.1 Main board 8
2.2 Co-processor board 8
2.3 Communication board 9
2.4 Internal communication buses 9
2.5 Input module (P742 and P743 only) 10
2.5.1 Transformer board 11
2.5.2 Input board 11
2.5.3 Universal opto isolated logic inputs 11
2.6 Power supply module (including output relays) 12
2.6.1 Power supply board (including RS485 communication interface (K Bus courier)) 12
2.6.2 Output relay board 13
2.6.3 Auxiliary power supply 13
2.7 IRIG-B board (P741 only) 13
2.8 Mechanical layout 13

1. HARDWARE OVERVIEW
The relay hardware is based on a modular design whereby the relay is made up of
several modules which are drawn from a standard range. Some modules are
essential while others are optional depending on the user’s requirements.
The different modules that can be present in the relay are as follows:
1.1 Power supply module

The power supply module provides a power supply to all of the other modules in the
relay, at three different voltage levels. The power supply board also provides the
RS485 electrical connection (K-bus courier) for the rear communication port. This
communication is used on P741, never on P742 or P743.
On a second board the power supply module contains :
• relays which provide the output contacts (P742 and P743),
• an auxiliary power supply (P741).
1.2 Main board

The main board performs some functions for the relay (fixed and programmable
scheme logic…) and controls the operation of modules which are on its
interconnection bus within the relay. The main board also contains and controls the
user interfaces (LCD, LEDs, keypad and communication interfaces).
1.3 Co-processor board

In P742 and P743, the co-processor board controls the operation of I/O modules
within the relay and manages the communication with the P741 relay.
In P741, the co-processor board controls the communication boards and manages
the communication with others P741 of the system (if present).
1.4 Internal Communication board

Only present within P741 relay.
The communication board manages the communication with the P742 and P743
relays.
1.5 Input module

The input module is only present in P742 and P743 relays. The input module
converts the information contained in the analogue and digital input signals into a
format suitable for the co-processor board. The standard input module consists of
two boards:
• a transformer board to provide electrical isolation
• a main input board which provides analogue to digital conversion and the
isolated digital inputs.
1.6 Input and output boards
P741 P742 P743

Opto-inputs 8 x UNI(1) 16 x UNI(1) 24 x UNI(1)
Relay outputs 6 n/o and 2 c/o 6 n/o and 2 c/o 15 n/o and 6 c/o
(1) Universal voltage range opto inputs n/o – normally open
c/o – change over
1.7 IRIG-B board

This board, which is optional, can be used where an IRIG-B signal is available to
provide an accurate time reference for the relay. IRIG-B board can only be used in
P741 relay and is controlled by the main board.
All modules are connected by a parallel data and address bus which allows the
processor board to send and receive information to and from the other modules as
required. There is also a separate serial data bus for conveying sample data from the
input module to the coprocessor. Following figures show the modules of the relay and
the flow of information between them. There are two independant buses. Through the
first bus, the main board controls the coprocessor board and the IRIG-B board
(optional, only in P741). Through the second bus, the coprocessor board controls the
input/output boards and input module in P742 and P743 relays, it controls the
communication boards in P741 relay. So the coprocessor board is controlled by the
first bus and controls the second bus. Functionnaly, electrically, mechanically both
interconnection buses are very similar.
Relay n Communication
Power Boards
Supply (n=1 to 8)
Universal
Relay board Opto
Auxiliary
Board
Power Supply
(for Comm. Boards)
Interconnexion buses
Coprocessor IRIG-B
Board Board
(Optional)
TRIP
ALARM
OUT OF SERVICE
HEALTHY
= CLEAR
= READ
= ENTER
Main board
P3701ENa
FIGURE 1: MiCOM P741 Architecture

P743 Only
Power Universal
Relay Input
Supply Opto
Board Module
P743 Only
P743 Only
Board
P743 Only
Universal Universal
Relay Relay Opto Opto
Board Board Board Board
Coprocessor
Board
TRIP
ALARM
OUT OF SERVICE
HEALTHY
= CLEAR
= READ
= ENTER
Main Board
P3702ENa
FIGURE 2: MiCOM P742 & P743 Architecture

2. HARDWARE MODULES
The relay is based on a modular hardware design where each module performs a
separate function within the relay operation. This section describes the functional
operation of the various hardware modules.
2.1 Main board

The main board is based around a TMS320C32 floating point, 32-bit digital signal
processor (DSP) operating at a clock frequency of 20MHz. The processor board is
located directly behind the relay’s front panel which allows the LCD and LEDs to be
mounted on the processor board along with the front panel communication ports.
These comprise the 9-pin D-connector for RS232 serial communications (e.g. using
MiCOM S1 and Courier communications) and the 25-pin D-connector relay test port
for parallel communication.
All serial communication is handled using a two-channel 85C30 serial
communications controller (SCC).
The memory provided on the main processor board is split into two categories,
volatile and non-volatile:
• The volatile memory is fast access (zero wait state) SRAM which is used for
the storage and execution of the processor software, and data storage as
required during the processor’s calculations.
• The non-volatile memory is sub-divided into 3 groups: 2MB of flash memory
for non-volatile storage of software code and text together with default
settings, 256kB of battery backed-up SRAM for the storage of disturbance,
event, fault and maintenance record data and 32kB of E2PROM memory for
the storage of configuration data, including the present setting values.
2.2 Co-processor board

The co-processor board is based around a TMS320VC5402 , 16-bit digital signal
processor (DSP) operating at a clock frequency of 100MHz.
The feature of the co-processor board are :
• 128 K * 16 bits high speed memory for external code execution.

• 128 K * 16 bits high speed memory for data storage.
• Interface with first interconnection bus from main board.
• 4 K * 16 bits double access memory for communication with main board.
• Interface with second interconnection bus towards peripheral boards.
• Serial communication interface on optical fiber with 4 full duplex channels.
The communication uses a synchronous protocole with a date rate of 2.5
Mbit/s.
On the co-processor board only 2 of the 4 optical channels are provided.
On board DC-DC converter which gives 3.3V chip power supply from the
interconnection bus 22V rail.
After power on, the main board loads the software in coprocessor board via double
access memory. When software starts, the microprocessor configures the board. After
this, optical communication can begin.
In P741 relay, coprocessor board controls 1 opto board, 1 relay board and up to 8
communication boards via its own interconnection bus.
In P742 and P743 relays, coprocessor board controls opto boards and relay boards
via its own interconnection bus. Coprocessor board provides the sample
synchronisation to input module and receives the samples from input module.
2.3 Communication board

The communication board looks like the coprocessor board. The Differences are :
• Four duplex optical channels are provided.
• The second interconnection bus is not provided. The communication board
controls no board.
This board is only used within P741 relay. It performs the communication with the
P742 and P743 relays.
Up to 8 communication boards can be interfaced within P741 relay. So up to 32

P742 or P743 relays can be interfaced from a P741 relay.
2.4 Internal communication buses

The relay has two internal interconnection buses :
• The first is controlled by the main board. Via its interconnection bus the main
board controls the coprocessor board (P741, P742 & P743) and the IRIG-B
board (P741 only).
• The second is controlled by the coprocesseur board. Via its interconnection
bus the coprocessor board controls relay boards (P741, P742 & P743), opto
boards (P741, P742 & P743), input module (P742 & P743), communication
boards (P741).
These two interconnection buses are very similar. Both are based on a 64-way ribbon
cable. The main part of the buses is a parallel link with 6 address lines for board
selection, 16 data lines and control lines. On the main controlled bus, main board
drive address and control lines. On the coprocessor controlled bus, coprocessor
board drive address and control lines.
Other parts of the buses are :

• the sample serial link from input module to coprocessor board which loads
analogue channel samples.
• power supply which are directly wired between the two interconnection
buses.
• serial lines for rear RS485 communication which are also directly wired
between the two interconnection buses. So in any way main board keeps
control of the rear RS485 communication.
2.5 Input module (P742 and P743 only)

The input module provides the interface between the coprocessor board and the
analogue and digital signals coming into the relay. The input module consist of two
PCBs; the main input board and a transformer board.
The P742 and P743 provide four current inputs (3 phases and neutral).
P741 relay don’t use this board.
Up to 4 current inputs
Up to 4
CT CT
Diffn Up to 4 Diffn
to to
single single
Low Up to 4 Low
pass pass
filter filter
16:1
Multiplexer
Calibration
Trigger from
E2 PROM
Buffer processor board
16-bit
Sample
ADC control
8 digital inputs
Noise Filter
Threshold
Serial Bus Interface
interface
Serial sample Parallel bus

data bus
FIGURE 3: Main Input Board

2.5.1 Transformer board

The transformer board holds up to four current transformers (CTs). The current inputs
will accept either 1A or 5A nominal current (menu and wiring options).
The transformers are used to step-down the currents to levels appropriate to the
relay’s electronic circuitry and to provide effective isolation between the relay and the
power system. The connection arrangements of the current transformer secondary
provide differential input signals to the main input board to reduce noise.
2.5.2 Input board

The main input board is shown as a block diagram in Figure 3. It provides the
circuitry for the digital input signals and the analogue-to-digital conversion for the
analogue signals. Hence it takes the differential analogue signals from the CTs on the
transformer board, converts these to digital samples and transmits the samples to the
coprocessor board via the sample serial data bus. On the input board the analogue
signals are passed through an anti-alias filter before being multiplexed into a single
analogue-to-digital converter chip. The A – D converter provides 16-bit resolution
and a serial data stream output. The digital input signals are opto isolated on this
board to prevent excessive voltages on these inputs causing damage to the relay's
internal circuitry.
2.5.3 Universal opto isolated logic inputs

The P741, P742 and P743 relays are fitted with universal opto isolated logic inputs
that can be programmed for the nominal battery voltage of the circuit of which they
are a part. i.e. thereby allowing different voltages for different circuits e.g. signalling,
tripping. They nominally provide a Logic 1 or “ON” value for Voltages ≥80% of the
set voltage and a Logic 0 or “OFF” value for the voltages ≤60% of the set voltage.
This lower value eliminates fleeting pickups that may occur during a battery earth
fault, when stray capacitance may present up to 50% of battery voltage across an
input. Each input also has selectable filtering which can be utilised. This allows use of
a pre-set filter of ½ cycle which renders the input immune to induced noise on the
wiring: although this method is secure it can be slow, particularly for inter-tripping.
This can be improved by switching off the ½ cycle filter in which case one of the
following methods to reduce ac noise should be considered. The first method is to use
double pole switching on the input, the second is to use screened twisted cable on the
input circuit.
2.6 Power supply module (including output relays)

The power supply module contains two PCBs, one for the power supply unit itself and
the other for the output relays (P742 and P743) or for an auxiliary power supply
(P741). The power supply board also contains the input and output hardware for the
rear communication port which provides an RS485 communication interface (K-Bus
Courier).
2.6.1 Power supply board (including RS485 communication interface (K Bus courier))
One of three different configurations of the power supply board can be fitted to the
relay. This will be specified at the time of order and depends on the nature of the
supply voltage that will be connected to the relay. The three options are shown in
table 1 below.
Nominal dc range Nominal ac range

24 – 48V dc only
48 – 110V 30 – 100V rms
110 – 250V 100 – 240V rms
Table 1: Power supply options
The output from all versions of the power supply module are used to provide isolated
power supply rails to all of the other modules within the relay. Three voltage levels
are used within the relay, 5.1V for all of the digital circuits, 16V for the analogue
electronics, e.g. on the input board, and 22V for driving the output relay coils and for
coprocessor and communication boards 3.3V power supply (through on board DC-
DC converter).
All power supply voltages including the 0V ground line are distributed around the
relay via the 64-way ribbon cables. One further voltage level is provided by the
power supply board which is the field voltage of 48V. This is brought out to terminals
on the back of the relay so that it can be used to drive the optically isolated digital
inputs.
The two other functions provided by the power supply board are the RS485
communications interface and the watchdog contacts for the relay. The RS485
interface is used with the relay’s rear communication port to provide communication
using K Bus Courier. The RS485 hardware supports half-duplex communication and
provides optical isolation of the serial data being transmitted and received.
All internal communication of data from the power supply board is conducted via the
output relay board which is connected to the parallel bus.
The watchdog facility provides two output relay contacts, one normally open and one
normally closed which are driven by the coprocessor board. These are provided to
give an indication that the relay is in a healthy state.
2.6.2 Output relay board

The output relay board holds eight relays, six with normally open contacts and two
with changeover contacts. The relays are driven from the 22V power supply line. The
relays’ state is written to or read from using the parallel data bus.
In model P743, additional output contacts may be provided, through the use of up to
two extra relay boards. In this case only 5 normally open contacts are used per
board.
2.6.3 Auxiliary power supply

In P741 the power supply module contains main power supply and an auxiliary
power supply. The auxiliary power supply adds power on 22 V rail for the up to 8
communication boards within the relay.
The three input voltage options are the same as for main supply. The relay board is
provided as an alone board.
2.7 IRIG-B board (P741 only)

The IRIG-B board is an order option which can be fitted to provide an accurate timing
reference for the relay. This can be used wherever an IRIG-B signal is available. The
IRIG-B signal is connected to the board via a BNC connector on the back of the relay.
The timing information is used to synchronise the relay’s internal real-time clock to an
accuracy of 1ms. The internal clock is then used for the time tagging of the event,
fault maintenance and disturbance records.
2.8 Mechanical layout

The case materials of the relay are constructed from pre-finished steel which has a
conductive covering of aluminium and zinc. This provides good earthing at all joints
giving a low impedance path to earth which is essential for performance in the
presence of external noise. The boards and modules use a multi-point earthing
strategy to improve the immunity to external noise and minimise the effect of circuit
noise. Ground planes are used on boards to reduce impedance paths and spring
clips are used to ground the module metalwork.
Heavy duty terminal blocks are used at the rear of the relay for the current and
voltage signal connections. Medium duty terminal blocks are used for the digital logic
input signals, the output relay contacts, the power supply and the rear communication
port. ST connectors are used for the optical communication. A BNC connector is used
for the optional IRIG-B signal. 9-pin and 25-pin female D-connectors are used at the
front of the relay for data communication.
Inside the relay the PCBs plug into the connector blocks at the rear, and can be
removed from the front of the relay only. The connector blocks to the relay’s CT
inputs are provided with internal shorting links inside the relay which will
automatically short the current transformer circuits before they are broken when the
board is removed.
The front panel consists of a membrane keypad with tactile dome keys, an LCD and
12 LEDs mounted on an aluminium backing plate.
Functional Description P740/EN FT/D11
MiCOM P740
FUNCTIONAL DESCRIPTION
P740/EN FT/D11 FunctionalDescription
MiCOM P740
CONTENTS
1. SOFTWARE OVERVIEW 3
1.1 Real-time operating system 4
1.2 System services software 4
1.3 Platform software 4
1.4 Communication software 4
1.5 Protection & control software 4
2. RELAY SOFTWARE 5
2.1 Operating system 5
2.2 System services software 5
2.3 Communication software 5
2.4 Platform software 7
2.4.1 Record logging 7
2.4.2 Settings database 7
2.4.3 Database interface 7
2.5 Protection and control software 8
2.5.1 Overview - protection and control distribution 8
2.5.2 Topology software 8
2.5.3 Signal processing 8
2.5.4 Programmable scheme logic 9
2.5.5 Event and Fault Recording 10
2.5.6 Disturbance recorder 10
P740/EN FT/D11 Functional Description

1. SOFTWARE OVERVIEW
The busbar protection is a distributed system composed of two different software: the
first one is used in central unit (P741) and the second one in peripheral units (P742 &
P743). The whole of functions implemented in P740 relays can be split into five
elements:
1. the operating system,

2. the system services software,
3. the platform software,
4. the communication software,
5. the protection and control software.
Protection & Control software
Disturbance Measurements & event,

recorder task fault & disturbance records
Programmable & Protection

fixed scheme logic algorithms
Platform software
Signal processing & Topology Event, Fault,

saturation detection algorithms Disturbance,
Settings
Maintenance
database
record logging.
Protection &
control settings
Data exchanged Local & remote

Front panel interface
between CU & PU: Sample data, communications
(LCD & Keypad)
Logic inputs & interface - Courier
Curent samples Outputs contacts
& signal quality ;
Trip order ;
Internal courrier com. ;
Control of interfaces to keypad,
Date & time.
LCD, LEDs, Front & Rear comm. ports
Communication software System services software
Relay hardware P3704ENa
FIGURE 1: Software Overview

1.1 Real-time operating system

As explain in the hardware overview, each relay contains one main board and one
coprocessor board. These two boards use two different operating system:
• For main board software: a real time operating system is used to provide a
framework for the different parts of the relay’s software to operate within.
To this end the software is split into tasks. The real-time operating system is
responsible for scheduling the processing of these tasks such that they are
carried out in the time available and in the desired order of priority.
• For coprocessor board software: a sequencer manages all the functions

implemented on the coprocessor board. Each function is executed at fixed
frequency; consequently the CPU load of the coprocessor is fixed and
independent of the network’s frequency.
1.2 System services software
The system services software provides the low-level control of the relay hardware. For
example, the system services software controls the boot of the relay’s software from
the non-volatile flash EPROM memory at power-on, and provides driver software for
the user interface via the LCD and keypad, and via the serial communication ports.
The system services software provides an interface layer between the control of the
relay’s hardware and the rest of the relay software.
1.3 Platform software
The platform software deals with the management of the relay settings, the user
interfaces and logging of event, alarm, fault and maintenance records. All of the
relay settings are stored in a database within the relay which provides direct
compatibility with Courier communications.
The platform software notifies the protection & control software of all setting changes
and logs data as specified by the protection & control software.
1.4 Communication software
The communication software manages optical fibre communication between the

central unit and the peripheral units. This includes the control of data exchanged
transmitted and the synchronisation of peripheral units. With this object, the
communication software interfaces with the sequencer used in coprocessors boards.
1.5 Protection & control software
The protection and control software performs the calculations for all of the protection
algorithms for all the protections algorithms of the P740 relays. This includes digital
signal processing such as saturation detection, Fourier filtering and ancillary tasks
such as the measurements. The protection & control software interfaces with the
platform software for settings changes and logging of records, and with the system
services software for acquisition of sample data and access to output relays and
digital opto-isolated inputs.
2. RELAY SOFTWARE
The relay software was introduced in the overview of the relay at the start of this
chapter. The software can be considered to be made up of five sections:
• the operating system
• the system services software
• the communication software
• the platform software
• the protection & control software
This section describes in detail the latter two of these, the platform software and the
protection & control software, which between them control the functional behaviour of
the relay. Figure 2 shows the structure of the relay software.
2.1 Operating system
• Real-time operating system for main board: the real-time operating system is used to
schedule the processing of the tasks to ensure that they are processed in the time
available and in the desired order of priority. The operating system is also
responsible in part for controlling the communication between the software tasks
through the use of operating system messages.
• Sequencer for coprocessor and communication boards: the sequencer executed all
functions at fixed frequency depending of the priority of the functions. The highest
frequency, 2400Hz, is the frequency of sample acquisition, signal processing and trip
decision. To start analog acquisition at the same time on all peripheral units, the
sequencers of all peripheral units and central unit are synchronized and control the
analog acquisition interfacing with system services software.
2.2 System services software

As shown in figure 3, the system services software provides the interface between the
relay’s hardware and the higher-level functionality of the platform software and the
protection & control software. For example, the system services software provides
drivers for items such as the LCD display, the keypad and the remote communication
ports, and controls the boot of the processor and downloading of the processor code
into SRAM from non-volatile flash EPROM at power up.
2.3 Communication software

In accordance with sequencer used in coprocessor board, the communication
software sends frames at fixed frequency equal to 2400Hz. Likewise the contents of
the frames is independent of the frequency and of the status of the protections. The
frames are split in fixed parts according to the priority of each application. For
example trip order and current sample are respectively transmitted at 2400Hz and
1200Hz whereas the internal courier communication or date & time are exchange at
low frequency.
PERIPHERAL UNIT
Coprocessor board Main board
Local and global Fixed scheme Programmable Overcurrent

measurements logic scheme logic protection
Saturation detection Event & fault Logic of breaker

algorithm Local Topology
recording failure
Signal processing & local confirmation Disturbance recorder

threshold for busbar protection of peripheral unit
PERIPHERAL UNIT
PERIPHERAL UNIT
Optical PERIPHERAL UNIT

Fibre
CENTRAL UNIT
Coprocessor & Main board
communications boards
Programmable Event & fault
Sum of current for busbar protection scheme logic recording
Fixed scheme Global Disturbance recorder

logic topology of central unit
P3705ENa
FIGURE 2: MiCOM P740 system overview

2.4 Platform software

The platform software has three main functions:
• to control the logging of records that are generated by the protection
software, including alarms and event, fault, and maintenance records.
• to store and maintain a database of all of the relay’s settings in non-volatile
memory.
• to provide the internal interface between the settings database and each of
the relay’s user interfaces, i.e. the front panel interface and the front and
rear communication ports, using Courier communication protocol.
2.4.1 Record logging

The logging function is provided to store all alarms, events, faults and maintenance
records. The records for all of these incidents are logged in battery backed-up SRAM
in order to provide a non-volatile log of what has happened. The relay maintains four
logs: one each for up to 32 alarms, 250 event records, 5 fault records and 5
maintenance records. The logs are maintained such that the oldest record is
overwritten with the newest record. The logging function can be initiated from the
protection software or the platform software is responsible for logging of a
maintenance record in the event of a relay failure. This includes errors that have been
detected by the platform software itself or error that are detected by either the system
services or the protection software function.
2.4.2 Settings database

The settings database contains all of the settings and data for the relay, including the
protection, disturbance recorder and control & support settings. The settings are
maintained in non-volatile E2 PROM memory. The platform software’s management
of the settings database includes the responsibility of ensuring that only one user
interface modifies the settings of the database at any one time. This feature is
employed to avoid conflict between different parts of the software during a setting
change. For changes to protection settings and disturbance recorder settings, the
platform software operates a ‘scratchpad’ in SRAM memory. This allows a number of
setting changes to be applied to the protection elements, disturbance recorder and
saved in the database in E2 PROM. (See also ‘Introduction Chapter’ on the user
interface). If a setting change affects the protection & control task, the database
advises it of the new values.
2.4.3 Database interface

The other function of the platform software is to implement the relay’s internal
interface between the database and each of the relay’s user interfaces. The database
of settings and measurements must be accessible from all of the relay’s user
interfaces to allow read and modify operations. The platform software presents the
data in the appropriate format for each user interface.
2.5 Protection and control software

The protection and control software is responsible for processing all of the protection
elements and measurement functions of the relay. To achieve this it has to
communicate with the system services software, the communication software and the
platform software as well as organize its own operations. The protection software has
the highest priority of any of the software tasks in the relay in order to provide the
fastest possible protection response.
2.5.1 Overview - protection and control distribution

The figure 2 shows the parts of AREVA software and their allocation on the different
boards of the peripheral and central units.
The P740 relays contained two global protections, busbar protection and circuit
breaker failure, and one local function, overcurrent protection. Overcurrent protection
is implemented on peripheral unit and is totally independent of the central unit. On
the contrary, busbar protection and circuit breaker failure are distributed between
central unit and peripheral units. Local functions such as saturation detection
algorithm, logic of circuit breaker failure and local confirmation threshold are
performed on each peripheral unit. Sum of current, logic of differential protection
and circuit breaker failure are processed on central unit.
2.5.2 Topology software

Topology algorithm determines dynamically the electric scheme of the substation
from the auxiliary contact of circuit breaker and isolators. The results of local topology
performed on peripheral unit are sending to central unit which determines global
topology of the substation. At the end of process, central unit know the node of
current and zone to trip according to the fault location.
2.5.3 Signal processing

The sampling frequency of analogue signal is fixed to 2400Hz apart from the electric
network frequency.
To ensure that the frequency is identical on each PU, analog acquisition is based on
interruption signal from communication software. Central unit send frames on optical
fibers in diffusion towards all peripheral units. So they received data at the same
instant, this reception signal starts the acquisition of analog signal.
The main signal processing algorithms are:

• Flux calculation and prediction algorithm to detect CT saturation
• Zero sequence supervision
• Detection of signal variation
• Local threshold to block busbar protection on external fault
All this information are transmitted to central unit with the sample of current, they
represent signal quality. The sum of current is processed in central unit each 1200Hz
but the signal processing is executed at 2400Hz on peripheral unit.
The protection and control calculates the Fourier components for the analogue
signals. The Fourier components are calculated using a one-cycle, 48-sample
Discrete Fourier Transform (DFT). The DFT is always calculated using the last cycle of
samples from the 2-cycle buffer, i.e. the most recent data is used. The DFT used in
this way extracts the power frequency fundamental component from the signal and
produces the magnitude and phase angle of the fundamental in rectangular
component format. The DFT provides an accurate measurement of the fundamental
frequency component, and effective filtering of harmonic frequencies and noise. This
performance is achieved in conjunction with the relay input module which provides
hardware anti-alias filtering to attenuate frequencies above the half sample rate. The
Fourier components of the input current signals are stored in memory so that they can
be accessed by all of the protection elements’ algorithms. The samples from the input
module are also used in an unprocessed form by the disturbance recorder for
waveform recording and to calculate true rms values of current.
2.5.4 Programmable scheme logic

The purpose of the programmable scheme logic (PSL) is to allow the relay user to
configure an individual protection scheme to suit their own particular application. This
is achieved through the use of programmable logic gates and delay timers.
The input to the PSL is any combination of the status of the digital input signals from
the opto-isolators on the input board, the outputs of the protection elements, e.g.
protection starts and trips, and the outputs of the fixed protection scheme logic. The
fixed scheme logic provides the relay’s standard protection schemes. The PSL itself
consists of software logic gates and timers. The logic gates can be programmed to
perform a range of different logic functions and can accept any number of inputs.
The timers are used either to create a programmable delay, and/or to condition the
logic outputs, e.g. to create a pulse of fixed duration on the output regardless of the
length of the pulse on the input. The outputs of the PSL are the LEDs on the front
panel of the relay and the output contacts at the rear.
The execution of the PSL logic is event driven; the logic is processed whenever any of
its inputs change, for example as a result of a change in one of the digital input
signals or a trip output from a protection element. Also, only the part of the PSL logic
that is affected by the particular input change that has occurred is processed. This
reduces the amount of processing time that is used by the PSL. The protection and
control software updates the logic delay timers and checks for a change in the PSL
input signals every time it runs.
This system provides flexibility for the user to create their own scheme logic design.
However, it also means that the PSL can be configured into a very complex system,
and because of this setting of the PSL is implemented through the PC support MiCOM
S1.
2.5.5 Event and Fault Recording

A change in any digital input signal or protection element output signal causes an
event record to be created. When this happens, the protection and control task sends
a message to the supervisor task to indicate that an event is available to be processed
and writes the event data to a fast buffer in SRAM which is controlled by the
supervisor task. When the supervisor task receives either an event or fault record
message, it instructs the platform software to create the appropriate log in battery
backed-up SRAM. The operation of the record logging to battery backed-up SRAM is
slower than the supervisor’s buffer. This means that the protection software is not
delayed waiting for the records to be logged by the platform software. However, in
the rare case when a large number of records to be logged are created in a short
period of time, it is possible that some will be lost if the supervisor’s buffer is full
before the platform software is able to create a new log in battery backed-up SRAM.
If this occurs then an event is logged to indicate this loss of information.
2.5.6 Disturbance recorder

The disturbance recorder operates as a separate task from the protection and control
task. It can record the waveforms for up to 8 analogue channels and the values of up
to 32 digital signals. For peripheral unit the recording time is user selectable up to a
maximum of 10 seconds and for central unit the record duration is fixed to 600ms.
The disturbance recorder is supplied with data by the protection and control task once
per cycle. The disturbance recorder collates the data that it receives into the required
length disturbance record. It attempts to limit the demands it places on memory
space by saving the analogue data in compressed format whenever possible. This is
done by detecting changes in the analogue input signals and compressing the
recording of the waveform when it is in a steady-state condition. The compressed
disturbance records can be decompressed by MiCOM S1 which can also store the
data in COMTRADE format, thus allowing the use of other packages to view the
recorded data.
Application Notes P740/EN AP/D11
MiCOM P740
APPLICATION NOTES
P740/EN AP/D11 Application Notes
MiCOM P740
CONTENTS
1. INTRODUCTION 5
1.1 Protection of Substation Busbars 5
1.2 P740 Scheme 5
1.2.1 Protection features 6
1.2.2 Non-Protection Features 7
2. APPLICATION OF INDIVIDUAL PROTECTION FUNCTIONS 8

2.1 Configuration Columns 8
2.2 Busbar Biased Current Differential Protection 11
2.2.1 Operating principle 11
2.2.2 Application of Kirchoffs law 11
2.3 Central Unit 13
2.3.1 Differential Protection Configuration 13
2.3.2 Bias Characteristic and Differential current setting 14
2.3.3 Scheme supervision by "check zone” element 14
2.3.4 Sensitive earth fault element 15
2.3.5 Current Circuit Supervision 19
2.3.6 Threshold coherency. 19
2.3.7 Signal Quality 20
2.3.8 Tripping Criteria 21
2.4 Peripheral Unit 21
2.4.1 Busbar Elements 21
2.4.1.1 Busbar Protection Configuration 21
2.4.1.2 Busbar Trip Confirmation (87BB)

or Central Breaker Fail Trip Confirmation (50BF) 22
2.4.2 Non-directional Phase Fault Overcurrent Protection 22
2.4.2.1 IDMT Characteristics 25
2.4.3 Non-Directional Earth Fault Overcurrent Protection 25
2.4.4 External Fault Detection by High-Set Overcurrent or Earth Fault Element 26
2.4.4.1 Application Example 26
2.4.5 Supervision 27
2.4.6 Zero Sequence Current (ΙO) Supervision. 28
3. CIRCUIT BREAKER FAIL (CBF) 29

3.1 Distributed Tripping, Control and Indication Elements (Peripheral Units) 29
3.2 Circuit Breaker Fail Criteria 30
3.2.1 Current Criterion 30
3.2.2 Logic Criterion 30
3.2.2.1 Overcurrent Criterion 30
3.3 Processing A Circuit Breaker Failure Condition 30

3.3.1 Internally Initiated CBF i.e. Tripping from the Differential Element 87BB 32
3.3.1.1 Description of the Logic for Internally Initiated CBF 33
3.3.1.1.1 Initial Trip 33
3.3.1.1.2 Re-Trip after time tBF1 33
3.3.1.1.3 Back Trip after time tBF2 33
3.3.2 Externally Initiated 50BF 34

3.3.2.1 Local re-trip after time tBf3 35
3.3.2.2 General zone trip after time tBF4 35

3.3.3 Separate external 50BF protection to the busbar protection 35
4. CURRENT TRANSFORMERS 36
4.1 CT Mismatch 37
4.1.1 Adjusting the Scheme Base Ratio 37
4.2 CT Requirements 38
4.2.1 Notation 38
4.2.2 Feeders connected to sources of significant power (i.e. lines and generators) 39
4.2.3 Out of service feeders or those with low power contribution (low infeed) 39
4.2.4 CT Specification according to IEC 185, 44-6 and BS 3938 (British Standard) 39
4.2.5 Support of IEEE C Class CTs 41
4.3 CT Saturation detection 42
4.4 CT Location 45
5. CIRCUIT BREAKER FUNCTION 46

5.1 Circuit breaker state monitoring 46
5.1.1 Circuit Breaker State Monitoring Features 46
5.2 Circuit Breaker Control 47
5.3 Trip relays 49
5.4 Suggested Trip Circuit Supervision using psl editor 49
6. ISOLATION AND REDUCED FUNCTION MODE 52

6.1 Central processing unit (P741) 52
6.2 Peripheral Units (P742 and P743) 53
6.3 System operation under failed communications situation 57
6.4 Waiting Configuration 57
7. TOPOLOGY 58
7.1 Topology Configurator 58
7.2 Nodal Assignment 59
7.3 Topology Communication 59
7.4 Topology data 59
7.5 Topology processing 60
7.5.1 CTs on one side of bus coupler, CB closes before status acquisition. 60
7.5.2 CTs on both sides of bus coupler, CB closes before status acquisition. 61
7.5.3 CTs on one side of bus coupler, CB closed and fault evolves between CT and CB.62
7.5.4 CTs on both sides of coupler, CB closed and fault evolves between CT and CB. 64
8. PSL CONFIGURATION AND INTEGRATION 65

8.1 Factory default settings 65
8.1.1 Logic input mapping 65
8.1.2 Relay output mapping 66
8.1.3 Relay output conditioning 67
8.1.4 LED mapping 68
8.1.5 LED output conditioning 68
8.1.6 Fault recorder start mapping 68
9. COMMUNICATIONS BETWEEN PU AND CU 69

9.1 Communications link 69
9.2 Direct optical fibre link, 850nm multi-mode fibre 69
9.3 Optical budgets 70
10. UNDERTAKING A NUMERICAL DIFFERENTIAL BUSBAR PROTECTION

PROJECT 71
10.1 General Substation information 71
10.2 Short Circuit Levels 71
10.3 Switchgear 71
10.4 Cubicle specifications 72
10.5 Substation Architecture 72
11. STANDARD CONFIGURATIONS 73
12. MEASUREMENTS 84
12.1 Measured currents 84
12.2 Sequence currents 84
12.3 Settings 84
12.3.1 Common Conventional Ratio (Ibp) 85

12.3.2 Default Display 85
12.3.3 Local Values 85
12.3.4 Remote Values 85
13. EVENT & FAULT RECORDS 86

13.1 Types of Event 89
13.1.1 Change of state of opto-isolated inputs 89
13.1.2 Change of state of one or more output relay contacts 89
13.1.3 Relay alarm conditions 90
13.1.3.1 Protection element starts and trips 90
13.1.3.2 General events 90
13.1.3.3 Fault records 91
13.1.3.4 Maintenance reports 91
13.1.3.5 Setting Changes 91
13.1.4 Resetting of event/fault records 91
13.1.5 Viewing event records via MiCOM S1 Support Software 92
13.1.6 Event Filtering 93
14. DISTURBANCE RECORDER 94
15. COMMISSIONING TEST MENU 97

15.1 Opto I/P status 98
15.2 Relay O/P status 98
15.3 Test Port status 99
15.4 LED status 99
15.5 Test mode 99
15.5.1 Test mode for PU 99
15.5.2 Test mode for CU 100
15.6 Test pattern 100
15.7 Contact test 100
15.8 Test LEDs 100
15.9 Busbar Monitoring (only in CU) 101
15.10 Busbar (BB) & Circuit Breaker Fail (CBF) Disable (only in CU) 101
15.11 Position Pattern (only in PU) 101
15.12 Position Test (only in PU) 101
16. MONITOR TOOL 102

1. INTRODUCTION
1.1 Protection of Substation Busbars
The busbars in a substation are possibly one of the most critical elements in a power
system. If a fault is not cleared or isolated quickly, not only could substantial damage
to the busbars and primary plant result, but also a substantial loss of supply to all
consumers who depend upon the substation for their electricity. It is therefore
essential that the protection associated with them provide reliable, fast and
discriminative operation.
As with any power system the continuity of supply is of the utmost importance,
however, faults that occur on substation busbars are rarely transient but more usually
of a permanent nature. Circuit breakers should, therefore, be tripped and not subject
to any auto-reclosure.
The busbar protection must also remain stable for faults that occur outside of the
protected zone as these faults will usually be cleared by external protection devices. In
the case of a circuit breaker failure, it may be necessary to open all of the adjacent
circuit breakers, this can be achieved by issuing a backtrip to the busbar protection.
Security and stability are key requirements of a busbar protection scheme. Should the
busbar protection maloperate under such conditions substantial loss of supply could
result unnecessarily.
Many different busbar configurations exist. A typical arrangement is a double busbar
substation with a transfer bar. The positioning of the primary plant can also vary and
also needs to be considered which in turn introduces endless variations, all of which
have to be able to be accommodated within the busbar protection scheme.
Backup protection is also an important feature of any protection scheme. In the event
of equipment failure, such as signalling equipment or switchgear for example it is
necessary to provide alternative forms of fault clearance. It is desirable to provide
backup protection, which can operate with minimum time delay and yet discriminate
with other protection elsewhere on the system.
1.2 P740 Scheme
Using the latest numerical technology, MiCOM relays include devices designed for
application to a wide range of power system plant such as motors, generators,
busbars, feeders, overhead lines and cables.
Each relay in the range is designed around a common hardware and software
platform in order to achieve a high degree of commonality between products. One
such product is the P740 busbar protection scheme. The scheme has been designed
to cater for the protection of a wide range of busbar configurations. The scheme
comprises of three relays the Central Unit - P741, and the Peripheral Units – P742
and P743. Which, together with the topology configurator software, allows flexibility
for all configurations.
The P740 range also includes a comprehensive range of non-protection features to
aid with power system analysis and fault analysis.
1.2.1 Protection features

There are three modules that make up the P740 scheme. The P741 is the Central
Unit (CU), whilst the P742 and P743 are both variants of the Peripheral Unit (PU).
The central unit co-ordinates the scheme, receiving signals from all the peripheral
units associated with the protected busbar(s) and acting on these signals, initiating a
buszone protection trip when necessary. One peripheral unit is associated with each
CT location, usually one per incomer/feeder and one/two for each bus coupler/bus
section depending of number of CT (1 or 2). The peripheral units acquire the
analogue signals from the associated CT and the binary signals from the auxiliary
contacts of the primary plant (CB and isolator(s)). The peripheral units also
incorporate the main circuit breaker failure logic together with backup protection.
The difference between the P742 and P743 is the amount of I/O that each can
accommodate. The P743 allows for increased I/O, this is found to be particularly
useful in double busbar applications. Especially where single pole breakers and a
transfer bar are employed, in these applications the I/O requirements are large in
comparison to those required for a single busbar application where a P742 may be
more suitable.
The main features of the P740 scheme are summarised below:
− Current differential busbar protection – Phase segregated biased differential
protection (*) provides the main protection element for the scheme. This
protection provides high-speed discriminative protection for all fault types
(Note: * Sometimes referred to as low impedance type)
− Sensitive differential earth fault protection – provided for high impedance
earthed systems and incorporates bias current control to guarantee stability
under external faults
− Non-directional phase fault over current protection – provides two stage backup
protection
− Non-directional earth fault protection – provides two stage backup protection
− Low Burden – Allows the protection to be installed in series with other
equipment on a common CT secondary
− Accommodates different CT classes , ratios and manufacturer
− Circuit breaker failure protection – two stage breaker fail logic that can be
initiated internally or externally.
1.2.2 Non-Protection Features

The non-protection features for the scheme are summarised below:
− Scheme can be centralised/distributed – if space is not available to locate the
busbar protection centrally it is possible to decentralise the scheme and locate
the units within other protection cubicles.
− Local, zone and scheme measurements – various measurements are available
locally via the relay LCD or remotely via the serial communication link
− Event, fault and disturbance recording – Comprehensive post fault analysis
available via event lists, disturbance records and fault records which can be
accessed locally via the relay LCD or remotely via the serial communication link
(PU -> CU)
− Real time clock/time synchronisation – Time synchronisation available via
IRIG-B input (option in Central Unit)
− Four settings groups – Independent remotely selectable setting groups to allow
for customer specific applications
− CB and isolator state monitoring – indication of the circuit breaker/isolator
position via the auxiliary contacts, scheme acts accordingly should discrepancy
conditions be detected
− CB control – available locally via the HMI
− Commissioning test facilities
− Continuous self monitoring – extensive self checking routines to ensure
maximum reliability
− Communications supervision – detects communication failure between units
and enables remedial action to be taken e.g. switch to communication
independent backup protection locally and disregard feeder at a zone level
− Graphical programmable scheme logic – allowing user defined protection and
control logic to be tailored to the specific application
2. APPLICATION OF INDIVIDUAL PROTECTION FUNCTIONS

The following sections detail the individual protection functions in addition to where
and how they may be applied. Each section also provides an extract from the
respective menu columns to demonstrate how the settings are actually applied to the
relay.
Each relay in the P740 series has a Configuration column. As this affects all of the
protection functions it is described in the following section.
2.1 Configuration Columns
The configuration column for the Central Unit is shown in the following table:-
MENU TEXT DEFAULT SETTING AVAILABLE SETTING

CONFIGURATION
Restore Defaults No Operation No Operation
All Settings
Setting Group 1
Setting Group 2
Setting Group 3
Setting Group 4
Setting Group Select via Menu Select via Menu
Select via Optos
Active Settings Group 1 Group 1
Group 2
Group 3
Group 4
Save Changes No Operation No Operation
Save
Abort
Copy From Group 1 Group 1
Group 2
Group 3
Group 4
Copy to No Operation No Operation
Group 1
Group 2
Group 3
Group 4
Setting Group 1 Enabled Enabled/Disabled
Setting Group 2 Disabled Enabled/Disabled
Diff Busbar Prot Enabled Enabled/Disabled
Optos Setup Visible Visible/Invisible
Input Labels Visible Visible/Invisible
Output Labels Visible Visible/Invisible

CONFIGURATION
Recorder Control Visible Visible/Invisible
Disturb Recorder Visible Visible/Invisible
Measure't Setup Visible Visible/Invisible
Comms Settings Visible Visible/Invisible
Commission Test Visible Visible/Invisible
Setting Values Primary Primary/Secondary
PU in service 0 PU7 to PU39 (0 = on) (1 = off)
PU connected 0 PU from address 7 to address 39
Table 1
In the central unit an additional configuration column “PU Conf & Status” is present
to configure the hardware to the software topology.

PU CONF & STATUS
PU in service Listing the PU’s in service. For example a topology scheme
may define 12 PU:
5 PU for current phase and 7 PU for future.
This would be set to 5.
PU connected This give a list of PU’s connected and synchronized with the
CU. After reboot the CU waits for the list of connected PU’s
to equal the PU’s in service before enabling the busbar
protection.
If there is a discrepancy the CU will not start and the scheme
will be locked.
PU topo valid This gives a list of PU’s with valid topology data. After
rebooting the CU checks the topology configuration on all
PU’s and reports the result in this cell.
If there is a discrepancy the central unit will not start and the
scheme will be locked.
Reset Circt Flt After a circuitry fault has been detected, the user must accept
and clear the error, using the command from this cell.
Circuitry Fault List of zones blocked for circuitry fault
Circ Fault Phase Phase in circuitry fault
Table 2
The configuration column for the Peripheral Unit is shown in table 3 below:-

CONFIGURATION
Restore Defaults No Operation No Operation
All Settings
Setting Group 1
Setting Group 2
Setting Group 3
Setting Group 4
Setting Group Select via Menu Select via Menu
Select via Optos
Active Settings Group 1 Group 1
Group 2
Group 3
Group 4
Save Changes No Operation No Operation
Save
Abort
Copy From Group 1 Group 1
Group 2
Group 3
Group 4
Copy to No Operation No Operation
Group 1
Group 2
Group 3
Group 4
Setting Group 1 Enabled Enabled/Disabled
BB Trip Confirm Enabled Enabled/Disabled
Optos Setup Visible Visible/Invisible
Overcurrent Prot Disabled Enabled/Disabled
earth Fault Prot Disabled Enabled/Disabled
CB Fail & I> Enabled Enabled/Disabled
Input Labels Visible Visible/Invisible
Output Labels Visible Visible/Invisible
CT & VT Ratios Visible Visible/Invisible
Recorder Control Invisible Visible/Invisible
Disturb Recorder Invisible Visible/Invisible
Measure't Setup Invisible Visible/Invisible

CONFIGURATION
Commission Tests Invisible Visible/Invisible
Setting Values Secondary Primary/Secondary
Table 3
The aim of the configuration column is to allow general configuration from a single
point in the menu. Items that are disabled or made invisible do not appear in the
main relay menu.
2.2 Busbar Biased Current Differential Protection
The primary protection element of the P740 scheme is phase segregated biased
current differential protection. The technique used is purely numerical and uses
nodal analysis throughout the scheme, on a per zone and per scheme basis. The
analysis is carried out in the central unit therefore communication between the central
unit and all peripheral units is essential. This is achieved via a direct optical
connection utilising a 2.5 Mbits/sec data rate.
2.2.1 Operating principle

The basic operating principle of the differential protection is based on the application
of Kirchhoff’s law. This compares the amount of current entering and leaving the
protected zone. Under normal operation, the amount of current flowing into the area
concerned is equal in to the amount of the current flowing out of the area. Therefore
the currents cancel out. In contrast, when a fault occurs the differential current that
arises is equal to the derived fault current.
Io1
Ii1
x
S1 x Ii = | ΣIin |
Io2
Ii2
x Io = | ΣIon |
S2 x
Io3 Ibias = I i + Io
Ii3
x
S3 x Io4
Idiff = I i - I o
Substation Simplified Scheme
Import ΣIi Export ΣIo

S x x
P3766ENa
Figure 1: Differential busbar protection principle
2.2.2 Application of Kirchoffs law

Several methods of summation can be used for a differential protection scheme:
− Vector sum
− Instantaneous sum
The algorithms applied in MiCOM P740 use the instantaneous sum method. This
method has the advantage of cancelling the harmonic and DC components of
external origin in the calculation and in particular under transformer inrush
conditions.
The other advantage of using an instantaneous sum lies in the speed of decision,
which in turn is dictated by the sampling frequency.
Differential currents may also be generated under external fault conditions due to CT
error. To provide stability for through fault conditions the relay adopts a biasing
technique, which effectively raises the setting of the relay in proportion to the through
fault current thereby preventing relay maloperation.
The bias current is the scalar sum of the currents in the protected zone. Each of these
calculations is done on a per phase basis for each node and then summated.
Figure 2 shows the characteristics of the P740 scheme phase differential element.
i diff (t) 90
%
Trip
to
20
=
-k
i1 i2 bias
ge
nta
rce
Pe
i3 i4 ID > 2 Restrain
Is
ID > 1
i bias (t)
i diff (t) = i1 + i2 + i3 + i4 = Si
i bias (t) = i 1 + i2 + i3 + i4 = S i
P3721ENa
Figure 2: P740 Scheme Characteristic

The characteristic is determined from the following protection settings:
ID>2 High-set differential current threshold setting which controls the set slope of
the bias characteristic (Is + k Ibias)
IS The origin of the bias characteristic slope
k Percentage bias setting (“slope”)
When an external fault condition causes CT saturation, a differential current is
apparent and is equal to the current of the saturated CT. The measured differential
current may be determined as an internal fault and initiate an unwanted trip of the
bus bar. In order to avoid a risk of tripping under these circumstances, MiCOM P740
uses an ultra fast innovative algorithm based on the prediction of the next samples
and the calculation of the image of the flux of the CT core. This signal-processing
algorithm makes it possible to block a trip sample within a window of 3 samples. A
settable timer ‘Block Duration’ is used to block the differential element in case of CT
saturation detection (settable from 0 to 2s, default value 150 ms).
2.3 Central Unit
2.3.1 Differential Protection Configuration

Following is a copy of the Differential Elements 87BB column on the relay menu,
which is found in the central unit P741. All configuration settings applicable to this
element are found in this column. A different configuration column is found in the
P742 and P743. This is shown in section 2.4.1.
The differential element has independent settings for phase and earth (sensitive)
faults, which are used for all zones. The check zone element uses only the minimum
pick up level setting ID>2. Ibp is the common base current, refer to section 4.2.
MENU TEXT DEFAULT MINIMUM MAXIMUM STEPSIZE

SETTING
BUSBAR ELEMENTS - DIFF BUSBAR PROT -
Diff Phase Fault
Current Is 0.1*Ibp 0.02*Ibp 1*Ibp 0.01*Ibp
Phase slope k 40% 20% 90% 1%
ID>2 Current 1.2*Ibp 0.1*Ibp 4*Ibp 0.01*Ibp
ID>1 Current 0.05*Ibp 0.01*Ibp 0.5*Ibp 0.01*Ibp
ID>1 Alarm 5s 0s 100s 0.1s
Timer
Diff Earth Fault
Diff Earth Fault Disabled Enabled/Disabled
IBiasPh>Cur. 2*Ibp 0.1*Ibp 10*Ibp 0.1*Ibp
Earth Cur. ISN 0.06*Ibp 0.02*Ibp 1*Ibp 0.01*Ibp
Earth Slope kN 20% 20% 90% 1%
IDN>2 Current 0.1*Ibp 0.03*Ibp 2*Ibp 0.05*Ibp
IDN>1 Current 0.05*Ibp 0.01*Ibp 0.5*Ibp 0.01*Ibp
IDN>1 Alarm 5s 0s 100s 0.1s
Timer
Table 4 Busbar element configuration column for the Central Unit.

Note 1: Only values for Group 1 settings are shown. Identical
columns/rows exist for setting groups 2, 3 and 4.
2: Ibp refer to Section 4.1.1 for more information.
2.3.2 Bias Characteristic and Differential current setting

The operation of the busbar differential protection is based on the application of an
algorithm having a biased characteristic, (Figure 2) in which a comparison is made
between the differential current and a bias or restraining current. A trip is only
permitted if this differential current exceeds the set slope of the bias characteristic.
This characteristic is intended to guarantee the stability of protection during external
faults where the scheme has current transformers with differing characteristics, likely
to provide differing performance.
The algorithm operands are as follows:
− Differential Current
idiff(t) = Σ i
− Bias or restraining current
ibias(t) = Σ i
− Origin of the bias characteristic
Is
− Slope of the bias characteristic
k
− Tripping permitted by bias element for:
idiff(t) > Is + k x ibias(t)
The main differential current element of MiCOM P740 will only be able to operate if the
differential current reaches a threshold ID>2. In general, this setting will be adjusted above
the highest normal full load current.
2.3.3 Scheme supervision by "check zone” element
The use of a "check zone" element is based on the principle that in the event of a fault
on one of the substation busbars, the differential current measured in the faulty zone
will be equal to that measured in the entire scheme.
One of the most frequent causes of maloperation of differential busbar protection
schemes is an error in the actual position of an isolator or CB in the substation to that
replicated in the scheme (auxiliary contacts discrepancy). This would produce a
differential current in one or more current nodes. However, if an element monitors
only the currents "entering" and "leaving" the substation, the resultant will remain
negligible in the absence of a fault, and the error will lie with the zone’s assumption
of the plant position at this particular point in time.
For security, the P740 scheme will only trip a particular busbar zone if that zone
differential element AND the check zone are in agreement to trip.
The principal advantage of this element is total insensitivity to topological
discrepancies. Under such circumstances the "check zone" element will see two
currents with equal amplitude but of opposite sign in adjacent zones.
The check zone is the sum of all the current nodes entering and leaving the sub-
station (bus section, dead zone, blind spot).
Scheme differential current = sum of all differential current nodes:
idiff(t) CZ = Σ idiff
INCLUDEPICTUREMERGEFORMAT
Z12
BB1 BB2
Z1 Z2
CZ= S Idiff
P3723ENa
Figure 3: Check Zone Element

Examples showing how the topology accommodates such conditions using the check
zone are shown in section 7.4.
The Check Zone will operate if the sum of all differential current nodes is greater than
ID>2.
2.3.4 Sensitive earth fault element

The sensitive earth fault element is included for high impedance earthed systems and
has bias current control to guarantee stability under external faults or when there are
significant errors in the measurement CTs. The element is usually disabled for
effectively earthed systems with low impedance or solid earthing. The sensitive earth
fault settings are shown in table 4 and are also repeated below.
MENU TEXT DEFAULT MINIMUM MAXIMUM STEP SIZE

SETTING
Earth Faults
Earth Fault Disabled Enabled/Disabled
IBiasPh> Cur. 2*Ibp 0.1*Ibp 10*Ibp 0.1*Ibp
Earth Cur. ISN 0.06*Ibp 0.02*Ibp 1*Ibp 0.01*Ibp
Earth slope kN 20% 20% 90% 1%
IDN>2 Current 0.1*Ibp 0.03*Ibp 2*Ibp 0.05*Ibp
IDN>1 Current 0.05*Ibp 0.01*Ibp 0.5*Ibp 0.01*Ibp
IDN>1 Alarm 5s 0s 100s 0.1s
Timer
Table 5

The current control and blocking matrix is shown in Table 6.

There is a separate characteristic for the sensitive earth fault element. This is shown
in Figure 4.
i diff (t) 90
%
Trip
to
20
k=
s-
i1 i2 eb
ia
ntag
rce
Pe
i3 i4 ID > 2 Restrain
Is
ID > 1
i bias (t)
i diff (t) = i1 + i2 + i3 + i4 = Si
i bias (t) = i 1 + i2 + i3 + i4 = S i
P3721ENa
Figure 4: Sensitive earth fault characteristic

This element is automatically enabled/disabled via the load (flowing) current. The
point at which the sensitive earth fault protection is enabled/disabled (IbiasPh>Cur.)
is settable in the range 0.1 to 10 times Ibp, where Ibp is the scheme base current. This
threshold is usually set to be equal to the minimum phase to phase short circuit
current.
Under earth fault conditions the risk of CT saturation is minimal and therefore the
slope of the characteristic can be set low, however, should the fault evolve to a phase
fault, it is important that the normal characteristic be restored.
Table 6 shows the current control for the SEF element.
PROTECTION Before External Internal External Internal

ELEMENT fault single single phase to phase to
detection phase phase phase phase
fault fault fault fault
CURRENT CONTROL
ibias A > phase A bias 0 0 or 1 0 or 1 1 1
current threshold
ibias B > phase B bias 0 0 or 1 0 or 1 1 1
current threshold
ibias C > phase C bias 0 0 or 1 0 or 1 1 1
current threshold
SEF blocking order : 0 0 or 1 0 or 1 1 1

a + b+ c
IDN>1, ISN, 0 0 1 0 before 0 or 1
(it is assumed that these saturation
PROTECTION Before External Internal External Internal

ELEMENT fault single single phase to phase to
detection phase phase phase phase
fault fault fault fault
thresholds are set less 1 during
than the minimum earth saturation
fault current)
IDN>2 0 0 0 or 1 0 before 1
(this threshold can be set saturation
greater or less than
1 during
maximum earth fault
saturation
current)
Table 6 Sensitive earth fault current control / blocking elements configuration

column
Note: In the above table a “1” signifies that the setting has been
exceeded in the case of thresholds and a “0” vice versa. A “1”
in the SEF blocking order shows that the logic statement Ibias A
and Ibias B and Ibias C is true and “0” shows that it is false. A “1”
(or true condition) blocks/disables the SEF protection, as
described below whilst a “0” (or false condition) keeps the SEF
protection active/enabled.
It can be seen that for an internal phase to earth fault only the phase on which the
fault has occurred will exceed the setting IbiasPh>Cur but a block will not be issued
as PhA + PhB + PhC = 0. The IDN>1 and ISN settings will be exceeded and if
appropriate evolve to issue a IDN>2 trip.
For an external phase fault the SEF will be disabled via blocking order.
It can be seen that for an internal phase to phase fault the bias current will be
sufficient to enable the SEF blocking order. The SEF protection is then blocked and
no trip issued from this element irrespective of SEF setting thresholds being exceeded.
The main phase differential protection is then able to react to the fault and issue a
trip accordingly.
For an external phase to phase fault the SEF will be disabled via the blocking order.
The sensitive differential earth fault protection is delayed by 20ms to prevent any
maloperation during CT saturation condition.
2.3.5 Current Circuit Supervision

During normal operation the differential current in the scheme should be zero or
negligible. Any anomaly is detected via a given threshold ID>1.
An unbiased Overcurrent element is used to supervise the current circuit. A
differential current will result if the secondary circuit of a CT becomes open circuited;
the amplitude of this current is proportional to the load current flowing in the circuit
monitored by the faulty current circuit.
The setting is chosen to be as low as possible (minimum suggested setting is 3% of
the base current Ibp) but also allow for standing differential current for example due to
CT mismatch and varying magnetising current losses. 5 to 20% is a typical
application range.
The element is typically time delayed for 5 seconds (set greater than the maximum
clearance time). Instead the time delay allows the relevant protection element (which
should be substantially faster) to clear the fault instead i.e. ID>2 in the case of an
internal phase fault.
2.3.6 Threshold coherency.

The measuring elements have several level detectors for differential current. The
protection reacts to any setting inconsistency in the detection of these levels in a
specific order. The supervision threshold, ID>1 being the first threshold, with all the
other thresholds above it needing confirmation by it. If the thresholds are not
exceeded in the correct sequence then an error is detected and an alarm and, or,
blocking signal is issued.
The differential element is blocked until the thresholds ID>1, IS and ID>2 are
exceeded in the correct sequence.
I bp 4
I D>2
1
0.5 Is
0.1
0.01 0.02
I D>1 Is I D>2
Settings as multiples of I bp
P3767ENa
Figure 5: Threshold Coherency

The thresholds must be set so that:

(ID>1) ! (IS) ! (ID>2) and (IDN>1) ! (ISN) ! (IDN>2)
Table 7 below shows operation depending on the threshold coherency.
ID>1 IS + k.Ibias ID>2 Status Operation

0 0 0 Normal -
1 0 0 Circuitry fault Block and circuitry fault alarm
after tCF
1 0 1 External fault External fault with CT saturation
or circuitry or block circuitry fault alarm
fault after tCF
1 1 0 Circuitry fault Block and circuitry fault alarm
after tCF
1 1 1 Internal fault Trip
Table 7 Threshold Coherency Conditions
ID>1 IS + k.Ibias ID>2 Status

0 0 1 Incoherent setting
Table 8 Threshold Incoherent Setting
2.3.7 Signal Quality

An additional check is carried out to confirm that the signals used to determine the
previous criteria are satisfactory.
This includes checking for CT saturation conditions (information from peripheral unit,
refer to Section 4.3), that no plant discrepancies exist (via check zone as discussed
earlier), and that a change (increase) in current flow has been detected by at least
two peripheral units (∆I detection). The latter condition is used, as internal or external
faults will cause a change in levels in at least two circuits whereas an CT fail only
affect a single circuit’s levels (faulty CT).
When a trip is issued for a bus zone by the central unit a signal is sent to all
peripheral units associated with the faulted bus zone. The peripheral units carry out a
further local confirmation via local Overcurrent protection, I>BB or IN>BB, before
allowing a trip to take place. This is covered in Section 2.4.1.2.
2.3.8 Tripping Criteria

Before a trip signal is issued five trip criteria at the top level, i.e. the Central Unit, and
one at the local level, i.e. the Peripheral Units, must be met.
These criteria are:
− Top level (Central Unit)
− Bias characteristic and Differential current setting exceeded (Idiff> Is + k Ibias)
− Idiff > (ID>2)
− Check Zone Operation
− Setting Coherency: (ID>1) ! (IS) ! (ID>2) and (IDN>1) ! (ISN) ! (IDN>2)
− Signal quality (CT supervision, CT saturation, AD converter, etc)
− Local Level (Peripheral Unit)
− Local confirmation by an instantaneous Overcurrent element
(enabled/disabled) (I>BB or IN>BB)
2.4 Peripheral Unit
2.4.1 Busbar Elements
2.4.1.1 Busbar Protection Configuration

Following is a copy of the Differential Elements 87BB column on the relay menu,
which is found in the peripheral units P742 and P743. A different configuration
column is found in the P741. This is shown in section 2.3.1. All configuration
settings applicable to this element are found in this column.
Note: In is the CT nominal current.
SETTING
BB Trip Confirm
I>BB Current Set 1.2*In 0.05*In 4*In 0.01*In
IN>BB Current 0.2*In 0.05*In 4*In 0.01*In
Table 9 Peripheral Unit differential protection elements configuration column.

The settings required for the local confirmation of a busbar trip are included in this
column.
Note: Only values for Group 1 settings are shown. Identical
columns/rows exist for setting groups 2, 3 and 4.
2.4.1.2 Busbar Trip Confirmation (87BB) or Central Breaker Fail Trip Confirmation (50BF)
The peripheral units can be enabled to control the trip command issue by the central
unit (87BB or 50BF) if a local fault threshold, either phase or earth (i.e. I>BB or
IN>BB), is exceeded.
This criterion provides additional scheme stability. Should the command proceed,
and a trip be issued to the circuit breaker this element can confirm the evolution of a
circuit breaker failure condition. If the element is still operated after a set time delay
a breaker failure condition must exist.
2.4.2 Non-directional Phase Fault Overcurrent Protection

Non-directional Phase fault Overcurrent protection is provided as an alternative form
of back-up protection. The P742 and P743 relays have two Overcurrent stages for
backup protection. The first stage is selectable IDMT or definite time whilst the
second stage is definite time only. The Overcurrent protection can be selectively
enabled or disabled.
The Overcurrent elements will need to be co-ordinated with any other protection
elements on the system, in order to provide discriminative fault clearance. The
Overcurrent protection menu column is shown in Table 9. Note In is the CT nominal
current.

SETTING
BB TRIP CONFIRM
BACKUP OVERCURRENT
I>1 Function Disabled Disabled, DT, IEC S Inverse, IEC V Inverse, IEC E
Inverse, UK LT Inverse, IEEE M Inverse, IEEE V
Inverse, IEEE E Inverse, US Inverse, US ST Inverse
I>1 Current Set 3*In 0.1* In 32* In 0.01* In
I>1 Time Delay 1s 0s 100s 0.01s
I>1 TMS 1 0.025 1.2 0.025
I>1 Time Dial 7 0.5 15 0.1
I>1 Reset Char DT DT/Inverse
I>1tReset 0 0 100 0.1
I>2 Function Disabled Disabled/Blocking Busbar/High Set O/C/Both
I>2 Current Set 20* In 0.10* In 32* In 0.01* In
I>2 Time Delay 1s 0s 10s 0.01s
Table 10 Phase Fault Overcurrent Protection Configuration Column

For the IDMT characteristics the following options are available.

The IEC/UK IDMT curves conform to the following formula:
K
t =T ×( + L)
(I / Is)α − 1 EQEQ
The IEEE/US IDMT curves conform to the following formula:
TD K
t= ×( + L)
7 (I / Is)α − 1 EQEQ
t = operation time
K = constant
Ι = measured current
Ιs = current threshold setting
α = constant
L = ANSI/IEEE constant (zero for IEC curves)
T = Time multiplier setting for IEC/UK curves
TD = Time multiplier setting for IEEE/US curves
Figure 6: IDMT Characteristic Curves

Figure 7: IEEE Characteristic Curves

IDMT characteristics
IDMT Curve description Standard K constant α constant L constant

Standard Inverse IEC 0.14 0.02 0
Very Inverse IEC 13.5 1 0
Extremely Inverse IEC 80 2 0
Long Time Inverse UK 120 1 0
Moderately Inverse IEEE 0.0515 0.02 0.114
Very Inverse IEEE 19.61 2 0.491
Extremely Inverse IEEE 28.2 2 0.1217
Inverse US-C08 5.95 2 0.18
Short Time Inverse US-C02 0.02394 0.02 0.01694
Table 11 IDMT Characteristics
2.4.2.1 IDMT Characteristics

Note that the IEEE and US curves are set differently to the IEC/UK curves, with regard
to the time setting. A time multiplier setting (TMS) is used to adjust the operating time
of the IEC curves, whereas a time dial setting is employed for the IEEE/US curves.
Both the TMS and Time Dial settings act as multipliers on the basic characteristics but
the scaling of the time dial is approximately 10 times that of the TMS, as shown in the
previous menu. The menu is arranged such that if an IEC/UK curve is selected, the
‘Ι> Time Dial’ cell is not visible and vice versa for the TMS setting.
2.4.3 Non-Directional Earth Fault Overcurrent Protection

The P742 and P743 relays include backup non-directional earth fault protection. The
earth fault element has two stages of protection. The earth fault element needs to be
co-ordinated with any other protection elements on the system, in order to provide
discriminative fault clearance. The inverse time characteristics available for the earth
fault protection, are the same as those for the Overcurrent element. The earth fault
settings are shown below.
Note: Ιn is the CT nominal current.
SETTING
OVERCURRENT
O/C EARTH FAULT
ΙN>1 Function Disabled Disabled, DT, IEC S Inverse, IEC V Inverse, IEC E
Inverse, UK LT Inverse, IEEE M Inverse, IEEE V
Inverse, IEEE E Inverse, US Inverse, US ST Inverse
ΙN>1 Current Set 0.3*Ιn 0.1*Ιn 32*Ιn 0.01*Ιn
ΙN>1 Time Delay 1s 0s 100s 0.01s
ΙN>1 TMS 1 0.025 1.2 0.025
ΙN>1 Time Dial 7 0.5 15 0.1
ΙN>1 Reset Char DT DT/Inverse
ΙN>1tReset 0 0 100 0.1
ΙN>2 Function Disabled Disabled/Blocking Busbar/High Set O/C/Both
ΙN>2 Current Set 20* Ιn 0.10*Ιn 32* Ιn 0.01* Ιn
ΙN>2 Time Delay 1s 0s 10s 0.01s
Table 12 Earth Fault Overcurrent Protection Configuration Column

2.4.4 External Fault Detection by High-Set Overcurrent or Earth Fault Element

There are feeders where, if the power is sufficiently low in relation to the maximum
short circuit power of the busbar, it can be impossible to distinguish between an
internal or external fault by measuring the current magnitude.
The feeders in question are mainly transformer feeders where the short circuit
reactance poses significant limitations. Thus, knowing the feeder’s maximum
possible contribution to the busbar fault current, it is easy to infer that exceeding this
value will indicate an external fault. In certain cases it is just the presence of a current
that will indicate an external fault.
Normally the P740 scheme may detect a fault, but a saturation condition is also
detected before this is allowed. In this scenario saturation may not occur until after
the scheme has eliminated a saturation condition and allowed a trip to be issued for
the external fault.
An ultra high-speed detection is carried out by each of the peripheral units (P742 and
P743) and can generate a blocking signal from the moment of the first sample at
0.42 ms.
This function can be activated independently for phase faults (Ι>2) and for earth
faults (ΙN>2). A setting example for these thresholds is shown in Figure 8.
2.4.4.1 Application Example
Example of use of high speed detectors

I>2 and/or IN>2 to block the 87BB
element before CT saturation
3000/5A 3000/5A
3000/5A
150/5A 150/5A
25VA 25VA
5P10 5P10
I>2 enabled
IN>2 enabled
I>2 enabled Blocking order
IN>2 enabled ph-ph <300A 1500/5A ph-ph 30 000A
ph-N 0A ph-N 7 500A to 87BB element
TR11 TR12
115/13,8K 115/13,8K
25 MVA 25 MVA
X = 12% X = 12%
P3770ENa
Figure 8: Transformer Feeder example

An example where this facility is required, where there is a high risk of CT saturation,
is shown in the above example.
The problem, lies in the transformer feeder circuits TR11 and TR12 both 115/13.8kV,
rated power 25 MVA with a reactance of 12%. Both feeders are equipped with
150/5 A CTs. (If rating is 25 MVA I=125A @115 kV). Maximum busbar short circuit
current is 30kA phase to phase and 7.5kA phase to earth.
The contribution of each transformer feeder under internal fault conditions is as

follows:-
1. Less than 300 A for phase to phase faults Would the contribution from the
transformers be a maximum of 1045 A ie 1/X% x Ifull load
2. 0 A for phase to earth faults.
When an external fault occurs on one of the transformer feeders, the fault MVA will
be the same as that for an internal fault but the feeder will be subjected to an
excessively high Overcurrent condition as compared to normal load conditions at
rated current.
In the example shown, under the external fault condition, the short-circuit phase to
phase current is 200 times the primary rated current. (150 A x 200=30 kA). Taking
into account the CT and initial flux estimated at 80% of that at full load, saturation
will be detected at 10 times In, where In is the CT nominal current – in this case in
primary values (150 A x 10 = 1500 A)
With Ιsaturation = 1500 A and Ιshort-circuit = 30000 A = 20 x Ιsaturation.
If the assumption is taken that there is no remnant flux, saturation will be detected
1.4 ms after the appearance of the fault. At which time the current will have reached
0.4 times the maximum value i.e. 1200 A.
Data relating to transformer flux derived from typical magnetising characteristics.
Conclusion: An ultra fast Overcurrent detector in the P742 and P743 when used on
HV/MV transformer feeders makes it possible to pre-empt CT saturation and establish
an external fault condition. The setting used for this detection is Ι>2 for phase faults
and ΙN>2 for earth faults. The detection of I>2 used a settable drop-off timer
(‘Block Duration’).
In this example a setting of 1305 A can be used for both phase and earth faults.
2.4.5 Supervision
Following is a copy of the SUPERVISION column on the relay menu, which is found in
the peripheral units P742 and P743. All configuration settings applicable to this
element are found in this column.
Note: In is the CT nominal current.
SETTING
SUPERVISION ELEMENTS
ΙO Supervision
Error Factor KCE 0.40 0.01 1 0.01
Alarm Delay TCE 5 0 10 0.1
Table 13 Supervision Configuration Column

2.4.6 Zero Sequence Current (ΙO) Supervision.

The four current inputs to the peripheral units are used to verify that the calculated
zero sequence current is within the correct range for CT supervision purposes. This
then provides continuous supervision of the local current transformer and of the relay
measurement chaining (CTs, ADC, etc…).
The residual current 3Ιo is derived from the three phases Ιa + Ιb + Ιc and compared
to the measured value of ΙN from the neutral CT input.
|3ΙO - ΙN |
During an earth fault the two values should be the same and the sum should
therefore be equal to zero or below the threshold (CTS ΙN> Set) and the CT
supervision alarm will not be issued.
If a CT becomes disconnected a difference between the derived and measured value
will appear, i.e. a CT problem has been detected and after a user settable time delay
(CTS Time delay) the alarm will be issued.
This calculation is then compared to a further criterion to verify and monitor CT
connections and associated current circuits.
|3ΙO - ΙN |> 0.05 Ιn + KCE x (|Ιa| + |Ιb| + |Ιc| + |ΙN| )
(Where KCE is a calculation error coefficient and In is the nominal current)
The calculation error coefficient in the above formula is set between 0.01 and 1
thereby allowing for small discrepancies and preventing false blocking of the
differential elements whilst the constant value of 0.05 In provides stability under no
load or low load conditions.
Main causes for alarms from zero sequence current calculations are:-
− Commissioning with load current – detection of connection errors (input
inverted/rated current incorrect)
− Maintenance with load current – By pass of analogue input, when a separate
neutral CT is made available.
− Failure of an analogue channel – e.g. A/D converter failure
Once detected the alarm will be issued after a user settable time delay (Alarm Delay
TCE).
Because the peripheral units sample at 2400Hz discrepancies between the measured
and derived values are identified and responded to very quickly. If any anomalies
arise for either of the above calculations the differential elements associated with the
faulty peripheral unit are instantaneously blocked. The blocking signal remains in
place for 10ms with an alarm signal sent after the time delay. The time delay is
usually set above the time required to trip under fault conditions.
3. CIRCUIT BREAKER FAIL (CBF)

Following is a copy of the CB FAIL column on the relay menu, which is found in the
peripheral units P742 and P743. The P740 scheme has integral CB fail protection
within its logic but can also accept external initiation from other protection. All
configuration settings applicable to this element are found in this column: -

SETTING
CB FAIL
Control by I< I<; 52a or both
I< Current Set 0.05*In 0.05*In 1*In 0.01*In
I> Status Disabled Enabled/Disabled
I> Current Set 1.2*In 0.05*In 4*In 0.01*In
IN> Current Set 0.2*In 0.05*In 4*In 0.01*In
INTERNAL TRIP
CB Fail Timer 1 0.05 0 10 0.01
CB Fail Timer 2 0.2 0 10 0.01
EXTERNAL TRIP
CB Fail Timer 3 0.05 0 10 0.01
CB Fail Timer 4 0.2 0 10 0.01
Table 14 Circuit Breaker Fail Configuration Column

Note: CB Fail 2 Timer > CB Fail 1 Timer
and
CB Fail 4 Timer > CB Fail 3 Timer
The detailed logic of the circuit breaker failure element follows.
3.1 Distributed Tripping, Control and Indication Elements (Peripheral Units)

As the P740 scheme has been designed for use as either a centralised or distributed
scheme, the hardware corresponds to one circuit breaker and can accommodate 1 or
2 trip coils:
− 1 main trip coil
− 1 back-up trip coil
Furthermore these can be either 3 single-phase trip coils or 1 three-phase trip coil.
These can be combined for example 3 single-phase trip coils on the main system and
1 three-phase trip coil for the back-up system.
3.2 Circuit Breaker Fail Criteria
3.2.1 Current Criterion

The criterion normally used for the detection of an open circuit breaker pole is the
disappearance of the current i.e. undercurrent element. This function is generally
preferred above other elements due to the response time. In P740 this method of
detection is utilised and has the threshold I<.
3.2.2 Logic Criterion

This criterion is based on checking the state of the circuit breaker auxiliary contacts.
i.e. to see if the 52a contact is open for open circuit breaker conditions.
3.2.2.1 Overcurrent Criterion

One of the most common causes of busbar mal-tripping is error introduced in the
back tripping of adjacent sections. To prevent such an error it is possible to condition
the operation of 50BF protection only when there is presence of a significant current
i.e. a short-circuit on the concerned feeder. This confirmation is provided by the I>
threshold which is set by default at 1.2 times the nominal rated current of the CT
and/or by the threshold setting of residual current IN> set by default to 0.2 times the
rated current.
3.3 Processing A Circuit Breaker Failure Condition
Due to the nature of the busbar protection, the substation topology can manage the
system under circuit breaker failure conditions (50BF).
There are several options for circuit breaker failure protection installations. Generally
these depend on the substation construction and wiring:
− Internally initiated CBF i.e. Initiation from the differential element, 87BB, trip
− Externally initiated, for example by the feeder protection, but using the busbar
protection’s integral 50BF protection to execute tripping procedure
− Separate 50BF protection to the busbar protection
The breaker failure logic uses fast acting undercurrent elements to provide the
required current check. These elements reset within 15ms, thereby allowing the use
of the P740 relay at all voltage levels.
Since the Overcurrent element within the peripheral units may also be used in
blocking schemes to provide back-up protection, it is possible to reset the Overcurrent
start signals after the breaker fail time delay has elapsed. This ensures that the
upstream back-up protection can be maintained by removal of the blocking signal.
This would also ensure that the possible risk of re-trip on re-closure of the circuit
breaker is minimised.
TpA
1 TpB External trip signal from peripheral unit
TpC
(21, 87T, etc….) CB FAIL ALARM
MiCOM P740
2
I< 0 TBF3 TBF4- TBF3
3 IA
A Tn1
& &
Application Notes
0 0
Figure 9:
I< 0 TBF3 TBF4- TBF3
0
IB & & 250ms
B Tn1 0 0 =1 8
BB/FF Busbar Trip
I< 0 TBF3 TBF4- TBF3 on feeder fault
IC & &
C Tn1 0 0
Dead pole detection

TBF3 Retrip time delay TBF4 Back trip time delay
CB Fail Logic
I> 0
IA =1 &
a Tn2
9
Re trip Phase A
Feeder Fault
I> 0
IB =1 & 10
b Tn2
Re trip Phase B
Feeder Fault
I> 0
IC =1 & 11
c
Tn2 Retrip Phase C
Feeder Fault
IN> 0 I, IN> Retrip & back trip confirmation
IN
Fault Detection
N Tn2
4 52a Phase A
=1
52a Phase B
5 =1
52a Phase C Busbar2 Trip on
6 3 phases Trip ( TpABC)
=1 Busbar1 Fault
TBF1 TBF2-T BF1

Trip signal to local CB Bus Coupler 0
7 &
from Busbar protection =1 0 0 & 250ms
12
=1 TBF1 Back trip time delay TBF2 Back trip time delay
52a Enable
=1 & 13
=1 Local retrip on
Busbar Fault
I, IN> Retrip & back trip confirmation
P740/EN AP/D11
Page 31/103
P3738ENa
DDB Ext. CB Fail DDB BF Trip Request

>1
Trip signal towards CU
DDB O/C Protection
DDB Ext. 3ph Trip
DDB External Trip A

>1 1 8 DDB CBF Ext Backtrip
DDB External Trip B

>1 2 12 DDB CBF Int Backtrip
DDB External Trip C

>1 3 13 DDB Int Retrip 3ph
CB Fail
DDB CB Aux. 3ph (52a) Logic
DDB CB Aux. A (52a) 9
>1 4 (See Fig 9) DDB Ext. Retrip ph A
DDB CB Aux. B (52a) 10

>1 5 DDB Ext. Retrip ph B
DDB CB Aux. C (52a) 11

>1 6 DDB Ext. Retrip ph C
Trip signal from CU 7
P3739ENa
Figure 9bis: CB Fail Logic (DDB Inputs & Outputs)
3.3.1 Internally Initiated CBF i.e. Tripping from the Differential Element 87BB
When a tripping order is generated by the busbar protection (87BB or 50BF) but not
executed due to a circuit breaker failure condition, the following circuit breakers are
required to be tripped instead:
− The remote end circuit breaker if the faulty circuit breaker is that of a feeder
(line or transformer). This intertripping is optional (via PSL) and may not be
required on feeders, which may be serviced automatically via the distance or
other line protection.
− All the circuit breakers in the adjacent busbar zone if the faulty circuit breaker is
that of a bus coupler or bus section.
The tripping order from the busbar protection is referenced as TpABC, it is always
three-phase and initiates timers tBF1 and tBF2. The first timer is associated with the
local re-trip function while the second timer is associated with the conveyance of the
signal to the central unit for tripping of the adjacent zone in the cases of bus
coupler/bus section circuit breaker failure.
3.3.1.1 Description of the Logic for Internally Initiated CBF
BBx
Trip signal
from CU
T pABC: Tripping signal from 87BB Local
Main busbar protection trip signal & Circuit
Breaker
I>BB (note 2)
Local
Local overcurrent element 87BB confirmation
Retrip
& tBF1 &
I<
Dead pole detection threshold
I> (note 2)
Local overcurrent element CBF confirmation
&
tBF2-tBF1 Back trip
(Note 1)
Note 1: Signal to CU for back-trip (including adjacent zone(s) if failed CB is bus section or bus coupler circuit breaker
Note 2: I>BB and I> could be enabled or disabled (scheme shown is with the 2 functions enhanced)
P3771ENa
Figure 10: CB Fail Element Logic – Internally Initiated

3.3.1.1.1 Initial Trip
A trip signal is issued by the central unit and then confirmed by the local peripheral
unit. If the threshold for the local Overcurrent protection setting for busbar protection
(I>BB) is exceeded then the local circuit breaker trip coil is energised and
subsequently the local circuit breaker is tripped.
3.3.1.1.2 Re-Trip after time tBF1
The peripheral unit’s dead pole detection threshold (I<) and external protection
initiation (I>) trigger the first breaker failure timer (tBF1). This signal in turn is passed
through an AND gate with the signal from the local Overcurrent protection for busbar
protection (I>BB) (if a circuit breaker failure condition has evolved this will still be
present) and a re-trip command is issued. Re-trip output contacts should be assigned
using the PSL editor (including in default PSL settings).
3.3.1.1.3 Back Trip after time tBF2
A signal from the first circuit breaker timer triggers the second breaker failure timer
(tBF2). This in turn is passed through an AND gate with the signal from the local
overcurrent protection for busbar protection (I>BB), if a circuit breaker failure
condition has persisted this will still be present, and a general bus-zone trip signal
issued via the central unit. In summary tBF1 is used for re-trip and tBF2 for general
bus zone trip
Because the busbar protection scheme uses the system topology, during circuit
breaker failure conditions, circuit breaker operations are executed according to on
the current state of the system. It is therefore of paramount importance that should
an internally initiated scheme be implemented, the circuit breaker tripping order,
must be thoroughly defined within the scheme topology to guarantee correct scheme
operation.
CU 87BB
CB Fail signal (3) Back Trip Order (4)
BB1 BB2
Trip Order (1)

Other
Protection Main Trip
CB
or Retrip
Failed
(2)
Back Trip
PU
50BF
PU PU
50BF 50BF
P3758ENa
Figure 11: Circuit Breaker Failure Logic

Fault in Z2 and CBA failed:
Back trip Z2 to Z1
PU PU PU PU PU PU PU PU PU PU
CBA
Z1 Z2 Z1 Z2
PU PU PU PU
PU PU
PU PU
Z3 PU PU Z4 Z3 PU PU Z4
CBB
PU PU PU PU PU PU PU PU PU PU
Fault in Z3 and CBB failed:

Back trip to remote end
Remote Substation P3740ENa Remote Substation P3741ENa
Figure 11bis: Examples
3.3.2 Externally Initiated 50BF
BBx
External Tp A, Tp B or Tp C: Tripping signal from external protection Local

Protection Circuit
Initiation Breaker
Local
Retrip
& tBF3 & (Note 2)
I<
Dead pole detection threshold
I>
Local oversurrent element CBF confirmation
&
tBF4-tBF3 Back trip
(Note 1)
Note 1: Signal to CU for back-trip (including adjacent zone(s) if failed CB is bus section or bus coupler circuit breaker
Note 2: Optional, refer to section 3.3.2.1
Note 3: I > could be enable or disable
P3772ENa
Figure 12: CB Fail Element Logic – Externally Initiated

Taking into account the relationship between the busbar protection and the circuit
breaker failure protection certain operators prefer an integrated solution where the
breaker failure may be initiated by external protection but executed in the busbar
scheme. Tripping is then worked out in the section or zone.
On an overhead line for example the external commands may be generated by the
distance protection (21). Generally these commands are on a per phase basis and
therefore the tripping commands must be to. In the diagrams these signals are
labelled TpA, TpB, TpC (Tripping pole A, B or C).
The logic is similar to that for internally initiated CB fail protection but utilises tBf3 for
re-trip and tBF4 for back-trip functions.
3.3.2.1 Local re-trip after time tBf3

This re-trip command can be applied via either the main or back up trip coil. It is
possible to choose between the 3 following modes:
− Local re-trip activated/deactivated via PSL. The relay used for this function can
use the same fixed logic for the busbar protection or other independent relays.
− A re-trip can be applied after a time tBF3. This is typically set at 50ms when a
single phase trip and re-trip is used. This prevents loss of phase selectivity by
allowing the main protection trip to execute via the main CB trip coil before re-
trip command is executed by the back-up CB trip coil.
− Single or three phase re-trip is possible. If the feeder protection executes single-
phase tripping, the three-phase re-trip must be carried out in time tBF3 and this
must be adjusted to have a value higher than the normal operation time of the
circuit breaker. Typical setting under this condition is 150ms.
3.3.2.2 General zone trip after time tBF4

When both the local trip and re-trip have failed, the countdown continues with a
second timer adjusted to have a value of tBF4 - tBF3. The end of this time thus
corresponds to total time tBF4, beyond which a persistent circuit breaker failure
condition is declared.
Information is then relayed to the Central unit for routing to the other peripheral
units, and the associated circuit breakers, in the adjacent zone(s) for a general three-
phase back-trip.
3.3.3 Separate external 50BF protection to the busbar protection

This is the most common solution utilising conventional wiring. The 50BF relay is
completely independent of all others. When a circuit breaker failure condition occurs
the external protection trips all adjacent circuit breakers as defined in the separate
scheme (DDB Ext. CB fail).
In view of the connection between the functions of the busbar protection and the
circuit breaker failure protection some operators prefer one of the more integrated
system solutions previously mentioned.
4. CURRENT TRANSFORMERS
Following is a copy of the CT ratio column in the peripheral unit menu. Only P742
and P743 units have the CT ratio menu as they are connected to the primary plant.
All configuration settings specific to the current transformers can be found in this
column:-

SETTING
CT RATIO
Note: Practical largest range 50/In to 5000/In in the same substation
Phase CT Primary 1000A 1A 30000A 1A
Phase CT Sec'y In 1A 1A 5A 4A
CT Class X 5P (IEC185)
X (BS3938)
TPX (IEC44-6)
TPY (IEC44-6)
TPZ (IEC44-6)
RBPh / RBN 1 0.5 10 0.1
Power Parameters
BRITISH 250/In 100/In 5000/In 10/In
STANDARD
Knee voltage Vk
IEC 25 5 100 1
Rated Burden VA
IEC 25 / In2Ω 5 / In2Ω 100 / In2Ω 1 / In2Ω
Rated Burden
Ohm
(calculated value)
IEC 10 10 50 5
Rated short-circuit
factor Kscc
Secondary RCT 0.5 0.1 50 0.1
Eff Burden Ohm 25 / In2Ω 1 / In2Ω 200 / In2Ω 1 / In2Ω
Eff Burden VA 25 0.1 200 0.01
(calculated value)
Table 15 Peripheral Unit CT Configuration Column

It is important that the CT settings are entered in full as these are required to calculate
additional parameters for use in the saturation detection algorithms that run within
the peripheral units.
4.1 CT Mismatch
A P740 scheme can accommodate different CT ratios throughout the protected zone.
This mismatch must, therefore, be accounted for by the scheme. This is achieved by
using a base ratio to which the central unit converts all of the analogue values when
undertaking scheme calculations.
The interface permits a range of 1 A to 30000 A. In practice the range 50 A to
5000 A is most common and should not be exceeded. In practice, a common base
current of 1000 A is usually selected.
4.1.1 Adjusting the Scheme Base Ratio

As has been mentioned in Section 4.1 using a base current and adjusting all
analogue values to this current when undertaking scheme calculations, i.e. differential
current calculation, means that CT mismatch can be accommodated.
As scheme calculations are carried out in the central unit the setting for this base
current is only found in this unit. To set the scheme base ratio the setting for the
common base current, or common setting base, in the central unit must be adjusted
in the Measurement Set-up menu column in the Central Unit.

SETTING
Common conventional ratio
Ibp Current Set 1000 A 1A 10000 A 1A
Table 16 Scheme base current setting in CU

This current setting corresponds to primary values and can be set to between 1A and
10,000A. In practice a common base current of the highest primary nominal current
of main CT is recommended, as this is easy to manipulate.
Changing the base current in this cell adjusts the base for the entire scheme and no
further setting changes need to be carried out.
2000/5 1000/5 500/5

3000/5
P.U. P.U. P.U. P.U.

5/3 ibase 5/2 ibase 5/1 ibase 5/0.5 ibase
C.U.
Available i
base
4000A / 3000A / 2000A /1000A
P3773ENa
Figure 13: Accommodating CT mismatch using the scheme base current

As can be seen in the above example all analogue values are converted to the base
value via relevant ratio.
e.g. Ibp taken as 1000 A as recommended
− Feeder 1 equipped with the 3000/5 CT.
All values need to be adjusted by 5/3 Ibp.
− Feeder 2 equipped with the 500/5 CT.
All values need to be adjusted by 5/0.5 Ibp .
For a current of 1250 A
Feeder 1 Isecondary = (1250 x 5)/3000 = 2.083 A
Converted to base current
Icorrected = 2.083 x 3 x 1000/5 = 1250 A
Feeder 2 Isecondary = (1250 x 5)/500 = 12.5 A
Converted to base current
Icorrected = 12.5 x 0.5 x 1000/5 = 1250 A
This shows that even though the values obtained at the CT secondary are different,
when the base current correction is applied the value is the same and therefore
correct on a scheme basis.
These values are then used for all scheme calculations.
4.2 CT Requirements
4.2.1 Notation
IF max maximum fault current (same for all feeders)

IF max int maximum contribution from a feeder to an internal fault (depends on
the feeder).
Inp CT primary rated current
In nominal secondary current (1A or 5A)
RCT CT secondary winding Resistance
RB Total external load resistance
Vk CT knee point voltage
SVA Nominal output in VA,
KSSC Short-circuit current coefficient (generally 20)
General recommendations for the specification of protection CTs use common rules
of engineering which are not directly related to a particular protection.
4.2.2 Feeders connected to sources of significant power (i.e. lines and generators)
The primary rated current is specified above a 1/20th of the maximum contribution of
the feeder to internal faults.
i.e. Inp = IF max int/20
e.g. A power line likely to import electricity at 20 kA gives rated primary current Inp
as 1000 A.
This recommendation is used for the majority of line or transformer protection
applications.
4.2.3 Out of service feeders or those with low power contribution (low infeed)
Because of CT construction, thermal behaviour, and electrodynamics the CT primary
rated current cannot be as low as required compared to the maximum fault current.
In the case of a CT with primary bushings and not wound there is not a precise limit
but a practical one. The primary rated current could not be lower than the 1/200th
of the maximum short-circuit current crossing the CT at the time of an external fault
i.e. Inp = IF max /200
This is possible using the fast overcurrent detection I>2 to distinguish between an
internal or external fault in case of CT saturation below than 2 ms
e.g. For a sub station whose maximum short-circuit current would be 30 kA, the CTs
on the least powerful feeders are to be specified for a rated primary current Inp =
150 A, even if the normal consumption of the feeder is much lower than this value
(Sub-station transformer feeder)
4.2.4 CT Specification according to IEC 185, 44-6 and BS 3938 (British Standard)
1. Class X according to British Standard: Minimum knee point voltage for
saturation
Vk min = 0.5 x secondary IF max x (RCT + RB)
The recommended specification makes it possible to guarantee a saturation time >
1.4 ms with a remnant flux of 80 % of maximum flux (class X or TPX). This provides a
sufficient margin of security for CT saturation detection, which operates in less 2 ms.
2. Class 5P to IEC 185. Conversion of class X (BS) with the 5P equivalent (IEC)
3. Class TPX and TPY according to IEC 44-6. IEC defines a composite error as a
percentage of a multiple of the rated current (IN) on a definite load SVA.
e.g. CT 1000/5 A – 50VA 5P 20.
This definition indicates that the composite error must be lower than 5%, for a
primary current of 20Inp when the external load is equal to 2 ohms (50VA to In). If
secondary resistance, RCT, is known it is easy to calculate the magnetising EMF
developed with the fault current (20In). Actually if the error is 5% (= 5A) with this
EMF, the point of operation is beyond the knee point voltage for saturation. By
convention one admits that the knee point voltage, Vk, is 80% of this value. For a
conversion between a class 5P (IEC) and a class X (BS) CT one uses the relation:
Vk=0.8 X [(SVA x Kssc)/In + (RCT x Kscc x In) ]
SVA = (In x Vk/0.8 Kssc) – RCT x In2
In particular cases, calculation could reveal values too low to correspond to industrial
standards. In this case the minima will be: SVA min = 10 VA 5P 20 which
corresponds to a knee point voltage of approximately Vkmin = 70 V at 5A or 350V at
1A. Class TPY would permit lower values of power, (demagnetisation air-gap).
Taking into account the weak requirements of class X or TPX one can keep
specifications common.
For accuracy, class X or class 5P current transformers (CTs) are strongly
recommended. The knee point voltage of the CTs should comply with the minimum
requirements of the formulae shown below.
Vk ≥ k (RCT + RB)
Where:
Vk = Required knee point voltage
k = Dimensioning factor
RCT = CT secondary resistance
RL = Circuit resistance from CT to relay
RB = Burden resistance
k is a constant depending on:
If = Maximum value of through fault current for stability (multiple of
In)
X/R = Primary system X/R ratio
Thus the following expression can be derived.
Vk ≥ IF.(1+X/R).(RCT + RB)
The following CT requirement can be developed for the P740 scheme
Vk > 0.5 x (secondary If max) x (RCT + RB)
With RB = 2 RL
4.2.5 Support of IEEE C Class CTs

MiCOM Px40 series protection is compatible with ANSI/IEEE current transformers as
specified in the IEEE C57.13 standard. The applicable class for protection is class
“C”, which specifies a non air-gapped core. The CT design is identical to IEC class P,
or British Standard class X, but the rating is specified differently. The following table
allows C57.13 ratings to be translated into an IEC/BS knee point voltage
IEEE C57.13 – “C” Classification (volts)
C50 C100 C200 C400 C800
CT Ratio RCT (ohm)
Vk Vk Vk Vk Vk
100/5 0.04 56.5 109 214 424 844
200/5 0.8 60.5 113 218 428 848
400/5 0.16 68.5 121 226 436 856
800/5 0.32 84.5 137 242 452 872
1000/5 0.4 92.5 145 250 460 880
1500/5 0.6 112.5 165 270 480 900
2000/5 0.8 132.5 185 290 500 920
3000/5 1.2 172.5 225 330 540 960
Table 17 IEC/BS Knee Point Voltage Vk offered by “C” class CTs

Assumptions:
1. For 5A CTs, the typical resistance is 0.002 ohms/secondary turn
2. IEC/BS knee is typically 5% higher than ANSI/IEEE knee
Given:
3. IEC/BS knee is specified as an internal EMF, whereas the “C” class voltage is
specified at the CT output terminals. To convert from ANSI/IEEE to IEC/BS
requires the voltage drop across the CTs secondary winding resistance to be
added.
4. IEEE CTs are always rated at 5A secondary
5. The rated dynamic current output of a “C” class CT (Kssc) is always 20 x In
Vk = (C x 1.05) + (In. RCT. Kssc)
Where:
Vk = Equivalent IEC or BS knee point voltage
C = C Rating
In = 5A
RCT = CT secondary winding resistance
Kssc = 20 times
4.3 CT Saturation detection

Innovative methods are used to detect CT saturation in the P740. The values
associated with the CT saturation algorithms are entered into the Peripheral Unit’s CT
ratio menu column shown in table 14 and are used to define the CT’s characteristic.
The algorithms for CT saturation detection are executed in the peripheral units.
The first algorithm to be examined is the detection of variation of current.
The PU calculates the derived current and compares it to the magnitude of the
waveform. With 2400Hz sampling, maximum variation between 2 successive samples
of sinusoidal current can not exceed 14% of the magnitude.
The magnitude of the current is the maximum value of the current measure during
the last period with a minimum of 50% of nominal current. A variation is detected is
derived current exceed 20% of this magnitude.
This instantaneous value is maintained 150ms for the first variation then 50ms for the
next ones, as shown as figure 14.
Figure 14:
The second algorithm, by integration of the secondary current, presumes of

maximum flux in the core.
The flux calculation starts when the first variation of current is detected, then if the
calculated flux reached 20% of the maximum flux, a CT saturation is presumed as
shown in figure 15.
Figure 15: Determination of Signal Quality in Peripheral Unit

CT saturation detection starts at the first variation of current detected and stop if there
is no variation during 100ms. CT saturation is detected when there are a variation of
current and a presumption of maximum flux detected, as shown figure 4. When CT
saturation appears, blocking order is sent to CU to lock the relevant zones.
P3774ENa
Figure 16: Determination of Signal Quality in Peripheral Unit

Blocking of the differential protection via the high speed external fault element is
discussed in Section 2.4.4.
4.4 CT Location
There are no restrictions imposed as to the location of current transformers within the
system, however, when the topological model is created the position and orientation
of the current transformers must be defined correctly to ensure the correct operation
of the protection.
A suggested current transformer location is to position the current transformer for the
busbar protection, line side of the circuit breaker whilst the line protection current
transformers are positioned busbar side of the circuit breaker. This then covers the
largest possible busbar zone providing an overlap with the line protection therefore
eliminating any possible blind spots. This is shown in Figure 17.
P3775ENa
Figure 17: CT Location

5. CIRCUIT BREAKER FUNCTION

5.1 Circuit breaker state monitoring
An operator at a remote location requires a reliable indication of the state of the
switchgear. Without an indication that each circuit breaker is either open or closed,
the operator has insufficient information to decide on switching operations. The relay
incorporates circuit breaker state monitoring, giving an indication of the position of
the circuit breaker, or, if the state is unknown, an alarm is raised.
5.1.1 Circuit Breaker State Monitoring Features

MiCOM relays can be set to monitor normally open (52a) and normally closed (52b)
auxiliary contacts of the circuit breaker. Under healthy conditions, these contacts will
be in opposite states. Should both sets of contacts be open, this would indicate one of
the following conditions:
− Auxiliary contacts / wiring defective
− Circuit Breaker (CB) is defective
− CB is in isolated position
Should both sets of contacts be closed, only one of the following two conditions would
apply:
− Auxiliary contacts / wiring defective
− Circuit Breaker (CB) is defective
If any of the above conditions exist, an alarm will be issued after a 200ms time delay.
A normally open / normally closed output contact can be assigned to this function via
the programmable scheme logic (PSL). The time delay is set to avoid unwanted
operation during normal switching duties.
In the PSL CB AUX could be used or not, following the four options:
− None
− Both 52A and 52B (2 optos)
− Both 52A and 52B (6 optos)
Where ‘None’ is selected no CB status will be available. This will directly affect any
function within the relay that requires this signal, for example CB control, Topology,
etc.
If both 52A and 52B are used then status information will be available and in
addition a discrepancy alarm will be possible, according to the following table. 52A
and 52B inputs are assigned to relay opto-isolated inputs via the PSL.
Auxiliary Contact Position CB State Detected Action

52A 52B
Open Closed Breaker Open Circuit breaker healthy
Closed Open Breaker Closed Circuit breaker healthy
Closed Closed CB Failure Alarm raised if the condition
persists for greater than 200ms
Open Open State Unknown Alarm raised if the condition
persists for greater than 200ms
5.2 Circuit Breaker Control

The relay includes the following options for control of a single circuit breaker:
− Local tripping and closing, via the relay menu
− Local tripping and closing, via relay opto-isolated inputs
It is recommended that separate relay output contacts are allocated for remote circuit
breaker control and protection tripping. This enables the control outputs to be
selected via a local/remote selector switch as shown below. Where this feature is not
required the same output contact(s) can be used for both protection and remote
tripping.
Pr o te c tio n + ve
trip
R e m o te
c o n tro l
trip Trip
0
R e m o te c lo s e
c o n tro l
c lo se
Lo c a l
R e m o te
Trip C lo se
ve
Remote Control of Circuit Breaker

The following table is taken from the relay menu and shows the available settings
and commands associated with circuit breaker control.
Menu text Default setting Setting range Step size

Min Max
CB CONTROL
Prot Trip Pulse 0.2s 0.05s 2s 0.01s
Trip Latched Disabled Enabled, Disabled
Reset Trip Latch No Yes, No

CB Control by Disabled Disabled, Local, Remote,
Local+Remote, Opto, Opto+local,
Opto+Remote, Opto+Rem+local
Man Close Pulse 0.5s 0.1s 10s 0.01s
Man Trip Pulse 0.5s 0.1s 5s 0.01s

Man Close Delay 10s 0.01s 600s 0.01s
A manual trip will be permitted provided that the circuit breaker is initially closed.
Likewise, a close command can only be issued if the CB is initially open. To confirm
these states it will be necessary to use the breaker 52A and/or 52B contacts via PSL. If
no CB auxiliary contacts are available no CB control (manual or auto) will be
possible.
Once a CB Close command is initiated the output contact can be set to operate
following a user defined time delay (‘Man Close Delay’). This would give personnel
time to move away from the circuit breaker following the close command. This time
delay will apply to all manual CB Close commands.
The length of the trip or close control pulse can be set via the ‘Man Trip Pulse’ and
‘Man Close Pulse’ settings respectively. These should be set long enough to ensure
the breaker has completed its open or close cycle before the pulse has elapsed.
Note : The manual close commands for each user interface are found in the System
Data column of the menu.
If an attempt to close the breaker is being made, and a protection trip signal is
generated, the protection trip command overrides the close command.
If the CB fails to respond to the control command (indicated by no change in the state
of CB Status inputs) a ‘CB Fail Trip Control’ or ‘CB Fail Close Control’ alarm will be
generated after the relevant trip or close pulses have expired. These alarms can be
viewed on the relay LCD display or can be assigned to operate output contacts for
annunciation using the relays programmable scheme logic (PSL).
5.3 Trip relays

Relays 1, 2, and 3 of PU are used for tripping relays : busbar protection, overcurrent
protection and back-trip breaker failure from CU. Even if relay 1, 2, and 3 are not
used is PSL, there are closed if there is trip command from these functions. However
these relays can be affected in PSL for additional functions (breaker-failure retrip for
example).
The settings [CB CONTROL, Prot Trip Pulse] is parameter for Dwell timer used to
assure a minimum tripping duration on relay 1, 2, and 3.
5.4 Suggested Trip Circuit Supervision using psl editor

The scheme shown in Figure 18 is designed to provide full H7 compliant trip circuit
supervision.
The object of this arrangement is to ensure that all wiring in the trip circuit is
monitored, regardless of circuit breaker state. Furthermore the open circuit or short
circuit failure of any component in the supervision path would not cause a circuit
breaker trip.
P3776ENa
Figure 18: Trip Circuit Supervision

As previously mentioned the resistors should be sized so that shorting of any one
device will not lead to a trip:-
− With R1 and R2 in parallel and R3 shorted on CB operation if 52a and 52b
overlap, current must be small
− With just R2 in circuit, current is typically 2mA
− With R3 + (R1 // R2) in circuit, current is typically 2mA
P3777ENa
Figure 19: Trip Circuit Supervision – CB Closed

Figure 19 shows the trip circuit supervision current path with breaker closed. It can
be seen that all the wires in the trip circuit, plus the trip coil are supervised.
P3778ENa
Figure 20: Trip Circuit Supervision – CB Open

Figure 20 shows the trip circuit supervision current path with breaker open. It can be
seen that all the wires in the trip circuit, plus the trip coil are supervised. This provides
full “pre-closing” supervision
Suggested resistor values are shown in the table below.
Opto Tested to meet Resistor Values (ohms) Drain Current in

Voltage Minimum Voltage circuit/ through
Range (DC) (80% of lower DC trip coil
voltage rating)
R1=R2=1.2K
48/54 38.4 2mA
R3=0.6K
R1=R2=2.5K
110/125 88.0 2mA
R3=1.2K
R1=R2=5K
220/250 176.0 2mA
R3=2.5K
Table 18 Trip circuit supervision resistor requirements
Due to the fact that under the circuit conditions shown, the effect of the trip coil
inductance in the circuit causes the drop off voltage of the opto-input circuit output to
become unstable at 24.1V. Therefore this circuit should only be employed for opto-
input applications between 48 and 250V.
For guaranteed operation it is recommended that the opto-inputs be set to the
voltage settings below:
Applied Relay Voltage Setting

voltage (DC)
48/54 24
110/125 48
220/250 110
Table 19 Trip circuit supervision opto input voltage settings

For correct operation of the trip circuit supervision the following logic must be
implemented in the PSL:
400
Opto Input 52a
Pick-Up Relay Contact
0
400
Any Trip Pick-Up Latching LED

0
P3733ENa
Figure 21: PSL for Trip Circuit Supervision

6. ISOLATION AND REDUCED FUNCTION MODE

The scheme permits maintenance on the busbar and, or busbar protection whilst
maintaining some form of protection if possible. Two levels in the Central Unit and
two levels in the Peripheral Units allow this to be possible. A command to one or
more of the affected units via the commissioning test menu will then force the scheme
to a selected (reduced) operating mode. The levels are as follows.
6.1 Central processing unit (P741)
A central instruction for a reduced operation mode of the busbar protection on two
levels can be applied selectively zone by zone.
− Busbar monitoring – the busbar protection is monitored (87BB) only (i.e. trip
inhibited, measurements enabled). All other protection remains in service and
trips can still be issued for CBF conditions.
Trip orders for relevant CB’s by 50BF

21-50BF ... Trip orders by 87BB blocked
PU CU
P3734ENa
Figure 22: Central Unit: Busbar monitoring

Additionally, all protection functions are disabled when the system is awaiting
configuration downloads (topology is missing).
− Busbar & CBF disabled - both the busbar and circuit breaker fail conditions are
monitored but all trips are inhibited.
At least both No Trip orders

isolators or for relevant CB’s
CB closed 21-50BF ...
(Trip by 50BF & 87BB blocked)
PU CU
P3735ENa
Figure 23: CU – Busbar and Circuit Breaker Fail disabled

Under the condition shown in Figure 23, the circuit breaker is closed as is one of the
busbar isolators thereby connecting the feeder to a busbar. However all I/O is
disconnected and the protection is out of service. The peripheral unit still relays
information regarding the analogue values to the central unit but as the i/o is
effectively disconnected the scheme cannot respond to changes in plant position so
the differential element is deactivated for that zone.
If this case is true for all feeders the protection is in busbar and circuit breaker fail
disabled mode only (87BB) i.e. all trips inhibited, measurements enabled.
6.2 Peripheral Units (P742 and P743)
Three levels of command can be applied selectively to each peripheral unit.
− Normal operating conditions
− I/O disabled
− Out of Service
There also exists a “forcing ” function, which makes it possible, via the front panel
user interface, to modify the image of the switchgear positions of the associated bay.
This acts as a tool for commissioning, which makes it possible to check CT
orientation, as well as the LV wiring, by effectively modelling the primary plant
positions without having to interfere with the control circuits, can be used in
conjunction with the above operating modes.
Figure 24: PU – I/O disabled

In the mode shown in Figure 24 all inputs to and tripping contacts (RL1, RL2, RL3)
from the relay are effectively disconnected. The topology algorithm remembers the
plant positions prior to switching to maintenance status. As the peripheral unit
continues to monitor the analogue values the central unit will maintain a balanced
condition with the remainder of the system still in normal operation. However, the
local Overcurrent protection is still enabled and able to react to a fault condition by
creating a CB fail condition and back tripping the zone(s).
Figure 25: PU – Out of Service

In this mode the feeder is totally disconnected from the system. All I/O (tripping
contact only) is disconnected and no information is passed back to the central unit for
inclusion in zone calculations and hence the protection scheme. Hence the central
unit can keep the zone elements in service as the contribution of this feeder will be
zero. Whilst in this mode the peripheral unit can be tested locally for example
secondary injections tests can be carried out.
Figure 26: Forcing plant position state

Under certain conditions it may be desirable to force the positions of the primary
plant to enable scheme testing to be carried out, for example during commissioning.
This can be done via the user interface.
In the first example the forced scheme theoretically connects the feeder to busbar 2,
whilst in practice it is connected to busbar 1. Zone 1 will see a differential current
equal to –iload whilst zone 2 will see a differential current equal to +iload this will give a
check zone (ΣΣ idiff ) equal to zero.
In the second example the forced scheme theoretically totally disconnects the feeder.
An end zone or extra node, is created by the topology in order to fully replicate the
scheme. This lies between the feeder CT and the circuit breaker. However, it must be
remembered that in practice the feeder is still connected to busbar 1. Zone 1 will see
a differential current equal to –iload. This extra node will see a differential current
equal to +iload and which when included in the check zone (ΣΣ idiff ) will give a
result equal to zero.
Extra nodes (end zones) are covered in topology processing section 7.4.
Local
87BB 50BF I/O Tripping Meas
50/51
CU
BB Monitoring Monitored In service Not Disabled No 87BB Enabled
Applicable only input trips
BB & CBF Monitored Disabled Not Disabled No 87BB Enabled
disabled Applicable only input or 50BF
trips
System Blocked Blocked Not Disabled Disabled Disabled
configuration Applicable
& download
PU
I/O disabled Enabled Enabled In service Inputs Disabled Disabled
disabled on this on this
Only feeder. feeder.
tripping Enabled Enabled
relays RL1, for for
RL2, RL3 remainder remainder
disabled of scheme of scheme
Out of Service Enabled (no Enabled Out of Inputs Disabled Disabled
contribution service disabled on this on this
from this (for feeder Only feeder. feeder.
feeder) fault) tripping Enabled Enabled
relays RL1, for for
RL2, RL3 remainder remainder
disabled of scheme of scheme
Forcing Enabled Enabled Cleared Part Disabled Disabled
via 50BF enabled. on this on this
backtrip. Plant feeder. feeder.
positions Enabled Enabled
Enabled
forced to for for
req status remainder remainder
of scheme of scheme
Table 20 Reduce function mode summary

6.3 System operation under failed communications situation

With each start or reboot of CU, all the zones are set to BB and CBF disabled mode
as described above. They will remain in this mode until all peripheral units are
recognised as being in service and synchronised. (PU CONF & STATUS/PU in
service).
If a PU that was considered to be out of service but suddenly communicates with the
CU, the CU automatically places all zones to a waiting system configuration mode
while waiting for an input from the user to either assign the PU in service or
disconnect additional PUs.
During operation, if the communication with a PU is broken, the zone connected to
the CT of the non-communicating PU is temporarily suspended. If the
communication is restored, the differential protection is restored for the zone. On the
other hand, if the break in communications persists longer than permitted (ID>1
Alarm Timer), the zone protection is suspended.
For the reinstatement of the zone the user must intervene:
− If communication is restored the user must reset alarm by the same command
to reset circuitry fault (PU CONF & STATUS -> Reset circuitry)
− If the failed feeder needs to be withdrawn from service in order to replace a
faulty fibre the PU must be removed from the list of PUs in service.
On the PU, an alarm will indicate loss of communication with the CU.
On the CU, an alarm will indicate that one or more PUs are no longer synchronised.
In the PU CONF & STATUS column, it is possible to view the list of synchronised PU
(PU connected) after having altered the list of PU in service (PU in service).
If at the time of the initial startup, the topology of the substation was implemented
including futures (for example 15 PU including 6 extensions), it is possible to boot the
system only activating the existing 9 PUs in the cell PU in service.
When the future 6 PUs are connected, it will be sufficient to connect them and
indicate that they are now in service in the CU menu columns.
6.4 Waiting Configuration

Alarm “Config error” occurs when the configuration is incorrect:
− Topology download in relay does not correspond to this relay address
(be careful to erase topology by sending a default setting file)
− For CU: check the coherency of threshold:
ID>2 > IS > ID>1 and IDN>2 > ISN > IDN>1
7. TOPOLOGY
The topological analysis of the state of the sub-station in real time is one of the
primary factors of the reliability of numerical differential busbar protection. Thus in
the case of a power system fault, this analysis determines the sections of the
substation concerned with the fault and only takes those sections out of service. The
algorithms available for topological analysis make this level of discrimination
possible and it is these algorithms that are utilized in the P740 scheme.
7.1 Topology Configurator
For the P740 scheme the system topology is determined by replication of the circuit,
i.e. the connections between the various pieces of plant on the system, via a graphical
interface. This topological replication is carried out from a single line diagram of the
system, which is used to recreate the system using the topology configurator software.
This is carried out by AREVA personnel at an authorised AREVA competence centre.
P740 Scheme Editor P740 Synoptic

The topology configurator uses standard symbols for creating the system model by
simply dragging and dropping in the configurator screen.
Bar Link
Node
Current Transformer Feeder
Circuit Breaker (CB) Isolator
Figure 27: Topology configurator objects

The switchgear/busbars are then labelled and assigned to relevant peripheral units.
When the topology has been fully defined it is compiled and then downloaded to
each PU and the CU.
7.2 Nodal Assignment

Three files are created from the topological model. The first identifies each piece of
primary plant such as circuit breakers, isolators, current transformer (CT), bus section
and feeders. The second file identifies the connections between each piece of primary
plant and the third calculates the topological nodal assignment thus making it
possible to link to each peripheral unit with associated primary plant of the system.
Algorithms search to determine the electrical topology. These operate in real time in
the hardware of the P740 scheme. They start with the information obtained
regarding the state of the primary plant. A state table is created and associated with
each device. According to the algorithm, this state table gathers the data related to
the physical states of the primary plant taken by the unit.
The results of these algorithms are then subjects of a further algorithm, developed
from operational research. This algorithm identifies commonality between nodes and
merges nodes where appropriate. The new node includes all common nodes.
The principal characteristics of this algorithm mean that the scheme has the following
benefits:-
− Adaptability to various sub-station configurations
− Permanent identification of current nodes
− Permanent identification of physical links for each zone
− Reference to the neighbouring circuit breakers for each point of the circuit
These algorithms offer flexibility to the operator not met in non-numeric conventional
systems.
The global substation topology is updated every 33ms.
The above improve the overall function and discrimination of the protection scheme
and therefore reliability of the network.
7.3 Topology Communication
The peripheral units relay the information regarding their associated topological
model to the central unit. The central unit gathers the information from all attached
peripheral units and calculates the topological scheme for these as well as carrying
out the calculations for the system topology.
7.4 Topology data
Topology results are displayed in Central Unit and locally in Peripheral Units.
For the Central Unit, zones included in each current node are displayed in Topology
1 column and current transformer (or Peripheral Unit) included in each current node
are displayed in Topology 2 column.
For the Peripheral Unit, link between current transformer and zones are displayed in
Topology column.
Note: If the topology scheme is equipped with a transfer bus outside the protection
zone, this link is never reported in Topology column because current
transformer is connected to feeder.
7.5 Topology processing

The following scenarios demonstrate how the dynamic topology processing
accommodates anomalies and discrepancies in the scheme.
7.5.1 CTs on one side of bus coupler, CB closes before status acquisition.
Zone 1 BB1 ILOAD through CB BB2 Zone 2

EN 1
Idiff Z1 = 0 Idiff Z2 = + Iload
Idiff EN1
=-iload
CB CLOSED
but auxiliary
contact OPEN
P3742ENa
Check Zone Idiff = Σidiff = idiff Z1 + idiff EN1 + idiff EN2 + idiff Z2 = 0
Figure 28: CT’s on one side of bus coupler, CB closes before status
acquisition
As the CB has closed but the status has not yet been refreshed the topology still
believes the CB to be open.
Treating this as an open bus coupler circuit breaker the topology algorithm will have
created an end node (EN1). This is located between the CT and the circuit breaker.
This then fully replicates the scheme upto the open bus coupler CB on both sides.
Note that in this example zone 2’s limits now extend upto the circuit breaker.
If the circuit breaker was open no load current would flow through the circuit breaker
and hence the extra node. The differential current in the two main zones would equal
zero, as the current flowing into the zones would still equal the current flowing out,
and the current measured in the extra node would also be equal to zero.
However, if the circuit breaker is actually closed, the load current will flow through the
circuit breaker and the extra node. The differential current in main zone 1 will still
equal zero, as the current flowing into the zone will still equal the current flowing out,
but the current measured in the extra node and in main zone 2 will be equal in
magnitude but opposite in sign. (±iload)
Zone 1 would not operate and when the check zone element is calculated, the
differential currents seen in zone 2 and the extra node (idiffEN), which result from the
discrepancy in the plant status, can be seen to be cancelled out.
Check zone Idiff = Σidiff = idiffZ1+ idiffEN1 + idiffZ2 = 0 + (-iload) + (+iload) = ∅
Again the system retains its stability for discrepancies in plant status.
7.5.2 CTs on both sides of bus coupler, CB closes before status acquisition.
Zone 1 BB1 ILOAD through CB BB2 Zone 2

EN 1 EN 2
Idiff Z1 = 0 Idiff Z2 = 0
Idiff EN1 Idiff EN1
=-iload =+iload
CB CLOSED
but auxiliary
contact OPEN
P3743ENa
Check Zone Idiff = Σidiff = idiff Z1 + idiff EN1 + idiff EN2 + idiff Z2 = 0
Figure 29: CT’s on both sides of bus coupler, CB closes before status
acquisition
As the CB has closed but the status has not yet been refreshed the topology still
believes the CB to be open.
Treating this as an open bus coupler the topology algorithm will have created two
end nodes (EN1 and EN2). These are located between the CTs and the circuit
breaker. These then fully replicate the scheme upto the open bus coupler CB on both
sides.
If the circuit breaker was open no load current would flow through the circuit breaker
and hence the two extra nodes. The differential current in the two main zones would
equal zero, as the current flowing into the zones would still equal the current flowing
out, and the current measured in the extra nodes would also be equal to zero.
However, if the circuit breaker is actually closed, the load current will flow through the
circuit breaker and hence the two extra nodes. The differential current in the two
main zones will still equal zero, as the current flowing into the zone(s) will still equal
the current flowing out, but the current measured in the extra nodes will be equal in
magnitude but opposite in sign. (±iload)
The main zones would not operate and when the check zone element is calculated,
the differential currents seen in the extra nodes (idiffEN), which result from the
discrepancy in the plant status and which are taken into account for the check zone
calculation, can be seen to be cancelled out.
Check zone Idiff = Σidiff = idiffZ1+ idiffEN1 + idiffEN2 + idiffZ2 =0 + (-iload) + (+iload) = ∅
Hence, the system retains its stability even when there are discrepancies in plant
status.
7.5.3 CTs on one side of bus coupler, CB closed and fault evolves between CT and CB.
Zone 1 BB1 BB2 Zone 2
Idiff Z1 = 0 Idiff Z2 = ifault
P3744ENa
Figure 30: CT’s on one side of bus coupler, CB closed and fault evolves
between CB & CT
Treating this as a closed bus section circuit breaker the topology algorithm will have
extended the limits of the main zones to the bus coupler CT. This then fully replicates
the scheme.
Under normal operating conditions when the circuit breaker is closed load current
would flow through the circuit breaker and differential current in the two main zones
would equal zero, as the current flowing into the zones would still equal the current
flowing out.
However, if a fault was to occur between the CT and the circuit breaker the current
will flow from zone 1 into zone 2 which feeds the fault. The differential current in
main zone 1 will still equal zero, as the current flowing into the zone will still equal
the current flowing out, but the differential current measured in zone 2 will be equal
to that of the fault current.
In this case zone 2 would operate as will the check zone element.
Check zone Idiff = Σidiff = idiffZ1 + idiffZ2 = 0 + ifault = ifault > (ID>2)
However, when zone 2 trips the fault will still be present. The topology then analyses
the remainder of the system as follows.
Zone 1 BB1 Idiff EN1 = ifault BB2 Zone 2

EN 1
Idiff Z1 = 0
P3745ENa
Figure 31: Zone 2 tripped, fault still present

Treating this as an open bus coupler circuit breaker as before the topology algorithm
will have created an end node (EN1) which is located between the CT and the circuit
breaker. This then fully replicates the scheme upto the open bus coupler CB.
Remember that in this example zone 2’s limit extended upto the circuit breaker but
this zone has been tripped already.
As the topology algorithm updates scheme every 33ms this is the maximum time to
the creation of the extra node after auxiliary contact change of state.
The circuit breaker is now open and current would flow through the CT and into the
extra node to feed the fault. The differential current in the main zone would equal
zero, as the current flowing into the zone is still equal to the current flowing out,
whereas the current measured in the extra node will be equal to the fault current ifault.
Check zone Idiff = Σidiff = idiffZ1 + idiffEN = 0 + ifault = ifault
End zone Idiff = ifault
Hence, the system reacts to the continuing presence of the fault in the end zone and
trips the zone 1 as the check zone Idiff > (ID>2) and the end zone Idiff > (ID>2).
In this example it can be seen that the opposite zone is tripped first but the dynamic
topology reacts to the changed scheme and subsequently trips the adjacent main
zone.
7.5.4 CTs on both sides of coupler, CB closed and fault evolves between CT and CB.
Virtual Zone
Zone 1 BB1 = Z3 BB2 Zone 2
Idiff Z1= 0 Idiff Z2= 0
P3746ENa
Figure 32: CT’s both sides of bus coupler,

CB closed fault evolves between CT & CB
Treating this as a closed bus section circuit breaker the topology algorithm will have
created a virtual zone that surrounds the circuit breaker with the bus coupler CTs as
its limits called zone 3 in the event report and measurements. This then fully
replicates the scheme.
Under normal operating conditions when the circuit breaker is closed load current
would flow through the circuit breaker and hence the virtual zone. The differential
current in the two main zones would equal zero, as the current flowing into the zones
would still equal the current flowing out. This is also the case for the virtual zone
around the bus coupler.
However, if a fault was to occur in the virtual zone, current would flow into the virtual
zone and feed the fault. The differential current in the two main zones will still equal
zero, as the current flowing into the zone(s) will still equal the current flowing out, but
the differential current measured in the virtual zone will be equal to that of the fault
current.
The main zones would not operate but the virtual zone or zone 3, which surrounds
the bus coupler and has limits at the bus coupler CTs would operate. When the
check zone element is calculated, the differential current seen in the virtual zone or
zone 3, which results from the presence of the fault in the dead zone, will confirm the
presence of a fault and initiate a simultaneous trip of both main zones.
Check zone Idiff = Σidiff = idiffZ1+ idiffZ3 + idiffZ2 = ifault
Hence, the system reacts to a fault occurring between the CT and the CB
simultaneously tripping both adjacent zones.
When required, the bus coupler can operate first for a fault in the virtual zone or zone
3 and then the faulty zone 1 will remain in service. For such operation a special
topology scheme should be used.
8. PSL CONFIGURATION AND INTEGRATION

A standard PSL will be supplied, preloaded as with other relays in the MiCOM range.
The programmable scheme logic (PSL) is multi-functional and includes the following
options:
− Enables the mapping of opto-isolated inputs, relay output contacts and the
programmable LED's.
− Provides relay output conditioning (delay on pick-up/drop-off, dwell time,
latching or self-reset).
− Fault Recorder start mapping, i.e. which internal signals initiate a fault record.
− Enables customer specific scheme logic to be generated through the use of the
PSL editor inbuilt into the MiCOM S1 support software.
It is strongly recommended that due to the nature of busbar protection this PSL is not
modified after factory testing, unless modifications are carried out by competent
AREVA personnel. Further information regarding editing and the use of PSLs can be
found in the MiCOM S1 user manual. Note that changes to these defaults can only
be carried out using the PSL editor and not via the relay front plate.
The standard PSL is shown in Configuration/Mapping Chapter. The following section
details the default settings of the PSL.
8.1 Factory default settings
8.1.1 Logic input mapping
P741 P742 P743

1 L1 Reset Lached L1 Reset Latches L2 Reset Latches
2 L2 Ext. Start L2 Reset Latches L2 Reset Latches
Disturbance Recorder
3 L3 Reset Circuitry Fault L3 Q1 closed L3 Q1 close
4 L4 Ext. Check Zone L4 Q1 open L4 Q1 open
5 L5 Not used L5 Q2 closed L5 Q2 closed
6 L6 Not used L6 Q2 open L6 Q2 open
7 L7 Not used L7 CB Aux 3ph (52a) L7 CB Aux 3ph (52a)
8 L8 Not used L8 CB Aux 3ph (52b) L8 CB Aux 3ph (52b)
9 L9 Q3 closed L9 Q3 closed
10 L10 Q3 open L10 Q3 open
11 L11 Not Used L11 Not Used
12 L12 Ext 3Ph Trip L12 Ext 3Ph Trip
13 L13 CB not available L13 CB not available
14 L14 Ext CB Fail L14 Ext CB Fail
15 L15 Man CB Close cmd L15 Man CB Close cmd
16 L 16 Not Used L 16 Not Used
P741 P742 P743

17 L17 Not Used
18 L18 Not Used
19 L19 Not Used
20 L20 Not Used
21 L21 Not Used
22 L22 Not Used
23 L23 Not Used
24 L24 Not Used
Table 21 Logic input mapping

8.1.2 Relay output mapping
P741 P742 P743

1 R1 Fault phase A R1 Main trip Phase A R1 Main trip Phase A
2 R2 Fault phase B R2 Main trip Phase B R2 Main trip Phase B
3 R3 Fault phase C R3 Main trip Phase C R3 Main trip Phase C
4 R4 Z1 trip R4 Local CB failed R4 Local CB failed
5 R5 Z2 trip R5 Local CB not available R5 Local CB not available
6 R6 Circuitry fault R6 CB fail 3ph retrip R6 CB fail 3ph retrip
7 R7 Z1 off R7 Trip + end fault R7 Trip + end fault
8 R8 Z2 off R8 CB & isolator R8 CB & isolator
supervision supervision
9 R9 Not Used
10 R10 Not Used
11 R11 Not Used
12 R12 Not Used
13 R13 Not Used
14 R14 Not Used
15 R15 Not Used
16 R16 Not Used
17 R17 Not Used
18 R18 Not Used
19 R19 Not Used
20 R20 Not Used
21 R21 Not Used
Table 22 Relay output mapping

8.1.3 Relay output conditioning
P741 P742 P743

1 Pick-Up 0ms Pick-Up 0ms Pick-Up 0ms
9 Not Used
10 Not Used
11 Not Used
12 Not Used
13 Not Used
14 Not Used
15 Not Used
16 Not Used
17 Not Used
18 Not Used
19 Not Used
20 Not Used
21 Not Used
Table 23 Relay output conditioning

8.1.4 LED mapping
P741 P742 P743

1 Fault Phase A Q1 Position Closed Q1 Position Closed
2 Fault Phase B Q2 Position Closed Q2 Position Closed
3 Fault Phase C Q3 Position Closed Q3 Position Closed
4 Trip 87BB Not Used Not Used
5 Trip 50BF Local CB not available Local CB not available

6 Circuitry Fault Trip 87BB Trip 87BB
7 Not used Dead Zone Signal Dead Zone Signal
8 Not used Not used Not used
Table 24 LED mapping
8.1.5 LED output conditioning
P741 P742 P743

1 Latched Not latched Not latched
4 Latched Not Used Not Used
5 Latched Not Latched Not Latched
6 Not latched Latched Latched
7 Not Used Latched Latched
8 Not Used Not Used Not Used
Table 25 LED output conditioning
8.1.6 Fault recorder start mapping
P741 P742 P743

Any Trip Any Trip Any Trip
Table 26 Fault recorder start mapping

Should a specific modification be required to the standard PSL, this should be
specified at order and it will, where possible, be incorporated into the scheme build
and tested accordingly.
9. COMMUNICATIONS BETWEEN PU AND CU

The P740 scheme can be either centralised in one cubicle or distributed in cubicles
housing other protection depending on the availability of space. Either way the
peripheral units still need to communicate with the central unit and vice versa. Each
central unit has upto 8 communication boards each accommodating inputs from 4
peripheral units. Thus each central unit can accommodate up to 32 peripheral units.
9.1 Communications link
The following communication media is used for the communication channel within
the P740 scheme. The data rate is 2.5 Mbits/sec.
9.2 Direct optical fibre link, 850nm multi-mode fibre
The units are connected directly using two 850nm multi-mode optical fibres for each
signalling channel. Multi-mode fibre type 62.5/125µm is suitable and standard
BFOC/2.5 type fibre optic connectors are used. These are commonly known as “ST”
connectors (“ST” is a registered trademark of AT&T).
BB1 BB2
P742 P742
P742 P742
P742 P742 P742 P741 P742 P742 P742

P741
P742 P742 P742 P742 P742 P742
Peripheral units Peripheral units

Optical fibre Central unit Optical fibre
Figure 33: Module Interconnection

This is typically suitable for connection up to 1km.
9.3 Optical budgets

When using fibre optics as a method of communication the type of fibre used and the
distance between devices needs to be considered. The following table shows the
optical budgets of the communications interface.
Parameter 850nm Multi mode

Min. transmit output level (average power) -19.8dBm
Receiver sensitivity -25.4dBm
(average power)
Optical budget 5.6dB
Less safety margin (3dB) 2.6dB 3dB
Typical cable loss 2.6dB/km
Max. transmission distance 1km
Table 27 Optical Budget

The total optical budget is given by transmitter output level minus the receiver
sensitivity and will indicate the total allowable losses that can be tolerated between
devices. A safety margin of 3dB is also included in the above table. This allows for
degradation of the fibre as a result of ageing and any losses in cable joints. The
remainder of the losses will come from the fibre itself. The figures given are typical
only and should only be used as a guide.
10. UNDERTAKING A NUMERICAL DIFFERENTIAL BUSBAR PROTECTION

PROJECT
The substation construction will influence the protection scheme installed. It is
advisable that a scheme evaluation is conducted as soon as possible, preferably at
the same time as the definition of the equipment specification.
Only a few system parameters are required and it is vital that these are included.
10.1 General Substation information
− Number of independent zones
− Number of feeders, bus couplers, bus sections
− Positions of bus sections
− Positions of switchgear plant i.e. circuit breakers, isolators
− Positions of CTs
− Planned future extensions with circuit breaker, isolator and current transformer
(CT)
10.2 Short Circuit Levels
− Maximum external fault current (phase to phase and phase to ground faults)
− Minimum internal fault current (phase to phase and phase to ground faults)
10.3 Switchgear
− Nominal CT ratio
− Highest nominal primary current (CT In Max)
− Lowest nominal primary current (CT In Min)
− CT Knee point voltage (Vk)
− CT secondary resistance (RCT)
− Length and cross section of the conductors between CT and peripheral unit. (In
the absence of precise information, an estimate taken from the lowest CT ratio
will suffice).
− Auxiliary contacts of disconnecting switches and tripping orders for circuit
breaker failure (irrespective of the how the CB fail scheme is to be implemented
i.e. internally or externally initiated).
10.4 Cubicle specifications

Cubicle specification is contract specific.
However, AREVA propose the following:
− Single cubicle: 800x800x2000
− Double cubicle: 1600x800x2000
− Model: Schroff type Proline
− Color: RAL 7032
10.5 Substation Architecture
Due to the flexibility of the differential busbar protection there is an infinite number of
busbar configurations that can be accommodated via the topology. Each may have
very different architecture and, therefore, vary in complexity.
You will find in the following pages example topologies of layouts most frequently
encountered. For each example, the number of central units and peripheral units
necessary to protect the busbars is specified.
Generally, the elements of the protection architecture will be identified in a similar
manner to the principal parts of the sub-station e.g. by the letters A and B.
Note: A cubicle needs to be considered for a centralised solution
whereas if the peripheral units are distributed and the scheme is
distributed there is no requirement for a dedicated cubicle.
In both cases, and before any delivery, the topology will be thoroughly tested on
appropriate test platforms.
11. STANDARD CONFIGURATIONS

The following information relates only to the more common standard schemes. For
further information on the accommodation of other busbar configurations consult
your AREVA representative.
P3782ENa
Figure 34: Single busbar application with bus section isolator

The above example shows a single busbar with a bus section isolator. It is split into
two zones. There are n feeders connected to the busbar. This configuration requires
1 central unit and n + 1 peripheral units (the additional peripheral unit being for the
bus section isolator). The type of peripheral unit used for each bay will depend on
the i/o requirements of the bay in question.
P3783ENa
Figure 35: Single busbar application with bus section circuit breaker
The above example shows a single busbar with a bus section circuit breaker. It is split
into two zones. There are n feeders connected to the busbar. The bus section circuit
breaker has CTs on either side. This configuration requires 1 central unit and n + 2
peripheral units (the additional peripheral units being for the bus section CTs). The
type of peripheral unit used for each bay will depend on the i/o requirements of the
bay in question.
It is recommended that the CTs for feeder protection are sited such as to overlap with
the CTs defining the limits of each busbar protection zone.
P3784ENa
Figure 36: Breaker and a half scheme

The above example shows a breaker and a half scheme. The recommended solution
is to have two separate schemes. There are n feeders connected to each busbar.
Each scheme will require 1 central unit and n peripheral units. An other solution is to
use only one central unit and n peripheral units. The type of peripheral unit used for
each bay will depend on the i/o requirements of the bay in question.
P3785ENa
Figure 37: Double busbar application with bus coupler

The above example shows a double busbar with a bus coupler. It is split into two
zones. There are n feeders connected to the busbar. The bus coupler circuit breaker
can have either a single CT (solution 1) on one side or CTs on both sides (solution 2).
This configuration requires 1 central unit and n + 1 peripheral units for solution 1 or
n + 2 peripheral units for solution 2. (The additional peripheral units being for the
bus coupler CTs). The type of peripheral unit used for each bay will depend on the
i/o requirements of the bay in question.
P3786ENa
Figure 38: Traditional double busbar application with bus coupler and bus
section
The above example shows a double busbar with both a bus section and a bus
coupler. It is split into four zones. There are n feeders connected to the busbar. The
bus coupler and bus section circuit breakers can have either a single CT (solution 1
and 2) on one side or CTs on both sides (solution 1a or 2a). This configuration
requires 1 central unit and n plus the following number of peripheral units. The total
number of peripheral units required allows for a peripheral unit for the bus section
isolator on the upper bar.
Solution Solution A Solution B Solution C Solution D

1 CT on BC 2 CT on BC 1 CT on BC 2 CT on BC
& 1 CT on BS & 2 CT on BS & 2 CT on BS & 1 CT on BS
Solution 1 ! " ! "
Solution 1a " ! " !
Solution 2 ! " " !
Solution 2a " ! ! "
Number of n+3 n+5 n+4 n+4
peripheral units
required
If a second bus coupler is added i.e. one bus coupler either side of the bus section
Using solution 1 ! " ! "
for the 2nd
coupler
Using solution " ! " !
1a for the 2nd
coupler

peripheral units
required
Table 28 Number of required PU’s for figure 37

The number of additional peripheral units being dependant on the number of bus
section/bus coupler CTs. The type of peripheral unit used for each bay will depend
on the i/o requirements of the bay in question.
P3787ENa
Figure 39: Double busbar application with bus coupler and bus section with
additional bus section isolators
coupler. The bus section also has additional bus section isolators and allows for bus
section bypass. The scheme is split into four zones. There are n feeders connected to
the busbar. The bus coupler and bus section circuit breakers can have either a single
CT (solution 1 and 2) on one side or CTs on both sides (solution 1a or 2a). This
configuration requires 1 central unit and n plus the following number of peripheral
units. The total number of peripheral units required allow for a peripheral unit for the
bus section isolators.

Solution 1 ! " ! "
Solution 1a " ! " !
Solution 2 ! " " !
Solution 2a " ! ! "
peripheral units
required

for the 2nd
coupler
1a for the 2nd
coupler
peripheral units
required
P3788ENa
Figure 40: Double busbar application with bus coupler and double bus
section circuit breaker arrangement
coupler. There are circuit breakers on both the upper and lower bars. The scheme is
split into four zones. There are n feeders connected to the busbar. The bus coupler
and bus section circuit breakers can have either a single CT (solution 1 and 2) on one
side or CTs on both sides (solution 1a or 2a). This configuration requires 1 central
unit and n plus the following number of peripheral units. The total number of
peripheral units required allows for a peripheral unit for the bus section isolator on
the upper bar.

& 1 CT on & 2 CT on & 2 CT on & 1 CT on
each BS each BS each BS each BS
Solution 1 ! " ! "
Solution 1a " ! " !
Solution 2 ! " " !
Solution 2a " ! ! "
peripheral units
required
for the 2nd
coupler
1a for the 2nd
coupler
peripheral units
required

P3789ENa
Figure 41: Double busbar application with a bus coupler. The transfer
busbar is not included in the protection zone.
The above example shows a double busbar with a bus coupler and a transfer busbar.
As the transfer busbar is not included in the protected zone it can be considered
similarly to figure 37, but an additional peripheral unit must be included for the
transfer bay.
It is split into two zones. There are n feeders connected to the busbar. The bus
coupler circuit breaker can have either a single CT (solution 1) on one side or CTs on
both sides (solution 2). This configuration requires 1 central unit and n + 2
peripheral units for solution 1 or n + 3 peripheral units for solution 2. (The
additional peripheral units being for the bus coupler CTs and the transfer bay). The
type of peripheral unit used for each bay will depend on the i/o requirements of the
bay in question.
P3790ENa
Figure 42: Double busbar application with a bus coupler. The transfer
busbar is included in the protection zone.
The above example shows a double busbar with a bus coupler and a transfer busbar.
The transfer busbar is included in the protected zone. It can be considered similarly to
figure 36, where an additional peripheral unit has been included for the transfer bay.
The only difference being the positioning of the CT’s and therefore the peripheral
units.
Again it is split into two zones. With an additional zone for the transfer bay, there are
n feeders connected to the busbar. The bus coupler circuit breaker can have either a
single CT (solution 1) on one side or CTs on both sides (solution 2). This
configuration requires 1 central unit and n + 2 peripheral units for solution 1 or n +
3 peripheral units for solution 2. (The additional peripheral units being for the bus
coupler CTs and the transfer bay). The type of peripheral unit used for each bay will
depend on the i/o requirements of the bay in question.
P3791ENa
Figure 43: Triple busbar application with bus coupler and bus section
The above example shows a triple busbar with both a bus section and a bus coupler.
The bus section also has additional bus section isolators and allows for bus section
bypass. The scheme is split into six zones. There are n feeders connected to the
busbar. The bus coupler and bus section circuit breakers can have either a single CT
(solution 1 and 2) on one side or CTs on both sides (solution 1a or 2a). This
configuration requires 1 central unit and n plus the following number of peripheral
units. The total number of peripheral units required allows for a peripheral unit for
the bus section isolators.

Solution 1 ! " ! "
Solution 1a " ! " !
Solution 2 ! " " !
Solution 2a " ! ! "
peripheral units
required
for the 2nd
coupler
1a for the 2nd
coupler
peripheral units
required

P3792ENa INCLUDEPICTUREM
ERGEFORMAT
Figure 44: Double bus bar with two circuit breakers per feeder
The above example shows a double busbar with two circuit breakers on each feeder.
The scheme is split into two zones. There are n feeders connected to the busbar.
This configuration requires 1 central unit and 2n peripheral units. In each bay the
two peripheral units will share the CT, but each circuit breaker will be assigned to a
separate peripheral unit.
P3793ENa
Figure 45: Mesh Corner

The above example shows a mesh corner arrangement. The scheme is split into four
zones. This configuration requires 1 central unit and 12 peripheral units.
P3794ENa
Figure 46: Six main bus for s/s CB bus-sections and CB by-pass
The above example shows a six busbar arrangement with both a bus section and a
bus coupler. It is also possible to include bypass facilities. The scheme is split into six
zones. There are n feeders connected to the busbar. The bus coupler, bus section
and bypass circuit breakers can have either a single CT (solution 1, 2 and 3) on one
side or CTs on both sides (solution 1A, 2A and 3A).
This configuration requires 1 central unit and n plus the following number of
peripheral units.

Solution 1 ! " ! "
Solution 1a " ! " !
Solution 2 ! " " !
Solution 2a " ! ! "
peripheral units
required
If bypass facilities are to be included
3a
Number of n+5 n + 10 n+8 n+8
peripheral units
required
and no bypass facilities

for the 2nd
coupler
1a for the 2nd
coupler
Number of n+5 n + 10 n+8 n+7
peripheral units
required
and bypass facilities are included
3a
Number of n+6 n + 12 n+9 n + 10
peripheral units
required

12. MEASUREMENTS
The relay produces a variety of both directly measured and calculated power system
quantities. These measurement values are updated on a per second basis and are
summarised below:
− Phase currents: IA, IB, IC, IN
− Sequence currents: I0, I1, I2
− Differential and Bias currents: Idiff A, B, C, N and Ibias A, B, C, N
− check zone differential currents: Idiff CZ A, B, C, N
There are also measured values from the protection functions, which are also
displayed under the measurement columns of the menu; these are described in the
section on the relevant protection function.
For the Central Unit both bias and differential current for all zones, including the
check zone differential current are displayed in the Measurement columns in addition
to relevant zone bias and differential currents.
For the Peripheral Unit phase currents, phase currents and sequence current values
relating to the associated bay CT are displayed in the Measurement columns in
addition to relevant zone bias and differential currents.
12.1 Measured currents
The relay produces phase current values. They are produced directly from the DFT
(Discrete Fourier Transform) used by the relay protection functions and present both
magnitude and phase angle measurement.
12.2 Sequence currents
Sequence quantities are produced by the relay from the measured Fourier values;
these are displayed as magnitude values.
12.3 Settings
There are different set-up menus for the Central Unit P741 and the Peripheral Units
P742 and P743. The following settings under the heading Measurement Set-up can
be used to configure the relay measurement function in the P741.

SETTING
Default Display Description Description/Plant Reference/Frequency/Access
Level/3Ph + N Current/Date and Time
Common conventional ratio
Ibp Current Set 1,000A 1A 10,000A 1A
Table 33 Measurement Setup Column P741

The following settings under the heading Measurement Setup can be used to
configure the relay measurement function in the P742/P743.

SETTING
Default Display Description Description/Plant Reference/Frequency/Access
Level/3Ph + N Current/Date and Time
Local Values Secondary Primary/Secondary
Remote Values Primary Primary/Secondary
Table 34 Measurement Setup Column P742/P743
12.3.1 Common Conventional Ratio (Ibp)

This was discussed in section 4.2. Changing the ratio in this cell adjusts the base ratio
for the calculations over the entire scheme and no further setting changes need to be
carried out.
This current corresponds to primary values, which can be set to between 1A and
10,000A. In practice, a common base current of 1,000A is usually selected.
12.3.2 Default Display

This setting can be used to select the default display from a range of options, note
that it is also possible to view the other default displays whilst at the default level
using the ! and " keys. However, once the 15 minute timeout elapses the default
display will revert to that selected by this setting.
12.3.3 Local Values

This setting controls whether measured values via the front panel user interface and
the front Courier port are displayed as primary or secondary quantities.
12.3.4 Remote Values

This setting controls whether measured values via the rear communication port are
displayed as primary or secondary quantities.
13. EVENT & FAULT RECORDS

The relay records and time tags up to 250 events and stores them in non-volatile
(battery backed up) memory. This enables the system operator to establish the
sequence of events that occurred within the relay following a particular power system
condition, switching sequence etc. When the available space is exhausted, the oldest
event is automatically overwritten by the new one.
The real time clock within the relay provides the time tag to each event, to a
resolution of 1ms.
The event records are available for viewing either via the front plate LCD or remotely,
via the communications ports.
Local viewing on the LCD is achieved in the menu column entitled ‘VIEW RECORDS’.
This column allows viewing of event, fault and maintenance records. Different
columns exist in the Central unit and the Peripheral Unit. The column for the Central
Unit is shown below in table 35. The column displayed in the Peripheral Units is
shown in table 36.
VIEW RECORDS
LCD Text Description for CU
Last Record
Menu Cell Ref
Time & Date Time & Date Stamp for the event given by the internal
Real Time Clock
Record Text Up to 32 Character description of the occurrence (refer
to following sections)
Record Value Up to 32 bit binary flag or integer representative of the
occurrence (refer to following sections)
Select Fault Setting range from 0 to 4. This selects the required fault
record from the possible 5 that may be stored. A value
of 0 corresponds to the latest fault and so on.
Active Group Active group when fault recorder starts
Faulted Phase Phase initiating fault recorder starts
Start Elements Note relevant for CU
Trip Elements Trip 87BB, Trip 87BB block, Trip 50BF, Trip 50BF block,
Dead Zone signal, Manual trip zone.
Time Stamp Time and date of fault recorder start
Fault Alarms
System Frequency
Fault duration - if fault detected by differential protection => delay
between first detection of differential current and
disappearance of differential current
- if breaker failure order received from PU => delay
between reception of order and disappearance
IA diff Differential current of faulted zone
IB diff Differential current of faulted zone
VIEW RECORDS
LCD Text Description for CU
IC diff Differential current of faulted zone
IN diff Differential current of faulted zone
IA bias Differential current of faulted zone
IB bias Bias current of faulted zone
IC bias Bias current of faulted zone
IN bias Bias current of faulted zone
IA CZ diff Differential current of check zone
IB CZ diff Differential current of check zone
IC CZ diff Differential current of check zone
IN CZ diff Differential current of check zone
Faulted Zone Zone where fault is detected
Select Report (Maint) Setting range from 0 to 4. This selects the required
report from the possible 5 that may be stored. A value
of 0 corresponds to the latest report and so on.
The following cells show all the fault flags, protection
starts, protection trips, fault location, measurements etc.
associated with the fault, i.e. the complete fault record.
Report Text (Maint) Up to 32 Character description of the occurrence (refer
Type (Maint) These cells are numbers representative of the
occurrence. They form a specific error code which
should be quoted in any related correspondence to
AREVA.
Data
Reset Indication Either Yes or No. This serves to reset the trip LED
indications provided that the relevant protection element
has reset.
Table 35 View Records Column for the Central Unit
VIEW RECORDS
LCD Text Description for PU
Last Record
Menu Cell Ref
Time & Date Time & Date Stamp for the event given by the internal
Real Time Clock
Record Text Up to 32 Character description of the occurrence (refer
Record Value Up to 32 bit binary flag or integer representative of the
occurrence (refer to following sections)
Select Fault Setting range from 0 to 4. This selects the required fault
VIEW RECORDS
LCD Text Description for PU
record from the possible 5 that may be stored. A value
of 0 corresponds to the latest fault and so on.
Active Group Active group when fault recorder starts
Faulted Phase Phase initiating fault recorder starts
Start Elements Start I>1, Start I>2, Start I>2BB, Start I>BB, Start IN>1,
Start IN>2, Start IN>2BB, Start IN>BB
Trip Elements Trip I>1, Trip I>2, Trip IN>1, Trip IN>2, Trip 87BB,
Trip CBFail tBF1, Trip CBFail tBF2, Trip CBFail tBF3, Trip
CBFail tBF4, Trip 50BF (CU), Manual Trip zone, Trip
87BB block
Time Stamp Time and date of fault recorder start
Fault Alarms
System Frequency
Relay Trip Time Delay between reception of signal and end of trip on PU
IA Feeder currents
IB Feeder currents
IC Feeder currents
IN Feeder currents
Select Report (Main) Setting range from 0 to 4. This selects the required
report from the possible 5 that may be stored. A value
of 0 corresponds to the latest report and so on.
The following cells show all the fault flags, protection
starts, protection trips, fault location, measurements etc.
associated with the fault, i.e. the complete fault record.
Report Text (Maint) Up to 32 Character description of the occurrence (refer
Type (Maint) These cells are numbers representative of the
occurrence. They form a specific error code which
should be quoted in any related correspondence to
AREVA.
Data
Reset Indication Either Yes or No. This serves to reset the trip LED
indications provided that the relevant protection element
has reset.
Table 36 View Records Column for the Peripheral Unit

Note: That a full list of all the event types and the meaning of their
values is given in the Configuration/Mapping Chapter (P740/EN
GC/A11).
13.1 Types of Event

An event may be a change of state of control input or output relay, an alarm
condition, setting change etc. The following sections show the various items that
constitute an event:-
13.1.1 Change of state of opto-isolated inputs

If one or more of the opto (logic) inputs has changed state since the last time that the
protection algorithm ran, the new status is logged as an event. When this event is
selected to be viewed on the LCD, three applicable cells will become visible as shown
below;
Time & Date of Event

“LOGIC INPUTS”
“Event Value
0101010101010101”
The Event Value is an 8, 16 or 24 bit word showing the status of the opto inputs,
where the least significant bit (extreme right) corresponds to opto input 1 etc. The
same information is present if the event is extracted and viewed via PC.
13.1.2 Change of state of one or more output relay contacts

If one or more of the output relay contacts has changed state since the last time that
the protection algorithm ran, then the new status is logged as an event. When this
event is selected to be viewed on the LCD, three applicable cells will become visible
as shown below;
Time & Date of Event

“OUTPUT CONTACTS”
“Event Value
010101010101010101010”
The Event Value is an 8, 16 or 21-bit word showing the status of the output contacts,
where the least significant bit (extreme right) corresponds to output contact 1 etc. The
same information is present if the event is extracted and viewed via PC.
13.1.3 Relay alarm conditions

Any alarm conditions generated by the relays will also be logged as individual events.
The following table shows examples of some of the alarm conditions and how they
appear in the event list:-
Alarm Condition Resulting Event

Event Text Event Value
Battery Fail Battery Fail ON/OFF Number from 0 to 31
Field Voltage Fail Field V Fail ON/OFF Number from 0 to 31
Setting group via opto Setting Grp Invalid ON/OFF Number from 0 to 31
invalid
Protection Disabled Prot’n Disabled ON/OFF Number from 0 to 31
Frequency out of range Freq out of Range ON/OFF Number from 0 to 31
CB Trip Fail Protection CB Fail ON/OFF Number from 0 to 31
Table 37 Alarm Configuration Column
The previous table shows the abbreviated description that is given to the various
alarm conditions and also a corresponding value between 0 and 31. This value is
appended to each alarm event in a similar way as for the input and output events
previously described. It is used by the event extraction software, such as MiCOM S1,
to identify the alarm and is therefore invisible if the event is viewed on the LCD.
Either ON or OFF is shown after the description to signify whether the particular
condition has become operated or has reset.
13.1.3.1 Protection element starts and trips

Any operation of protection elements, (either a start or a trip condition), will be
logged as an event record, consisting of a text string indicating the operated element
and an event value. Again, this value is intended for use by the event extraction
software, such as MiCOM S1, rather than for the user, and is therefore invisible when
the event is viewed on the LCD.
13.1.3.2 General events

A number of events come under the heading of ‘General Events’ - an example is
shown below:-
Nature of Event Displayed text in event record Displayed value

Level 1 password modified, PW1 edited UI, F or R 0
either from user interface,
front or rear port
Table 38
A complete list of the ‘General Events’ is given in the Configuration/Mapping
Chapter (P740/EN GC).
13.1.3.3 Fault records

Each time a fault record is generated, an event is also created. The event simply
states that a fault record was generated, with a corresponding time stamp.
Note: That viewing of the actual fault record is carried out in the ‘Select
Fault’ cell further down the ‘VIEW RECORDS’ column, which is
selectable from up to 5 records. These records consist of fault
flags, fault measurements etc. Also note that the time stamp
given in the fault record itself will be more accurate than the
corresponding stamp given in the event record as the event is
logged some time after the actual fault record is generated.
13.1.3.4 Maintenance reports

Internal failures detected by the self-monitoring circuitry, such as watchdog failure,
field voltage failure etc are logged into a maintenance report. The Maintenance
Report holds up to 5 such ‘events’ and is accessed from the ‘Select Maint’ cell at the
bottom of the ‘VIEW RECORDS’ column.
Each entry consists of a self explanatory text string and a ‘Type’ and ‘Data’ cell, which
are explained in the menu extract at the beginning of this section and in further detail
in Configuration / Mapping Chapter (P740/EN GC).
Each time a Maintenance Report is generated, an event is also created. The event
simply states that a report was generated, with a corresponding time stamp.
13.1.3.5 Setting Changes

Changes to any setting within the relay are logged as an event. Two examples are
shown in the following table:-
Type of Setting Change Displayed Text in Event Record Displayed Value

Control/Support Setting C & S Changed 0
Group 1 Change Group 1 Changed 1
Table 39
Note: Control/Support settings are communications, measurement,
CT/VT ratio settings etc, which are not duplicated within the four
setting groups. When any of these settings are changed, the
event record is created simultaneously. However, changes to
protection or disturbance recorder settings will only generate an
event once the settings have been confirmed at the ‘setting trap’.
13.1.4 Resetting of event/fault records

If it is required to delete either the event, fault or maintenance reports, this may be
done from within the ‘RECORD CONTROL’ column.
13.1.5 Viewing event records via MiCOM S1 Support Software

When the event records are extracted and viewed on a PC they look slightly different
than when viewed on the LCD. The following shows an example of how various
events appear when displayed using MiCOM S1:-
As can be seen, the first line gives the description and time stamp for the event, whilst
the additional information that is displayed below may be collapsed via the +/-
symbol.
For further information regarding events and their specific meaning, refer to
Configuration / Mapping Chapter (P740/EN GC).
13.1.6 Event Filtering

It is possible to disable the reporting of events from any user interface that supports
setting changes. The settings, which control the various types of events, are in the
Record Control column.
The effect of setting each to disabled is as follows:
Alarm Event None of the occurrences that produce an alarm will result in
an event being generated.
The presence of any alarms is still reported by the alarm LED
flashing and the alarm bit being set in the communications
status byte.
Alarms can still be read using the Read key on the relay front
panel.
Relay O/P Event No event will be generated for any change in relay output
state.
Opto Input No event will be generated for any change in logic input state.
Event
General Event No General Events will be generated.
Fault Rec Event No event will be generated for any fault that produces a fault
record.
The fault records can still be viewed by operating the “Select
Maint”setting in column 0100.
Protection Event Any operation of protection elements will not be logged as an
event.
Table 40
Note: That some occurrences will result in more than one type of event,
e.g. a battery failure will produce an alarm event and a
maintenance record event.
If the Protection Event setting is Enabled a further set of settings is revealed which
allow the event generation by individual DDB signals to be enabled or disabled.
14. DISTURBANCE RECORDER

The integral disturbance recorder has an area of memory specifically set aside for
record storage. The number of records that may be stored is dependent upon the
selected recording duration but the relays typically have the capability of storing a
minimum of 20 records in the PU and 8 records in the CU, duration depends on the
unit, 1.2 seconds in the CU and 10.5 seconds in the PU. Disturbance records
continue to be recorded until the available memory is exhausted, at which time the
oldest record(s) are overwritten to make space for the newest one.
The recorder stores actual samples that are taken at a rate of 12 samples per cycle.
Minimum delay between 2 disturbance records (CU) is 5s.
Each disturbance record consists of eight analogue data channels and thirty-two
digital data channels. Note that the relevant CT ratios for the analogue channels are
also extracted to enable scaling to primary quantities).
The Disturbance recorder settings are different for the Central Unit and the Peripheral
Units as shown in the configuration columns below.
Note: When a 5A CT is used it must be ensured that the CT ratio
entered is ≥ 5:5 to ensure correct operation of the disturbance
recorder.
The ‘DISTURBANCE RECORDER’ menu column for the central unit is shown in table
41:-
MENU TEXT DEFAULT SETTING SETTING RANGE STEP SIZE

MIN MAX
DISTURB RECORDER
Duration 1.2s Fixed value
Trigger Position 50% 0 50% 17%
Trigger Mode Single Non settable
Analog Channel 1 IA diff
Analog Channel 2 IB diff
Analog Channel 3 IC diff
Analog Channel 4 IN diff
Analog Channel 5 IA bias
Analog Channel 6 IB bias
Analog Channel 7 IC bias
Analog Channel 8 IN bias
Digital Inputs 1 to 32 Relays 1 to 8 and Any of 8 O/P Contacts or Any of 8
Opto’s 1 to 8 Opto Inputs or Internal Digital
Signals
Table 41 Disturbance Recorder Menu Column for the Central Unit

The ‘DISTURBANCE RECORDER’ menu column for the peripheral unit is shown in
table 42:-
MENU TEXT DEFAULT SETTING SETTING RANGE STEP SIZE

MIN MAX
DISTURB RECORDER
Duration 1.5 0.1s 10.5s 0.01s
Trigger Position 33.3% 0 100% 0.1%
Trigger Mode Single Single or Extended
Analog Channel 1 IA
Analog Channel 2 IB
Analog Channel 3 IC
Analog Channel 4 IN
Analog Channel 5 Not used
Digital Inputs 1 to 32 Relays 1 to 8 and Any of 8 or 21 O/P Contacts or Any
Opto’s 1 to 16/24 of 16 or 24 Opto Inputs or Internal
Digital Signals
Inputs 1 to 32 No trigger except No trigger, Trigger L/H, Trigger H/L
Trigger dedicated trip relay
outputs which are set
to trigger L/H
Table 42 Disturbance Recorder Menu Column for the Peripheral Unit

Note: The available analogue and digital signals will differ between
relay types and models and so the individual Courier database
in Chapter Configuration/Mapping (P740/EN GC) should be
referred to when determining default settings etc.
The pre and post fault recording times are set by a combination of the ‘Duration’ and
‘Trigger Position’ cells. ‘Duration’ sets the overall recording time and the ‘Trigger
Position’ sets the trigger point as a percentage of the duration. For example, the
default settings for the peripheral units show that the overall recording time is set to
1.5s with the trigger point being at 33.3% of this, giving 0.5s pre-fault and 1s post
fault recording times.
If a further trigger occurs whilst a recording is taking place, the recorder will ignore
the trigger if the ‘Trigger Mode’ has been set to ‘Single’. However, if this has been
set to ‘Extended’, the post trigger timer will be reset to zero, thereby extending the
recording time.
As can be seen from the menu, each of the analogue channels is selectable from the
available analogue inputs to the relay. The digital channels may be mapped to any
of the opto isolated inputs or output contacts, in addition to a number of internal
relay digital signals, such as protection starts, LED’s etc. The complete list of these
signals may be found by viewing the available settings in the relay menu or via a
setting file in MiCOM S1. Any of the digital channels may be selected to trigger the
disturbance recorder on either a low to high or a high to low transition, via the ‘Input
Trigger’ cell. The default trigger settings are that any dedicated trip output contacts
(e.g. relay 3) will trigger the recorder.
It is not possible to view the disturbance records locally via the LCD; they must be
extracted using suitable software such as MiCOM S1.
15. COMMISSIONING TEST MENU

To help minimise the time required to test MiCOM relays the relay provides several
test facilities under the ‘COMMISSION TESTS’ menu heading. There are menu cells
which allow the status of the opto-isolated inputs, output relay contacts, internal
digital data bus (DDB) signals and user-programmable LEDs to be monitored.
Additionally there are cells to test the operation of the output contacts and user-
programmable LEDs.
The following table shows the commissioning test relay menu, including the available
setting ranges and factory defaults:
Menu text Default setting Settings

COMMISSION TESTS
Opto I/P Status - -
Relay O/P Status - -
Test Port Status - -
LED Status - -
Monitor Bits 64 to 71 step 1 per bit 0 to 511 step 1
Test Mode Disabled Enabled/Disabled
Test Pattern All bits set to 0 0 = Not Operated
1 = Operated
Contact Test No Operation No Operation
Apply Test
Remove Test
Test LEDs No Operation No Operation
Apply Test
87BB Monitoring All bits set to 0 0 = In Service
Each bit represents 1 1 = Out of Service
zone
87BB & 50BF disabled All bits set to 0 0 = In Service
Each bit represents 1 1 = Out of Service
zone
BB Trip Pattern All bits set to 0 0 = In Service
1 = Out of Service
BB Trip Command No Operation No Operation
Apply Test
Table 43 Commissioning Tests Column for CU

Menu text Default setting Settings

COMMISSION TESTS
Opto I/P Status - -
Relay O/P Status - -
Test Port Status - -
LED Status - -
Monitor Bits 64 to 71 step 1 per bit 0 to 511 step 1
Test Mode Disabled Enabled/Disabled
Test Pattern All bits set to 0 0 = Not Operated
1 = Operated
Contact Test No Operation No Operation
Apply Test
Remove Test
Test LEDs No Operation No Operation
Apply Test
Position Pattern 0 0 – 79 step 1
Position Test No operation No Operation
Apply Test
Table 44 Commissioning Tests Column for PU

15.1 Opto I/P status
This menu cell displays the status of the relay’s opto-isolated inputs as a binary string,
a ‘1’ indicating an energised opto-isolated input and a ‘0’ a de-energised one. If the
cursor is moved along the binary numbers the corresponding label text will be
displayed for each logic input.
It can be used during commissioning or routine testing to monitor the status of the
opto-isolated inputs whilst they are sequentially energised with a suitable dc voltage.
15.2 Relay O/P status
This menu cell displays the status of the digital data bus (DDB) signals that result in
energisation of the output relays as a binary string, a ‘1’ indicating an operated state
and ‘0’ a non-operated state. If the cursor is moved along the binary numbers the
corresponding label text will be displayed for each relay output.
The information displayed can be used during commissioning or routine testing to
indicate the status of the output relays when the relay is ‘in service’. Additionally fault
finding for output relay damage can be performed by comparing the status of the
output contact under investigation with it’s associated bit.
Note: When the ‘Test Mode’ cell is set to ‘Enabled’ this cell will
continue to indicate which contacts would operate if the relay
was in-service, it does not show the actual status of the output
relays.
15.3 Test Port status

This menu cell displays the status of the eight digital data bus (DDB) signals that have
been allocated in the ‘Monitor Bit’ cells. If the cursor is moved along the binary
numbers the corresponding DDB signal text string will be displayed for each monitor
bit.
By using this cell with suitable monitor bit settings, the state of the DDB signals can be
displayed as various operating conditions or sequences are applied to the relay.
Thus the programmable scheme logic can be tested.
As an alternative to using this cell, the optional monitor/download port test box can
be plugged into the monitor/download port located behind the bottom access cover.
Details of the monitor/download port test box can be found in section 6.11 of this
chapter.
15.4 LED status
The ‘LED Status’ cell is an eight bit binary string that indicates which of the
user-programmable LEDs on the relay are illuminated when accessing the relay from
a remote location, a ‘1’ indicating a particular LED is lit and a ‘0’ not lit.
THE MONITOR/DOWNLOAD PORT DOES NOT HAVE ELECTRICAL ISOLATED AGAINST
INDUCED VOLTAGES ON THE COMMUNICATIONS CHANNEL. IT SHOULD THEREFORE ONLY
BE USED FOR LOCAL COMMUNICATIONS.
15.5 Test mode
15.5.1 Test mode for PU

This cell is used to allow secondary injection testing to be performed on the relay,
without operation of the trip command, or commissioning of other relays in the same
bay as the PU, without mal-operation of the breaker failure protection. It also enables
the user to directly test the output contacts and the effect of plant position via the
application of controlled tests signals (forcing – see Sections 15.11 and 15.12).
Two test modes are available:
− In the ‘I/O disable’ mode, the busbar protection remains in service on the
feeder but no trip is possible on local breaker (tripping contacts RL1, RL2, RL3
disabled). The topology algorithm uses last known position of the circuit
breaker and isolator(s). Secondary injection cannot be carried out as it could
invoke a differential protection trip command.
− In the ‘Out of Service’ mode, the feeder must be physically disconnected from
any zone. The busbar protection does not take into account this feeder and it is
not possible to trip the breaker(tripping contacts RL1, RL2, RL3 disabled). The
topology algorithm uses last known position of the circuit breaker and
isolator(s). This mode allows secondary injection testing to be performed on the
relay.
When a test mode is select, the relay is out of service causing an alarm condition to
be recorded and the yellow ‘Out of Service’ LED to illuminate. Once testing is
complete the cell must be set back to ‘Disabled’ to restore the relay back to service.
15.5.2 Test mode for CU

This cell is used to allow commissioning of busbar and general breaker failure
protection. It also enables a facility to directly test the output contacts by applying
menu controlled tests signals. During the test mode, opto inputs and outputs contacts
remain in last known state before the test mode is selected.
To select test mode this cell should be set to ‘Enabled’ which takes the relay out of
service causing an alarm condition to be recorded and the yellow ‘Out of Service’
LED to illuminate. Once testing is complete the cell must be set back to ‘Disbled’ to
restore the relay back to service.
WHEN THE ‘TEST MODE’ CELL IS SET TO ‘ENABLED’, THE RELAY SCHEME LOGIC DOES NOT
DRIVE THE OUTPUT RELAYS AND HENCE THE CU WILL NOT TRIP THE ASSOCIATED CIRCUIT
BREAKER IF A BUSBAR FAULT OCCURS (COMMISSIONING MODE 1 AND 2).
HOWEVER, THE COMMUNICATIONS CHANNELS WITH REMOTE RELAYS REMAIN ACTIVE,

WHICH, IF SUITABLE PRECAUTIONS ARE NOT TAKEN, COULD LEAD TO THE REMOTE ENDS
TRIPPING WHEN CURRENT TRANSFORMERS ARE ISOLATED OR INJECTION TESTS ARE
PERFORMED.
15.6 Test pattern

The ‘Test Pattern’ cell is used to select the output relay contacts that will be tested
when the ‘Contact Test’ cell is set to ‘Apply Test’. The cell has a binary string with
one bit for each user-configurable output contact which can be set to ‘1’ to operate
the output under test conditions and ‘0’ to not operate it.
15.7 Contact test
When the ‘Apply Test’ command in this cell is issued the contacts set for operation
(set to ‘1’) in the ‘Test Pattern’ cell change state. After the test has been applied the
command text on the LCD will change to ‘No Operation’ and the contacts will remain
in the Test State until reset issuing the ‘Remove Test’ command. The command text
on the LCD will again revert to ‘No Operation’ after the ‘Remove Test’ command has
been issued.
Note: When the ‘Test Mode’ cell is set to ‘Enabled’ the ‘Relay O/P
Status’ cell does not show the current status of the output relays
and hence can not be used to confirm operation of the output
relays. Therefore it will be necessary to monitor the state of each
contact in turn.
15.8 Test LEDs
When the ‘Apply Test’ command in this cell is issued the eight user-programmable
LEDs will illuminate for approximately 2 seconds before they extinguish and the
command text on the LCD reverts to ‘No Operation’.
15.9 Busbar Monitoring (only in CU)

The ‘BB monitoring’ cell is used to select the status of each zone. This cell has a
binary string with one bit per zone which can be set to ‘1’ to disable busbar
protection and ‘0’ to keep the zone in operating mode. When a zone is set to ‘1’, the
current sum calculation remains active for monitoring but a trip order cannot be
generated by the busbar protection, only from the breaker failure protection. Zones
can be in busbar monitoring when others zones remain active.
15.10 Busbar (BB) & Circuit Breaker Fail (CBF) Disable (only in CU)
The ‘BB & CBF disable’ cell is used to select the status of each zone. This cell has a
binary string with one bit per zone which can be set to ‘1’ to disable busbar &
breaker failure protection and ‘0’ to maintain the zone in operating mode. When a
zone is set to ‘1’, the current sum calculation remains active for monitoring but trip
orders cannot be sent by either the busbar protection or the breaker failure
protection. Zones can be in ' BB & CBF disable ' when others zones remain active.
15.11 Position Pattern (only in PU)
The ‘Position Pattern’ cell is used to force the position of the circuit breaker and
isolator in the topology algorithm when the ‘Position Test’ cell is set to ‘Apply Test’.
This cell has a binary string with one bit per each isolator and one for circuit breaker.
These can be set to ‘1’ to simulate the closed position or ‘0’ to simulate the open
position.
15.12 Position Test (only in PU)
When the ‘Apply test’ command in this cell is issued, the states set in the position
pattern cell are sent to the topology algorithm. After the test has been applied the
command text on the LCD will change to ‘No operation’ and the topology does not
change until the ‘Remove Test’ command has been applied.
16. MONITOR TOOL

Software monitor of MiCOM S1 is designed for 8 zones substation. Consequently, if
you open connection with P741 which protects 4 zones substation, there are error
message to inform you that cells corresponding to topology and measurements of
zone 5 to 8 can not be displayed.
You can use monitor tool even if this error message appears.
To remove error message, you have to remove cells in the default file :
• Open file celllist.txt with text editor (for example notepad). This file is
located in directory Monitor in the path of MiCOM S1 install (default is
c:\Programmes Files\AREVA\MiCOM S1\Monitor)
• Go to line [P741], referring to documentation “Menu Database -
P740/EN GC”
• Remove addresses of cell that you don’t want to display after the line
/Measurement.
For example, to remove cell [Topology 1, Current node 5], delete line
0405
• Save file
Later if you want to display new zone, do reverse operation.
Technical Data P740/EN TD/D11
TECHNICAL DATA
P740/EN TD/D11 Technical Data
CONTENTS
1. REFERENCE CONDITIONS 3
2. PROTECTION FUNCTIONS 3
3. CONTROL 12
4. MEASUREMENTS AND RECORDING FACILITIES 13
5. POST FAULT ANALYSIS 14
6. PLANT SUPERVISION 16
7. LOCAL AND REMOTE COMMUNICATIONS 17
8. DIAGNOSTICS 18
9. RATINGS 19
10. CT REQUIREMENTS (P740 RANGE) 22
11. HIGH VOLTAGE WITHSTAND (P740 RANGE) 25
12. ELECTRICAL ENVIRONMENT 26
13. ATMOSPHERIC ENVIRONMENT 31
14. MECHANICAL ENVIRONMENT 32
15. INFLUENCING QUANTITIES 34
16. MISCELLANEOUS 35
17. EC EMC COMPLIANCE (P740 RANGE) 36
18. EC LVD COMPLIANCE (P740 RANGE) 36

1. REFERENCE CONDITIONS
The accuracy claims within this document are relevant for relays operating under the
following reference conditions.
Quantity Reference conditions Test tolerance

General
Ambient temperature 20 °C ±2°C
Atmospheric pressure 86kPa to 106kPa -
Relative humidity 45 to 75 % -
Input energising quantity Reference conditions Test tolerance

Current Ιn ±5%
Voltage Vn ±5%
Frequency 50 or 60Hz ±0.5%
Auxiliary supply DC 24V, 48V or 110V ±5%
AC 63.5V or 110V
Settings Reference value

Time Multiplier Setting 1.0
Time Dial 7
2. PROTECTION FUNCTIONS
The following functional claims are applicable to the P740 range of busbar differential
relays.
Note however that not all the protection functions listed below are applicable to every
relay.
2.1 Phase busbar differential protection
2.1.1 Phase current biased differential characteristic settings
Name Range Step Size

Ιs [0.02 - 1.0] x Ιbp 0.01 x Ιbp
ΙD>2 [0.1 – 4] x Ιbp 0.01x Ιbp
K 20 – 90% 1%
Characteristic shape determined by the following formula:

For Ιdiff greater than: ΙD>2
|Ιdiff| = k|Ιbias|+ ΙS
Idiff
0perate
Differential
Current
Percentage
bias k
Restrain
ID>2
IS
ID>1
Bias Current Ibias
2.2 Earth fault busbar differential protection
2.2.1 Earth current biased differential characteristic settings

ΙSN [0.02 - 1.0] x Ιbp 0.01 x Ιbp
ΙDN>2 [0.03 – 2] x Ιbp 0.01x Ιbp
K 20 – 90% 1%
Characteristic shape determined by the following formula:

For Ιdiff greater than: ΙDN>2
|Ιdiff| = k|Ιbias|+ ΙSN
Idiff
0perate
Differential
Current
Percentage
bias k
Restrain
IDN>2
ISN
IDN>1
Bias Current Ibias

2.3 Three Phase Overcurrent Protection
2.3.1 Setting ranges
Stage Range Step size

Phase element 1st Stage 0.1 – 32Ιn 0.01Ιn
" " 2nd Stage 0.1 – 32Ιn 0.01Ιn
2.3.2 Time delay settings

Each overcurrent element has an independent time setting and each time delay is
capable of being blocked by an optically isolated input:
Element Time delay type

1st Stage Definite Time (DT) or IDMT
2nd Stage DT
Curve type Reset time delay

IEC / UK curves DT only
All other IDMT or DT
2.3.2.1 Inverse Time (IDMT) Characteristic

IDMT characteristics are selectable from a choice of four IEC/UK and five IEEE/US
curves as shown in the table below.
The IEC/UK IDMT curves conform to the following formula:
 K 
t = T ×  α + L
 (I Is ) −1 
The IEEE/US IDMT curves conform to the following formula:
TD  K 
t= × + L
7  (I Is )α
−1

Where: t = operation time
K = constant
ΙS = current threshold setting
α = constant
L = ANSI/IEEE constant (zero for IEC/UK curves)
T = Time Multiplier Setting for IEC/UK curves
TD = Time Dial Setting for IEEE/US curves
IDMT Curve description Standard K Constant α Constant L Constant

Standard Inverse IEC 0.14 0.02 0
Very Inverse IEC 13.5 1 0
Extremely Inverse IEC 80 2 0
Long Time Inverse UK 120 1 0
Moderately Inverse IEEE 0.0515 0.02 0.114
Very Inverse IEEE 19.61 2 0.491
Extremely Inverse IEEE 28.2 2 0.1217
Inverse US-C08 5.95 2 0.18
Short Time Inverse US-C02 0.02394 0.02 0.01694
2.3.2.2 Time Multiplier Settings for IEC/UK curves

TMS 0.025 to 1.2 0.025
2.3.2.3 Time Dial Settings for IEEE/US curves

TD 0.5 to 15 0.1
2.3.2.4 Definite Time Characteristic
Element Range Step Size

All stages 0 to 100s 10ms
2.3.2.5 Reset Characteristics

For all IEC/UK curves, the reset characteristic is definite time only.
For all IEEE/US curves, the reset characteristic can be selected as either inverse curve or
definite time.
The definite time can be set (as defined in IEC) to zero. Range 0 to 100 seconds in
steps of 0.01 seconds.
The Inverse Reset characteristics are dependent upon the selected IEEE/US IDMT curve
as shown in the table below.
All inverse reset curves conform to the following formula:
 TD   tr 

tReset =  ×
 7   1− (I Is ) 
α
Where: tReset = reset time

tr = constant
ΙS = current threshold setting
α = constant
TD = Time Dial Setting (Same setting as that employed by IDMT curve)
IEEE/US IDMT Standard tr Constant α Constant

Curve description
Moderately Inverse IEEE 4.85 2
Very Inverse IEEE 21.6 2
Extremely Inverse IEEE 29.1 2
Inverse US-C08 5.95 2
Short Time Inverse US-C02 2.261 2
Inverse Reset Characteristics
2.3.3 Accuracy
Pick-up Setting ±5%

Drop-off 0.95 x Setting ±5%
Minimum trip level of IDMT elements 1.05 x Setting ±5%
IDMT characteristic shape ±5% or 40ms whichever is greater
(under reference conditions)*
IEEE reset ±5% or 40ms whichever is greater
DT operation ±2% or 50ms whichever is greater
DT reset Setting ±5%
Directional boundary accuracy (RCA ±90°) ±2° hysteresis 2°
Characteristic UK curves IEC 60255-3 – 1998
US curves IEEE C37.112 – 1996
* Reference conditions TMS=1, TD=7 and Ι> setting of 1A, accuracy operating range
2-20Ιs
2.3.4 IEC IDMT Curves
IEC Curves
1000
100
Operating Time (Seconds)
10
Curve 4
Curve 1
1
Curve 2
Curve 3
0.1
1 10 100
Current (Multiple of Is)
Curve 1 Standard Inverse

Curve 2 Very Inverse
Curve 3 Extremely Inverse
Curve 4 UK Long Time Inverse
2.3.5 ANSI/IEEE IDMT curves
ANSI/IEEE Curves
100
10
Operating Time (Seconds)
1 Curve 5
Curve 6
Curve 9
Curve 8
Curve 8
0.1
1 10 100
Current (Multiple of Is)
Curve 5 IEEE Moderately inverse

Curve 6 IEEE Very inverse
Curve 7 IEEE Extremely inverse
Curve 8 US Inverse
Curve 9 US Short time inverse
2.4 Earth Fault Protection
2.4.1 Setting ranges
2.4.1.1 Earth Fault, Sensitive Earth Fault
Element Range Step Size

Earth Fault 1st Stage 0.1 - 32Ιn 0.01Ιn
" " 2nd Stage 0.1 - 32Ιn 0.01Ιn
2.4.2 EF time delay characteristics
The earth-fault measuring elements for EF and SEF are followed by an independently
selectable time delay. These time delays are identical to those of the Phase Overcurrent
time delay. The reset time delay is the same as the Phase overcurrent reset time.
2.4.3 Accuracy
2.4.3.1 Earth fault
Pick-up Setting ±5%

Drop-off >0.85 x Setting
Minimum trip level of IDMT elements 1.05 x Setting ±5%
IDMT characteristic shape ±5% or 40ms whichever is greater
(under reference conditions)*
IEEE reset ±10% or 40ms whichever is greater
DT operation ±2% or 50ms whichever is greater
DT reset ±5% or 50ms whichever is greater
Repeatability 7.5%
* Reference conditions TMS=1, TD=7 and ΙN> setting of 1A, accuracy operating
range 2-20Ιs
2.5 Transient Overreach and Overshoot
2.5.1 Accuracy
Additional tolerance due to increasing X/R ±5% over the X/R ratio of 1 to 90
ratios
Overshoot of overcurrent elements <40ms
2.6 Programmable scheme logic
2.6.1 Level settings

Time delay t 0-14400000ms 1ms
2.6.2 Accuracy
Output conditioner timer Setting ±2% or 50ms whichever is greater

Dwell conditioner timer Setting ±2% or 50ms whichever is greater
Pulse conditioner timer Setting ±2% or 50ms whichever is greater
3. CONTROL
The following claims for Control Functions are applicable to the P740 range of busbar
differential relays (model specific as detailed).
3.1 Display Control and Setting Groups
Settings Range Step size

Setting groups 1-4 1
3.1.2 Performance
Setting groups 4 independent setting groups including

independent programmable scheme logic for
each group.
3.2 Inhibit current differential protection
3.2.1 Performance
Current differential algorithm blocked by

Energising the opto input assigned to inhibit busbar differential Compliant
protection
Unhealthy communications link Compliant
Loss of power supply to any relay Compliant
4. MEASUREMENTS AND RECORDING FACILITIES

The following claims for Measurement & Recording facilities are applicable to the P740
range of busbar differential relays (model specific as detailed).
4.1 Measurements
Accuracy under reference conditions.
Measurand Range Accuracy

Phase current 0.05 to 3 Ιn ±1.0% of reading
Phase local current 0.05 to 3 Ιn ±1.0% of reading or ±(f-fn)/fn %
Phase remote current 0.05 to 3 Ιn ±1.0% of reading or ±(f-fn)/fn %
Phase differential 0.05 to 3 Ιn ±5.0%
current
Bias current 0.05 to 3 Ιn ±5.0%
Frequency 45 to 65Hz ±1%
4.2 IRIG-B and Real Time Clock
4.2.1 Features
Real time 24 hour clock settable in hours, minutes and seconds

Calendar settable from January 1994 to December 2092
Clock and calendar maintained via battery after loss of auxiliary supply
Internal clock synchronisation using IRIG-B
4.2.2 Performance
Year 2000 Compliant

Real time clock accuracy < ±2 seconds / day
External clock synchronisation Conforms to IRIG standard 200-98, format B
5. POST FAULT ANALYSIS

The following claims for Post Fault Analysis Functions are applicable to the P740 range
of busbar differential relays (model specific as detailed).
5.1 Fault Records
5.1.1 Features
Fault record generation on protection Time and date

operation indicating Setting group
Start / trip element
Faulted current magnitudes
Remote, bias and differential currents
Frequency
Protection operating time
Alarm events generated on the Protection disabled/test mode
following indications CB alarms
Frequency out of range
Battery status
Differential protection inhibited
Configuration / reconfiguration error
Field voltage fail
Signal fail alarm
differential fail alarm
Setting groups
5.1.2 Performance
Fault record display indication and information Correct

Alarm events display indication and information Correct
Time and date stamping ±10ms of applied fault/event
Fault Clearance time ±2%
CB operating time ±10ms
Protection operating time ±2%
5.2 Disturbance Records
Settings (P742, P743) Range Step size

Duration 0.1 – 10.5s 10ms
Trigger position 0 – 100% 0.1%
4 analogue channels, 32 digital channels
Settings (P741) Range Step size
Duration 1.2 s (Fixed)
Trigger position 0 – 50% 16.67%
8 analogue channels, 32 digital channels
5.2.2 Accuracy
Waveshape Comparable with applied quantities

Magnitude and relative phases ±5% of applied quantities
Duration ±2%
Trigger position ±2% (minimum trigger 100ms)
6. PLANT SUPERVISION
The following claims for Plant Supervision Functions are applicable to the P740 range
of Busbar differential relays (model specific as detailed).
6.1 CB State Monitoring Control, breaker fail and backtrip, breaker fail timer
Setting Range Step

Breaker fail timer 1 0 – 10s 0.01s
Breaker fail timer 2 0 – 10s 0.01s
6.1.2 Accuracy
Timers ±2% or 40ms whichever is greater

Reset <30ms
7. LOCAL AND REMOTE COMMUNICATIONS

The following claims for Local & Remote Communications are applicable to the P740
range of busbar differential relays (model specific as detailed).
7.1 Front Port
Setting
Protocol Courier
Message format IEC 60870-5 FT1.2
Baud rate 9 200 bits/s
7.2 Rear Port
Rear port settings Setting options Setting available for:

Physical links EIA(RS)485 or Fibre optic Courier
EIA(RS)485 only
Remote address 0 - 255 (step 1) Courier
Baud rate 64,000 bits/s Courier
Inactivity timer 1 - 30 minutes (step 1) All
7.2.1 Performance
Front and rear ports conforming to Courier communication protocol Compliant

8. DIAGNOSTICS
The following claims for Diagnostic Functions are applicable to the P740 range of
Busbar differential relays
8.1 Features
Power up self checking with watchdog indication of healthy condition

Watchdog and front display indication of a hardware or software failure occurring
during power up or during normal in service operation
8.2 Performance
Power up / continuous self checks Compliant

Watchdog operation Compliant
Co-processor failure detection Compliant
Time to power up < 11s
9. RATINGS
The following claims for Ratings are applicable to the P740 range of busbar differential
relays (model specific as detailed).
9.1 Nominal ratings
9.1.1 Currents (All P740 range)

Ιn = 1A or 5A ac rms.
Separate terminals are provided for the 1A and 5A windings, with the neutral input of
each winding sharing one terminal.
All current inputs will withstand the following, with any current function setting:
Withstand Duration
4 Ιn Continuous rating
4.5 Ιn 10 minutes
5 Ιn 5 minutes
6 Ιn 3 minutes
7 Ιn 2 minutes
30 Ιn 10 seconds
50 Ιn 3 seconds
100 Ιn 1 second
Pass Criteria Winding temperatures <105° C

Dielectric withstand and insulation resistance unimpaired
9.1.2 Auxiliary voltages P740 range

Three auxiliary power supply versions are available:
Nominal Ranges Operative dc range Operative ac range

24/54 V dc 19 - 65 V Not available
48/125 V dc (30/100 V ac rms.) ** 37 - 150 V 24 – 110 V
110/250 V dc (100/240 V ac rms.) ** 87 - 300 V 80 – 265 V
** rated for AC or DC operation.
Pass Criteria All functions operate as specified within the operative ranges
All power supplies operate continuously over their operative ranges,
and environmental conditions
9.1.3 ‘Universal’ Logic inputs (P740 range)
Battery Voltage (V dc) Logical “off” (V dc) Logical “on” (V dc)

24/27 <16.2 >19.2
30/34 <20.4 >24
48/54 <32.4 >38.4
110/125 <75 >88
220/250 <150 >176
9.1.4 Output contacts (P740 range)
Make & Carry 30A for 3s

Carry 250A for 30ms
10A continuous
Break DC: 50W resistive
DC: 37.5W inductive (L/R = 40ms)
AC: 1250VA
AC: 1250 inductive (P.F. = 0.7)
Maxima: 10A and 300V
Loaded contact: 10,000 operation minimum
Unloaded contact: 100,000 operations minimum
Watchdog Contact
Break DC: 30W resistive
DC: 15W inductive (L/R = 40ms)
AC: 275VA inductive (P.F. = 0.7)
9.1.5 Field voltage (P740 range)
Rated field voltage output 48V dc

Rated field voltage current limit 112mA ±20%
Operating range 40V to 60V
Alarm voltage 35 V ±5%
9.2 Burdens
9.2.1 Current (P742 and P743)
Reference current (Ιn)

Phase <0.15VA at rated current
9.2.2 Auxiliary voltage
P740 range
Typical values
Type Case size Minimum*

P741 Size 16”/80TE 37 to 41w
(8 Comms boards)
P742 Size 8”/40TE 16W to 23 W
P743 Size 12”/60TE 22W to 32 W
* no output contacts or optos energised

For each energised Opto powered from the Field Voltage or each energised Output
Relay:
Each additional energised opto 0.09W

input (24/27, 30/34, 48/54V)
Each additional energised opto 0.12W (110/125V)
input
Each additional energised opto 0.19W (220/250V)
input
Each additional energised output 0.13W
relay
9.2.3 Optically isolated inputs

Peak current of opto inputs when energised is 3.5mA (0-300V)
Maximum input voltage 300V dc (any setting).
10. CT REQUIREMENTS (P740 RANGE)

10.1 Notation
IF max maximum fault current (same for all feeders)

IF max int maximum contribution from a feeder to an internal fault (depends on
the feeder).
Inp CT primary rated current
In nominal secondary current (1A or 5A)
RCT CT secondary winding Resistance
RB Total external load resistance
Vk CT knee point voltage
SVA Nominal output in VA,
KSSC Short-circuit current coefficient (generally 20)
General recommendations for the specification of protection CTs use common rules of
engineering which are not directly related to a particular protection.
10.2 CT Specification according to IEC 185, 44-6 and BS 3938 (British Standard)
1. Class x according to British Standard: Minimum knee point voltage for saturation
Vk min = 0.25 x secondary IF max x (RCT + RB)
The recommended specification makes it possible to guarantee a saturation time >
1.4 ms with a remnant flux of 80 % of maximum flux (class X or TPX). This provides a
sufficient margin of security for CT saturation detection, which operates in less 1ms.
2. Class 5P to IEC 185. Conversion of class X (BS) with the 5P equivalent (IEC)
3. Class TPX and TPY according to IEC 44-6. IEC defines a composite error as a
percentage of a multiple of the rated current (IN) on a definite load SVA.
e.g. CT 1000/5 A – 50VA 5P 20.
This definition indicates that the composite error must be lower than 5%, for a primary
current of 20Inp when the external load is equal to 2 ohms (50VA to IN). If secondary
resistance, RCT, is known it is easy to calculate the magnetising EMF developed with the
fault current (20IN). Actually if the error is 5% (= 5A) with this EMF, the point of
operation is beyond the knee point voltage for saturation. By convention one admits
that the knee point voltage, Vk, is 80% of this value. For a conversion between a class
5P (IEC) and a class X (BS) CT one uses the relation:
Vk=0.8 X [(SVA x Kssc)/In + (RCT x Kscc x In) ]
SVA = (In x Vk/0.8 Kssc) – RCT x In ²
In particular cases, calculation could reveal values too low to correspond to industrial
standards. In this case the minima will be: SVA min = 10 VA 5P 20 which corresponds
to a knee point voltage of approximately Vkmin = 70 V at 5A or 350V at 1A. Class TPY
would permit lower values of power, (demagnetisation air-gap). Taking into account
the weak requirements of class X or TPX one can keep specifications common.
For accuracy, class X or class 5P current transformers (CTs) are strongly recommended.
The knee point voltage of the CTs should comply with the minimum requirements of
the formulae shown below.
Vk min ≥ 0.5 x (secondary If max) x (RCT + RB)
Where:
Vk = Required knee point voltage
RCT = CT secondary resistance
RB = Circuit impedance from CT to relay
If = Maximum value of through fault current for stability
(multiple of In)
10.3 Support of IEEE C Class CTs

MiCOM Px40 series protection is compatible with ANSI/IEEE current transformers as
specified in the IEEE C57.13 standard. The applicable class for protection is class “C”,
which specifies a non air-gapped core. The CT design is identical to IEC class P, or
British Standard class X, but the rating is specified differently. The following table
allows C57.13 ratings to be translated into an IEC/BS knee point voltage:
IEEE C57.13 – “C” Classification (volts)

CT Ratio RCT (ohm) 50 100 200 400 800
100/5 0.04 56.5 109 214 424 844
200/5 0.08 60.5 113 218 428 848
400/5 0.16 68.5 121 226 436 856
800/5 0.32 84.5 137 242 452 872
1000/5 0.4 92.5 145 250 460 880
1500/5 0.6 112.5 165 270 480 900
2000/5 0.8 132.5 185 290 500 920
3000/5 1.2 172.5 225 330 540 960
Table 1 IEC/BS Knee Point Voltage Vk offered by “C” class CTs

Assumptions:
4. For 5A CTs, the typical resistance is 0.002 ohms/secondary turn
5. IEC/BS knee is typically 5% higher than ANSI/IEEE knee
Given:
6. IEC/BS knee is specified as an internal EMF, whereas the “C” class voltage is
specified at the CT output terminals. To convert from ANSI/IEEE to IEC/BS
requires the voltage drop across the CTs secondary winding resistance to be
added.
7. IEEE CTs are always rated at 5A secondary
8. The rated dynamic current output of a “C” class CT (Kssc) is always 20 x In
Vk = (C x 1.05) + (In. Rct. Kssc)
Where:
Vk = Equivalent IEC or BS knee point voltage
C = C Rating
In = 5A
Rct = CT secondary winding resistance
Kssc = 20
11. HIGH VOLTAGE WITHSTAND (P740 RANGE)

11.1 Dielectric withstand, impulse, insulation resistance and ANSI test requirements
insulation test voltage
11.1.1 Impulse
IEC 60255-5:1977
5kV 1.2/50µs impulse, common and differential mode - input, power supply, &
terminal block communications connections.
11.1.2 Dielectric withstand

IEC 60255-5:1977
2kV rms. for 1 minute between all terminals connected together and case earth.
2kV rms. for 1 minute between all terminals of independent circuits with terminals on
each independent circuit connected together.
1kV rms. for 1 minute across watchdog contacts.
11.1.3 ANSI dielectric withstand

ANSI/IEEE C37.90. (1989) (Reaff. 1994)
1kV rms. for 1 minute across open contacts of the watchdog contacts.
1kV rms. for 1 minute across open contacts of changeover output contacts.
1.5kV rms. for 1 minute across normally open output contacts.
11.1.4 Insulation resistance

IEC 60255-5:1977
100 MΩ minimum.
12. ELECTRICAL ENVIRONMENT

12.1 Performance criteria
The following three classes of performance criteria are used within sections 12.2 to
12.12 (where applicable) to specify the performance of the MiCOM relay when
subjected to the electrical interference. The performance criteria are based on the
performance criteria specified in EN 50082-2:1995.
12.1.1 Class A
During the testing the relay shall not maloperate, upon completion of the testing the
relay shall function as specified. A maloperation shall include a transient operation of
the output contacts, operation of the watchdog contacts, reset of any of the relays
microprocessors or an alarm indication.
The relay communications and IRIG-B signal must continue uncorrupted via the
communications ports and IRIG-B port respectively during the test, however relay
communications and the IRIG-B signal may be momentarily interrupted during the
tests, provided that they recover with no external intervention.
12.1.2 Class B
During the testing the relay shall not maloperate, upon completion of the testing the
relay shall function as specified. A maloperation shall include a transient operation of
the output contacts, operation of the watchdog contacts, reset of any of the relays
microprocessors or an alarm indication. A transitory operation of the output LEDs is
acceptable provided no permanent false indications are recorded.
The relay communications and IRIG-B signal must continue uncorrupted via the
communications ports and IRIG-B port respectively during the test, however relay
communications and the IRIG-B signal may be momentarily interrupted during the
tests, provided that they recover with no external intervention.
12.1.3 Class C
The relay shall power down and power up again in a controlled manner within 5
seconds. The output relays are permitted to change state during the test as long as they
reset once the relay powers up.
Communications to relay may be suspended during the testing as long as
communication recovers with no external intervention after the testing.
12.2 Auxiliary supply tests, dc interruption, etc.
12.2.1 DC voltage interruptions

P740 Range
IEC 60255-11:1979.
DC Auxiliary Supply Interruptions 2, 5, 10, 20ms. Performance criteria - Class A.
DC Auxiliary Supply Interruptions 50, 100, 200ms, 40s. Performance criteria - Class
C.
12.2.2 DC voltage fluctuations

P740 range
IEC 60255-11:1979.
AC 100Hz ripple superimposed on DC max. and min. auxiliary supply at 12% of
highest rated DC.
Performance criteria - Class A.
12.3 AC voltage dips and short interruptions
12.3.1 AC Voltage short interruptions

P740 range
IEC 61000-4-11:1994.
AC Auxiliary Supply Interruptions 2, 5, 10, 20ms. Performance criteria - Class A.
AC Auxiliary Supply Interruptions 50, 100, 200ms, 1s, 40s. Performance criteria -
Class C.
12.3.2 AC voltage dips

P740 range
IEC 61000-4-11:1994
AC Auxiliary Supply 100% Voltage Dips 2, 5, 10, 20ms. Performance criteria - Class A.
AC Auxiliary Supply 100% Voltage Dips 50, 100, 200ms, 1s, 40s. Performance criteria
- Class C.
AC Auxiliary Supply 60% Voltage Dips 50, 100, 200ms, 1s, 40s. Performance criteria -
Class C.
AC Auxiliary Supply 30% Voltage Dips 50, 100, 200ms, 1s, 40s. Performance criteria -
Class C.
12.4 High Frequency Disturbance IEC 60255-22-1:1988 Class III. (P740 range)
1MHz burst disturbance test.
2.5kV common mode.
Power supply, field voltage, CTs, VTs, opto inputs, output contacts, IRIG-B and terminal
block communications connections.
1kV differential mode.
Power supply, field voltage, CTs, VTs, opto inputs and output contacts.
Performance criteria Class A.
12.5 Fast Transients (P740 range)

IEC 60255-22-4:1992 (EN 61000-4-4:1995), Class III and Class IV.
2kV 5kHz (Class III) and 4kV 2.5kHz (Class IV) direct coupling.
Power supply, field voltage, opto inputs, output contacts, CTs, VTs.
2kV 5kHz (Class III) and 4kV 2.5kHz (Class IV) capacitive clamp.
IRIG-B and terminal block communications connections.
12.6 Conducted / Radiated emissions (P740 range)
12.6.1 Conducted emissions

EN 55011:1998 Class A, EN 55022:1994 Class A.
0.15 - 0.5MHz, 79dBµV (quasi peak) 66dBµV (average).
0.5 - 30MHz, 73dBµV (quasi peak) 60dBµV (average).
12.6.2 Radiated emissions

EN 55011:1998 Class A, EN 55022:1994 Class A.
30 - 230MHz, 40dBµV/m at 10m measurement distance.
230 - 1000MHz, 47dBµV/m at 10m measurement distance.
12.7 Conducted / Radiated Immunity (P740 range)
12.7.1 Conducted immunity

EN 61000-4-6:1996 Level 3.
10V emf @ 1kHz 80% am, 150kHz to 80MHz.
Spot tests at 27MHz, 68MHz.
12.7.2 Radiated immunity

IEC 60255-22-3:1989 Class III (EN 61000-4-3: 1997 Level 3).
10 V/m 80MHz - 1GHz @ 1kHz 80% am.
Spot tests at 80MHz, 160MHz, 450MHz, 900MHz.
12.7.3 Radiated immunity from digital radio telephones

ENV 50204:1995
10 V/m 900MHz ± 5 MHz and 1.89GHz ±5MHz, 200Hz rep. freq., 50% duty cycle
pulse modulated.
12.8 Electrostatic Discharge (P740 range)
IEC 60255-22-2:1996 Class 3 & Class 4.
Class 4: 15kV air discharge.
Class 3: 6kV contact discharge.
Tests carried out both with and without cover fitted.
12.9 Surge Immunity (P740 range)
IEC 61000-4-5:1995 Level 4.
4kV common mode 12Ω source impedance, 2kV differential mode 2Ω source
impedance.
Power supply, field voltage, CTs, VTs.
4kV common mode 42Ω source impedance, 2kV differential mode 42Ω source
impedance.
Opto inputs, output contacts.
4kV common mode 2Ω source impedance applied to cable screen.
Terminal block communications connections and IRIG-B.
Performance criteria Class A under reference conditions.
12.10 Power Frequency Interference (P740 range)
NGTS* 2.13 Issue 3 April 1998, section 5.5.6.9.
500V rms. common mode.
250V rms. differential mode.
Voltage applied to all non-mains frequency inputs. Interference applied to all
permanently connected communications circuits via the induced voltage method.
* National Grid Technical Specification
12.11 Surge Withstand Capability (SWC)

ANSI/IEEE C37.90.1 (1990) (Reaff. 1994)
Oscillatory SWC Test.
2.5kV – 3kV, 1 - 1.5MHz - common and differential mode – applied to all circuits
except for IRIG-B and terminal block communications, which are tested common mode
only via the cable screen.
Fast Transient SWC Tests
4 - 5kV crest voltage - common and differential mode - applied to all circuits except for
IRIG-B and terminal block communications, which are tested common mode only via
the cable screen.
Performance criteria Class A (see section 8.2).
12.12 Radiated Immunity
ANSI/IEEE C37.90.2 1995
35 V/m 25MHz - 1GHz, no modulation applied to all sides.
35 V/m 25MHz - 1GHz, 100% pulse modulated, front only.
Performance criteria Class A (see section 8.2).
12.13 Power Frequency Magnetic Field Immunity
IEC 61000-4-8:1994 Level 5.
100A/m field applied continuously in all planes for the EUT in a quiescent and tripping
state
1000A/m field applied for 3s in all planes for the EUT in a quiescent and tripping state
13. ATMOSPHERIC ENVIRONMENT

13.1 Temperature
IEC 60068-2-1:1990/A2:1994 - Cold
IEC 60068-2-2:1974/A2:1994 - Dry heat
IEC 60255-6:1988.
Operating temperature range °C Storage temperature range °C

Cold Dry heat Cold Dry heat
Temperature Temperature Temperature Temperature
-25 55 -25 70
13.2 Humidity
IEC 60068-2-3:1969
Damp heat, steady state, 40° C ± 2° C and 93% relative humidity (RH) +2% -3%,
duration 56 days.
IEC 60068-2-30:1980.
Damp heat cyclic, six (12 + 12 hour cycles) of 55°C ±2°C 93% ±3% RH and 25°C
±3°C 93% ±3% RH.
13.3 Enclosure protection
IEC 60529:1989.
IP52 Category 2.
IP5x – Protected against dust, limited ingress permitted.
IPx2 – Protected against vertically falling drops of water with the product in 4 fixed
positions of 15° tilt with a flow rate of 3mm/minute for 2.5 minutes.
14. MECHANICAL ENVIRONMENT

14.1 Performance criteria
The following severity classes are used, where applicable, to specify the performance to
specify the performance of the MiCOM relay, when subjected to mechanical testing.
14.1.1 Severity Classes

The following table details the Class and Typical Applications of the vibration, shock
bump and seismic tests detailed previously
Class Typical Application

1 Measuring relays and protection equipment for normal use in power
plants, substations and industrial plants and for normal
transportation conditions
2 Measuring relays and protection equipment for which a very high
security margin is required or where the vibration (shock and bump)
(seismic shock) levels are very high, e.g. shipboard application and
for severe transportation conditions.
14.1.2 Vibration (sinusoidal)
IEC 60255-21-1:1988
Cross over frequency - 58 to 60 Hz
Vibration Response
Severity Class Peak Peak Number of Frequency

displacement acceleration sweeps in each range (Hz)
below cross above cross axis
over frequency over frequency
(mm) (gn)
2 0.075 1 1 10 – 150
Vibration Endurance
Severity Class Peak Number of Frequency

acceleration sweeps in each range (Hz)
(gn) axis
2 2.0 20 10 – 150
14.1.3 Shock and bump

IEC 60255-21-2:1988
Type of test Severity Peak Duration of Number of

Class acceleration pulse Pulses in each
(gn) (ms) direction
Shock response 2 10 11 3
Shock withstand 1 15 11 3
Bump 1 10 16 1000
14.1.4 Seismic
IEC 60255-21-3:1993
Cross over frequency - 8 to 9Hz
x = horizontal axis, y = vertical axis
Severity Peak Peak Number of Frequency

Class displacement acceleration sweep cycles range (Hz)
below cross over above cross over in each axis
frequency (mm) frequency (gn)
x y x y
2 7.5 3.5 2.0 1.0 1 1- 35
15. INFLUENCING QUANTITIES

15.1 Harmonics (P740 range)
Tolerances quoted are an additional tolerance with respect to measured accuracy
without harmonics.
Harmonics applied 2nd – 17th 10% harmonics

Measurements / filtered relay inputs Unaffected by harmonics
15.2 Frequency (P740 Range)
Operating frequency 45Hz – 65Hz Affect

Overcurrent protection Unaffected by frequency
Earth fault protection Unaffected by frequency
Sensitive earth fault protection Unaffected by frequency
Disturbance recorder Unaffected by frequency
Differential protection Unaffected by frequency
16. MISCELLANEOUS
16.1 Analogue inputs, Logic inputs, Outputs relays (P740 range)
Relay 1A/5A dual Logic Output Output Test port

rated CTs inputs relays LEDs
P741 0 8 8 8 TTL logic
output
P742 4 16 8 8 TTL logic
output
P743 0 24 21 8 TTL logic
output
status status test pattern DDB*
displayed displayed available signals
on LCD on LCD on front mapped to
user front port
interface for test
purposes
*Digital Data Bus

16.2 Front user interface (P740 range)
All relay settings configurable from front user interface with the Compliant
exception of programmable scheme logic.
Back light inactivity timer 15 min.
±1min.
Two levels of password protection. Protection critical cells have Compliant
high level password protection with other cells requiring a lower or
no password
Password protection removable Compliant
16.3 Battery life (P740 range)
Battery life (assuming relay energised for 90% of time) > 10 years
Low battery voltage, failure or absence of battery will be indicated Compliant
The relay is protected against incorrect insertion of battery Compliant
Removal of the battery with the relay energised will no affect Compliant
records, events or real time clock
16.4 Frequency tracking (P740 range)
Relay will frequency track over its entire operating range 45 – 65Hz
The relay will frequency track off any current inputs Compliant
The relay will frequency track down to the following
Levels: Current
Effect of harmonic None, relay
tracks off
fundamental
frequency
16.5 K-Bus compatibility (P740 range)
Relay K-Bus interface compatible with other relays of different Compliant

product families using K-Bus.
Relay K-Bus port operates over 1km range with loading at either Compliant
end of transmission line.
17. EC EMC COMPLIANCE (P740 RANGE)

Compliance to the European Community Directive 89/336/EEC amended by
93/68/EEC is claimed via the Technical Construction File route.
The Competent Body has issued a Technical Certificate and a Declaration of
Conformity has been completed.
The following Generic Standards used to establish conformity:
EN 50081-2:1994
EN 50082-2:1995.
18. EC LVD COMPLIANCE (P740 RANGE)

Compliance with European Community Directive on Low Voltage 73/23/EEC is
demonstrated by reference to generic safety standards:
EN 61010-1:1993/A2: 1995
EN 60950:1992/A11 1997
Installation P740/EN IN/D11
MiCOM P740
INSTALLATION
P740/EN IN/D11 Installation
MiCOM P740
MiCOM P740 Page 1/9
CONTENTS
1. RECEIPT OF RELAYS 2
2. HANDLING OF ELECTRONIC EQUIPMENT 2
3. STORAGE 3
4. UNPACKING 3
5. RELAY MOUNTING 4
5.1 Rack mounting 5
5.2 Panel mounting 6
6. RELAY WIRING 7
6.1 Medium and heavy duty terminal block connections 7
6.2 RS485 port (P741 only) 8
6.3 IRIG-B connections (P741 only) 8
6.4 RS232 port 8
6.5 Download/monitor port 8
6.6 Earth connection 9
1. RECEIPT OF RELAYS
Protective relays, although generally of robust construction, require careful treatment

prior to installation on site. Upon receipt, relays should be examined immediately to
ensure no external damage has been sustained in transit.
If damage has been sustained, a claim should be made to the transport contractor
and AREVA T&D should be promptly notified.
Relays that are supplied unmounted and not intended for immediate installation
should be returned to their protective polythene bags and delivery carton.
Section 3 of this chapter gives more information about the storage of relays.
2. HANDLING OF ELECTRONIC EQUIPMENT
A person’s normal movements can easily generate electrostatic potentials of several

thousand volts. Discharge of these voltages into semiconductor devices when
handling electronic circuits can cause serious damage which, although not always
immediately apparent, will reduce the reliability of the circuit. This is particularly
important to consider where the circuits use complementary metal oxide
semiconductors (CMOS), as is the case with these relays.
The relay’s electronic circuits are protected from electrostatic discharge when housed
in the case. Do not expose them to risk by removing the front panel or printed circuit
boards unnecessarily.
Each printed circuit board incorporates the highest practicable protection for it’s
semiconductor devices. However, if it becomes necessary to remove a printed circuit
board, the following precautions should be taken to preserve the high reliability and
long life for which the relay has been designed and manufactured.
1. Before removing a printed circuit board, ensure that you are at the same
electrostatic potential as the equipment by touching the case.
2. Handle analogue input modules by the front panel, frame or edges of the
circuit boards. Printed circuit boards should only be handled by their edges.
Avoid touching the electronic components, printed circuit tracks or connectors.
3. Do not pass the module to another person without first ensuring you are both
at the same electrostatic potential. Shaking hands achieves equipotential.
4. Place the module on an anti-static surface, or on a conducting surface which is
at the same potential as yourself.
5. If it is necessary to store or transport printed circuit boards removed from the
case, place them individually in electrically conducting anti-static bags.
In the unlikely event that you are making measurements on the internal electronic
circuitry of a relay in service, it is preferable that you are earthed to the case with a
conductive wrist strap. Wrist straps should have a resistance to ground between
500kΩ to 10MΩ. If a wrist strap is not available you should maintain regular contact
with the case to prevent a build-up of electrostatic potential. Instrumentation which
may be used for making measurements should also be earthed to the case whenever
possible.
More information on safe working procedures for all electronic equipment can be
found in BS EN 100015:Part 1:1992. It is strongly recommended that detailed
investigations on electronic circuitry or modification work should be carried out in a
special handling area such as described in the aforementioned British Standard
document.
MiCOM P740 Page 3/9
3. STORAGE
If relays are not to be installed immediately upon receipt, they should be stored in a
place free from dust and moisture in their original cartons. Where de-humidifier
bags have been included in the packing they should be retained. The action of the
de-humidifier crystals will be impaired if the bag is exposed to ambient conditions
and may be restored by gently heating the bag for about an hour prior to replacing
it in the carton.
To prevent battery drain during transportation and storage a battery isolation strip is
fitted during manufacture. With the lower access cover open, presence of the battery
isolation strip can be checked by a red tab protruding from the positive side.
Care should be taken on subsequent unpacking that any dust which has collected on
the carton does not fall inside. In locations of high humidity the carton and packing
may become impregnated with moisture and the de-humidifier crystals will lose their
efficiency.
Prior to installation, relays should be stored at a temperature of between –25ûC to
+70ûC.
4. UNPACKING
Care must be taken when unpacking and installing the relays so that none of the
parts are damaged and additional components are not accidentally left in the
packing or lost.
Note: With the lower access cover open, the red tab of the battery isolation strip will
be seen protruding from the positive side of the battery compartment. Do not
remove this strip because it prevents battery drain during transportation and
storage and will be removed as part of the commissioning tests.
Relays must only be handled by skilled persons.
The site should be well lit to facilitate inspection, clean, dry and reasonably free from
dust and excessive vibration. This particularly applies to installations which are being
carried out at the same time as construction work.
5. RELAY MOUNTING
MiCOM relays are dispatched either individually or as part of a panel/rack

assembly.
Individual relays are normally supplied with an outline diagram showing the
dimensions for panel cut-outs and hole centres. This information can also be found
in the product publication.
Secondary front covers can also be supplied as an option item to prevent
unauthorised changing of settings and alarm status. They are available in sizes 40TE
(GN0037 001) and 60TE (GN0038 001). Note that the 60TE cover also fits the 80TE
case size of the relay.
The design of the relay is such that the fixing holes in the mounting flanges are only
accessible when the access covers are open and hidden from sight when the covers
are closed.
If a P991 or MMLG test block is to be included, it is recommended that, when viewed
from the front, it is positioned on the right-hand side of the relay (or relays) with
which it is associated. This minimises the wiring between the relay and test block,
and allows the correct test block to be easily identified during commissioning and
maintenance tests.
FIGURE 1: LOCATION OF BATTERY ISOLATION STRIP
If it is necessary to test correct relay operation during the installation, the battery
isolation strip can be removed but should be replaced if commissioning of the
scheme is not imminent. This will prevent unnecessary battery drain during
transportation to site and installation. The red tab of the isolation strip can be seen
protruding from the positive side of the battery compartment when the lower access
cover is open. To remove the isolation strip, pull the red tab whilst lightly pressing the
battery to prevent it falling out of the compartment. When replacing the battery
isolation strip, ensure that the strip is refitted as shown in Figure 1, ie. with the strip
behind the battery with the red tab protruding.
MiCOM P740 Page 5/9
5.1 Rack mounting
MiCOM relays may be rack mounted using single tier rack frames (our part number
FX0121 001), as illustrated in Figure 2. These frames have been designed to have
dimensions in accordance with IEC60297 and are supplied pre-assembled ready to
use. On a standard 483mm (19”) rack system this enables combinations of widths of
case up to a total equivalent of size 80TE to be mounted side by side.
The two horizontal rails of the rack frame have holes drilled at approximately 26mm
intervals and the relays are attached via their mounting flanges using M4 Taptite
self-tapping screws with captive 3mm thick washers (also known as a SEMS unit).
These fastenings are available in packs of 5 (our part number ZA0005 104).
Note: Conventional self-tapping screws, including those supplied for mounting
MIDOS relays, have marginally larger heads which can damage the front
cover moulding if used.
Once the tier is complete, the frames are fastened into the racks using mounting
angles at each end of the tier.
P0147XXb
FIGURE 2: RACK MOUNTING OF RELAYS
Relays can be mechanically grouped into single tier (4U) or multi-tier arrangements
by means of the rack frame. This enables schemes using products from the MiCOM
and MiDOS product ranges to be pre-wired together prior to mounting.
Where the case size summation is less than 80TE on any tier, or space is to be left for
installation of future relays, blanking plates may be used. These plates can also be
used to mount ancillary components. Table 1 shows the sizes that can be ordered.
Further details on mounting MiDOS relays can be found in publication R7012,
“MiDOS Parts Catalogue and Assembly Instructions”.
Case size summation Blanking plate part number

5TE GJ2128 001
10TE GJ2128 002
15TE GJ2128 003
20TE GJ2128 004
25TE GJ2128 005
30TE GJ2128 006
35TE GJ2128 007
40TE GJ2128 008
TABLE 1: BLANKING PLATES
5.2 Panel mounting
The relays can be flush mounted into panels using M4 SEMS Taptite self-tapping
screws with captive 3mm thick washers (also known as a SEMS unit).
These fastenings are available in packs of 5 (our part number ZA0005 104).
Note: Conventional self-tapping screws, including those supplied for mounting
MIDOS relays, have marginally larger heads which can damage the front
cover moulding if used.
Alternatively tapped holes can be used if the panel has a minimum thickness of
2.5mm.
For applications where relays need to be semi-projection or projection mounted, a
range of collars are available.
Where several relays are to mounted in a single cut-out in the panel, it is advised
that they are mechanically grouped together horizontally and/or vertically to form
rigid assemblies prior to mounting in the panel.
Note: It is not advised that MiCOM relays are fastened using pop rivets as this will
not allow the relay to be easily removed from the panel in the future if repair
is necessary.
If it is required to mount a relay assembly on a panel complying to BS EN60529
IP52, it will be necessary to fit a metallic sealing strip between adjoining relays (Part
no GN2044 001) and a sealing ring selected from Table 2 around the complete
assembly.
MiCOM P740 Page 7/9
Width Single tier Double tier

10TE GJ9018 002 GJ9018 018
15TE GJ9018 003 GJ9018 019
20TE GJ9018 004 GJ9018 020
25TE GJ9018 005 GJ9018 021
30TE GJ9018 006 GJ9018 022
35TE GJ9018 007 GJ9018 023
40TE GJ9018 008 GJ9018 024
45TE GJ9018 009 GJ9018 025
50TE GJ9018 010 GJ9018 026
55TE GJ9018 011 GJ9018 027
60TE GJ9018 012 GJ9018 028
65TE GJ9018 013 GJ9018 029
70TE GJ9018 014 GJ9018 030
75TE GJ9018 015 GJ9018 031
80TE GJ9018 016 GJ9018 032
TABLE 2: IP52 SEALING RINGS
Further details on mounting MiDOS relays can be found in publication R7012,

“MiDOS Parts Catalogue and Assembly Instructions”.
6. RELAY WIRING
This section serves as a guide to selecting the appropriate cable and connector type
for each terminal on the MiCOM relay.
6.1 Medium and heavy duty terminal block connections
Loose relays are supplied with sufficient M4 screws for making connections to the
rear mounted terminal blocks using ring terminals, with a recommended maximum
of two ring terminals per relay terminal.
If required, AREVA T&D can supply M4 90° crimp ring terminals in three different
sizes depending on wire size (see Table 3). Each type is available in bags of 100.
Part number Wire size Insulation colour

ZB9124 901 0.25 – 1.65mm2 (22 – 16AWG) Red
ZB9124 900 1.04 – 2.63mm2 (16 – 14AWG) Blue
ZB9124 904 2.53 – 6.64mm2 (12 – 10AWG) Uninsulated*
TABLE 3: M4 90° CRIMP RING TERMINALS
* To maintain the terminal block insulation requirements for safety, an insulating

sleeve should be fitted over the ring terminal after crimping.
The following minimum wire sizes are recommended:

Current Transformers 2.5mm2
Auxiliary Supply, Vx 1.5mm2
RS485 Port See separate section
Other circuits 1.0mm2
Due to the limitations of the ring terminal, the maximum wire size that can be used
for any of the medium or heavy duty terminals is 6.0mm2 using ring terminals that
are not pre-insulated. Where it required to only use pre-insulated ring terminals, the
maximum wire size that can be used is reduced to 2.63mm2 per ring terminal. If a
larger wire size is required, two wires should be used in parallel, each terminated in
a separate ring terminal at the relay.
The wire used for all connections to the medium and heavy duty terminal blocks,
except the RS485 port, should have a minimum voltage rating of 300Vrms.
It is recommended that the auxiliary supply wiring should be protected by a 16A high
rupture capacity (HRC) fuse of type NIT or TIA. For safety reasons, current
transformer circuits must never be fused. Other circuits should be appropriately fused
to protect the wire used.
6.2 RS485 port (P741 only)
Connections to the RS485 port are made using ring terminals. It is recommended
that a 2 core screened cable is used with a maximum total length of 1000m or
200nF total cable capacitance. A typical cable specification would be:
Each core: 16/0.2mm copper conductors
PVC insulated
Nominal conductor area: 0.5mm2 per core
Screen: Overall braid, PVC sheathed
6.3 IRIG-B connections (P741 only)
The IRIG-B input and BNC connector have a characteristic impedance of 50Ω. It is
recommended that connections between the IRIG-B equipment and the relay are
made using coaxial cable of type RG59LSF with a halogen free, fire retardant
sheath.
6.4 RS232 port
Short term connections to the RS232 port, located behind the bottom access cover,
can be made using a screened multi-core communication cable up to 15m long, or
a total capacitance of 2500pF. The cable should be terminated at the relay end with
a 9-way, metal shelled, D-type male plug.
6.5 Download/monitor port
Short term connections to the download/monitor port, located behind the bottom
access cover, can be made using a screened 25-core communication cable up to 4m
long. The cable should be terminated at the relay end with a 25-way, metal shelled,
D-type male plug.
MiCOM P740 Page 9/9
6.6 Earth connection
Every relay must be connected to the local earth bar using the M4 earth studs in the
bottom left hand corner of the relay case. The minimum recommended wire size is
2.5mm2 and should have a ring terminal at the relay end. Due to the limitations of
the ring terminal, the maximum wire size that can be used for any of the medium or
heavy duty terminals is 6.0mm2 per wire. If a greater cross-sectional area is
required, two parallel connected wires, each terminated in a separate ring terminal
at the relay, or a metal earth bar could be used.
Note: To prevent any possibility of electrolytic action between brass or copper earth
conductors and the rear panel of the relay, precautions should be taken to
isolate them from one another. This could be achieved in a number of ways,
including placing a nickel-plated or insulating washer between the conductor
and the relay case, or using tinned ring terminals.
Before carrying out any work on the equipment, the user should be familiar
with the contents of the Safety and Technical Data sections and the ratings on
the equipment's rating label
Commissioning/Maintenance P740/EN CM/D11
COMMISSIONING AND
MAINTENANCE
P740/EN CM/D11 Commissioning/Maintenance

CONTENTS
1. INTRODUCTION 5
2. SETTING FAMILIARISATION 6
3. EQUIPMENT REQUIRED FOR COMMISSIONING 7
3.1. Minimum equipment required 7

3.2. Optional equipment 7
4. PRODUCT CHECKS 8
4.1. With the relay de-energised 8

4.1.1. Visual inspection 9
4.1.2. Current transformer shorting contacts 9
4.1.3. Insulation 11
4.1.4. External wiring 12
4.1.5. Watchdog contacts 12
4.1.6. Auxiliary supply 12
4.2. With the relay energised 13
4.2.1. Watchdog contacts 13
4.2.2. Date and time 13
4.2.3. Light Emitting Diodes (LED’s) 14
4.2.4. Field voltage supply 15
4.2.5. Input opto-isolators 15
4.2.6. Output relays 16
4.2.7. Current differential communications 17
4.2.8. Current inputs (P742, P743 only) 17
5. SETTING CHECKS 19
5.1. Apply application-specific settings 19

5.2. How to measure the Burden Resistance (RB) 20
5.3. Demonstrate Correct Relay Operation 20
5.3.1. Current Differential Bias Characteristic 22
5.3.2. Phase Overcurrent Protection (P742 and P743) 26
5.3.3. Breaker Failure Protection 28
5.4. Check Application Settings 30
6. END TO END TESTS 31
7. ON-LOAD CHECKS 31
8. FINAL CHECKS 32
9. MAINTENANCE 33
9.1. Maintenance period 33

9.2. Maintenance checks 33
9.2.1. Alarms 33
9.2.2. Opto-isolators 33
9.2.3. Output relays 33
9.2.4. Measurement accuracy 34
9.3. Method of repair 34
9.3.1. Replacing the complete relay 34
9.3.2. Replacing a PCB 36
9.4. Recalibration 50
9.4.1. P740 relay 50
9.5. Changing the relay battery 50
9.5.1. Instructions for replacing the battery. 50
9.5.2. Post modification tests 51
9.5.3. Battery disposal 51
9.6. Cleaning 51
10. COMMISSIONING TEST RECORD: 52
10.1. Peripheral Units: P742/P743 52
11. SETTING RECORD 60
11.1. Central Unit: P741 60

11.2. Peripheral Units: P742/P743 68
1. INTRODUCTION
The MiCOM P740 Busbar Differential Protection is fully numerical in their design,
implementing all protection and non-protection functions in software. The relays
employ a high degree of self-checking and, in the unlikely event of a failure, will give
an alarm. As a result of this, the commissioning tests do not need to be as extensive
as with non-numeric electronic or electromechanical relays.
To commission numeric relays, it is only necessary to verify that the hardware is
functioning correctly and the application-specific software settings have been applied
to the relay (PSL, topology, differential and breaker failure protection linked to the
topology/PSL). It is considered unnecessary to test every function of the relay if the
settings have been verified by one of the following methods:
- Extracting the settings applied to the relay using appropriate setting software
(preferred method)
- Via the operator interface.
Unless previously agreed to the contrary, the customer will be responsible for
determining the application-specific settings to be applied to the relay and for testing
of any scheme logic applied by external wiring and/or configuration of the relay’s
internal programmable scheme logic.
Blank commissioning test and setting records are provided at the end of this chapter
for completion as required.
As the relay’s menu language is user-selectable, it is acceptable for the
Commissioning Engineer to change it to allow accurate testing as long as the menu is
restored to the customer’s preferred language on completion.
To simplify the specifying of menu cell locations in these Commissioning Instructions,
they will be given in the form [courier reference: COLUMN HEADING, Cell Text]. For
example, the cell for selecting the menu language (first cell under the column
heading) is located in the System Data column (column 00) so it would be given as
[SYSTEM DATA, Language].
Before carrying out any work on the equipment, the user should be familiar with the
contents of the Safety and Technical Data sections and the ratings on the equipment’s
rating label.
2. SETTING FAMILIARISATION
When commissioning a MiCOM P740 Busbar protection for the first time, sufficient
time should be allowed to become familiar with the method by which the settings are
applied.
The Introduction (P740/EN IT) contains a detailed description of the menu structure of
P740 relays.
With the secondary front cover in place all keys except the ! key are accessible. All
menu cells can be read. LED’s and alarms can be reset. However, no protection or
configuration settings can be changed, or fault and event records cleared.
Removing the secondary front cover allows access to all keys so that settings can be
changed, LED’s and alarms reset, and fault and event records cleared. However,
menu cells that have access levels higher than the default level will require the
appropriate password to be entered before changes can be made.
Alternatively, if a portable PC is available together with suitable setting software (such
as MiCOM S1), the menu can be viewed a page at a time to display a full column of
data and text. This PC software also allows settings to be entered more easily, saved
to a file on disk for future reference or printed to produce a setting record. Refer to
the PC software user manual for details. If the software is being used for the first
time, allow sufficient time to become familiar with its operation.
3. EQUIPMENT REQUIRED FOR COMMISSIONING

3.1. Minimum equipment required
Overcurrent test set with interval timer
Multimeter with suitable ac current range, and ac and dc voltage ranges of
0 – 440V and 0 – 250V respectively
Continuity tester (if not included in multimeter)
Optical power meter with sensitivity 0 to –50dBm (to measure the optical signal level)
Note: Modern test equipment may contain many of the above features
in one unit.
3.2. Optional equipment
Multi-finger test plug type P992 (if test block type P991 installed) or MMLB (if using
MMLG blocks)
An electronic or brushless insulation tester with a dc output not exceeding 500V (for
insulation resistance testing when required). This equipment will be required only if
the dielectric test has been no done during the manufacturing process.
A portable PC, with appropriate software (this enables the rear communications port
to be tested, if this is to be used, and will also save considerable time during
commissioning).
A printer (for printing a setting record from the portable PC).
4. PRODUCT CHECKS
These product checks cover all aspects of the relay which should be checked to
ensure that it has not been physically damaged prior to commissioning, is functioning
correctly and all input quantity measurements are within the stated tolerances.
If the application-specific settings have been applied to the relay prior to
commissioning, it is advisable to make a copy of the settings so as to allow their
restoration later. This could be done by:
− Obtaining a setting file on a diskette from the customer (this requires a portable
PC with appropriate setting software for transferring the settings from the PC to
the relay)
− Extracting the settings from the relay itself (this again requires a portable PC
with appropriate setting software)
− Manually creating a setting record. This could be done using a copy of the
setting record located at the end of this chapter to record the settings as the
relay’s menu is sequentially stepped through via the front panel user interface.
If password protection is enabled and the customer has changed password 2 that
prevents unauthorised changes to some of the settings, either the revised password 2
should be provided, or the customer should restore the original password prior to
commencement of testing.
Note: In the event that the password has been lost, a recovery
password can be obtained from AREVA by quoting the serial
number of the relay. The recovery password is unique to that
relay and is unlikely to work on any other relay.
4.1. With the relay de-energised
The following group of tests should be carried out without the auxiliary supply being
applied to the relay and with the trip circuit isolated.
The current and voltage transformer connections must be isolated from the relay for
these checks. If a P991 test block is provided, the required isolation can easily be
achieved by inserting test plug type P992 which effectively open-circuits all wiring
routed through the test block.
Before inserting the test plug, reference should be made to the scheme (wiring)
diagram to ensure that this will not potentially cause damage or a safety hazard. For
example, the test block may be associated with protection current transformer circuits.
It is essential that the sockets in the test plug which correspond to the current
transformer secondary windings are linked before the test plug is inserted into the test
block.
DANGER: Never open circuit the secondary circuit of a current transformer

since the high voltage produced may be lethal and could damage
insulation.
If a test block is not provided, the voltage transformer supply to the relay should be
isolated by means of the panel links or connecting blocks. The line current
transformers should be short-circuited and disconnected from the relay terminals.
Where means of isolating the auxiliary supply and trip circuit (e.g. isolation links,
fuses, MCB, etc.) are provided, these should be used. If this is not possible, the
wiring to these circuits will have to be disconnected and the exposed ends suitably
terminated to prevent them from being a safety hazard.
4.1.1. Visual inspection
Carefully examine the relay to see that no physical damage has occurred since
installation.
The rating information given under the top access cover on the front of the relay
should be checked to ensure it is correct for the particular installation.
Ensure that the case earthing connections, bottom left-hand corner at the rear of the
relay case, are used to connect the relay to a local earth bar using an adequate
conductor.
4.1.2. Current transformer shorting contacts
If required, the current transformer shorting contacts can be checked to ensure that
they close when the heavy duty terminal block (block reference B for P742 and A for
P743 in Figure 1and Figure 2) is disconnected from the current input PCB.
A B C D E
F
1 1 2 3 19 1 1 1
2 2 2 2
3 3 3 3
4 5 6 20
4 4 4 4 TX
5 5 5 5
CH1 RX
6 6 6 6
7 7 8 9 21 7 7 7
TX
8 8 8 8
9 9 9 9
10 11 12 22 CH2 RX
10 10 10 10
11 11 11 11
12 12 12 12
13 14 15 23
13 13 13 13
14 14 14 14
15 15 15 15
16 17 18 24
16 16 16 16
17 17 17 17
18 18 18 18
Figure 1: Rear terminal blocks on P742

A B C D E F G H J
1 2 3 19 1 1 1 1 1 1 1
2 2 2 2 2 2 2
3 3 3 3 3 3 3
4 5 6 20
4 4 4 4 4 4 4 TX
5 5 5 5 5 5 5
CH1 RX
6 6 6 6 6 6 6
7 8 9 21 7 7 7 7 7 7 7
TX
8 8 8 8 8 8 8
9 9 9 9 9 9 9
10 11 12 22 CH2 RX
10 10 10 10 10 10 10
11 11 11 11 11 11 11
12 12 12 12 12 12 12
13 14 15 23
13 13 13 13 13 13 13
14 14 14 14 14 14 14
15 15 15 15 15 15 15
0 17 18 24
16
16 16 16 16 16 16 16
17 17 17 17 17 17 17
18 18 18 18 18 18 18
Figure 2 : Rear terminal blocks on P743
The heavy duty terminal block is fastened to the rear panel using four crosshead
screws. These are located top and bottom between the first and second, and third
and fourth, columns of terminals (see Figure 2).
Note: The use of a magnetic bladed screwdriver is recommended to
minimise the risk of the screws being left in the terminal block or
lost.
Pull the terminal block away from the rear of the case and check with a continuity
tester that all the shorting switches being used are closed. Table 1 shows the
terminals between which shorting contacts are fitted.
Shorting contact between terminals

Current
input P742 P743
1A – common – 5A 1A – common – 5A
ΙA B3 – B2 – B1 A3 – A2 – A1
ΙB B6 – B5 – B4 A6 – A5 – A4
ΙC B9 – B8 – B7 A9 – A8 – A7
ΙN B12 – B11 – B10 A12 – A11 – A10
Table 1: Current transformer shorting contact locations.
P0299ENa
Figure 3 :Location of securing screws for heavy duty terminal blocks.
4.1.3. Insulation
Insulation resistance tests are only necessary during commissioning if it is required for
them to be done and they have not been performed during installation.
Isolate all wiring from the earth and test the insulation with an electronic or brushless
insulation tester at a dc voltage not exceeding 500V. Terminals of the same circuits
should be temporarily connected together.
The main groups of relay terminals are:

a) Current transformer circuits
b) Auxiliary voltage supply.
c) Field voltage output and opto-isolated control inputs.
d) Relay contacts.
e) Case earth.
The insulation resistance should be greater than 100MΩ at 500V.
On completion of the insulation resistance tests, ensure all external wiring is correctly
reconnected to the relay.
4.1.4. External wiring
Check that the external wiring is correct to the relevant relay diagram or scheme
diagram. The relay diagram number appears on the rating label under the top
access cover on the front of the relay. The corresponding connection diagram will
have been supplied with the AREVA order acknowledgement for the relay.
If a P991 test block is provided, the connections should be checked against the
scheme (wiring) diagram. It is recommended that the supply connections are to the
live side of the test block [coloured orange with the odd numbered terminals (1, 3, 5,
7 etc.). The auxiliary supply is normally routed via terminals 13 (supply positive) and
15 (supply negative), with terminals 14 and 16 connected to the relay’s positive and
negative auxiliary supply terminals respectively. However, check the wiring against
the schematic diagram for the installation to ensure compliance with the customer’s
normal practice.
4.1.5. Watchdog contacts
Using a continuity tester, check that the watchdog contacts are in the states given in
Table 2 for a de-energised relay.
Terminals Contact state

Relay de-energised Relay energised
L11 – L12 (P741) Closed Open
E11 – E12 (P742)
H11 – H12 (P743)
L13 – L14 (P741) Open Closed
E13 – E14 (P742)
H13 – H14 (P743)
Table 2: Watchdog contact status
4.1.6. Auxiliary supply
The P740 relay can be operated from either a dc only or an ac/dc auxiliary supply
depending on the relay’s nominal supply rating. The incoming voltage must be
within the operating range specified in Table 3.
Without energising the relay measure the auxiliary supply to ensure it is within the
operating range.
Nominal supply rating DC [AC rms] DC operating range AC operating range

24 – 48V [–] 19 to 65V -
48 – 110V [30 – 100V] 37 to 150V 24 to 110V
110 – 250V [100 – 240V] 87 to 300V 80 to 265V
Table 3 Operational range of auxiliary supply Vx.
It should be noted that the P740 relay range can withstand an ac ripple of up to 12%
of the upper rated voltage on the dc auxiliary supply.
Do not energise the relay or interface unit using the battery charger with the
battery disconnected as this can irreparably damage the relay’s power supply
circuitry.
Energise the relay only if the auxiliary supply is within the specified operating ranges.
If a test block is provided, it may be necessary to link across the front of the test plug
to connect the auxiliary supply to the relay.
4.2. With the relay energised
The following group of tests verify that the relay hardware and software is functioning
correctly and should be carried out with the auxiliary supply applied to the relay.
The current and voltage transformer connections must remain isolated from the relay
for these checks. The trip circuit should also remain isolated to prevent accidental
operation of the associated circuit breaker.
4.2.1. Watchdog contacts
Using a continuity tester, check the watchdog contacts are in the states given in Table
2 for an energised relay.
4.2.2. Date and time
Before setting the date and time, ensure that the factory-fitted battery isolation strip,
that prevents battery drain during transportation and storage, has been removed.
With the lower access cover open, presence of the battery isolation strip can be
checked by a red tab protruding from the positive side of the battery compartment.
Whilst lightly pressing the battery, to prevent it from falling out of the battery
compartment, pull the red tab to remove the isolation strip.
The date and time should now be set to the correct values. The method of setting will
depend on whether accuracy is being maintained via the optional Inter-Range
Instrumentation Group standard B (IRIG-B) port on the rear of the P741 relay.
4.2.2.1 With an IRIG-B signal for Central Unit (P741) only
If a satellite time clock signal conforming to IRIG-B is provided and the P741 relay
has the optional IRIG-B port fitted, the satellite clock equipment should be energised.
To allow the relay’s time and date to be maintained from an external IRIG-B source
cell [DATE and TIME, IRIG-B Sync] must be set to ‘Enabled’.
Ensure the relay is receiving the IRIG-B signal by checking that cell [DATE and TIME,
IRIG-B Status] reads ‘Active’.
Once the IRIG-B signal is active, adjust the time offset of the universal co-ordinated
time (satellite clock time) on the satellite clock equipment so that local time is
displayed.
Check the time, date and month are correct in cell [DATE and TIME, Date/Time]. The
IRIG-B signal does not contain the current year so it will need to be set manually in
this cell.
In the event of the auxiliary supply failing, with a battery fitted in the compartment
behind the bottom access cover, the time and date will be maintained. Therefore,
when the auxiliary supply is restored, the time and date will be correct and not need
to be set again.
To test this, remove the IRIG-B signal, then remove the auxiliary supply from the relay.
Leave the relay de-energised for approximately 30 seconds. On re-energisation, the
time in cell [DATE and TIME, Date/Time] should be correct.
Reconnect the IRIG-B signal.
The P741 will synchronise all peripheral units (P742/P743) every 10s and during the
power on of the scheme.
4.2.2.2 Without an IRIG-B signal for Central Unit (P741) or Peripheral Unit (P742/P743)
If the time and date is not being maintained by an IRIG-B signal, ensure that cell
[DATE and TIME, IRIG-B Sync] is set to ‘Disabled’.
Set the date and time to the correct local time and date using cell [DATE and TIME,
Date/Time].
In the event of the auxiliary supply failing, with a battery fitted in the compartment
behind the bottom access cover, the time and date will be maintained. Therefore
when the auxiliary supply is restored the time and date will be correct and not need to
be set again.
To test this, remove the auxiliary supply from the relay for approximately 30 seconds.
On re-energisation, the time in cell [DATE and TIME, Date/Time] should be correct.
4.2.3. Light Emitting Diodes (LED’s)
On power up the green LED should have illuminated and stayed on indicating that
the relay is healthy. The relay has non-volatile memory which remembers the state
(on or off) of the alarm, trip and, if configured to latch, user-programmable LED
indicators when the relay was last energised from an auxiliary supply. Therefore
these indicators may also illuminate when the auxiliary supply is applied.
If any of these LED’s are on then they should be reset before proceeding with further
testing. If the LED’s successfully reset (the LED goes out), there is no testing required
for that LED because it is known to be operational.
Note: It is likely that alarms related to the communications channels
will not reset at this stage.
4.2.3.1 Testing the alarm and out of service LED’s
The alarm and out of service LED’s can be tested using the COMMISSION TESTS
menu column. Set cell [COMMISSION TESTS, Test Mode] to ‘Contacts Blocked’.
Check that the out of service LED illuminates continuously and the alarm LED flashes.
It is not necessary to return cell [COMMISSION TESTS, Test Mode] to ‘Disabled’ at
this stage because the test mode will be required for later tests.
4.2.3.2 Testing the Trip LED
The trip LED can be tested by initiating a manual circuit breaker trip from the relay.
However, the trip LED will operate during the setting checks performed later.
Therefore no further testing of the trip LED is required at this stage. Please note that
the CB control function does not exist in the Central Unit (P741) as only the Peripheral
Unit (P742/P743) may trip/close the local circuit breakers.
4.2.3.3 Testing the user-programmable LEDS
To test the user-programmable LED’s set cell [COMMISSION TESTS, Test LED’s] to
‘Apply Test’. Check that all 8 LED’s on the right-hand side of the relay illuminate.
4.2.4. Field voltage supply
The relay generates a field voltage of nominally 48V dc that can be used to energise
the opto-isolated inputs (alternatively the substation battery may be used).
Measure the field voltage across the terminals 7 and 9 on the terminal block given in
Table 4. Check that the field voltage is within the range 40V to 60V when no load is
connected and that the polarity is correct.
Repeat for terminals 8 and 10.
Supply rail Terminals

P741 P742 P743
+ve L7 & L8 E7 & E8 H7 & H8
–ve L9 & L10 E9 & E10 H9 & H10
Table 4: Field voltage terminals
4.2.5. Input opto-isolators
This test checks that all the opto-isolated inputs on the relay are functioning correctly.
The P741 relay has 8 opto-isolated inputs while the P742 relay has 16 opto-isolated
inputs and P743 relays has 24 opto-isolated inputs.
The opto-isolated inputs should be energised one at a time, see external connection
diagrams (P740/EN CO) for terminal numbers. Ensuring correct polarity, connect the
field supply voltage to the appropriate terminals for the input being tested.
Note: The opto-isolated inputs may be energised from an external dc

auxiliary supply (e.g. the station battery) in some installations.
Check that this is not the case before connecting the field voltage
otherwise damage to the relay may result.
The status of each opto-isolated input can be viewed using either cell [SYSTEM DATA,
Opto I/P Status] or [COMMISSION TESTS, Opto I/P Status], a ‘1’ indicating an
energised input and a ‘0’ indicating a de-energised input. When each opto-isolated
input is energised one of the characters on the bottom line of the display will change
to indicate the new state of the inputs.
4.2.6. Output relays
This test checks that all the output relays are functioning correctly. The P741 and
P742 relays have 8 output relays while P743 relay has 21 output relays.
Note: For P743, the output boards are equipped with 8 output relays
but only 7 are used on each board. See external Connection
Diagrams Chapter (P740/EN CO) for terminal numbers.
Ensure that the relay is still in test mode by viewing cell [COMMISSION TESTS, Test
Mode] to ensure that it is set to ‘Blocked’.
The output relays should be energised one at a time. To select output relay 1 for
testing, set cell [COMMISSION TESTS, Test Pattern] as appropriate.
Connect a continuity tester across the terminals corresponding to output relay 1 as
given in external connection diagram (P740/EN CO).
To operate the output relay set cell COMMISSION TESTS, Contact Test] to ‘Apply
Test’. Operation will be confirmed by the continuity tester operating for a normally
open contact and ceasing to operate for a normally closed contact. Measure the
resistance of the contacts in the closed state.
Reset the output relay by setting cell [COMMISSION TESTS, Contact Test] to ‘Remove
Test’.
Note: It should be ensured that thermal ratings of anything connected
to the output relays during the contact test procedure is not
exceeded by the associated output relay being operated for too
long. It is therefore advised that the time between application
and removal of contact test is kept to the minimum.
Repeat the test for relays 2 to 8 for P741 and P742 relays, 2 to 21 for P743 relay.
Return the relay to service by setting cell [COMMISSION TESTS, Test Mode] to
‘Disabled’.
4.2.7. Current differential communications
This test verifies that the P742 or P743 relay’s fibre optic communications ports used
for communications to the P741 Central Unit, are operating correctly.
J K L M N
A B C D E F G H 1 1 1
2 2 2
3 3 3
5 5 5
IRIG-B
CH1 RX CH1 RX CH1 RX CH1 RX CH1 RX CH1 RX CH1 RX CH1 RX CH1 RX
6 6 6
7 7 7
TX TX TX TX TX TX TX TX TX
8 8 8
9 9 9
CH2 RX CH2 RX CH2 RX CH2 RX CH2 RX CH2 RX CH2 RX CH2 RX CH2 RX

10 10 10
11 11 11
TX TX TX TX TX TX TX
TX
TX
RX
12 12 12
13 13 13
14 14 14
RX RX RX RX RX RX RX CH4 RX
CH4 CH4 CH4 CH4 CH4 CH4 CH4 16 16 16
17 17 17
18 18 18
Figure 4 : P741 Rear Terminal blocks and communication ports

When connecting or disconnecting optical fibres care should be taken not to look
directly into the transmit port or end of the optical fibre.
From central unit, the cell [PU CONF & STATUS, PU connected] displayed the list of
peripheral units connected to the central unit.
From peripheral unit, it is possible to check the communication with the central unit
by disconnecting the optical fibre, an alarm “Fibre Com Error” should appear.
4.2.8. Current inputs (P742, P743 only)
This test verifies that the accuracy of current measurement is within the acceptable
tolerances.
All relays will leave the factory set for operation at a system frequency of 50Hz.
If operation at 60Hz is required then this must be set in cell [SYSTEM
DATA, Frequency].
Apply current equal to the line current transformer secondary winding rating to each
current transformer input of the corresponding rating in turn, see Table 1 or external
connection diagram (P740/EN CO) for appropriate terminal numbers, checking its
magnitude using a multimeter. The corresponding reading can then be checked in
the relay’s MEASUREMENTS 1 column and value displayed recorded.
The measured current values displayed on the relay LCD or a portable PC connected
to the front communication port will either be in primary or secondary Amperes. If
cell [MEASURE’T SETUP, Local Values] is set to ‘Primary’, the values displayed should
be equal to the applied current multiplied by the corresponding current transformer
ratio set in the ‘CT and VT RATIOS’ menu column (see SEQARABIC). If cell
[MEASURE’T SETUP, Local Values] is set to ‘Secondary’, the value displayed should be
equal to the applied current.
The measurement accuracy of the relay is ±5%. However, an additional allowance
must be made for the accuracy of the test equipment being used.
Cell in MEASUREMENTS 1 column (02) Corresponding CT Ratio

(in ‘CT and VT RATIOS‘
column(0A) of menu)
[IA Magnitude]
[IB Magnitude] [Phase CT Primary]__
[IC Magnitude] [Phase CT Secondary]
[IN Magnitude]
Table 5: CT ratio settings

5. SETTING CHECKS
The setting checks ensure that all of the application-specific relay settings (i.e. both
the relay’s function and programmable scheme logic settings), for the particular
installation, have been correctly applied to the relay.
Note: The trip circuit should remain isolated during these checks to
prevent accidental operation of the associated circuit breaker.
5.1. Apply application-specific settings

There are two methods of applying the settings to the relay:
− Transferring them from a pre-prepared setting file to the relay using a portable
PC running the appropriate software via the relay’s front EIA(RS)232 port,
located under the bottom access cover. This method is preferred for
transferring function settings as it is much faster and there is less margin for
error. If programmable scheme logic other than the default settings with which
the relay is supplied are to be used then this is the only way of changing the
settings.
If a setting file has been created for the particular application and provided on
a diskette, this will further reduce the commissioning time and should always be
the case where application-specific programmable scheme logic is to be
applied to the relay.
− Enter them manually via the relay’s operator interface. This method is not
suitable for changing the programmable scheme logic.
Note: It is essential that where the installation needs application-
specific Programmable Scheme Logic, that the appropriate .psl
file is downloaded (sent) to the relay, for each and every setting
group that will be used. If the user fails to download the
required .psl file to any setting group that may be brought into
service, then factory default PSL will still be resident. This may
have severe operational and safety consequences.
5.2. How to measure the Burden Resistance (RB)

Insertion of the test block to open current circuit
Short-circuit of the secondary
P992 or MMLG
PU winding of the current transformer
A
(HV site)
IA CTA
A
B
IB CTB
V
C
IC CTC
IN
N
P3747ENb
1. Short-circuit of the secondary winding of the 3 current transformers (see above).

2. Open the current circuit by inserting the test block
3. Connect the current test set in the test block (phase + neutral).
4. Inject a current (1A) and measure the voltage at the terminals of the resistor
circuitry.
5. Calculate the burden resistance RB by using the following equation:
RB = Umeasured / Iinjected
Repeat the previous operation for each resistance :
RAN between boundary A and N
RBN between boundary B and N
RCN between boundary C and N
RAB between boundary A and B
Calculate the resistance RBA, RBB, RBC, and RBN, by using the following equation:
RBA = (RAB + RAN - RBN ) / 2
RBN = RAN - RBA
RBB = RAB - RBA
RBC = RCN - RBN
The highest value of the 3 phases (RBA, RBB, RBC) should be multiplicated by 1.25
(increase of 25% for a temperature at 75°) and set in the cell [CT/VT ratio, RB in
ohm].
The highest value of the 3 phases (RBA, RBB, RBC) should be divided by the neutral
resistance RBN and set in the cell [CT/VT ratio, RBPh / RBN].
1 – RBph / RBN
PU
IA CTA
IB CTB
IC CTC
IN
P3900ENa
2 – RBPh / RBN = 3
PU
IA CTA
IB CTB
IC CTC
IN
P3901ENa
5.3. Demonstrate Correct Relay Operation

Tests below have already demonstrated that the relay is within calibration, thus the
purpose of these tests is as follows:
− To determine that the primary protection function of the relay, current
differential, can trip according to the correct application settings.
− To verify correct setting of any backup phase overcurrent protection.
− To verify correct assignment of the inputs, relays and trip contacts, by
monitoring the response to a selection of fault injections.
5.3.1. Current Differential Bias Characteristic
To avoid spurious operation of any Overcurrent, earth fault or breaker fail elements,
these should be disabled for the duration of the differential element tests. This is
done in the relay’s CONFIGURATION column. Ensure that cells, [Overcurrent Prot],
[Earth Fault Prot] and [CB Fail & I<] are all set to “Disabled”. Make a note of which
elements need to be re-enabled after testing.
5.3.1.1 Connect the test circuit
The following tests require a injection test set, able to feed the relays with two currents
variable in phase and magnitude, connected as shown in Figure 5.
This method will be preferred for a centralised solution
I1
P742/3 A
FO Peripheral
Unit 1
P741 Test
Central
Unit
Box
I2
FO A
P742/3
Peripheral
Unit 2
P3748ENa
Figure 5: Connection for Bias Characteristic Testing – Centralised Solution

As shown in figure 5bis, this method will be used for a distributed solution when only
one peripheral unit is available.
I2
P741 FO A Test
Central P742/3
Unit Peripheral Box
Unit 1
P3749ENa
Figure 5bis: Connection for Bias Characteristic Testing – Distributed Solution

A current I1 is injected into the A phase of the PU1 which is used as the bias current
and another current I2 is injected into the A phase of the PU2 which is used as
differential current.
Currents I1 and I2 are in anti-phase, i.e.: 180° out of phase and I2>I1
Idiff: I1+I2 = I2 - I1
Ibias: ∑I= I1+I2 = I1 + I2
k : Percentage bias, Characteristic limit: Idiff = IS + k Ibias
I2 – I1 = IS + k (I1 + I2) with I2 = I1 + ∆I
∆I = IS + k (2 I1 + ∆I)
∆I (1 – k) = IS + 2 k I1
∆I = (IS + 2 k I1 ) / (1 – k)
1) If only one current is available, we will have I1 = 0

∆I = IS / (1 – k)
i diff (t)
Ibias = Idiff = I2 = D I
k
pe
Slo
A
Idiff = I2 = D I
Is
45°
0 i bias
Ibias = I2 = D I
P3750ENa
In this case, we increase I2 from 0 to A point until the differential element operates.
Note: ID>2 will be set below the A point during the test. ID>1 alarm
timer will be set to 100s during the test.
To calculate and check the slope k, k = (I2-IS)/I2
2) If 2 currents are available:
i diff (t)
k
pe
Slo
C
Idiff = I1- I2
A
Is
45° i bias
0
B
Ibias = I1 + I2 P3759ENa
Ibias is fixed to a value greater than the A point. So Ibias = I1 + I2 = fixed value (Point B)
we set I1 = - I2 = Ibias / 2 so Idiff = 0
In this case, we increase I1 and decrease I2 from the same primary value ∆I (note that
all PUs transmit the primary currents to central unit). When we reach the point C, the
differential element should have to operate.
To calculate the slope k, k = [(I1 – I2) – IS] / (I1 + I2)
The differential current will increase twice the value ∆I.
Note: ID>2 will be set below the A point during the test. ID>1 alarm
timer will be set to 100s during the test.
5.3.1.2 Slope
If a LED has been assigned in central or/and peripheral units to display the trip
information, these may be used to indicate correct operation. If not, monitor option
will need to be used – see the next paragraph.
On P741 go Central Unit GROUP1-->BUSBAR PROTECT and set ID>1 Alarm timer to
100s
On P742/3 go to COMMISSION TESTS column in the menu, scroll down and change
cells [Monitor Bit 1] to [BUSBAR_TRIPPING]. Doing so, cell [Test Port Status] will
appropriately set or reset the bits that now represent BUSBAR_TRIPPING (with the
rightmost bit representing Busbar Trip. From now on you should monitor the
indication of [Test Port Status]. Make a note of which elements need to be re-enabled
or re-set after testing.
Test of ID>2:
ID>1 Alarm Timer should be set to 100s during testing.
Inject a I2 current smaller than ID>2 and slowly increase I2 until tripping.
Test of the operating time of the differential element:
Inject a I2 current greater than twice ID>2 threshold and measure the operating time
of the differential element.
Test of ID>1:
ID>1 Alarm Timer should be set to 100ms.
Inject a I2 current smaller than ID>1 and slowly increase I2 until circuit fault appears
(LED Alarm of LED circuitry fault).
Test of ID>1 Alarm Timer:
ID>1 Alarm Timer should be set to 5s.
Inject a I2 current greater than twice the ID>1 threshold and check that the Circuitry
Fault Alarm is coming in 5s.
Note: Same tests can be applied for the Differential Sensitive Earth
Fault Protection.
Note: the differential SEF is 20ms delayed and controlled by a
settable threshold Ibias ph> to unblock/block the sensitive
element depending of the restrain phase currents.
5.3.2. Phase Overcurrent Protection (P742 and P743)
If the overcurrent protection function is being used, both Ι>1 and I>2 elements
should be tested.
To avoid spurious operation of any current differential, earth fault, breaker fail or CT
supervision elements, these should be disabled for the duration of the overcurrent
tests. This is done in the relay’s CONFIGURATION column. Make a note of which
elements need to be re-enabled after testing.
5.3.2.1 Connect the test circuit
Determine which output relay has been selected to operate when an Ι>1 trip and an
I>2 occur by viewing the relay’s programmable scheme logic.
The programmable scheme logic can only be changed using the appropriate
software. If this software has not been available then the default output relay
allocations will still be applicable.
If the trip outputs are phase-segregated (i.e. a different output relay allocated for
each phase), the relay assigned for tripping on ‘A’ phase faults should be used.
If stage 1 is not mapped directly to an output relay in the programmable scheme
logic, output relay 1,2 or 3 could be used for the test as it operates for trip condition
(phase A, B and C).
The associated terminal numbers can be found from the external connection diagram
(Chapter P740/EN CO)SEQARABIC.
Connect the output relay so that its operation will trip the test set and stop the timer.
Connect the current output of the test set to the ‘A’ phase current transformer input of
the relay.
Ensure that the timer will start when the current is applied to the relay.
5.3.2.1.1 Perform the test

Ensure that the timer is reset.
Apply a current of twice the setting in cell [GROUP 1 OVERCURRENT, Ι>1 Current
Set] to the relay and note the time displayed when the timer stops.
Check that the red trip LED has illuminated.
5.3.2.1.2 Check the operating time

Check that the operating time recorded by the timer is within the range shown in
SEQARABIC
Note: Except for the definite time characteristic, the operating times
given in SEQARABIC are for a time multiplier or time dial setting
of 1. Therefore, to obtain the operating time at other time
multiplier or time dial settings, the time given in SEQARABIC
must be multiplied by the setting of cell [GROUP 1
OVERCURRENT, Ι>1 TMS] for IEC and UK characteristics or cell
[GROUP 1 OVERCURRENT, Time Dial] for IEEE and US
characteristics.
In addition, for definite time and inverse characteristics there is an additional delay of
up to 0.02 second and 0.08 second respectively that may need to be added to the
relay’s acceptable range of operating times.
For all characteristics, allowance must be made for the accuracy of the test equipment
being used.
Characteristic Operating time at twice current setting and time

multiplier/time dial setting of 1.0
Nominal (seconds) Range (seconds)
DT [: Ι>1 Time Delay] setting Setting ±2%
IEC S Inverse 10.03 9.53 – 10.53
IEC V Inverse 13.50 12.83 – 14.18
IEC E Inverse 26.67 24.67 – 28.67
UK LT Inverse 120.00 114.00 – 126.00
IEEE M Inverse 0.64 0.61 – 0.67
IEEE V Inverse 1.42 1.35 – 1.50
IEEE E Inverse 1.46 1.39 – 1.54
US Inverse 0.46 0.44 – 0.49
US ST Inverse 0.26 0.25 – 0.28
Table 6: Characteristic operating times for Ι>1
Re-perform the tests for the function I>2
Upon completion of the tests any current differential, overcurrent, earth

fault, breaker fail or supervision elements which were disabled for
testing purposes must have their original settings restored in the
CONFIGURATION column.
5.3.3. Breaker Failure Protection
5.3.3.1 Separate external 50BF protection to the busbar protection
CB Fail PU3
PU1 PU2 PU4 PU5
External Fault
P3751ENa
For example as shown in the above figure, we simulate a CB fail in feeder 1 (PU1).
Therefore, we energise the opto input “External CB Fail” of the PU1 and we check
that the central unit issue a tripping order to PU2 and PU3.
Note: If the I>BB or IN>BB are enabled in menu “Busbar Trip
Confirm” in Peripheral Unit, the CB fail trip command issued by
the Central Unit will be confirmed by a measured phase currents
or neutral currents greater than I>BB (Phase) or IN>BB (Earth).
For example: PU2 and PU3 will operate only if the phase currents > I>BB else the
local trip will be not confirmed.
The trip of the backup phase overcurrent or earth fault overcurrent protection
initiates, as described above, the timers tBF3 and tBF4.
5.3.3.2 External initiation of BF Protection

Protective Relays
Trip A, B, C Trip Command

P742/3
Peripheral
Unit
P3752ENa
To test the retrip:

As shown in the above figure, we initiate the opto inputs “External Trip A,B,C” and
apply a current twice the I< threshold.
Check that the PU issue a retrip order after the settable time tBF3.
Note: If “I> enabled” is activated, then the retrip command will be
controlled locally by a measured phase currents greater than I>.
To test the backtrip:

Do the same test as for retrip however apply a faulty current for more than tBF4 and
check that the backtrip signal is sent to the CU.
Check that PU2 and PU3 connected to the bus-section 1 are tripped by the CU.
Note: If the I>BB or IN>BB are enabled in menu “Busbar Trip
Confirm” in Peripheral Unit, the CB fail trip command issued by
the Central Unit will be confirmed by a measured phase currents
or neutral currents greater than I>BB (Phase) or IN>BB (Earth).
For example: PU2 and PU3 will operate only if the phase currents > I>BB else the
local trip will be not confirmed.
CB unavailable:
Zone 1 Zone 2
PU3
PU1 PU2 PU4 PU5
P3753ENa
Apply an internal fault in zone 2 and energise the opto input of PU3 “CB
unavailable” and check that both bus-section 1 tripped simultaneously.
Note: If the input “CB unavailable” is energised, the CB will be not
tripped and is normally used only for bus-coupler.
5.3.3.3 Internal initiation Breaker Failure Protection
This Breaker failure Protection can be initiated only by a trip command issue by the
Central Unit.
Zone 1 Zone 2
PU3
PU1 PU2 PU4 PU5
P3753ENa
Simulate a busbar fault on the bus-section 2.

Continue to apply fault current in the bus-coupler until the timer tBF1 elapsed.
Check that the retrip signal is given by PU3 and backtrip signal is sent after tBF2.
Check that the CU issued a trip command to both bus-sections (PU1, PU2 PU4 and
PU5 should have operate).
5.4. Check Application Settings

The settings applied should be carefully checked against the required application-
specific settings to ensure that they are correct, and have not been mistakenly altered
during the injection test.
There are two methods of checking the settings:
− Extract the settings from the relay using a portable PC running the appropriate
software via the front EIA(RS)232 port, located under the bottom access cover.
Compare the settings transferred from the relay with the original written
application-specific setting record. (For cases where the customer has only
provided a printed copy of the required settings but a portable PC is available).
− Step through the settings using the relay’s operator interface and compare them
with the original application-specific setting record.
Unless previously agreed to the contrary, the application-specific programmable
scheme logic will not be checked as part of the commissioning tests.
Due to the versatility and possible complexity of the programmable scheme logic, it is
beyond the scope of these commissioning instructions to detail suitable test
procedures. Therefore, when programmable scheme logic tests must be performed,
written tests which will satisfactorily demonstrate the correct operation of the
application-specific scheme logic should be devised by the Engineer who created it.
These should be provided to the Commissioning Engineer together with the diskette
containing the programmable scheme logic setting file.
6. END TO END TESTS
Verify communications between Peripheral units (P742 or P743) and

Central Unit (P741) Advisable for distributed scheme.
The following communication checks confirm that the optical power at the transmit
and receive ports of the Peripheral Units and the Central Unit are within the
recommended operating limits.
Measure and record the optical signal strength received by the Peripheral Unit (P742
or P743) by disconnecting the optical fibre from the Channel 1 receive port and
connecting it to an optical power meter. The mean level should be in the range
− 16.8 dBm to −25.4dBm. If the mean level is outside of this range check the size
and type of fibre being used.
When connecting or disconnecting optical fibres care should be taken not to
look directly into the transmit port or end of the optical fibre.
Measure and record the optical power of the Channel 1 transmit port using the
optical power meter and length of optical fibre. The mean value should be in the
range –16.8dBm to –22.8dBm.
Ensure that all transmit (Tx) and receive (Rx) optical fibres between Peripheral Unit
and Central Unit are reconnected, ensuring correct placement.
Reset any alarm indications and check that no further communications failure alarms
are raised.
7. ON-LOAD CHECKS
The objectives of the on-load checks are to:
- confirm the external wiring to the current inputs is correct.
- ensure the on-load differential current is well below the relay setting.
However, these checks can only be carried out if there are no restrictions preventing
the energisation of the plant being protected and the other P740 relays in the group
have been commissioned.
Remove all test leads, temporary shorting leads, etc. and replace any external wiring
that has been removed to allow testing.
If it has been necessary to disconnect any of the external wiring from the relay in
order to perform any of the foregoing tests, it should be ensured that all connections
are replaced in accordance with the relevant external connection or scheme diagram.
Confirm current transformer wiring:
Measure the current transformer secondary values for each input using a multimeter
connected in series with the corresponding relay current input.
Check that the current transformer polarities are correct.
Ensure the current flowing in the neutral circuit of the current transformers is
negligible.
Compare the values of the secondary phase currents with the relay’s measured
values, which can be found in the MEASUREMENTS 1 menu column.
Note: Under normal load conditions the earth fault function will
measure little, if any, current. It is therefore necessary to simulate
a phase to neutral fault. This can be achieved by temporarily
disconnecting one or two of the line current transformer
connections to the relay and shorting the terminals of these
current transformer secondary windings.
If cell [MEASURE’T SETUP, Local Values] is set to ‘Secondary’, the currents displayed
on the LCD or a portable PC connected to the front EIA(RS)232 communication port
of the relay should be equal to the applied secondary current. The values should be
within 5% of the applied secondary currents. However, an additional allowance must
be made for the accuracy of the test equipment being used.
If cell [MEASURE’T SETUP, Local Values] is set to ‘Primary’, the currents displayed on
the relay should be equal to the applied secondary current multiplied by the
corresponding current transformer ratio set in ‘CT & VT RATIOS’ menu column (see
SEQARABIC). Again the values should be within 5% of the expected value, plus an
additional allowance for the accuracy of the test equipment being used.
Note: If a single dedicated current transformer is used for the earth
fault function, it is not possible to check the relay’s measured
values.
8. FINAL CHECKS
The tests are now complete.
Remove all test or temporary shorting leads, etc. If it has been necessary to
disconnect any of the external wiring from the relay in order to perform the wiring
verification tests, it should be ensured that all connections are replaced in accordance
with the relevant external connection or scheme diagram.
Ensure that the relay has been restored to service by checking that cell
[COMMISSION TESTS, Test Mode] is set to ‘Disabled’.
If the menu language has been changed to allow accurate testing it should be
restored to the customer’s preferred language.
If a P991/MMLG test block is installed, remove the P992/MMLB test plug and replace
the cover so that the protection is put into service.
Ensure that all event records, fault records, disturbance records, alarms and LED’s
have been reset before leaving the relay.
If applicable, replace the secondary front cover on the relay.
9. MAINTENANCE
9.1. Maintenance period
It is recommended that products supplied by AREVA T&D Information receive periodic
monitoring after installation. As with all products some deterioration with time is
inevitable. In view of the critical nature of protective relays and their infrequent
operation, it is desirable to confirm that they are operating correctly at regular
intervals.
AREVA protective relays are designed for a life in excess of 20 years.
MiCOM P740 current differential relays are self-supervising and so require less
maintenance than earlier designs of relay. Most problems will result in an alarm so
that remedial action can be taken. However, some periodic tests should be done to
ensure that the relay is functioning correctly and the external wiring is intact.
If a Preventative Maintenance Policy exists within the customer’s organisation then the
recommended product checks should be included in the regular programme.
Maintenance periods will depend on many factors, such as:
− operating environment
− accessibility of the site
− amount of available manpower
− importance of the installation in the power system
− consequences of failure
9.2. Maintenance checks
It is recommended that maintenance checks are performed locally (i.e. at the
substation itself).
the equipment’s rating label.
9.2.1. Alarms
The alarm status LED should first be checked to identify if any alarm conditions exist.
If so, press the read key ["] repeatedly to step through the alarms.
Clear the alarms to extinguish the LED.
9.2.2. Opto-isolators
The opto-isolated inputs can be checked to ensure that the relay responds to their
energisation by repeating the commissioning test.
9.2.3. Output relays
The output relays can be checked to ensure that they operate by repeating the
commissioning test.
9.2.4. Measurement accuracy
If the power system is energised, the values measured by the relay can be compared
with known system values to check that they are in the approximate range that is
expected. If they are then the analogue/digital conversion and calculations are being
performed correctly by the relay.
Alternatively, the values measured by the relay can be checked against known values
injected into the relay via the test block, if fitted, or injected directly into the relay
terminals. These tests will prove the calibration accuracy is being maintained.
9.3. Method of repair
P741, P742, P743 relays
If the relay should develop a fault whilst in service, depending on the nature of the
fault, the watchdog contacts will change state and an alarm condition will be flagged.
Due to the extensive use of surface-mount components faulty PCBs should be
replaced as it is not possible to perform repairs on damaged circuits. Thus either the
complete relay or just the faulty PCB, identified by the in-built diagnostic software,
can be replaced. Advice about identifying the faulty PCB can be found in the
Problem Analysis.
The preferred method is to replace the complete relay as it ensures that the internal
circuitry is protected against electrostatic discharge and physical damage at all times
and overcomes the possibility of incompatibility between replacement PCBs.
However, it may be difficult to remove an installed relay due to limited access in the
back of the cubicle and rigidity of the scheme wiring.
Replacing PCBs can reduce transport costs but requires clean, dry conditions on site
and higher skills from the person performing the repair. However, if the repair is not
performed by an approved service centre, the warranty will be invalidated.
the equipment’s rating label. This should ensure that no damage is caused
by incorrect handling of the electronic components.
9.3.1. Replacing the complete relay
The case and rear terminal blocks have been designed to facilitate removal of the
complete relay should replacement or repair become necessary without having to
disconnect the scheme wiring.
Before working at the rear of the relay, isolate all voltage and current supplies to the
relay.
Note: The MiCOM range of relays have integral current transformer
shorting switches which will close when the heavy duty terminal
block is removed.
Disconnect the relay earth, IRIG-B (Central unit only) and fibre optic connections, as
appropriate, from the rear of the relay.
Heavy duty terminal block Medium duty terminal block

P0149ENa
Figure 6 : Location of securing screws for terminal block

Note: The use of a magnetic bladed screwdriver is recommended to
minimise the risk of the screws being left in the terminal block or
lost
Without exerting excessive force or damaging the scheme wiring, pull the terminal
blocks away from their internal connectors.
Remove the screws used to fasten the relay to the panel, rack, etc. These are the
screws with the larger diameter heads that are accessible when the access covers are
fitted and open.
If the top and bottom access covers have been removed, do not remove the
screws with the smaller diameter heads which are accessible. These screws
secure the front panel to the relay.
Withdraw the relay carefully from the panel, rack, etc. because it will be heavy due to
the internal transformers.
To reinstall the repaired or replacement relay, follow the above instructions in
reverse, ensuring that each terminal block is relocated in the correct position and the
case earth, IRIG-B (Central Unit only) and fibre optic connections are replaced. To
facilitate easy identification of each terminal block, they are labelled alphabetically
with ‘A’ on the left hand side when viewed from the rear.
Once reinstallation is complete the relay should be recommissioned using the
instructions in sections 1 to 8 inclusive of this chapter.
9.3.2. Replacing a PCB
If the relay fails to operate correctly refer to the Problem Analysis chapter, to help
determine which PCB has become faulty.
To replace any of the relay’s PCBs it is necessary to first remove the front panel.
Before removing the front panel to replace a PCB the auxiliary supply must be
removed. It is also strongly recommended that the voltage and current
transformer connections and trip circuit are isolated.
Open the top and bottom access covers. With size 60TE/80TE cases the access
covers have two hinge-assistance T-pieces which clear the front panel moulding when
the access covers are opened by more than 90°, thus allowing their removal.
If fitted, remove the transparent secondary front cover. A description of how to do
this is given in the ‘Introduction’.
By applying outward pressure to the middle of the access covers, they can be bowed
sufficiently so as to disengage the hinge lug allowing the access cover to be removed.
The screws that fasten the front panel to the case are now accessible.
The size 40TE case has four crosshead screws fastening the front panel to the case,
one in each corner, in recessed holes. The size 60TE/80TE case has an additional
two screws, one midway along each of the top and bottom edges of the front plate.
Undo and remove the screws.
Do not remove the screws with the larger diameter heads which are
accessible when the access covers are fitted and open. These screws hold the
relay in its mounting (panel or cubicle).
When the screws have been removed, the complete front panel can be pulled
forward and separated from the metal case.
Caution should be observed at this stage because the front panel is connected
to the rest of the relay circuitry by a 64-way ribbon cable.
Additionally, from here on, the internal circuitry of the relay is exposed and
not protected against electrostatic discharges, dust ingress, etc. Therefore
ESD precautions and clean working conditions should be maintained at all
times.
The ribbon cable is fastened to the front panel using an IDC connector; a socket on
the cable itself and a plug with locking latches on the front panel. Gently push the
two locking latches outwards which will eject the connector socket slightly. Remove
the socket from the plug to disconnect the front panel.
The PCBs within the relay are now accessible. Figures 8, 9 and 10 show the PCB
locations for the Central Unit (P741) in a size 80 TE case, and for Peripheral Units
either in a size 40 TE case (P742) or in a size 60 TE case (P743).
Note: The numbers above the case outline identify the guide slot
reference for each printed circuit board. Each printed circuit
board has a label stating the corresponding guide slot number
to ensure correct re-location after removal. To serve as a
reminder of the slot numbering there is a label on the rear of the
front panel metallic screen.
0 1
1 2 1 5 5 5 5 5 5 5
SLOT 1
SLOT 2
SLOT 5
SLOT 6
SLOT 7
SLOT 8
SLOT 9
SLOT 10
SLOT 11
SLOT 12
SLOT 13
SLOT 14
SLOT 3
SLOT 4
ON 1 ON 1 ON 1 1
6 7 1 ON 3 4 1 ON ON 1 ON1 ON 1 ON
6 6 6 6 6 6 6 6 6
ENSURE SWITCH POSITIONS ON REF5 ARE POSITIONED AS SHOWN
P3754ENa
DESCRIPTION MATERIAL
REF
1 Assy Power Supply ZN0021 *
2 Assy Power Supply 2070583 *
3 Assy Opto Input ZN0017 002
4 Assy Relay Output ZN0019 001
5 Assy Comms 2070273 001
6 Assy IRIG-B ZN0007 *
7 Assy Coprocessor 2070273 002
Figure 7: P741 – PCB/module locations (viewed from front)

1 1
1 3
SLOT 1
SLOT 5
SLOT 6
SLOT 2
SLOT 4
SLOT 3
0
SER No.
2 29 23 or 24
1 ON
6
P3755ENa
REF
23 Assy Standard Input Module GN0010 033
24 Input Module (Univ. Inputs only) GN0010 040
29 Assembly Sreen Plate GN0058 001

FIT JUMPERS (REF 64) TO PL2 ON

PCB'S REF 2 AND 3 IN SLOT POSITIONS SHOWN.
0 1 1 1 1
1 2 1 29
SLOT10
SLOT 1
SLOT 2
SLOT 3
SLOT 5
SLOT 6
SLOT 7
SLOT 8
SLOT 9
SLOT 4
SER No.
29 23 or 24
2 2 3 3
1 ON
P3756ENa
REF
23 Assy Standard Input Module GN0010 033
24 Input Module (Univ. Inputs only) GN0010 040
29 Assembly Screen Plate GN0058 001
The 64-way ribbon cable to the front panel also provides the electrical connections
between PCBs with the connections being via IDC connectors.
The slots inside the case to hold the PCBs securely in place each correspond to a rear
terminal block. Looking from the front of the relay these terminal blocks are labelled
from right to left.
Note: To ensure compatibility, always replace a faulty PCB with one of
an identical part number.
9.3.2.1 Replacement of the main processor board
The main processor board is located in the front panel, not within the case as with all
the other PCBs. Place the front panel with the user interface face-down and remove
the six screws from the metallic screen, as shown in Figure 10. Remove the metal
plate.
There are two further screws, one each side of the rear of the battery compartment
recess, that hold the main processor PCB in position. Remove these screws.
The user interface keypad is connected to the main processor board via a flex-strip
ribbon cable. Carefully disconnect the ribbon cable at the PCB-mounted connector
as it could easily be damaged by excessive twisting.
The front panel can then be re-assembled with a replacement PCB using the reverse
procedure. Ensure that the ribbon cable is reconnected to the main processor board
and all eight screws are re-fitted.
P3007ENa
Figure 10:Front panel assembly

Refit the front panel using the reverse procedure to that given before. After refitting
and closing the access covers on size 60TE/80TE cases, press at the location of the
hinge-assistance T-pieces so that they click back into the front panel moulding.
After replacement of the main processor board, all the settings required for the
application will need to be re-entered. Therefore, it is useful if an electronic copy of
the application-specific settings is available on disk. Although this is not essential, it
can reduce the time taken to re-enter the settings and hence the time the protection is
out of service.
Once the relay has been reassembled after repair, it should be recommissioned in
accordance with the instructions in sections 1 to 8 inclusive of this chapter.
9.3.2.2 Replacement of the IRIG-B board (Central Unit only)
Depending on the model number of the central unit (P741), the IRIG-B board may
have connections for IRIG-B signals.
To replace a faulty board, disconnect all IRIG-B connections at the rear of the relay.
The board is secured in the case by two screws accessible from the rear of the relay,
one at the top and another at the bottom, as shown in Figure 11. Remove these
screws carefully as they are not captive in the rear panel of the relay.
Gently pull the IRIG-B board forward and out of the case.
To help identify that the correct board has been removed, Figure 12 illustrates the
layout of the IRIG-B board with IRIG-B (ZN0007 001).
L M N
1
2
3
4 TX
5
IRIG-B
CH1 RX
6
7
TX
8
9
CH2 RX
10
11
TX
RX
12
13
14
15
16
17
18
P3757ENa INCLUDEPICTUREMERGEFORMAT
Figure 11: Location of securing screws for IRIG-B board
ZN0007 C
SERIAL No.
P3009FRa
Figure 12: Typical IRIG-B board

Before fitting the replacement PCB check that the number on the round label adjacent
to the front edge of the PCB matches the slot number into which it will be fitted. If the
slot number is missing or incorrect write the correct slot number on the label.
The replacement PCB should be carefully slotted into the appropriate slot, ensuring
that it is pushed fully back on to the rear terminal blocks and the securing screws are
re-fitted.
Reconnect IRIG-B connection at the rear of the relay.
Refit the front panel using the reverse procedure to that given in section 9.3.1.2.
After refitting and closing the access covers on size 60TE/80TE cases, press at the
location of the hinge-assistance T-pieces so that they click back into the front panel
moulding.
9.3.2.3 Replacement of the input module
The input module comprises of two boards fastened together, the transformer board
and the input board.
The module is secured in the case by two screws on its right-hand side, accessible
from the front of the relay, as shown in Figure 13. Remove these screws carefully as
they are not captive in the front plate of the module.
Input module
Handle
P3010ENa
Figure 13: Location of securing screws for input module

On the right-hand side of the analogue input module there is a small metal tab which
brings out a handle. Grasping this handle firmly, pull the module forward, away
from the rear terminal blocks. A reasonable amount of force will be required to
achieve this due to the friction between the contacts of two terminal blocks, one
medium duty and one heavy duty.
Note: Care should be taken when withdrawing the input module as it
will suddenly come loose once the friction of the terminal blocks
has been overcome. This is particularly important with
unmounted relays as the metal case will need to be held firmly
whilst the module is withdrawn.
Remove the module from the case, taking care as it is heavy because it contains all
the relay’s input voltage and current transformers.
Before fitting the replacement module check that the number on the round label
adjacent to the front edge of the PCB matches the slot number into which it will be
fitted. If the slot number is missing or incorrect write the correct slot number on the
label.
The replacement module can be slotted in using the reverse procedure, ensuring that
it is pushed fully back on to the rear terminal blocks. To help confirm that the
module has been inserted fully there is a V-shaped cut-out in the bottom plate of the
case that should be fully visible. Re-fit the securing screws.
Note: The transformer and input boards within the module are
calibrated together with the calibration data being stored on the
input board. Therefore it is recommended that the complete
module is replaced to avoid on-site recalibration having to be
performed.
Refit the front panel using the reverse procedure to that given in section. After
refitting and closing the access covers on size 60TE/80TE cases, press at the location
of the hinge-assistance T-pieces so that they click back into the front panel moulding.
9.3.2.4 Replacement of the power supply board
The power supply board is fastened to a relay board to form the power supply
module and is located on the extreme left-hand side of all MiCOM differential busbar
relays.
Pull the power supply module forward, away from the rear terminal blocks and out of
the case. A reasonable amount of force will be required to achieve this due to the
friction between the contacts of the two medium duty terminal blocks.
The two boards are held together with push-fit nylon pillars and can be separated by
pulling them apart. Care should be taken when separating the boards to avoid
damaging the inter-board connectors located near the lower edge of the PCBs
towards the front of the power supply module.
The power supply board is the one with two large electrolytic capacitors on it that
protrude through the other board that forms the power supply module. To help
identify that the correct board has been removed, Figure 14 illustrates the layout of
the power supply board for all voltage ratings.
Before re-assembling the module with a replacement PCB check that the number on
the round label adjacent to the front edge of the PCB matches the slot number into
which it will be fitted. If the slot number is missing or incorrect write the correct slot
number on the label.
Re-assemble the module with a replacement PCB ensuring the inter-board connectors
are firmly pushed together and the four push-fit nylon pillars are securely located in
their respective holes in each PCB.
E1
D16 D14
R29
R53
D17
RD1
D1 C18 C8
LK2 LK1
C14 C25 REF 1
D3 D2 D15 C28 C29
L2
R26 C20 C19
R23
R24
R19 R28 R27
R25 C12
TR9
C10
C9
TR1
C7
IC3
D28
R16
R22 C13
R18
R21 IC1 R17 TR10
D24 R58 R59

C6 T1 C24 RD2
R33 R32
R8
R2
C32
D10
R62
R63
R5 R88 R31 C33
D13
D23
C5 C3 R9 R20 R15 D19 D20 C43
R7 C21 C11
D9 D4 R36 R45 R44
C16 R47 R57
PL1
R39
PC1
D5
T2 TR6 R56
D6
R48 C47
R37 R38
R43
R49 R46
IC4
C4 R4
R40
C46 C15 RD3
R11
PC2 R51 R50 R42 R41
R12 C45
IC2 TR7 R80 TR8
R10 D8
R52
C26
C36
R55 R54
C41
C42
R6 D11 D12 D7
C1 L1
R3 C2 D21
C22 C34 R79 R81 RL1
R13 R90 R78
TR4
C39
C23 C44 PC3 C37 R67 R89 RD4
R14 D25 TR3 TR5
R64
C17 D22
PC4 D18
R65
C35
R1 D26 D27 R68
C30
IC6
SERIAL No. ZN0001 D C40 C38
SK1 R70 IC5
R66
R30
R77
R76
C31 R69 PC5
E2
Figure 14: Typical power supply board for P742 & P743
2070584 B
P3761ENa
Figure 15bis: Additive power supply board for P741

Slot the power supply module back into the relay case, ensuring that it is pushed fully
back on to the rear terminal blocks.
Refit the front panel using the reverse procedure to that given in section. After refitting
9.3.2.5 Replacement of the relay board in the power supply module
Remove and replace the relay board in the power supply module as described in
above.
The relay board is the one with holes cut in it to allow the transformer and two large
electrolytic capacitors of the power supply board to protrude through. To help
identify that the correct board has been removed, Figure 15 illustrates the layout of
the relay board.
Before re-assembling the module with a replacement relay board check that the
number on the round label adjacent to the front edge of the PCB matches the slot
number into which it will be fitted. If the slot number is missing or incorrect write the
correct slot number on the label.
Ensure the setting of the link (located above IDC connector) on the replacement relay
board is the same as the one being replaced before replacing the module in the relay
case.
SERIAL No. F
ZN0019
E2
P3762ENa
Figure 16: Typical relay board
Note: Only for P743, relay number 6 is not used.

9.3.2.6 Replacement of the opto and separate relay boards (P741, P742, & P743)
To remove either, gently pull the faulty PCB forward and out of the case.
If the relay board is being replaced, ensure the setting of the link (located above IDC
connector) on the replacement relay board is the same as the one being replaced.
To help identify that the correct board has been removed, Figure 16 and Figure 17
illustrate the layout of the relay and opto boards respectively.
Before fitting the replacement PCB check that the number on the round label adjacent
to the front edge of the PCB matches the slot number into which it will be fitted. If the
slot number is missing or incorrect write the correct slot number on the label.
The replacement PCB should be carefully slid into the appropriate slot, ensuring that
it is pushed fully back on to the rear terminal blocks.
Refit the front panel using the reverse procedure to that given in section After
refitting and closing the access covers on size 60TE/80TE cases, press at the location
of the hinge-assistance T-pieces so that they click back into the front panel moulding.
C1
ZN0017
SERIAL No.
E
E1
P3760ENa
Figure 17: Typical opto board

9.3.2.7 Replacement of the Coprocessor board
Before replacing a faulty Coprocessor board, disconnect fibre optic cable connections
at the rear of the relay.
Using the small metal tab on the left hand side of the input module rotate handle
used for extraction until it is in a horizontal orientation. This is necessary so that the
two PCB connectors on the underside of the Coprocessor board PCB do not catch the
handle as the PCB is extracted.
Gently pull the faulty Coprocessor board PCB forward and out of the case.
P3763ENa
Figure 18: Typical Coprocessor board
To help identify that the correct board has been replace, Figure 18 illustrates the
layout of the Coprocessor board with dual fibre optic communications channels fitted.
The Coprocessor board boards with a single communications channel (used in relays
for two ended feeders where dual redundant communications channels are not
required) use the same PCB layout but have less components fitted.
it is pushed fully back and the board securing screws are re-fitted.
Refit the fibre optic cable connections, ensuring that they are in the correct locations.
9.3.2.8 Replacement of the Comms board
Before replacing a faulty Comms board (Communication board between central and
peripheral units), disconnect fibre optic cable connections at the rear of the relay.
Using the small metal tab on the left hand side of the input module rotate handle
used for extraction until it is in a horizontal orientation. This is necessary so that the
two PCB connectors on the underside of the Comms board PCB do not catch the
handle as the PCB is extracted.
Gently pull the faulty Comms board PCB forward and out of the case.
P3764ENa
Figure 19: Typical Comms board

To help identify that the correct board has been removed, Figure 19 illustrates the
layout of the Comms board with dual fibre optic communications channels fitted.
The Comms board boards with a single communications channel (used in relays for
two ended feeders where dual redundant communications channels are not required)
use the same PCB layout but have less components fitted.
it is pushed fully back and the board securing screws are re-fitted.
Refit the fibre optic cable connections, ensuring that they are in the correct locations.
9.4. Recalibration
9.4.1. P740 relay
Recalibration is not required when a PCB is replaced unless it happens to be one of

the boards in the input module, the replacement of either directly affects the
calibration.
Although it is possible to carry out recalibration on site, this requires test equipment
with suitable accuracy and a special calibration program to run on a PC. It is
therefore recommended that the work is carried out by the manufacturer, or entrusted
to an approved service centre.
9.5. Changing the relay battery
Each relay has a battery to maintain status data and the correct time when the
auxiliary supply voltage fails. The data maintained includes event, fault and
disturbance records and the thermal state at the time of failure.
This battery will periodically need changing, although an alarm will be given as part
of the relay’s continuous self-monitoring in the event of a low battery condition.
If the battery-backed facilities are not required to be maintained during an
interruption of the auxiliary supply, the steps below can be followed to remove the
battery, but do not replace with a new battery.
with the contents of the safety and technical data sections and the ratings on
the equipment's rating label.
9.5.1. Instructions for replacing the battery.
Open the bottom access cover on the front of the relay.

Gently extract the battery from its socket. If necessary, use a small insulated
screwdriver to prize the battery free.
Ensure that the metal terminals in the battery socket are free from corrosion, grease
and dust.
The replacement battery should be removed from its packaging and placed into the
battery holder, taking care to ensure that the polarity markings on the battery agree
with those adjacent to the socket.
Note: Only use a type ½AA Lithium battery with a nominal voltage of
3.6V and safety approvals such as UL (Underwriters Laboratory),
CSA (Canadian Standards Association) or VDE (Vereinigung
Deutscher Elektrizitätswerke).
Ensure that the battery is securely held in its socket and that the battery terminals are
making good contact with the metal terminals of the socket.
Close the bottom access cover.
9.5.2. Post modification tests
To ensure that the replacement battery will maintain the time and status data if the
auxiliary supply fails, check cell [0806: DATE and TIME, Battery Status] reads
‘Healthy’.
Additionally, if further confirmation that the replacement battery is installed correctly
is required, the commissioning test described in section 4.2.2, ‘Date and Time’, can
be performed.
9.5.3. Battery disposal
The battery that has been removed should be disposed of in accordance with the
disposal procedure for Lithium batteries in the country in which the relay is installed.
9.6. Cleaning
Before cleaning the equipment ensure that all ac and dc supplies, current
transformer and voltage transformer connections are isolated to prevent any chance
of an electric shock whilst cleaning.
The equipment may be cleaned using a lint-free cloth dampened with clean water.
The use of detergents, solvents or abrasive cleaners is not recommended as they may
damage the relay’s surface and leave a conductive residue.
10. COMMISSIONING TEST RECORD:

10.1. Peripheral Units: P742/P743
Date: Engineer:
Station: Circuit:
System Frequency:
Front Plate Information
Peripheral Unit Type P74_

Model number
Serial number
Rated current In
Auxiliary voltage Vx
Test Equipment Used

This section should be completed to allow future identification of protective devices
that have been commissioned using equipment that is later found to be defective or
incompatible but may not be detected during the commissioning procedure.
Overcurrent test set Model:

Serial No:
Optical power meter Model:
Serial No:
Insulation tester Model:

Serial No:
Setting software: Type:
Version:
*Delete as
appropriate
Have all relevant safety instructions been Yes/No*
followed?
4 Product Checks
4.1 With the relay de-energised
4.1.1 Visual inspection
Relay damaged? Yes/No*
Rating information correct for installation? Yes/No*
Case earth installed? Yes/No*
4.1.2 Current transformer shorting contacts close? Yes/No/Not checked*
4.1.3 Insulation resistance >100MΩ at 500V dc Yes/No/Not tested*

4.1.4 External Wiring
Wiring checked against diagram? Yes/No*
Test block connections checked? Yes/No/na*
4.1.5 Watchdog Contacts (auxiliary supply off)

Terminals 11 and 12 Contact closed? Yes/No*
Contact resistance ____Ω/Not measured*
Terminals 13 and 14 Contact open? Yes/No*
4.1.6 Measured auxiliary supply ______V ac/dc*
4.2 With the relay energised

4.2.1 Watchdog Contacts (auxiliary supply on)
Terminals 11 and 12 Contact open? Yes/No*
Terminals 13 and 14 Contact closed? Yes/No*
4.2.2 Date and time

Clock set to local time? Yes/No*
Time maintained when auxiliary supply Yes/No*
removed?
4.2.3 Light emitting diodes

4.2.3.1 Alarm (yellow) LED working? Yes/No*
Out of service (yellow) LED working? Yes/No*
4.2.3.2 Trip (red) LED working? Yes/No*
4.2.3.3 All 8 programmable LED’s working? Yes/No*
4.2.4 Field supply voltage

Value measured between terminals 7 and 9 ______V dc
Value measured between terminals 8 and 10 ______V dc
4.2.5 Input opto-isolators

Opto input 2 working? Yes/No*
Opto input 9 working? Yes/No/na*
For P742 Opto input 17 working? Yes/No/na*
For P743 Opto input 24 working? Yes/No/na*
4.2.6 Output relays

Relay 1 Working? Yes/No*
Contact resistance (N/C) ____Ω/Not measured*
(N/O) ____Ω/Not measured*
For P742 Relay 8 Working? Yes/No/na*
Relay 9 Working? Yes/No/na*
Relay 10 Working? Yes/No/na*
Contac t resistance (N/C) ____Ω/Not measured*

For P743 Relay 21 Working? Yes/No*
4.2.9 Current Inputs

Displayed Current Primary/Secondary*
Phase CT Ratio _______ /na*
Input CT Applied value Displayed value

ΙA _______A _______A
ΙB _______A _______A
ΙC _______A _______A
ΙN _______A _______A
5 Setting Checks
5.1 Application-specific function settings applied? Yes/No*
Application-specific programmable scheme Yes/No/na*
logic settings applied?
5.2.1.2 Current Differential lower slope pickup _________A

5.2.1.3 Current Differential upper slope pickup _________A
5.2.5 Protection function timing tested? Yes/No*

Applied current _________A
Expected operating time _________s
Measured operating time _________s
5.4 Application-specific function settings verified? Yes/No/na*

Application-specific programmable scheme Yes/No/na*
logic tested?
Signal strength received by P742/3
Channel 1 ______dBm/na*
Signal strength transmitted by 742/3
Channel 1 ______dBm/na*
Signal Strength within tolerance Yes/No/na*
Optical fibres reconnected?
Channel RX and TX Yes/No*
Alarms reset? Yes/No*
7 On-load Checks
Test wiring removed? Yes/No/na*
Disturbed customer wiring re-checked? Yes/No/na*
7.1 Confirm current transformer wiring

7.1.2 Current connections
CT wiring checked? Yes/No/na*
CT polarities correct? Yes/No*
Displayed current Primary/Secondary*
Phase CT ratio _______ /na*
Currents: Applied value Displayed value
ΙA _______A _______A
ΙB _______A _______A
ΙC _______A _______A
ΙN _______A/na* _______A/na*
7.3 Differential current checked? Yes/ No*
8 Final Checks
Test wiring removed? Yes/No/na*
Disturbed customer wiring re-checked? Yes/No/na*
Test mode disabled? Yes/No*
Circuit breaker operations counter reset? Yes/No/na*
Current counters reset? Yes/No/na*
Event records reset? Yes/No*
Fault records reset? Yes/No*
Disturbance records reset? Yes/No*
Alarms reset? Yes/No*
LED’s reset? Yes/No*
Secondary front cover replaced? Yes/No/na*
Commissioning Engineer Customer Witness
Date Date
11. SETTING RECORD

11.1. Central Unit: P741
Date: Engineer:
Station: Circuit:
System Frequency:
Central Unit type: P741

Model Number
Serial Number
Rated Current In
Auxiliary Voltage Vx
*Delete as appropriate
Setting Groups Used
Group 1 Yes/No*
Group 2 Yes/No*
Group 3 Yes/No*
Group 4 Yes/No*
800 SYSTEM DATA
0001 Language English/Francais/Deutsch/Espanol*

0004 Description
0005 Plant Reference
0006 Model Number
0008 Serial Number
0009 Frequency
000A Comms Level
000B Relay Address
0011 Software Ref.1
00D1 Password Control
00D2 Password Level 1
800 PU CONF & STATUS
0601 PU in service 0000 0000 0000 0000 0000 0000 0000 0000
32....................................................................
........................1
0602 PU Connected 0000 0000 0000 0000 0000 0000 0000 0000
32....................................................................
........................1
0603 PU Topo valid 0000 0000 0000 0000 0000 0000 0000 0000
32....................................................................
........................1
800 DATE AND TIME
0801 Date/Time
0806 Battery Status Dead/Healthy*
0807 Battery Alarm Disabled/Enabled*
800 CONFIGURATION
0902 Setting Group Select via Menu/Select via Optos*

0903 Active Settings Group 1/Group 2/Group 3/Group 4*
0907 Setting Group 1 Disabled/Enabled*
090A Setting Group 4 Disabled/Enabled*
0925 Input Labels Invisible/Visible*
0926 Output Labels Invisible/Visible*
0929 Recorder Control Invisible/Visible*
092A Disturb Recorder Invisible/Visible*
092B Measure’t Setup Invisible/Visible*
092D Commission Tests Invisible/Visible*
092E Setting Values Primary/Secondary*
0C00 DISTURB RECORDER
0C01 Duration
0C02 Trigger Position
0C03 Trigger Mode Single/Extended*
0C04 Analog Channel 1
0C0A Analog Channel 7
0C0B Analog Channel 8
0C0C Digital Input 1
0C0E Digital Input 2
0C10 Digital Input 3
0C1A Digital Input 8

0D00 MEASURE’T SETUP
0D01 Default Display 3Ph+N Current/ Date and

Time/Description/Plant Reference/ Frequency/
Access Level*
0D02 Local Values Primary/Secondary*
0D03 Remote Values Primary/Secondary*
0D04 Ibp Base Cur Pri
0F00 COMMISSION TESTS
0F05 Monitor Bit 1

0F06 Monitor Bit 2
0F07 Monitor Bit 3
0F08 Monitor Bit 4
0F09 Monitor Bit 5
0F0A Monitor Bit 6
0F0B Monitor Bit 7
0F0C Monitor Bit 8
0F0D Test Mode Disabled/Test Mode/Blocked*
0F0E Test Pattern
800 OPTOS SETUP
1101 Global Level

1101 Opto Input 1
1102 Opto Input 2
1103 Opto Input 3
1104 Opto Input 4
1105 Opto Input 5

1106 Opto Input 6
1107 Opto Input 7
1108 Opto Input 8
1109 Opto Input 9
110A Opto Input 10
110B Opto Input 11
110C Opto Input 12
110D Opto Input 13
110E Opto Input 14
110F Opto Input 15
1111 Opto Input 16
1112 Opto Input 17
1113 Opto Input 18
1114 Opto Input 19
1115 Opto Input 20
1116 Opto Input 21
1117 Opto Input 22
1118 Opto Input 23
1119 Opto Input 24
GROUP 1 PROTECTION SETTINGS

For Group 2,3 or 4 the first address figure must be respectively: 5 and 6, 7and 8 or 9
and A
800 DIFF BUSBAR PROT
Group 1 Settings Group 1 Group 2 Group 3 Group 4

Settings Settings Settings Settings
3002 Current Is
3003 Phase Slope k
3004 ID>2 Current
3005 ID>1 Current
3006 ID>1 Alarm Timer
3007 Diff. Earth Fault Enabled/
Disabled
3008 Ibias Ph> Cur.
3009 Earth Cur. IsN

300A Earth Slope kN
300B IDN>2 Current
300C IDN>1 Current
300D IDN>1 Alarm Tim
4A00 INPUT LABELS

4A01 Opto Input 1
4A02 Opto Input 2
4A03 Opto Input 3
4A04 Opto Input 4
4A05 Opto Input 5
4A06 Opto Input 6
4A07 Opto Input 7
4A08 Opto Input 8
4A09 Opto Input 9
4A0A Opto Input 10
4A0B Opto Input 11
4A0C Opto Input 12
4A0D Opto Input 13
4A0E Opto Input 14
4A0F Opto Input 15
4A10 Opto Input 16
4A11 Opto Input 17
4A12 Opto Input 18
4A13 Opto Input 19
4A14 Opto Input 20
4A15 Opto Input 21
4A16 Opto Input 22
4A17 Opto Input 23
4A18 Opto Input 24
4B00 OUTPUT LABELS

4B01 Relay 1
4B02 Relay 2
4B03 Relay 3
4B04 Relay 4
4B05 Relay 5
4B06 Relay 6
4B07 Relay 7
4B08 Relay 8
4B09 Relay 9
4B0A Relay 10
4B0B Relay 11
4B0C Relay 12
4B0D Relay 13
4B0E Relay 14
4B0F Relay 15
4B10 Relay 16
4B11 Relay 17
4B12 Relay 18
4B13 Relay 19
4B14 Relay 20
4B15 Relay 21
4B20 Virtual Relay 01
4B2A Virtual Relay 11

4B2B Virtual Relay 12
4B2C Virtual Relay 13
4B2D Virtual Relay 14
4B2E Virtual Relay 15
4B2F Virtual Relay 16
Date Date
11.2. Peripheral Units: P742/P743
Date: Engineer:
Station: Circuit:
System Frequency:
Peripheral Unit type: P742/P743 *

Model Number
Serial Number
Rated Current In
Auxiliary Voltage Vx
*Delete as appropriate
Setting Groups Used
Group 1 Yes/No*
Group 2 Yes/No*
Group 3 Yes/No*
Group 4 Yes/No*
800 SYSTEM DATA
0001 Language English/Francais/Deutsch/Espanol*

0004 Description
0005 Plant Reference
0006 Model Number
0008 Serial Number
0009 Frequency
000A Comms Level
000B Relay Address
0011 Software Ref.1
00D1 Password Control
800 CB CONTROL
0702 Trip Latched

0703 Reset Trip Latch
0704 CB Control By
0705 Man. Close Pulse Time
0706 Man. Trip Pulse Time
0707 Man. Close Delay
800 DATE AND TIME
0804 IRIG-B Sync Disabled/Enabled*

0805 IRIG-B Status Inactive/Active*
0806 Battery Status Dead/Healthy*
0807 Battery Alarm Disabled/Enabled*
0900 CONFIGURATION
0902 Setting Group Select via Menu/Select via Optos*

0903 Active Settings Group 1/Group 2/Group 3/Group 4*
090A Setting Group 4 Disabled/Enabled*
0910 BusBar Prot. Disabled/Enabled*
0911 Optos Setup
0912 Backup Phase O/C Disabled/Enabled*

0913 Backup Earth O/C Disabled/Enabled*
0914 CB Fail Disabled/Enabled*
0925 Input Labels Invisible/Visible*
0926 Output Labels Invisible/Visible*
0928 CT & VT Ratios Invisible/Visible*
0929 Recorder Control Invisible/Visible*
092A Disturb Recorder Invisible/Visible*
092B Measure’t Setup Invisible/Visible*
092D Commission Tests Invisible/Visible*
092E Setting Values Primary/Secondary*
0A00 CT AND VT RATIOS
0A07 Phase CT Primary

0A08 Phase CT Secondary
0A20 Transfo Class
0A24 Standard Input BS/IEC
0A25 Knee Voltage Vk BS
0A26 Rated Burden VA IEC
0A28 KSCC IEC
0A29 RCT Sec'y
0A2B Eff. Burden
0C00 DISTURB RECORDER
0C01 Duration
0C02 Trigger Position
0C03 Trigger Mode Single/Extended*

0D00 MEASURE’T SETUP
0D01 Default Display 3Ph+N Current/ Date and

Time/Description/Plant Reference/ Frequency/
Access Level*
0D02 Local Values Primary/Secondary*
0D03 Remote Values Primary/Secondary*
0F00 COMMISSION TESTS
0F05 Monitor Bit 1

0F06 Monitor Bit 2
0F07 Monitor Bit 3
0F08 Monitor Bit 4
0F09 Monitor Bit 5
0F0A Monitor Bit 6
0F0B Monitor Bit 7
0F0C Monitor Bit 8
0F0D Test Mode Disabled/Test Mode/Blocked*
0F0E Test Pattern
1100 OPTOS SETUP
1101 Global Level

1101 Opto Input 1
1102 Opto Input 2
1103 Opto Input 3
1104 Opto Input 4
1105 Opto Input 5
1106 Opto Input 6
1107 Opto Input 7
1108 Opto Input 8
1109 Opto Input 9
110A Opto Input 10
110B Opto Input 11
110C Opto Input 12
110D Opto Input 13
110E Opto Input 14
110F Opto Input 15
1111 Opto Input 16
1112 Opto Input 17
1113 Opto Input 18
1114 Opto Input 19
1115 Opto Input 20
1116 Opto Input 21
1117 Opto Input 22
1118 Opto Input 23
1119 Opto Input 24
GROUP 1 PROTECTION SETTINGS

For Group 2,3 or 4 the first address figure must be respectively: 5 and 6, 7and 8 or 9
and A
3000 BB TRIP CONFIRM

3001 I>BB Current set

3002 IN<BB Current
3500 BACKUP O/C PHASE

3501 Ι>1 Function

3502 Ι>1 Current Set
3503 Ι>1 Time Delay
3504 Ι>1 TMS
3505 Ι>1 Time Dial
3506 Ι>1 Reset Char
3507 Ι>1 tRESET
3508 Ι>2 Function
3509 Ι>2 Current Set
350A Ι>2 Time Delay
3800 O/C EARTH FAULT

3801 ΙN>1 Function
3802 ΙN>1 Current Set
3803 ΙN>1 Time Delay
3804 ΙN>1 TMS
3805 ΙN>1 Time Dial
3806 ΙN>1 Reset Char
3807 ΙN>1 tRESET
3808 ΙN>2 Function
3809 ΙN>2 Current Set
380A ΙN>2 Time Delay
4500 CB FAIL & I<

4501 Control By
4502 Ι< Current Set
4503 I> Status
4504 I> Current Set
4505 IN> Current Set
4507 CB Fail Timer 1
4508 CB Fail Timer 2
450A CB Fail Timer 3
450B CB Fail Timer 4
4600 SUPERVISION

460E Error Factor Kce
460F Opto Input 2
4A00 INPUT LABELS

4A01 Opto Input 1
4A02 Opto Input 2
4A03 Opto Input 3
4A04 Opto Input 4
4A05 Opto Input 5
4A06 Opto Input 6
4A07 Opto Input 7
4A08 Opto Input 8
4A09 Opto Input 9

4A0A Opto Input 10
4A0B Opto Input 11
4A0C Opto Input 12
4A0D Opto Input 13
4A0E Opto Input 14
4A0F Opto Input 15
4A10 Opto Input 16
4A11 Opto Input 17
4A12 Opto Input 18
4A13 Opto Input 19
4A14 Opto Input 20
4A15 Opto Input 21
4A16 Opto Input 22
4A17 Opto Input 23
4A18 Opto Input 24
4B00 OUTPUT LABELS

4B01 Relay 1
4B02 Relay 2
4B03 Relay 3
4B04 Relay 4
4B05 Relay 5
4B06 Relay 6
4B07 Relay 7
4B08 Relay 8
4B09 Relay 9
4B0A Relay 10
4B0B Relay 11
4B0C Relay 12
4B0D Relay 13
4B0E Relay 14
4B0F Relay 15

4B10 Relay 16
4B11 Relay 17
4B12 Relay 18
4B13 Relay 19
4B14 Relay 20
4B15 Relay 21
4B2A Virtual Relay 11
4B2B Virtual Relay 12
4B2C Virtual Relay 13
4B2D Virtual Relay 14
4B2E Virtual Relay 15
4B2F Virtual Relay 16
Date Date

Problem Analysis P740/EN PR/D11
PROBLEM ANALYSIS
P740/EN PR/D11 Problem Analysis

CONTENT
1. INTRODUCTION 4
2. INITIAL PROBLEM IDENTIFICATION 4
3. POWER UP ERRORS 5
4. ERROR MESSAGE/CODE ON POWER-UP 6
5. OUT OF SERVICE LED ILLUMINATED ON POWER UP 8
6. ERROR CODE DURING OPERATION 9
7. MIS-OPERATION OF THE RELAY DURING TESTING 10
8. ERROR CODES 12
1. INTRODUCTION
with the contents of the safety and technical data sections and the ratings on
the equipment’s rating label.
The purpose of this chapter of the service manual is to allow an error condition on
the relay to be identified so that appropriate corrective action can be taken.
Should the relay have developed a fault, it should be possible in most cases to
identify which relay module requires attention. The ‘Commissioning and
Maintenance’ chapter (P740/EN CM), advises on the recommended method of repair
where faulty modules need replacing. It is not possible to perform an on-site repair
to a faulted module.
In cases where a faulty relay/module is being returned to the manufacturer or one of
their approved service centres, completed copy of the Repair Form located at the end
of this manual should be included.
2. INITIAL PROBLEM IDENTIFICATION

Consult the table below to find the description that best matches the problem
experienced, then consult the section referenced to perform a more detailed analysis
of the problem.
Symptom Refer to
Relay fails to power up Section 3
Relay powers up but indicates error and halts during power- Section 4
up sequence
Relay powers up but Out of Service LED is illuminated Section 5
Relay reboots during normal operation Section 6
Error during normal operation Section 6
Misoperation of the relay during testing Section 7
Table 1: Problem Identification

3. POWER UP ERRORS
If the relay does not appear to power up then the following procedure can be used to
determine whether the fault is in the external wiring, auxiliary fuse, power supply
module of the relay or the relay front panel.
Test Check Action

1 Measure auxiliary voltage on If auxiliary voltage is present and
terminals 1 and 2, verify voltage correct, then proceed to test 2.
level and polarity against the Otherwise the wiring/fuses in auxiliary
rating label on front panel, under supply should be checked.
the top cover.
Terminal 1 is –dc, 2 is +dc
2 Do LEDs/ and LCD backlight If they illuminate or the contact closes
illuminate on power up, also check and no error code is displayed then
the N/O watchdog contact for error is probably in the main
closing. processor board (front panel)
If they do not illuminate and the
contact does not close then proceed
to test 3.
3 Check Field voltage output If field voltage is not present then the
(nominally 48V DC) fault is probably in the relay power
supply module. Consult the
Commissioning & Maintenance
chapter (P740/EN CM) for a
description of how to remove this
module. The part number of this
module can be checked to verify that
the rating of the module conforms to
the auxiliary rating printed on the
relay front panel.
Table 2: Failure of Relay to power up

4. ERROR MESSAGE/CODE ON POWER-UP

During the power-up sequence of the relay self-testing is performed as indicated by
the messages displayed on the LCD. If an error is detected by the relay during these
self-tests then an error message will be displayed and the power-up sequence will be
halted. If the error occurs when the relay application software is executing then a
maintenance record will be created and the relay will reboot.
Test Check Action
1 Is an error message or code If relay locks up and displays an error code

permanently displayed during permanently then proceed to test 2. If the
power up. relay prompts for input by the user proceed
to test 4. If the relay reboots
automatically then proceed to test 5.
2 Record displayed error, then Record whether the same error code is
remove and re-apply relay displayed when the relay is rebooted.
auxiliary supply.
If no error code is displayed then contact
the local service centre stating the error
code and relay information.
If the same code is displayed proceed to
test 3.
3 Error code Identification Refer to the Commissioning & Maintenance
location. chapter (P740/EN CMxxx) for module
Following text messages (in These messages indicate that a problem
English) will be displayed if a has been detected on the main processor
fundamental problem is board of the relay (located in the front
detected preventing the panel), or in the Current Differential
system from booting: processor board (located within the case).
Bus Fail – address lines
SRAM Fail - data lines
FLASH Fail format error
FLASH Fail checksum
Code Verify Fail
Other error codes relate to Refer to section 8 for a list of error codes.
errors detected in hardware or
software:
4 Relay displays message for The power up tests have detected corrupted
corrupt settings and prompts relay settings. It is possible to restore
for restoration of defaults to defaults to allow the power- up to be
the affected settings. completed. It will then be necessary to re-
apply the application- specific settings.
Test Check Action
5 Relay resets on completion of Error 0x0E080000, programmable scheme

power up – record error code logic error due to excessive execution time.
displayed. Restore default settings by performing a
power up with ! and " keys depressed,
confirm restoration of defaults at prompt
using # key. If relay powers up
successfully, check programmable logic for
feedback paths.
Refer to section 8 for a list of error codes.
Table 3: Power-up self-test error

5. OUT OF SERVICE LED ILLUMINATED ON POWER UP
Test Check Action

1 Using the relay menu If the setting is Enabled then disable the test
confirm whether the mode and, verify that the Out of Service
Commission Test/ Test Mode LED is extinguished.
setting is Enabled.
Otherwise proceed to test 2.
2 Select and view the last Check for H/W Verify Fail (this indicates a
maintenance record from discrepancy between the relay model
the menu (in the View number and the hardware). Examine the
Records). “Maint Data”,(this indicates the causes of
the failure using bit fields):
Bit Meaning
0 The application type field in the
model number does not match the
software ID
1 The application field in the model
number does not match the
software ID
2 The variant 1 field in the model
software ID
3 The variant 2 field in the model
software ID
4 The protocol field in the model
software ID
5 The language field in the model
software ID
Table 4: Out-of-service condition

6. ERROR CODE DURING OPERATION

The relay performs continuous self-checking. If an error is detected, then an error
message will be displayed, a maintenance record will be logged and the relay will
reset (after a 1.6 second delay). A permanent problem (for example due to a
hardware fault) will generally be detected on the power up sequence, following which
the relay will display an error code and halt. If the problem was transient in nature
then the relay should re-boot correctly and continue in operation. The nature of the
detected fault can be determined by examination of the maintenance record logged.
There are also two cases where a maintenance record will be logged due to a
detected error where the relay will not reset. These are detection of a failure of either
the field voltage or the lithium battery. In these cases the failure is indicated by an
alarm message. However, the relay will continue to operate.
If the field voltage is detected to have failed (the voltage level has dropped below
threshold), then a scheme logic signal is also set. This allows the scheme logic to be
adapted in the case of this failure (for example if a blocking scheme is being used).
In the case of a battery failure it is possible to prevent the relay from issuing an alarm
using the setting under the Date and Time section of the menu. This setting "Battery
Alarm" can be set to 'Disabled' to allow the relay to be used without a battery, without
an alarm message being displayed.
7. MIS-OPERATION OF THE RELAY DURING TESTING

7.1 Failure of output contacts
An apparent failure of the relay output contacts may be caused by the relay
configuration and the following tests should be performed to identify the real cause of
the failure. Note that the relay self-tests verify that the coil of the contact has been
energised. An error will be displayed if there is a fault in the output relay board.
Test Check Action

1 Is the Out of Service LED Illumination of this LED may indicate that the
illuminated. relay is in test mode or that the protection
has been disabled due to a hardware verify
error (see Table 4)
2 Examine the Contact status If the relevant bits of the contact status are
in the Commissioning operated then proceed to test 4.
section of the menu.
If not, proceed to test 3.
3 Verify by examination of the If the protection element does not operate,
fault record, or by using the verify whether the test is being correctly
test port whether the applied.
protection element is
If the protection element does operate, then
operating correctly.
it will be necessary to check the
programmable logic to ensure that the
mapping of the protection element to the
contacts is correct. If the mapping of the
protection has been correctly configured,
then the contact may be at fault. This can be
verified – see test 4.
4 Using the If the output relay does operate then the
Commissioning/Test mode problem must be in the external wiring to the
function, apply a test pattern relay. If the output relay does not operate
to the relevant relay output this could indicate a failure of the output
contacts and verify whether relay contacts (note that the self-tests verify
they operate (note the correct that the relay coil is being energised).
external connection diagram Ensure that the closed resistance is not too
should be consulted). high for the continuity tester to detect.
A continuity tester can be
used at the rear of the relay
for this purpose.
Table 5: Failure of output contacts

7.2 Failure of opto-isolated inputs

The opto-isolated inputs are mapped onto the relay internal signals using the
programmable scheme logic. If an input does not appear to be recognised by the
relay scheme logic the Commission Tests/Opto Status menu option can be used to
verify whether the problem is in the opto-isolated input itself or the mapping of its
signal to the scheme logic functions. If the opto-isolated input does appear to be
read correctly then it will be necessary to examine its mapping within the
programmable logic.
If the opto-isolated input state is not being correctly read by the relay the applied
signal should be tested. Verify the connections to the opto-isolated input using the
correct wiring diagram. Next, using a voltmeter verify that >80% of the programmed
nominal battery voltage threshold is present on the terminals of the opto-isolated
input in the energised state. If the signal is being correctly applied to the relay then
the failure may be on the input card itself. Depending on which opto-isolated input
has failed this may require replacement of either the complete analogue input
module (the board within this module cannot be individually replaced without re-
calibration of the relay) or a separate opto board.
7.3 Incorrect analogue signals (P742 and P743)
If it is suspected that the analogue quantities being measured by the relay are not
correct then the measurement function of the relay can be used to verify the nature of
the problem. The measured values displayed by the relay should be compared with
the actual magnitudes at the relay terminals. Verify that the correct terminals are
being used (in particular the dual rated CT inputs) and that the CT ratios set on the
relay are correct.
8. ERROR CODES
Error codes (as reported by the relay via the front panel or in the Maintenance
Records) can offer a considerable amount of information about the source of the
error.
The Hex Code is reported on the front user interface of the relay immediately prior to
a reboot sequence. If this code could not be observed, use the Maintenance Records
section of the View Records column to display the corresponding Decimal Code.
Hex Code Decimal Code Meaning

0x0C140001 202637313 The serial driver failed to initialise properly.
Check the serial port hardware on the power
supply board and the main processor board.
0x0C140002 202637314 The LCD driver failed to initialise properly. Check
the LCD on the main processor board.
0x0C140003 202637315 The Flash memory driver failed to initialise
properly. Check the Flash memory on the main
processor board.
0x0C140004 202637316 The date and time driver failed to initialise
properly. Check the real-time clock and battery-
backed SRAM on the main processor board.
0x0C140008 202637320 The database failed to initialise properly. Check
the EEPROM on the main processor board.
0x0C140009 202637321 The database took too long to commit a change.
Check the EEPROM on the main processor
board.
0x0C14000A 202637322 The IRIG-B driver failed to initialise properly.
Check the IRIG-B interface hardware on the IRIG-
(P741 only)
B board.
0x0C160010 202768400 The continuous self-checks have found an error
in the RAM bus. Check the RAM on the main
processor board.
in the RAM block. Check the RAM on the main
processor board.
in the Flash EPROM checksum. Check the Flash
EPROM on the main processor board, and then
try downloading a new program.
in the code comparison. Check the Flash EPROM
on the main processor board, and then try
downloading a new program.
in the battery backed SRAM. Check the battery,
then the RAM on the main processor board.

in the EEPROM. Check the EEPROM on the main
processor board.
0x0C1600A0 202768544 The continuous self-checks have found an error
on the acquisition board. Check the input board.
0x0C170016 202833942 Secondary initialisation tests detected a fast
watchdog failure. Check the on the main
processor board.
0x0C170017 202833943 Secondary initialisation tests detected a battery
backed SRAM failure. Check the battery backed
SRAM on the main processor board.
0x0C170018 202833944 Secondary initialisation tests detected a bus reset
test failure. Check the main processor board.
0x0C170019 202833945 Secondary initialisation tests detected a slow
watchdog failure.
0x0E020000 235012096 Excessive number of gates in PSL. Restore
defaults and download new PSL.
0x0E080000 235405312 PSL excessive execution time. Restore defaults
and download new PSL.
Table 6: Error Codes
Other error codes relate to problems within the main processor board software. It
will be necessary to contact AREVA T&D with details of the problem for a full analysis.

Connection Diagrams P740/EN CO/D11
MiCOM P740
CONNECTION DIAGRAMS
Version dated : 08/03

P740/EN CO/D11 Connection Diagrams
MiCOM P740
Connection Diagrams P740/EN CO/D11
CONTENTS
1. MiCOM P741 - CENTRAL UNIT 3
2. MiCOM P742 – PERIPHERAL UNIT 6
3. MiCOM P743 – PERIPHERAL UNIT 9


1.
MiCOM P740
Connection Diagrams
TERMINAL BLOCK DETAIL
74.9 116.55 142.45 12 OFF HOLES Dia. 3.4
1 2
TX
CH1 RX
MiCOM P741 - CENTRAL UNIT

TX
Connections for Connections for
communication boards I/O boards
159.0 168.0 CH2 RX
4.5 TX
CH3 RX
FIGURE 1: MiCOM P741 (80TE) – Hardware description
TX
62.0 155.4 129.5 FLUSH MOUNTING CH4

RX
PANEL CUT-OUT 17 18
408.9 DETAIL.
EACH TERMINATION ACCEPTS:- EACH TERMINATION ACCEPTS:-
ST CONNECTOR / MULTI-MODE FIBRE 2 x M4 RING TERMINALS
406.9
MOUNTING SCREWS : M4 x 12 SEM UNIT STEEL THREAD FORMING SCREW.
TERMINAL SCREWS : M4 x 7 BRASS CHEESE HEAD SCREWS WITH LOCK WASHERS PROVIDED.
TYPE OF FIBRE OPTIC CONNECTOR : ST
SECONDARY COVER (WHEN FITTED)
240.0 INCL. WIRING

FRONT VIEW
MiCOM
TRIP
ALARM
P740/EN CO/D11
OUT OF SERVICE
HEALTHY
= CLEAR 177.0 157.5 MAX.

= READ
= ENTER
Page 3/12
SIDE VIEW P3713ENa
413.2 30.0
Page 4/12
P740/EN CO/D11
J K L
A B C D E F G H M N
2 2 2
1 1 1
4 4 4
FIGURE 2: MiCOM P741 (80TE) – Rear View
6 6 6
IRIG-B
8 8 8
7 7 7
9 9 9
11 11 11
RX
13 13 13
16 16 16
15 15 15
17 17 17
1 TO 8 COMMUNICATION BOARDS
LOGICAL OUTPUT CONTACT BOARD
LOGICAL INPUT CONTACT BOARD
Connection Diagrams
POWER SUPPLY MODULE
CO-PROCESSOR BOARD
OPTIONAL IRIG-B BOARD
MiCOM P740
P3712ENa
MiCOM P740
Connection Diagrams
MiCOM P741 (PART)
L11
WATCHDOG
L12 CONTACT
L13
WATCHDOG
L14 CONTACT
L17
- J1
J2 TRIP A
J3
J4 TRIP B
L18
+ J5
TRIP C
MiCOM P741 (PART) TX1 L16
J6
J7
SCN RELAY 4
J8
RX1
K1 J9
- DATA READY 1 SK2 RELAY 5
TX2 J10
OPTO 1 K2 J11
+ FIBRE OPTIC DATA 10
RX2 J12 RELAY 6
K3 COMMUNICATION ACKNOWLEDGE
- J13
TX3 CURR DIFF EXTERNAL
FIGURE 3: MiCOM P741 (80TE) – Wiring Description
OPTO 2 K4 16 J14
RELAY 7
+ Position B RESET J15
RX3
5 to 8 PU*
K5 DOWNLOAD J16
- TX4 17
COMMAND J17
RELAY 8
OPTO 3 K6 TEST/ J18
+ RX4
DO-D7 2-9
DOWNLOAD
K7
- 11,12,15,13,
OPTO 4 K8 TO-T7
+ TX1
20,21,23,24
K9
- RX1 0V 19,18,22,25 TX1
OPTO 5 K10
+ TX2 RX1
NOT 14
K11 FIBRE OPTIC CONNECTED
RX2 TX2
- COMMUNICATION
OPTO 6 K12 CURR DIFF RX2 FIBRE OPTIC
TX3
+ Position C SK1 COMMUNICATION
1 CURR DIFF
K13 RX3 9 to 12 PU* TX3
- TX 2 Position F
OPTO 7 K14 TX4 RX3
21 to 24 PU*
+ RX 3
RX4 TX4
K15 4
- SERIAL
OPTO 8 0V 5 RX4
K16
+ PORT
K17 6
TX1
COMMON CTS 7
CONNECTION K18 RX1 TX1
PAPER 8
TX2 RTS 9 RX1
FIBRE OPTIC
TX1 RX2 COMMUNICATION TX2
FIBRE OPTIC
TX3
CURR DIFF RX2 COMMUNICATION
RX1 Position D
TX3
CURR DIFF
RX3 13 to 16 PU*
TX2 Position G
TX4 RX3 25 to 28 PU*
RX2
RX4 TX4
FIBRE OPTIC
COMMUNICATION TX3 RX4
CURR DIFF
Position A RX3
1 to 4 PU*
TX1
L1 *
-
TX4 AC OR DC TX1
RX1
AUX SUPPLY
Vx L2
TX2
+ RX1
RX4
FIBRE OPTIC
RX2 COMMUNICATION L7 TX2
+ FIBRE OPTIC
CURR DIFF RX2
TX3
Position E L8 COMMUNICATION
+
RX3 17 to 20 PU* 48V DC FIELD TX3 CURR DIFF
VOLTAGE OUT L9 Position H
- RX3
TX4 29 to 32 PU*
L10
RX4 - TX4
RX4
CASE
EARTH
* PU: Peripheral Unit
P740/EN CO/D11
(K) PIN TERMINAL (P.C.K. TYPE)
50 OHM KNC CONNECTOR
9-WAY & 25-WAY FEMALE D-TYPE SOCKET
Issue: Revision: Title:

BUSBAR PROTECTION
Page 5/12
CENTRAL UNIT P741
Drg
Date: 7/02/2003 Name:
CAD DATA 1:1 DIMENSIONS: mm Sht: 1
10P74101
T&D Protection & Controle No:
DO NOT SCALE Lattes Next
Date: Chkd:
Sht: 2
2.
Page 6/12
P740/EN CO/D11
TERMINAL BLOCK DETAIL TERMINAL BLOCK DETAIL
COPROCESSOR BOARD 3 ANALOG & I/O BOARDS
8 OFF HOLES Æ 3.4
1 2
23.3 155.4 1 19
MiCOM P742 – PERIPHERAL UNIT

TX
HEAVY DUTY MEDIUM DUTY
CH1 RX
4
TX
FLUSH MOUNTING PANEL

CH2 RX
159.0 168.0 CUT-OUT DETAIL
FIGURE 4: MiCOM P742 (40TE) – Hardware Description
18
10.35 181.3 4.5 16 24
202.0 17 18
200.0
TERMINAL SCREWS : M4 x 6 STEEL COMBINATION PAN HEAD MACHINE SCREW.
240.0 INCL. WIRING

FRONT VIEW
Connection Diagrams
MiCOM
TRIP
ALARM
OUT OF SERVICE
HEALTHY
= 177.0 157.5 MAX.
MiCOM P740
CLEAR
= READ
= ENTER
P3714ENa
SIDE VIEW
206.0 30.0
MiCOM P740
Connection Diagrams
A B C D E
F
1 2 3 19
2 2 2 2
1 1 1 1
4 4 4 4
3 4 5 6 20 3 3 3 TX
6 6 6 6
FIGURE 5: MiCOM P742 (40TE) – Rear View

5 5 5 5 CH1 RX
8 8 8 8
7 8 9 21
7 7 7 7
10 10 10 10 TX
9 9 9 9
12 12 12 12 CH2 RX
10 11 12 22
11 11 11 11
14 14 14 14
13 13 13 13
16 16 16 16
13 14 15 23
15 15 15 15
18 18 18 18
17 17 17 17
16 17 18 24
ANALOG INPUT MODULE 8 LOGICAL OUTPUTS
16 LOGICAL INPUTS
POWER SUPPLY
P740/EN CO/D11
COPROCESSOR BOARD
(Connexion to CU via optical fibre)
P3710ENa
Page 7/12
Page 8/12
P740/EN CO/D11
MiCOM P742 (PART)
DIRECTION OF FORWARD CURRENT FLOW A E11
P2 P1 WATCHDOG
A E12 CONTACT
S2 S1 E13
B WATCHDOG
E14 CONTACT
C C B E17
PHASE ROTATION - D1
TRIP A
D2
D3
E18
+ D4 TRIP B
MiCOM P742 (PART) E16 D5
SCN TRIP C
B1 5A D6
C11
- SK2 D7
IA OPTO 6 DATA READY 1
C12 D8 RELAY 4
B2 + DATA 10
C13 ACKNOWLEDGE D9
1A -
NOTE 2. B3 EXTERNAL D10 RELAY 5

C14 OPTO 7 16
B4 5A + RESET D11
C15 DOWNLOAD RELAY 6
IB - 17 D12
COMMAND
C16 OPTO 8 TEST/ D13
B5 +
DOWNLOAD DO-D7 2-9 D14
1A C17 RELAY 7
B6
COMMON 11,12,15,13, D15
B7 5A C18 CONNECTION TO-T7
20,21,23,24 D16
IC A1
- D17
0V 19,18,22,25 RELAY 8
B8 A2 OPTO 9 D18
+ NOT
1A 14
B9 A3 CONNECTED
-
A4 OPTO 10
+
1 SK1
A5
- 2
OPTO 11 TX
A6
+ RX 3
A7
B10 5A - 4
IN A8 OPTO 12 SERIAL
0V 5
+ PORT
A9 6
B11 - CTS 7
1A A10 OPTO 13
B12 + PAPER 8
A11 RTS 9
-
A12 OPTO 14
+
A13
-
A14 OPTO 15 TX1
C1 +
-
OPTO 1 A15 RX1
C2 - FIBRE OPTIC
+
A16 OPTO 16 COMMUNICATION
C3 +
- CURR DIFF
OPTO 2 A17 TX2
C4
+ COMMON *
A18 CONNECTION E1
C5 RX2 -
- AC OR DC
OPTO 3 C6 E2 AUX SUPPLY Vx
+
+
C7
- E7
+
OPTO 4 C8
+ E8
+
C9 48V DC FIELD
- E9 VOLTAGE OUT
OPTO 5 -
C10
+ E10
-
NOTES 1.
(a) C.T. SHORTING LINKS CASE

EARTH
Connection Diagrams
ANSI31_7
* POWER SUPPLY VERSION 24-48V (NOMINAL) D.C. ONLY
2. C.T. CONNECTIONS ARE SHOWN 1A CONNECTED AND ARE TYPICAL ONLY.
(b) PIN TERMINAL (P.C.B. TYPE) 3. THIS RELAY SHOULD BE ASSIGNED TO ANY TRIP TO ENSURE CORRECT
OPERATION OF THE PROTECTIVE RELAY.
4. OPTO INPUTS 1 & 2 MUST BE USED FOR SETTING GROUP CHANGES

50 OHM BNC CONNECTOR
IF THIS OPTION IS SELECTED IN THE RELAY MENU.
MiCOM P740

BUSBAR POTECTION
PERIPHERAL UNIT P742
Drg
Date: 7/02/2003 Name:
10P74201
T&D Protection & Controle No:
Date: Chkd:
Sht: 2
3.
MiCOM P740
Connection Diagrams
TERMINAL BLOCK DETAIL TERMINAL BLOCK DETAIL
COPROCESSOR BOARD 3 ANALOG & I/O BOARDS
12 OFF HOLES Æ3.4
1 2
23.25 116.55 142.45 1 19
MiCOM P743 – PERIPHERAL UNIT

TX
HEAVY DUTY MEDIUM DUTY
CH1 RX
4
FLUSH MOUNTING PANEL TX
CUT-OUT DETAIL
CH2 RX
159.0 168.0
FIGURE 7: MiCOM P743 (60TE) – Hardware Description
18
10.3 155.4 129.5 4.5 16 24

17 18
305.5
303.5
TERMINAL SCREWS : M4 x 6 STEEL COMBINATION PAN HEAD MACHINE SCREW.
240.0 INCL. WIRING

FRONT VIEW
MiCOM
P740/EN CO/D11
TRIP
ALARM
OUT OF SERVICE
HEALTHY
=
=
CLEAR
READ
177.0 157.5 MAX.
= ENTER
Page 9/12
P3715ENa
309.6 30.0 SIDE VIEW
Page 10/12
P740/EN CO/D11
A B C D E F G H
J
1 2 3 19
2 2 2 2 2 2 2
1 1 1 1 1 1 1
4 4 4 4 4 4 4
4 5 6 20 TX
3 3 3 3 3 3 3
FIGURE 8: MiCOM P743 (60TE) – Rear View 6 6 6 6 6 6 6
5 5 5 5 5 5 5 CH1 RX
8 8 8 8 8 8 8
7 8 9 21
7 7 7 7 7 7 7 TX
10 10 10 10 10 10 10
9 9 9 9 9 9 9
CH2 RX
12 12 12 12 12 12 12
10 11 12 22
11 11 11 11 11 11 11
14 14 14 14 14 14 14
13 13 13 13 13 13 13
16 16 16 16 16 16 16
13 14 15 23
15 15 15 15 15 15 15
18 18 18 18 18 18 18
17 17 17 17 17 17 17
16 17 18 24
COPROCESSOR BOARD
(connexion to CU via optic fibre)
Connection Diagrams
24 LOGICAL INPUTS 21 LOGICAL OUTPUTS
ANALOG INPUT POWER SUPPLY
MiCOM P740
P3711ENa
MiCOM P740
Connection Diagrams
H11
MiCOM P743 (PART) H12
WATCHDOG
DIRECTION OF FORWARD CURRENT FLOW A CONTACT
H13
P2 P1 WATCHDOG
A H14 CONTACT
S2 S1
B G1
G2 TRIP A
C C B H17
PHASE ROTATION - G3
G4 TRIP B
H18 G5
+ TRIP C
G6
MiCOM P743 (PART) H16
G7
SCN
A1 5A G8 RELAY 4
C1
IA - DATA READY 1 SK2 G9
C2 OPTO 9
A2 + DATA G10 RELAY 5
C3 10
ACKNOWLEDGE
1A - G13
NOTE 2. A3 C4 OPTO 10 EXTERNAL

+ 16 G14
A4 5A RESET RELAY 6
C5
- DOWNLOAD G15
IB C6 OPTO 11 17
+ COMMAND G16
A5 C7 TEST/
DO-D7 2-9 G17
- DOWNLOAD RELAY 7
1A C8 OPTO 12 G18
A6 + 11,12,15,13,
A7 5A C9 TO-T7
- 20,21,23,24 F1
IC C10 OPTO 13
+ F2 RELAY 8
C11 0V 19,18,22,25
A8 F3
-
1A C12 OPTO 14 NOT RELAY 9
A9 + 14 F4
CONNECTED
C13 F5
-
A10 5A C14 OPTO 15 F6 RELAY 10
+ SK1
IN 1
C15 F7
- TX 2
A11 C16 OPTO 16 F8 RELAY 11
+ RX 3
1A C17 F9
A12 4
COMMON F10 RELAY 12
C18 CONNECTION SERIAL
B1 0V 5
- PORT F13
OPTO 1 B2 6
F14
+ CTS 7 RELAY 13
B3 D1 F15
- - PAPER 8
OPTO 2 OPTO 17
F16
B4 D2 RTS 9
+ + F17
B5 D3 RELAY 14
- - F18
OPTO 3 D4 OPTO 18 TX1
B6 +
+ D5
B7 - RX1 E1
- D6 OPTO 19 FIBRE OPTIC RELAY 15
OPTO 4 + E2
B8 COMMUNICATION
+ D7 E3
- CURR DIFF
B9 TX2
D8 OPTO 20 E4 RELAY 16
- +
OPTO 5 B10 D9 E5
+ -
RX2
RELAY 17
B11 D10
+
OPTO 21
H1 * E6
- - E7
AC OR DC
OPTO 6 B12
D11
- AUX SUPPLY Vx H2 RELAY 18
+ D12 OPTO 22 + E8
B13 +
E9
- D13
- H7 RELAY 19
OPTO 7 B14 + E10
D14 OPTO 23
+ + H8
+ E13
B15 D15 48V DC FIELD
- - H9 E14
OPTO 8 B16 D16 OPTO 24 VOLTAGE OUT - RELAY 20
+ + E15
B17 D17 H10
- E16
COMMON COMMON
B18 D18 CONNECTION E17
CONNECTION RELAY 21
NOTES 1.
(a) CASE E18
EARTH
C.T. SHORTING LINKS
ANSI31_7
2. C.T. CONNECTIONS ARE SHOWN 1A CONNECTED AND ARE TYPICAL ONLY.
P740/EN CO/D11
(b) PIN TERMINAL (P.C.B. TYPE)
50 OHM BNC CONNECTOR
Page 11/12

BUSBAR POTECTION
PERIPHERAL UNIT P743
Drg
Date: 7/02/2003 Name:
10P74301
T&G Protection & Controle No:
Date: Chkd:
Sht: 2

Relay Menu Database P740/EN GC/D11
MiCOM P740
RELAY MENU DATABASE

P740/EN GC/D11 Relay Menu Database
MiCOM P740
A Menu Database (COURIER)
B Digital Data Bus (DDB)
C Default Programmable Scheme Logic (PSL)
This version of P740/EN GC/C11 is specific to the following models
Model number
P741-------01-B
P742-------01-B
P743-------01-B
For other models / software versions, please contact AREVA T&D for the relevant
information.
MiCOM P740
Relay Menu Database
This Chapter is split into several sections, these are as follows:

• Menu Database for Courier, User Interface
• Digital Data Bus (Internal Digital Signal)
• Default Programmable Logic
1. MENU DATABASE
This database defines the structure of the relay menu for the Courier interface and
the front panel user interface. This includes all the relay settings and measurements.
Indexed strings for Courier and the user interface are cross referenced to the Menu
Datatype Definition section (using a G Number). For all settable cells the setting limits
and default value are also defined within this database.
2. INTERNAL DIGITAL SIGNALS (DDB)

This table defines all of the relay internal digital signals (opto inputs, output contacts
and protection inputs and outputs). A relay may have up to 512 internal signals each
reference by a numeric index as shown in this table. This numeric index is used to
select a signal for the commissioning monitor port. It is also used to explicitly define
protection events produced by the relay.
3. DEFAULT PROGRAMMABLE LOGIC

This section documents the default programmable logic for the various models of the
relay is supply with the MiCOM S1 Scheme Logic Editor PC support software.
References
Introduction Chapter: User Interface operation and connections to relay
Courier User Guide R6512
MiCOM P740
MiCOM P740
A - MENU DATABASE
MiCOM P740
Relay Menu Database
abcd P740/EN GC/C11
Page A-1
MiCOM P740
A - Menu database for Courier, User Interface (MiCOM P741 only)

Courier Ref
Courier Text Courier Data Type LCD ref Data Default Setting Cell Type Min Max Step Password Comment
Col Row Courier Level
00 00 SYSTEM DATA
1 Language Indexed String G19 English Setting 0 3 1 2
2 Password ASCII Password(4 bytes) G20 AAAA Setting 65 90 1 0
4 Description ASCII Text(16 bytes) MiCOM P741 Setting 32 163 1 2
5 Plant Reference ASCII Text(16 bytes) ALSTOM Setting 32 163 1 2
6 Model Number ASCII Text(32 bytes) Model Number Data Cortec Code 18 characters
8 Serial Number ASCII Text(7 bytes) Serial Number Data
9 Frequency Unsigned Integer(1 byte) 50 Setting 50 60 10 2
0A Comms Level Unsigned Integer(2 bytes) 2 Data
0B Relay Address Unsigned Integer(2 bytes) 1 Setting 1 6 1 2 Rear Courier Address available via LCD
Address=255 with default settings
0C Plant Status Binary Flags(16 bits) Data
0D Control Status Binary Flags(16 or 32 bits) Data
0E Active Group Unsigned Integer(2 bytes) G1 Data
11 Software Ref. 1 ASCII Text(16 characters) Data
20 Opto I/P Status Binary Flag(32 bits) Data

Indexed String
21 Relay O/P Status Binary Flag(32 bits) Data
Indexed String
22 Alarm Status Binary Flag(32 bits) Data
Indexed String
D0 Access Level Unsigned Integer(2 bytes) G1 Data
D1 Password Control Unsigned Integer(2 bytes) G22 2 Setting 0 2 1 2
D2 Password Level 1 ASCII Password(4 characters) G20 AAAA Setting 65 90 1 1
01 00 VIEW RECORDS
1 Last Record Unsigned Integer(2) 0 Setting 0 249 1 0 Max value is oldest record
2 Menu Cell Ref Cell Reference N/A (From Record) Data Indicates type of event
See Event sheet
3 Time & Date IEC870 Time & Date (From Record) Data
Relay Menu Database
abcd P740/EN GC/C11
Page A-2
MiCOM P740

Courier Ref
4 Record Text Ascii String(32) Data See Event sheet
5 Record Value Binary Flag(32)/UINT32 Data Note DTL depends on event type
See Event sheet of Spreadsheet
6 Select Fault Unsigned Integer 0 Setting 0 4 1 0 Allows Fault Record to be selected
7 Active Group Unsigned Integer 0 Data
8 Faulted Phase Binary Flags (8 Bits) N/A GXX Data Started phases + tripped phases
9 Start Elements Binary Flags (32 Bits) N/A GXX Data Started elements
0A Trip Elements Binary Flags (32 Bits) N/A GXX Data Tripped elements 1
0C Time Stamp IEC870 Time & Date G12 Data
0D Fault Alarms Binary Flags (32 Bits) G87 Data Faullt Alarms/Warnings
0E System Frequency Courier Number (frequency) Data
0F Fault Duration Courier Number (time) Data
11 IA diff Courier Number (current) G24 Data
12 IB diff Courier Number (current) G24 Data
13 IC diff Courier Number (current) G24 Data
14 IN diff Courier Number (current) G24 Data
15 IA bias Courier Number (current) G24 Data
16 IB bias Courier Number (current) G24 Data
17 IC bias Courier Number (current) G24 Data
18 IN bias Courier Number (current) G24 Data
19 IA CZ diff Courier Number (current) G24 Data
1A IB CZ diff Courier Number (current) G24 Data
1B IC CZ diff Courier Number (current) G24 Data
1C IN CZ diff Courier Number (current) G24 Data
1D Faulted Zone Binary Flags (16 Bits) G212 Data
F0 Select Report Unsigned Integer Manual override to Setting 0 4 1 2 Allows Self Test Report to be selected
select a fault record.
Relay Menu Database
abcd P740/EN GC/C11
Page A-3
MiCOM P740

Courier Ref
F1 Report Text Ascii String(32) Data
F2 Type UINT32 Data
F3 Data UINT32 Data
FF Reset Indication Indexed String G11 No Command 0 1 1 1
02 00 MEASUREMENTS 1
1 IA Diff CZ Courier Number (current) G24 Data
2 IB Diff CZ Courier Number (current) G24 Data
3 IC Diff CZ Courier Number (current) G24 Data
4 IN Diff CZ Courier Number (current) G24 Data
03 00 MEASUREMENTS 2 Visibility depend of the number of the zone configured
1 Zx1: IA diff Courier Number (current) G24 Data
2 Zx1: IB diff Courier Number (current) G24 Data
3 Zx1: IC diff Courier Number (current) G24 Data
4 Zx1: IN diff Courier Number (current) G24 Data
5 Zx1: IA bias Courier Number (current) G24 Data
6 Zx1: IB bias Courier Number (current) G24 Data
7 Zx1: IC bias Courier Number (current) G24 Data
8 Zx1: IN bias Courier Number (current) G24 Data
,,,
79 Zx16: IA diff Courier Number (current) G24 Data Ligne = 8*Numzone - 7
7A Zx16: IB diff Courier Number (current) G24 Data
7B Zx16: IC diff Courier Number (current) G24 Data
7C Zx16: IN diff Courier Number (current) G24 Data
7D Zx16: IA bias Courier Number (current) G24 Data
7E Zx16: IB bias Courier Number (current) G24 Data

Relay Menu Database
abcd P740/EN GC/C11
Page A-4
MiCOM P740

Courier Ref
7F Zx16: IC bias Courier Number (current) G24 Data
80 Zx16: IN bias Courier Number (current) G24 Data
04 00 TOPOLOGY 1
01 Current Node 01 Binary Flag (16 bits) G212 Data Visible if <> 0
0A Current Node 10 Binary Flag (16 bits) G212 Data Visible if <> 0
0B Current Node 11 Binary Flag (16 bits) G212 Data Visible if <> 0
0C Current Node 12 Binary Flag (16 bits) G212 Data Visible if <> 0
0D Current Node 13 Binary Flag (16 bits) G212 Data Visible if <> 0
0E Current Node 14 Binary Flag (16 bits) G212 Data Visible if <> 0
0F Current Node 15 Binary Flag (16 bits) G212 Data Visible if <> 0
05 00 TOPOLOGY 2
Relay Menu Database
abcd P740/EN GC/C11
Page A-5
MiCOM P740

Courier Ref
0A Current Node 10 Binary Flag (32 bits) G217 Data Visible if <> 0
0B Current Node 11 Binary Flag (32 bits) G217 Data Visible if <> 0
0C Current Node 12 Binary Flag (32 bits) G217 Data Visible if <> 0
0D Current Node 13 Binary Flag (32 bits) G217 Data Visible if <> 0
0E Current Node 14 Binary Flag (32 bits) G217 Data Visible if <> 0
0F Current Node 15 Binary Flag (32 bits) G217 Data Visible if <> 0
06 00 PU CONF & STATUS
01 PU in service Binary Flags (32 Bits) G213 0 Setting 0 0xFFFFFFFF 1 1 PU declared in service
02 PU connected Binary Flags (32 Bits) G213 Data PU synchronised
03 PU topo valid Binary Flags (32 Bits) G213 Data PU with topology parameters valid
04 Reset Circt Flt Indexed String G11 No Command 0 1 1 2 Reset command after circuitry fault
05 CircuitryFfault Binary Flags (16 Bits) G212 Data Circuitry Fault by zone
06 Circ Fault Phase Binary Flags (4 Bits) GXX Data Circuitry Fault by phase
08 00 DATE AND TIME
1 Date/Time IEC870 Time & Date N/A G12 Setting 0
N/A Date Front Panel Menu only

36892 ADU if 1/1/2001 possible
N/A Time Front Panel Menu only
0.5
4 IRIG-B Sync Indexed String G37 Disabled Setting 0 1 1 2 Master CU : visibe if IRIG-B Fitted
Slave CU : 0804=0 (invisible)
5 IRIG-B Status ASCII String G17 Data Master CU : visible if 0804=1
Slave CU : 0805=0 (invisible)
6 Battery Status Indexed String G59 Data
Relay Menu Database
abcd P740/EN GC/C11
Page A-6
MiCOM P740

Courier Ref
7 Battery Alarm Indexed String G37 Enabled Setting 0 1 1 2
09 00 CONFIGURATION
1 Restore Defaults Indexed String G53 No Operation Command 0 5 1 2
2 Setting Group Indexed String G61 Select via Menu Setting 0 1 1 2
3 Active Settings Indexed String G90 Group 1 Setting 0 3 1 1
4 Save Changes Indexed String G62 No Operation Command 0 2 1 2
5 Copy From Indexed String G90 Group 1 Setting 0 3 1 2
6 Copy to Indexed String G98 No Operation Command 0 3 1 2
7 Setting Group 1 Indexed String G37 Enabled Setting 0 1 1 2
8 Setting Group 2 Indexed String G37 Disabled Setting 0 1 1 2
0A Setting Group 4 Indexed String G37 Disabled Setting 0 1 1 2
10 Diff Busbar Prot Indexed String G37 Enabled Setting 0 1 1 2
11 Optos Setup Indexed String G80 Visible Setting 0 1 1 2
25 Input Labels Indexed String G80 Visible Setting 0 1 1 1
26 Output Labels Indexed String G80 Visible Setting 0 1 1 1
29 Recorder Control Indexed String G80 Visible Setting 0 1 1 1
2A Disturb Recorder Indexed String G80 Visible Setting 0 1 1 1
2B Measure't Setup Indexed String G80 Visible Setting 0 1 1 1
2C Comms Settings Indexed String G80 Invisible Setting 0 1 1 1
2D Commission Tests Indexed String G80 Visible Setting 0 1 1 1
2E Setting Values Indexed String G54 Secondary Setting 0 1 1 1
0B 00 RECORD CONTROL
1 Clear Events Indexed String G11 No Command 0 1 1 1
2 Clear Faults Indexed String G11 No Command 0 1 1 1

Relay Menu Database
abcd P740/EN GC/C11
Page A-7
MiCOM P740

Courier Ref
3 Clear Maint Indexed String G11 No Command 0 1 1 1
0C 00 DISTURB RECORDER
1 Duration Courier Number (time) G2 1.2 Setting 1.2 1.2 0 2 FIXED VALUE: 1.2s
Cell not modifiable
2 Trigger Position Courier Number (%) G2 50 Setting 0 50 1 2 Ffixed step: 200ms
3 Trigger Mode Indexed String G34 Single Setting 0 1 1 2 Function not available => cell not modifiable
4 Analog Channel 1 Indexed String G214 IA diff Setting 0 8 1 2 Function not available => cell not modifiable
5 Analog Channel 2 Indexed String G214 IB diff Setting 0 8 1 2 Function not available => cell not modifiable
6 Analog Channel 3 Indexed String G214 IC diff Setting 0 8 1 2 Function not available => cell not modifiable
7 Analog Channel 4 Indexed String G214 IN diff Setting 0 8 1 2 Function not available => cell not modifiable
8 Analog Channel 5 Indexed String G214 IA bias Setting 0 8 1 2 Function not available => cell not modifiable
9 Analog Channel 6 Indexed String G214 IB bias Setting 0 8 1 2 Function not available => cell not modifiable
0A Analog Channel 7 Indexed String G214 IC bias Setting 0 8 1 2 Function not available => cell not modifiable
0B Analog Channel 8 Indexed String G214 IN bias Setting 0 8 1 2 Function not available => cell not modifiable
0C Digital Input 1 Indexed String G32 Unused Setting 0 DDB Size 1 2
0D Digital Input 2 Indexed String G32 Unused Setting 0 DDB Size 1 2
0E Digital Input 3 Indexed String G32 Unused Setting 0 DDB Size 1 2
0F Digital Input 4 Indexed String G32 Unused Setting 0 DDB Size 1 2
10 Digital Input 5 Indexed String G32 Unused Setting 0 DDB Size 1 2

Relay Menu Database
abcd P740/EN GC/C11
Page A-8
MiCOM P740

Courier Ref
1A Digital Input 15 Indexed String G32 Unused Setting 0 DDB Size 1 2
1B Digital Input 16 Indexed String G32 Unused Setting 0 DDB Size 1 2
1C Digital Input 17 Indexed String G32 Unused Setting 0 DDB Size 1 2
1D Digital Input 18 Indexed String G32 Unused Setting 0 DDB Size 1 2
1E Digital Input 19 Indexed String G32 Unused Setting 0 DDB Size 1 2
1F Digital Input 20 Indexed String G32 Unused Setting 0 DDB Size 1 2
2A Digital Input 31 Indexed String G32 Unused Setting 0 DDB Size 1 2
2B Digital Input 32 Indexed String G32 Unused Setting 0 DDB Size 1 2
2C Manual Trigger Indexed String G11 No Command 0 1 1 1
2D Zone To Record Binary Flags (16 Bits) G212 0 Setting 0 0x8000 1 2
0D 00 MEASURE'T SETUP
01 Default Display Indexed String G52 0 Setting 0 4 1 2 Aff; Total Zone …
2 Local Values Indexed String G54 Secondary Setting 0 1 1 2 Local Measurement Values
Relay Menu Database
abcd P740/EN GC/C11
Page A-9
MiCOM P740

Courier Ref
3 Remote Values Indexed String G54 Primary Setting 0 1 1 2 Remote Measurement Values
04 Ibp Base Cur Pri Courier Number (Current) G1 1000 Setting 1 10000 1 2
0F 00 COMMISSION TESTS

Indexed String
Indexed String
3 Test Port Status Binary Flags(8 bits) Data
Indexed String
4 LED Status Binary Flags(8 bits) 0-7 Data
5 Monitor Bit 1 Unsigned Integer Relay 1 Setting 0 511 1 1
0A Monitor Bit 6 Unsigned Integer Relay 6 Setting 0 511 1 1
0B Monitor Bit 7 Unsigned Integer Relay 7 Setting 0 511 1 1
0C Monitor Bit 8 Unsigned Integer Relay 8 Setting 0 511 1 1
0D Test Mode Indexed String G215 Disabled Setting 0 1 1 2
0E Test Pattern Binary Flags (21bits) G9 0 Setting 0 20 1 2

Indexed String
0F Contact Test Indexed String G93 No Operation Command 0 2 1 2
10 Test LEDs Binary Flags (8bits) G94 No Operation Command 0 1 1 2

Indexed String
12 87BB monitoring Binary Flags (16bits) G212 0xFFFF Setting 0 0xFFFF 1 2
13 87BB&50BF disabl Binary Flags (16bits) G212 0xFFFF Setting 0 0xFFFF 1 2
14 87BBTrip Pattern Binary Flags (16bits) G212 0 Setting 0 0xFFFF 1 2
15 87BB Trip Order Indexed String G94 No Operation Command 0 1 1 2
20 DDB 0-31 Binary Flag (32 bits) N/A Data Relay

Visible by Courier
Relay Menu Database
abcd P740/EN GC/C11
Page A-10
MiCOM P740

Courier Ref
21 DDB 32-63 Binary Flag (32 bits) N/A Data Opto
Visible by Courier
22 DDB 64-95 Binary Flag (32 bits) N/A Data
Visible by Courier
Visible by Courier
Visible by Courier
Visible by Courier
Visible by Courier
Visible by Courier
Visible by Courier
Visible by Courier
2A DDB 320-351 Binary Flag (32 bits) N/A Data
Visible by Courier
2B DDB 352-383 Binary Flag (32 bits) N/A Data
Visible by Courier
2C DDB 384-415 Binary Flag (32 bits) N/A Data
Visible by Courier
2D DDB 415-447 Binary Flag (32 bits) N/A Data
Visible by Courier
2E DDB 448-479 Binary Flag (32 bits) N/A Data
Visible by Courier
2F DDB 480-511 Binary Flag (32 bits) N/A Data
11 00 OPTOS SETUP
1 Global Nominal V Indexed String G200 2 Setting 0 5 1 2
02 Opto Input 1 Indexed String G201 2 Setting 0 4 1 2

Relay Menu Database
abcd P740/EN GC/C11
Page A-11
MiCOM P740

Courier Ref
GROUP 1
PROTECTION SETTINGS
30 00 GROUP 1
DIFF BUSBAR PROT
01 Diff Phase Fault (Sub-Heading)
02 Current Is Courier Number (Current) G2 0,1*Ibp Setting 0,02*Ibp 1*Ibp 0,01*Ibp 2
03 Phase Slope k Courier Number (%) G2 40 Setting 20 90 1 2
04 ID>2 Current Courier Number (Current) G2 1,2*Ibp Setting 0,1*Ibp 4*Ibp 0,01*Ibp 2
05 ID>1 Current Courier Number (Current) G2 0,05*Ibp Setting 0,01*Ibp 0,5*Ibp 0,01*Ibp 2
06 ID>1 Alarm Timer Courier Number (Time) G2 5 Setting 0.1 100 0.1 2
07 Diff Earth Fault Indexed String G37 Disabled Setting 0 1 1 2
08 IBiasPh> Cur. Courier Number (Current) G2 2*Ibp Setting 0,2*Ibp 10*Ibp 0,1*Ibp 2
09 Earth Cur. IsN Courier Number (Current) G2 0,1*Ibp Setting 0,02*Ibp 1*Ibp 0,01*Ibp 2
0A Earth Slope kN Courier Number (%) G2 20 Setting 20 90 1 2
0B IDN>2 Current Courier Number (Current) G2 0,1*Ibp Setting 0,05*Ibp 2*Ibp 0,05*Ibp 2
0C IDN>1 Current Courier Number (Current) G2 0,05*Ibp Setting 0,01*Ibp 0,5*Ibp 0,01*Ibp 2
0D IDN>1 Alarm Tim. Courier Number (Time) G2 5 Setting 0.1 100 0.1 2
DIFF BUSBAR PROT

4A 00 GROUP 1
INPUT LABELS
1 Opto Input 1 ASCII Text (16 chars) Opto Label 01 Setting 32 39 1 2

Relay Menu Database
abcd P740/EN GC/C11
Page A-12
MiCOM P740

Courier Ref
4B 00 GROUP 1
OUTPUT LABELS
1 Relay 1 ASCII Text (16 chars) Relay Label 01 Setting 0 7 1 2
GROUP 2
PROTECTION SETTINGS
50 00 Repeat of Group 1 columns/rows
GROUP 3
PROTECTION SETTINGS
GROUP 4
PROTECTION SETTINGS
C0 00 TOPO SETTINGS
01 Topology Size Unsigned integer Data
02 Topology Element 1 Binary Flag (32bits) Data

Relay Menu Database
abcd P740/EN GC/C11
Page A-13
MiCOM P740
A - Menu database for Courier, User Interface (MiCOM P742 and P743 only)
Courier Ref
00 00 SYSTEM DATA
1 Language Indexed String G19 English Setting 0 3 1 2
2 Password ASCII Password(4 bytes) G20 AAAA Setting 65 90 1 0
4 Description ASCII Text(16 bytes) MiCOM P742/P743 Setting 32 163 1 2
5 Plant Reference ASCII Text(16 bytes) ALSTOM Setting 32 163 1 2
6 Model Number ASCII Text(32 bytes) Model Number Data Cortec / 18 characters
8 Serial Number ASCII Text(7 bytes) Serial Number Data
9 Frequency Unsigned Integer(1 byte) 50 Setting 50 60 10 2
0A Comms Level Unsigned Integer(2 bytes) 2 Data
0B Relay Address Unsigned Integer(2 bytes) 7 Setting 7 102 1 2 Rear Courier Address available via LCD
1 Address=255 with default settings
0C Plant Status Binary Flags(16 bits) Data
0D Control Status Binary Flags(16 or 32 bits) Data
0E Active Group Unsigned Integer(2 bytes) G1 Data
10 CB Trip/Close Indexed String(2) G55 No Operation Command 0 2 1 2 Visible to Rear Port

(command Bks & isolators)
11 Software Ref. 1 ASCII Text(16 characters) Data
20 Opto I/P Status Binary Flag(32 bits) Data ADU extension 24 ou 32 bits
Indexed String
Indexed String
22 Alarm Status Binary Flag(32 bits) G96 Data
Indexed String
D0 Access Level Unsigned Integer(2 bytes) G1 Data
D1 Password Control Unsigned Integer(2 bytes) G22 2 Setting 0 2 1 2
01 00 VIEW RECORDS
1 Last Record Unsigned Integer(2) G1 0 Setting 0 249 1 0 Max value is oldest record
2 Menu Cell Ref Cell Reference N/A G13 (From Record) Data Indicates type of event
Relay Menu Database
abcd P740/EN GC/C11
Page A-14
MiCOM P740
Courier Ref
See Event sheet
3 Time & Date IEC870 Time & Date G12 (From Record) Data
4 Record Text Ascii String(32) Data See Event sheet
5 Record Value Binary Flag(32)/UINT32 G27 Data Note DTL depends on event type
See Event sheet of Spreadsheet
6 Select Fault Unsigned Integer G1 0 Setting 0 4 1 0 Allows Fault Record to be selected
7 Active Group Unsigned Integer G1 0 Data
8 Faulted Phase Binary Flags (8 Bits) N/A G16 Data Started phases + tripped phases
9 Start Elements Binary Flags (32 Bits) N/A GXX Data Started elements
0A Trip Elements Binary Flags (32 Bits) N/A GXX Data Tripped elements 1
0C Time Stamp IEC870 Time & Date G12 Data
0D Fault Alarms Binary Flags (32 Bits) G87 Data Faullt Alarms/Warnings
0E System Frequency Courier Number (frequency) G25 Data
10 Relay Trip Time Courier Number (time) G24 Data
11 IA Courier Number (current) G24 Data
12 IB Courier Number (current) G24 Data
13 IC Courier Number (current) G24 Data
14 IN Courier Number (current) G24 Data
15 VA Courier Number(voltage) G24 Data Build = Option Transfo Tension
16 VB Courier Number(voltage) G24 Data Build = Option Transfo Tension
17 VC Courier Number(voltage) G24 Data Build = Option Transfo Tension
18 VN Courier Number(voltage) G24 Data Build = Option Transfo Tension
F0 Select Report Unsigned Integer G27 Manual override to Setting 0 4 1 2 Allows Self Test Report to be selected
select a fault record.
F1 Report Text Ascii String(32) Data
F2 Type UINT32 G27 Data
F3 Data UINT32 G27 Data
FF Reset Indication Indexed String G11 No Command 0 1 1 1

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02 00 MEASUREMENTS 1
1 IA Magnitude Courier Number (current) G24 Data
2 IA Phase Angle Courier Number (angle) G30 Data
3 IB Magnitude Courier Number (current) G24 Data
4 IB Phase Angle Courier Number (angle) G30 Data
5 IC Magnitude Courier Number (current) G24 Data
6 IC Phase Angle Courier Number (angle) G30 Data
7 IN Magnitude Courier Number (current) G24 Data
8 IN Phase Angle Courier Number (angle) G30 Data
9 IN Derived Magn Courier Number (current) G24 Data
0A IN Derived Angle Courier Number (angle) G30 Data
0B I1 Magnitude Courier Number (current) G24 Data
0C I2 Magnitude Courier Number (current) G24 Data
0D I0 Magnitude Courier Number (current) G24 Data
04 00 TOPOLOGY
1 Link CT / zone Binary Flag(32 bits) G212 Data Zones connected to CT

Indexed String Isolator and/or breaker closed
2 Zx1: IA diff Courier Number (Current) G24 Data x1=n° of zone connected to isolator 1
IF xx=255, no zone connected
3 Zx1: IB diff Courier Number (Current) G24 Data
4 Zx1: IC diff Courier Number (Current) G24 Data
5 Zx1: IN diff Courier Number (Current) G24 Data
6 Zx1: IA bias Courier Number (Current) G24 Data
7 Zx1: IB bias Courier Number (Current) G24 Data
8 Zx1: IC bias Courier Number (Current) G24 Data
9 Zx1: IN bias Courier Number (Current) G24 Data
0A Zx2: IA diff Courier Number (Current) G24 Data x2=n° of zone connected to isolator 2
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Courier Ref
0B Zx2: IB diff Courier Number (Current) G24 Data
0C Zx2: IC diff Courier Number (Current) G24 Data
0D Zx2: IN diff Courier Number (Current) G24 Data
0E Zx2: IA bias Courier Number (Current) G24 Data
0F Zx2: IB bias Courier Number (Current) G24 Data
12 Zx3: IA diff Courier Number (Current) G24 Data x3=n° of zone connected to isolator 3
13 Zx3: IB diff Courier Number (Current) G24 Data
14 Zx3: IC diff Courier Number (Current) G24 Data
15 Zx3: IN diff Courier Number (Current) G24 Data
16 Zx3: IA bias Courier Number (Current) G24 Data
17 Zx3: IB bias Courier Number (Current) G24 Data
1A Zx4: IA diff Courier Number (Current) G24 Data x4=n° of zone connected to isolator 4
1B Zx4: IB diff Courier Number (Current) G24 Data
1C Zx4: IC diff Courier Number (Current) G24 Data
1D Zx4: IN diff Courier Number (Current) G24 Data
1E Zx4: IA bias Courier Number (Current) G24 Data
1F Zx4: IB bias Courier Number (Current) G24 Data
07 00 CB CONTROL
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Courier Ref
1 Prot Trip Pulse Courier Number (Time) G2 0.2 Setting 0.05 2 0.01 2 Protection trip pulse time
2 Trip Latched Indexed String G37 Disabled Setting 0 1 1 2 To hold relay closed after trip
3 Reset Trip Latch Indexed String G11 No Command 0 1 1 2 Cde to reset upholding
4 CB Control by Indexed String G99 Disabled Setting 0 7 1 2
5 Man Close Pulse Courier Number (Time) G2 0.5 Setting 0.1 5 0.1 2
6 Man Trip Pulse Courier Number (Time) G2 0.5 Setting 0.1 5 0.1 2
7 Man Close Delay Courier Number (Time) G2 10 Setting 0 60 1 2
08 00 DATE and TIME
1 Date/Time IEC870 Time & Date N/A G12 Setting 0
N/A Date Front Panel Menu only

35807
N/A Time Front Panel Menu only
0.5
6 Battery Status Indexed String G59 Data
7 Battery Alarm Indexed String G37 Enabled Setting 0 1 1 2
09 00 CONFIGURATION
1 Restore Defaults Indexed String G53 No Operation Command 0 5 1 2
2 Setting Group Indexed String G61 Select via Menu Setting 0 1 1 2
3 Active Settings Indexed String G90 Group 1 Setting 0 3 1 2
4 Save Changes Indexed String G62 No Operation Command 0 2 1 2
5 Copy From Indexed String G90 Group 1 Setting 0 3 1 2
6 Copy to Indexed String G98 No Operation Command 0 3 1 2
7 Setting Group 1 Indexed String G37 Enabled Setting 0 1 1 2
0A Setting Group 4 Indexed String G37 Disabled Setting 0 1 1 2

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Courier Ref
10 BB Trip Confirm Indexed String G37 Enabled Setting 0 1 1 2
11 Optos Setup Indexed String G80 Visible Setting 0 1 1 2
12 Overcurrent Prot Indexed String G37 Disabled Setting 0 1 1 2
13 Earth Fault Prot Indexed String G37 Disabled Setting 0 1 1 2
14 CB Fail & I< Indexed String G37 Disabled Setting 0 1 1 2
25 Input Labels Indexed String G80 Visible Setting 0 1 1 1
26 Output Labels Indexed String G80 Visible Setting 0 1 1 1
28 CT & VT Ratios Indexed String G80 Visible Setting 0 1 1 1
29 Recorder Control Indexed String G80 Visible Setting 0 1 1 1
2A Disturb Recorder Indexed String G80 Visible Setting 0 1 1 1
2B Measure't Setup Indexed String G80 Visible Setting 0 1 1 1
2D Commission Tests Indexed String G80 Visible Setting 0 1 1 2
2E Setting Values Indexed String G54 Secondary Setting 0 1 1 1
0A 00 CT AND VT RATIOS
07 Phase CT Primary Courier Number (Current) G35 1000 Setting 1 30000 1 2 I1=Phase CT secondary rating
08 Phase CT Sec'y Courier Number (Current) G2 1 Setting 1 5 4 2

Label M4=0A07/0A08
20 CT Class Indexed String G205 X Setting 0 3 1 2 Label M17=(0A07/0A08)^2
21 RBPh / RBN Unsigned Integer G1 1 Setting 0.5 10 0.1 2
23 Power Parameters (Sub-Heading)
24 Standard Input Indexed String G206 British Setting 0 1 1 2 British->0 / IEC->1
25 Knee Voltage Vk Courier Number (Voltage) G2 250 Setting 20 5000 10 2 0A24=0 => British
26 Rated Burden VA Courier Number (VA) G1 25 Setting 5 200 5 0A24=1 => IEC
27 Rated Burden Ohm Courier Number(Ohms) G35 25 / I1^2 Data 5 / I1^2 200 / I1^2 5 / I1^2 2 0A24=1 => IEC
Calculated not modifiable
28 KSCC Unsigned Integer G1 10 Setting 10 50 5 0A24=1 => IEC
29 RCT Sec'y Courier Number(Ohms) G35 0.5 Setting 0.1 50 0.1 2

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Courier Ref
2B Eff. Burden Ohm Courier Number(Ohms) G35 25 / I1^2 Setting 0,1 / I1^2 200 / I1^2 0,01 / I1^2 2
2C Eff. Burden VA Courier Number (VA) G1 25 Data 0.1 200 0.01 Calculaled not modifiable
0B 00 RECORD CONTROL
1 Clear Events Indexed String G11 No Command 0 1 1 1
2 Clear Faults Indexed String G11 No Command 0 1 1 1
3 Clear Maint Indexed String G11 No Command 0 1 1 1
0C 00 DISTURB RECORDER
1 Duration Courier Number (time) 1.5 Setting 0.1 10.5 0.01 2
2 Trigger Position Courier Number (%) 33.3 Setting 0 100 0.1 2
3 Trigger Mode Indexed String G34 Single Setting 0 1 1 2
4 Analog Channel 1 Indexed String G31 IA Setting 0 8 1 2
5 Analog Channel 2 Indexed String G31 IB Setting 0 8 1 2
6 Analog Channel 3 Indexed String G31 IC Setting 0 8 1 2
7 Analog Channel 4 Indexed String G31 IN Setting 0 8 1 2
8 Analog Channel 5 Indexed String G31 Unused Setting 0 8 1 2 Build = Option Transfo Tension
9 Analog Channel 6 Indexed String G31 Unused Setting 0 8 1 2 Build = Option Transfo Tension
0A Analog Channel 7 Indexed String G31 Unused Setting 0 8 1 2 Build = Option Transfo Tension
0B Analog Channel 8 Indexed String G31 Unused Setting 0 8 1 2 Build = Option Transfo Tension
0C Digital Input 1 Indexed String G32 Unused Setting 0 DDB Size 1 2 DDB Size different for each model
0D Input 1 Trigger Indexed String G66 No Trigger Setting 0 2 1 2
0E Digital Input 2 Indexed String G32 Unused Setting 0 DDB Size 1 2 DDB Size different for each model
0F Input 2 Trigger Indexed String G66 No Trigger Setting 0 2 1 2
10 Digital Input 3 Indexed String G32 Unused Setting 0 DDB Size 1 2 DDB Size different for each model
11 Input 3 Trigger Indexed String G66 No Trigger Setting 0 2 1 2
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Courier Ref
1A Digital Input 8 Indexed String G32 Unused Setting 0 DDB Size 1 2 DDB Size different for each model
1B Input 8 Trigger Indexed String G66 No Trigger Setting 0 2 1 2

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Courier Ref
0D 00 MEASURE'T SETUP
1 Default Display Indexed String G52 0 Setting 0 4 1 2
2 Local Values Indexed String G54 Secondary Setting 0 1 1 2 Local Measurement Values
3 Remote Values Indexed String G54 Primary Setting 0 1 1 2 Remote Measurement Values
0F 00 COMMISSION TESTS

Indexed String
Indexed String
3 Test Port Status Binary Flags(8 bits) Data
Indexed String
4 LED Status Binary Flags(8 bits) 0-7 Data
0A Monitor Bit 6 Unsigned Integer Relay 6 Setting 0 511 1 1
0B Monitor Bit 7 Unsigned Integer Relay 7 Setting 0 511 1 1
0C Monitor Bit 8 Unsigned Integer Relay 8 Setting 0 511 1 1
0D Test Mode Indexed String G215 Disabled Setting 0 1 1 2
0E Test Pattern Binary Flags (21bits) G9 0 Setting 0 20 1 2

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Courier Ref
Indexed String
0F Contact Test Indexed String G94 No Operation Command 0 2 1 2
10 Test LEDs Binary Flags (8bits) G94 No Operation Command 0 1 1 2

Indexed String
12 Position Pattern Binary Flags (7bits) G216 0 Setting 0 79 1 2 Forced Position for Isolators and Circuit Breaker
13 Position Test Indexed String G93 No Operation Command 0 2 1 2
20 DDB 0-31 Binary Flag (32 bits) N/A Data Relay

Visible by Courier and Modbus
21 DDB element 32-63 Binary Flag (32 bits) N/A Data Opto
22 DDB element 64-95 Binary Flag (32 bits) N/A Data
2A DDB element 320-351 Binary Flag (32 bits) N/A Data
2B DDB element 352-383 Binary Flag (32 bits) N/A Data
2C DDB element 384-415 Binary Flag (32 bits) N/A Data
2D DDB element 415-447 Binary Flag (32 bits) N/A Data
2E DDB element 448-479 Binary Flag (32 bits) N/A Data
2F DDB element 480-511 Binary Flag (32 bits) N/A Data
11 00 OPTOS SETUP
1 Global Nominal V Indexed String G200 2 Setting 0 5 1 2

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Courier Ref
0A Opto Input 9 Indexed String G201 2 Setting 0 4 1 2
0B Opto Input 10 Indexed String G201 2 Setting 0 4 1 2
0C Opto Input 11 Indexed String G201 2 Setting 0 4 1 2
0D Opto Input 12 Indexed String G201 2 Setting 0 4 1 2
0E Opto Input 13 Indexed String G201 2 Setting 0 4 1 2
0F Opto Input 14 Indexed String G201 2 Setting 0 4 1 2
GROUP 1
BUSBAR ELEMENT
30 00 GROUP 1
BB TRIP CONFIRM
01 I>BB Current Set Courier Number (Current) G2 1,2*I1 Setting 0,05*I1 4*I1 0,01*I1 2
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Courier Ref
02 IN>BB Current Courier Number (Current) G2 0,2*I1 Setting 0,05*I1 4*I1 0,01*I1 2
BB TRIP CONFIRM
35 00 GROUP 1
BACKUP OVERCURRENT
01 I>1 Function Indexed String G43 Disabled Setting 0 10 1 2
02 I>1 Current Set Courier Number (Current) G2 3*I1 Setting 0,10*I1 32*I1 0,01*I1 2
03 I>1 Time Delay Courier Number (Time) G2 1 Setting 0 100 0.01 2
04 I>1 TMS Courier Number (Time) G2 1 Setting 0.025 1.2 0.025 2 5 >= 3501 >=2
05 I>1 Time Dial Courier Number (Time) G2 7 Setting 0.5 15 0.1 2
06 I>1 Reset Char Indexed String G60 DT Setting 0 1 1 2
07 I>1 tReset Courier Number (Time) G2 0 Setting 0 100 0.1 2 5 >= 3501 >=1 OR (3506 = 0 AND 3501 >= 6)
08 I>2 Function Indexed String G209 Disabled Setting 0 3 1 2
09 I>2 Current Set Courier Number (Current) G2 20*I1 Setting 0,10*In 32*I1 0,01*I1 2
0A I>2 Time Delay Courier Number (Time) G2 1 Setting 0 100 0.01 2
OVERCURRENT
38 00 GROUP 1
EARTH FAULT
01 IN>1 Function Indexed String G43 Disabled Setting 0 10 1 2
02 IN>1 Current Set Courier Number (Current) G2 0,3*I1 Setting 0,10*I1 32*I1 0,01*I1 2
03 IN>1 Time Delay Courier Number (Time) G2 1 Setting 0 100 0.01 2
04 IN>1 TMS Courier Number (Time) G2 1 Setting 0.025 1.2 0.025 2 5 >= 3801 >=2
05 IN>1 Time Dial Courier Number (Time) G2 7 Setting 0.5 15 0.1 2
06 IN>1 Reset Char Indexed String G60 DT Setting 0 1 1 2
07 IN>1 tReset Courier Number (Time) G2 0 Setting 0 100 0.1 2 5 >= 3801 >=1 OR (3806 = 0 AND 3801 >= 6)
08 IN>2 Function Indexed String G209 Disabled Setting 0 3 1 2
09 IN>2 Current Set Courier Number (Current) G2 20*I1 Setting 0,10*I1 32*I1 0,01*I1 2
0A IN>2 Time Delay Courier Number (Time) G2 1 Setting 0 100 0.01 2

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Courier Ref
EARTH FAULT
45 00 GROUP 1
CB FAIL
01 Control by Indexed String G210 I< Setting 0 2 1 2 I<, 52a, I< & 52a
02 I< Current Set Courier Number (Current) G2 0,05*I1 Setting 0,05*I1 1*I1 0,01*I1 2
03 I> Status Indexed String G37 Disabled Setting 2
04 I> Current Set Courier Number (Current) G2 1,2*I1 Setting 0,05*I1 4*I1 0,01*I1 2 4503<>0 and 4501<>1
05 IN> Current Set Courier Number (Current) G2 0,2*I1 Setting 0,05*I1 4*I1 0,01*I1 2 4503<>0 and 4501<>1
06 INTERNAL TRIP (Sub Heading)
07 CB Fail Timer 1 Courier Number (Time) G2 0.05 Setting 0 10 0.01 2
08 CB Fail Timer 2 Courier Number (Time) G2 0.2 Setting 0 10 0.01 2 4508 > 4507
09 EXTERNAL TRIP (Sub Heading)
0A CB Fail Timer 3 Courier Number (Time) G2 0.05 Setting 0 10 0.01 2
0B CB Fail Timer 4 Courier Number (Time) G2 0.2 Setting 0 10 0.01 2 450B > 450A
CB FAIL
46 00 GROUP 1
SUPERVISION
0D I0 SUPERVISION (Sub Heading)
0E Error Factor Kce Courier Number (%) G2 40 Setting 1 100 1 2
0F Alarm Delay Tce Courier Number (Time) G2 5 Setting 0.1 10 0.1 2
SUPERVISION
4A 00 GROUP 1 Product Dependent
INPUT LABELS
1 Opto Input 1 ASCII Text (16 chars) G3 Opto Label 01 Setting 32 55 1 2
1
4 Opto Input 4 ASCII Text (16 chars) G3 etc.. Setting 32 55 1 2
5 Opto Input 5 ASCII Text (16 chars) G3 Setting 32 55 1 2

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Courier Ref
0A Opto Input 10 ASCII Text (16 chars) G3 Setting 32 55 1 2
0B Opto Input 11 ASCII Text (16 chars) G3 Setting 32 55 1 2
0C Opto Input 12 ASCII Text (16 chars) G3 Setting 32 55 1 2
0D Opto Input 13 ASCII Text (16 chars) G3 Setting 32 55 1 2
0E Opto Input 14 ASCII Text (16 chars) G3 Setting 32 55 1 2
0F Opto Input 15 ASCII Text (16 chars) G3 Setting 32 55 1 2
INPUT LABELS
4B 00 GROUP 1 Product Dependent
OUTPUT LABELS
1 Relay 1 ASCII Text (16 chars) G3 Relay Label 01 Setting 0 23 1 2
4 Relay 4 ASCII Text (16 chars) G3 etc … Setting 0 23 1 2
5 Relay 5 ASCII Text (16 chars) G3 Setting 0 23 1 2

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Courier Ref
0A Relay 10 ASCII Text (16 chars) G3 Setting 0 23 1 2
0B Relay 11 ASCII Text (16 chars) G3 Setting 0 23 1 2
0C Relay 12 ASCII Text (16 chars) G3 Setting 0 23 1 2
0D Relay 13 ASCII Text (16 chars) G3 Setting 0 23 1 2
0E Relay 14 ASCII Text (16 chars) G3 Setting 0 23 1 2
0F Relay 15 ASCII Text (16 chars) G3 Setting 0 23 1 2
OUTPUT LABELS
GROUP 2
PROTECTION SETTINGS
GROUP 3
PROTECTION SETTINGS
GROUP 4
PROTECTION SETTINGS
C0 00 TOPO SETTINGS
01 Topology Size Unsigned integer Data

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MiCOM P740
Courier Ref
,,,
FB Topology Element 250 Binary Flag (32bits) Data

MiCOM P740
B - DIGITAL DATA BUS

MiCOM P740
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B - Digital Data Bus (For P741 Only)
DDB N° Source Description English Text
0 Relay Relay Label 01 Output Label 01

32 Opto Opto Label 01 Opto Input 1
64 Led LED 1 Led 1
65 Led LED 2 Led 2
66 Led LED 3 Led 3
67 Led LED 4 Led 4
68 Led LED 5 Led 5
69 Led LED 6 Led 6
70 Led LED 7 Led 7
71 Led LED 8 Led 8
72 PSL (IN) SG Bit LSB LSB Setting Group
73 PSL (IN) SG Bit MSB MSB Setting Group
74 PSL (IN) Reset Circt Flt Reset Circuitry Fault
75 PSL (IN) Ext. Start DR Starting Disturbance Recorder
76 PSL (IN) Ext. CZ confirm. External CZ confirmation (0=confirmed)
77 PSL (IN) Reset Latches Reset Relays and Led latched in PSL
80 Virtual Relay Virtual Relay 01 Virtual Relays 01
103 PSL (OUT) System Minor Syst Error Minor System Error
104 PSL (IN) Alarm User 1 Self Reset User Alarm 1
112 PSL (OUT) 87BB Protection Fault 87BB zone 16 Fault current in zone 16
128 PSL (OUT) 87BB Protection Circt Flt zone 16 Circuitry fault in zone 16
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144 PSL (OUT) 87BB Protection Trp 87BB zone 16 Busbar trip in zone 16
160 PSL (OUT) 50BF Protection Trp 50BF zone 16 Breaker failure trip (50BF) in zone 16
176 PSL (OUT) Commissioning Test Man.Trip zone 16 Manual trip zone 16
192 PSL (OUT) Commissioning Test Lck Lev.1 zone16 Commissioning mode 87BB monitoring in zone 16
208 PSL (OUT) Commissioning Test Lck Lev.2 zone16 Commissioning mode 87BB & 50BF disabled in zone 16
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224 PSL (OUT) 87BB Protection Trip 87BB Busbar trip order (87BB)
225 PSL (OUT) 87BB Protection Trip 87BB block Busbar trip order blocked by commissioning mode
226 PSL (OUT) 87BB Protection Trip Manual zone Manual Trip Order
227 PSL (OUT) 50BF Protection Trip 50BF Breaker fail trip order (50BF)
228 PSL (OUT) 50BF Protection Trip 50BF block Breaker fail trip order blocked by commissioning mode
229 PSL (OUT) 87BB Protection Dead Zone Signal Fault in dead zone
230 PSL (OUT) 87BB Protection Fault phase A Fault current in phase A
231 PSL (OUT) 87BB Protection Fault phase B Fault current in phase B
232 PSL (OUT) 87BB Protection Fault phase C Fault current in phase C
233 PSL (OUT) 87BB Protection Earth fault Sensitive earth fault current
234 PSL (OUT) 87BB Protection Circuitry Fault Circuitry fault on 1 or several zones
235 PSL (OUT) Commissioning Test Alm Lck Level 1 Commissioning mode 87BB monitoring
236 PSL (OUT) Commissioning Test Alm Lck Level 2 Commissioning mode 87BB & 50BF disabled
237 PSL (OUT) Config. valid Valid configuration
238 PSL (OUT) Topology valid Topology file valid
240 PSL (OUT) Main System Er. Main system error
241 PSL (OUT) 1st CU main err. CU main error
242 PSL (OUT) 2nd CU main err. Remote CU main error
243 PSL (OUT) 87BB Protection Fault Check Zone Busbar fault detected by both CZ (internal & external)
244 PSL (OUT) 87BB Protection Circt Flt ph A Circuitry fault in phase A
245 PSL (OUT) 87BB Protection Circt Flt ph B Circuitry fault in phase B
246 PSL (OUT) 87BB Protection Circt Flt ph C Circuitry fault in phase C
247 PSL (OUT) 87BB Protection Circt Flt Earth Residual circuitry fault
256 PSL (OUT) System Err Chan A Com 1 PU communication error: com A board 1
257 PSL (OUT) System Err Chan B Com 1 PU communication error: com B board 1
258 PSL (OUT) System Err Chan C Com 1 PU communication error: com C board 1
259 PSL (OUT) System Err Chan D Com 1 PU communication error: com D board 1
288 PSL (OUT) System PU Adr 38 error Error: several PU adresse 38
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321 PSL (OUT) System 1st CU minor er. CU minor error
322 PSL (OUT) System 2nd CU minor er. Remote CU minor error
323 PSL (OUT) System Minor Err COM1 Minor error in COM 1 board
332 PSL (OUT) System Operating Mode 1
333 PSL (OUT) System Operating Mode 2
Expert Only
334 PSL (OUT) Disturbance Recorder Pre-fault
335 PSL (OUT) Disturbance Recorder Post-fault
336 Virtual Opto Virtual Opto 01 Virtual Opto 01
352 PSL (OUT) CommTest Enabled Commissionning Test enable
353 PSL (OUT) 87BB Enabled Busbar protection enable
354 PSL (OUT) 87BBN Enabled Busbar earth enable
355 PSL (OUT) Reset Circt Flt Reset after fault
356 PSL (OUT) Topo/Set Changed Change on topology or configuration
357 PSL (OUT) Manual Start DR Disturbance recorder - Manual start
358 PSL (OUT) PU Topo no valid Topology file error for one or several PU
359 PSL (OUT) Alarm Field Volt Alarm field voltage
360 PSL (OUT) Ext. CZ confirm. External CZ confirmation
367 PSL (OUT) General alarm General alarm
400 PSL Relay 01 Output relay 1 condition
408 PSL Relay 09 Reserved
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432 PSL LED Cond IN 1 Led 1 condition
440 Aux Timer Timer IN 1 Input timer 1
448 Aux Timer Timer OUT 1 Output timer 1
456 FRT Fault_REC_TRIG Fault Recorder Trigger
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B - Digital Data Bus (For P742 and P743 Only)
DDB No Source Description English Text
0 Relay Relay Label 01 Relay 1 - Trip Phase A / Relay 2 - Phase B / Relay 3 - Phase C
1 Relay Relay Label 02 87BB, 50BF(CU), I> and IN> trip are directly connected even they don't
2 Relay Relay Label 03 appear in PSL
3 Relay Relay Label 04 Relay 4
7 Relay Relay Label 08 Relay 8 - Setting P742
20 Relay Relay Label 21 Relay 21 - Setting P743
47 Opto Opto Label 16 Opto Input 16 - Setting P742
55 Opto Opto Label 24 Opto Input 24 - Setting P743
64 Led LED 1 Led 1
65 Led LED 2 Led 2
66 Led LED 3 Led 3
67 Led LED 4 Led 4
68 Led LED 5 Led 5
69 Led LED 6 Led 6
70 Led LED 7 Led 7
71 Led LED 8 Led 8
72 PSL (IN) Isolator Position Q1 Open Isolator 1 - Auxiliary contact open
73 PSL (IN) Isolator Position Q1 Closed Isolator 1 - Auxiliary contact closed
84 PSL (IN) CB Fail Ext. 3 ph Trip Integrated breaker failure logic - 3 phase initialisation
85 PSL (IN) CB Fail External Trip A Integrated breaker failure logic - Initialisation Phase A
86 PSL (IN) CB Fail External Trip B Integrated breaker failure logic - Initialisation Phase B
87 PSL (IN) CB Fail External Trip C Integrated breaker failure logic - Initialisation Phase C
88 PSL (IN) CB Control Man.CB Close Cmd CB Closing order (used in topology processing)
89 PSL (IN) CB Control CB not available CB auxiliary Contact not available
90 PSL (IN) CB Control Ext. CB Fail External breaker failure logique, input to send backtrip order to CU
91 PSL (IN) CB Control CB Aux. 3ph(52a) CB Auxiliary contact open 3ph (52a)
92 PSL (IN) CB Control CB Aux. 3ph(52b) CB Auxiliary contact closed 3ph (52b)
93 PSL (IN) CB Control CB Aux. A (52a) CB Auxiliary contact open Phase A (52a)
94 PSL (IN) CB Control CB Aux. A (52b) CB Auxiliary contact closed Phase A (52b)
95 PSL (IN) CB Control CB Aux. B (52a) CB Auxiliary contact open Phase B (52a)
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96 PSL (IN) CB Control CB Aux. B (52b) CB Auxiliary contact closed Phase B (52b)
97 PSL (IN) CB Control CB Aux. C (52a) CB Auxiliary contact open Phase C (52a)
98 PSL (IN) CB Control CB Aux. C (52b) CB Auxiliary contact closed Phase C (52b)
99 PSL (IN) Reset Lockout Reset trip relays 1, 2, 3
100 PSL (IN) SG Bit LSB LSB Setting Group
101 PSL (IN) SG Bit MSB MSB Setting Group
102 PSL (IN) Reset All values
103 PSL (IN) Reset Latches Reset relays and leds latched in PSL
104 PSL (IN) User Alarm 1 Self Reset User Alam 1
111 PSL (IN) Aux Volt Superv Auxiliary voltage supervision
112 Virtual relay Virtual Relay 01 Virtual Relay 1
128 PSL (IN) Isolator Position Man.Close Q1 Cmd Isolator 1 - Closing order (used in topology processing)
129 PSL (IN) Isolator Position Man.Close Q2 Cmd Isolator 2 - Closing order(used in topology processing)
134 PSL (IN) CB Control Man. Close CB CB Control : manual closing order
135 PSL (IN) CB Control Man. Trip CB CB Control : manual opening order
136 PSL (OUT) CB Fail Ext. Retrip Ph A CBF Phase A external retrip (TBF3)
137 PSL (OUT) CB Fail Ext. Retrip Ph B CBF Phase B external retrip (TBF3)
138 PSL (OUT) CB Fail Ext. Retrip Ph C CBF Phase C external retrip (TBF3)
139 PSL (OUT) CB Fail Int retrip 3 ph CBF 3Ph internal retrip (TBF1)
140 PSL (OUT) CB Fail CBF Int Backtrip CBF backtrip - internal (TBF2)
141 PSL (OUT) CB Fail CBF ext Backtrip CBF backtrip - external (TBF4)
142 PSL (OUT) CB Fail CB Fail Alarm CB Fail Alarm (TBF1 + TBF2 + TBF3 + TBF4)
144 PSL (OUT) Phase Overcurrent I>1 Start A Overcurrent Start I>1 phase A
145 PSL (OUT) Phase Overcurrent I>1 Start B Overcurrent Start I>1 phase B
146 PSL (OUT) Phase Overcurrent I>1 Start C Overcurrent Start I>1 phase C
147 PSL (OUT) Earth Fault IN>1 Start Overcurrent Start I>1 phase N
148 PSL (OUT) Phase Overcurrent I>1 Trip Overcurrent Phase Trip 3Ph I>1
149 PSL (OUT) Earth Fault IN>1 Trip Overcurrent Earth Trip 3Ph I>1
150 PSL (OUT) Phase Overcurrent I>2 Start A Overcurrent Start I>2 phase A
151 PSL (OUT) Phase Overcurrent I>2 Start B Overcurrent Start I>2 phase B
152 PSL (OUT) Phase Overcurrent I>2 Start C Overcurrent Start I>2 phase C
153 PSL (OUT) Earth Fault IN>2 Start Overcurrent Start I>2 phase N
154 PSL (OUT) Phase Overcurrent I>2 Trip Overcurrent Phase Trip 3Ph I>2
155 PSL (OUT) Earth Fault IN>2 Trip Overcurrent Earth Trip 3Ph I>2
160 PSL (OUT) 87BB Protection Zone 16 Off Zone 16 in commissioning mode or circuitry fault
176 PSL (OUT) 87BB Protection Trip Zone 16 Trip zone 16 from 87BB, 50BF or manual trip zone
Relay Menu Database
abcd P740/EN GC/B11
Page B-8
MiCOM P740
192 PSL (OUT) 87BB Protection I>BB Start A Overcurrent Ia>BB - Busbar Trip Confirmation
193 PSL (OUT) 87BB Protection I>BB Start B Overcurrent Ib>BB - Busbar Trip Confirmation
194 PSL (OUT) 87BB Protection I>BB Start C Overcurrent Ic>BB - Busbar Trip Confirmation
195 PSL (OUT) 87BB Protection IN>BB Start Overcurrent In>BB - Busbar Confirmation
196 PSL (OUT) 87BB Protection I>BB Block Ph A Overcurrent Ia>BB - Blocking Busbar on external fault
197 PSL (OUT) 87BB Protection I>BB Block Ph B Overcurrent Ib>BB - Blocking Busbar on external fault
198 PSL (OUT) 87BB Protection I>BB Block Ph C Overcurrent Ic>BB - Blocking Busbar on external fault
199 PSL (OUT) 87BB Protection IN>BB Block Overcurrent In>BB - Blocking Busbar on external fault
200 PSL (OUT) CT Saturation Saturation ph A Saturation Phase A
201 PSL (OUT) CT Saturation Saturation ph B Saturation Phase B
202 PSL (OUT) CT Saturation Saturation ph C Saturation Phase C
203 PSL (OUT) Monitoring Current Overflow Optical fibre current format > Max
204 PSL (OUT) CT Saturation Max Flux ph A Max flux presomption Phase A
205 PSL (OUT) CT Saturation Max Flux ph B Max flux presomption Phase B
206 PSL (OUT) CT Saturation Max Flux ph C Max flux presomption Phase C
207 PSL (OUT) Monitoring Alarm OffsetABCN Offset Analog board Phase A, B, C or N
208 PSL (OUT) CT Saturation Predict err ph A Variation error Phase A (from derived current)
209 PSL (OUT) CT Saturation Predict err ph B Variation error Phase B (from derived current)
210 PSL (OUT) CT Saturation Predict err ph C Variation error Phase C (from derived current)
212 PSL (OUT) Monitoring Sat ADC ph A ADC saturation Phase A
213 PSL (OUT) Monitoring Sat ADC ph B ADC saturation Phase B
214 PSL (OUT) Monitoring Sat ADC ph C ADC saturation Phase C
215 PSL (OUT) Monitoring Sat ADC Neutral ADC saturation Phase N
216 PSL (OUT) Monitoring Delta IA Variation Phase A
217 PSL (OUT) Monitoring Delta IB Variation Phase B
218 PSL (OUT) Monitoring Delta IC Variation Phase C
219 PSL (OUT) Monitoring Delta IN Variation Phase N
220 PSL (OUT) System Fibre Com Error PU/CU communication error
221 PSL (OUT) System PU Main Error PU main error
222 PSL (OUT) Monitoring Acq Error 3Io Sample acquisition error - 3*Io=In
223 PSL (OUT) Monitoring CT Fail Alarm 3*Io=In error with Tce timer
Trip 3ph from 87BB, 50BF(CU), I>, IN> or manual zone trip (CU). Trip
224 PSL (OUT) All Protection Internal Trip
command directly apply to relay 1, 2, 3 without PSL
225 PSL (OUT) 87BB Protection Trip 87BB Busbar trip in one zone, not especially on this PU
226 PSL (OUT) 87BB Protection Trip 87BB Block Busbar trip blocked by commissioning mode
227 PSL (OUT) 50BF Protection Trip 50BF (CU) 50BF backtrip from CU in one zone, not especially on this PU
228 PSL (OUT) Commissioning Test Man.Trip zone Manual trip in one zone, not especially on this PU
229 PSL (OUT) 50BF Protection Dead Zone Fault Dead zone alarm
230 PSL (OUT) 50BF Protection Circuitry Fault Circuitry fault on dead zone
232 PSL (OUT) System Operating mode 1
233 PSL (OUT) System Operating mode 2 for expert only
234 PSL (OUT) System Operating mode 3
235 PSL (OUT) System Config. valid Valid configuration
236 PSL (OUT) System Topology valid Topology file valid
237 PSL (OUT) System Topo/Set valid Configuration & Topology valid
256 PSL (OUT) Overcurrent Protection I> Any Trip Overcurrent Trip (phase or earth fault)
257 PSL (OUT) CB Control CBAvailabToTrip Circuit Breaker available to trip
258 PSL (OUT) 50BF Protection BF Trip Request Internal or external 50BF (backtrip order to CU)
264 PSL (OUT) Overcurrent Protection I> No Trip Overcurent trip - complement
265 PSL (OUT) CB Control CBNotAvailToTrip CB available to trip - complement
266 PSL (OUT) 50BF Protection BFTripNoRequest Internal or external 50BF - complement
273 PSL (OUT) CB Control Ctrl CB Trip Manual trip for local Circuit Breaker
274 PSL (OUT) CB Control Ctrl CB Close Manual closing for local Circuit Breaker
275 PSL (OUT) Commissioning Test PU OutOfService Commissioning Mode - PU out of service
276 PSL (OUT) Commissioning Test PU I/O Disabled Commissioning Mode - I/O disabled
279 PSL (OUT) CT Saturation Reset Flux for expert only
280 PSL (OUT) CT Saturation Restart Flux for expert only
281 PSL (OUT) Comm Test Enable Activation Commissionning Test
282 PSL (OUT) I>BB Enabled Activation OC Busbar Confirmation
283 PSL (OUT) Trip Rel Latched Activation latched trip relay
284 PSL (OUT) I>2 Block BB ON Activation OC Busbar Blocking Phase
285 PSL (OUT) IN>2 Block BB ON Activation OC Busbar Blocking Residual
286 PSL (OUT) Reset Trip Relay Reset latched trip relay 1,2 and 3
287 PSL (OUT) Topo/Set Changed Setting or topology change
Relay Menu Database
abcd P740/EN GC/B11
Page B-9
MiCOM P740
288 PSL (OUT) Isolator Position Q1 Closed Isolator 1 closed (used for topology processing)
300 PSL (OUT) CB Position CB Closed Cicuit breaer closed (used for topology processing)
301 PSL (OUT) CB Control CB Healthy Circuit Breaker 1 available (used for topology processing)
304 PSL (OUT) Isolator Position Q1 Status Forced Isolator 1 - Forced position
310 PSL (OUT) CB Position CB Status Forced Circuit Breaker 1 - Forced position
311 PSL (OUT) Commissioning Test Forced Mode ON Forced position enable
312 PSL (OUT) CB Control CB Aux. 52a Circuit Breaker open
313 PSL (OUT) CB Control CB Aux. 52b Circuit Breaker closed
314 PSL (OUT) CB Control CB Trip 3 ph Circuit Breaker trip 3 phases
315 PSL (OUT) CB Control CB Trip phase A Circuit Breaker trip phase A
316 PSL (OUT) CB Control CB Trip phase B Circuit Breaker trip phase B
317 PSL (OUT) CB Control CB Trip phase C Circuit Breaker trip phase C
318 PSL (OUT) Alarm Field Volt Alarm field voltage
319 PSL (OUT) General Alarm General alarm
320 PSL (OUT) CB Control CB Status Alarm CB status alarm - CB auxiliary contact supevision
321 PSL (OUT) CB Control Man CB Trip Fail CB control alarm - trip error
322 PSL (OUT) CB Control Man CB Cls Fail CB control alarm - closed error
323 PSL (OUT) CB Control Ctrl Cls in Prog Circuit Breaker closed in progress
324 PSL (OUT) CB Control Control Close Circuit Breaker closed control
325 PSL (OUT) CB Control Control Trip Circuit Breaker open control
326 PSL (OUT) All Protection Any Trip OR between DDB 136, 137, 138, 139, 224
Relay Menu Database
abcd P740/EN GC/B11
Page B-10
MiCOM P740

408 FRT Fault_REC_TRIG Fault recorder trigger
MiCOM P740
C - DEFAULT PROGRAMMABLE
SCHEME LOGIC (PSL)
MiCOM P740
MiCOM P740 Page C-1
MiCOM P741
PROGRAMMABLE SCHEME LOGIC (01) FOR CENTRAL UNIT
Input-Opto Couplers
Opto Label 01 Reset Latches

DDB #032 DDB #077
Opto Label 02 Ext. Start DR

DDB #033 DDB #075
Opto Label 03 Reset Circt Flt

DDB #034 DDB #074
Opto Label 04 Ext. CZ confirm

DDB #035 DDB #076
TRIP 87BB
DDB #224
20
TRIP 50BF FAULT_REC_TRIG
DDB #227 Dwell DDB #456
0
Dead Zone signal

DDB #229
Page C-2 MiCOM P740
MiCOM P741
Output Contact
0
Fault phase A Relay Label 01
DDB #230 Pick-Up DDB #000
0
0
Fault phase B Relay Label 02
0
0
Fault phase C Relay Label 03
0
Trp 87BB Zone 01

DDB #159
0
Trp 50BF Zone 01 Relay Label 04
0
Man. Trip Zone 01
DDB #191
Trp 87BB Zone 02

DDB #158
0
Trp 50BF Zone 02 Relay Label 05
0
Man. Trip Zone 02
DDB #190
0
Circuitry Fault Relay Label 06
0
Crct Flt Zone 01

DDB #143
0
Lck Lev.1 Zone01 Relay Label 07
0
Lck Lev.2 Zone01
DDB #223
Crct Flt Zone 02

DDB #142
0
Lck Lev.1 Zone02 Relay Label 08
0
Lck Lev.2 Zone02
DDB #222
MiCOM P740 Page C-3
MiCOM P741
Leds Front Panel
Fault phase A Output_led_01

DDB #230 Latching DDB #064 Phase A
Fault phase B Output_led_02

DDB #231 Latching DDB #065 Phase B
Fault phase C
DDB #232 Latching Output_led_03
DDB #066 Phase C
Trip 87BB
DDB #067 Busbar Trip
Trip 50BF
DDB #068
Breaker Fail
Circuitry Fault Output_led_06

DDB #234 Latching DDB #069 Circuitry Fault
Page C-4 MiCOM P740
MiCOM P742 & P743

PROGRAMMABLE SCHEME LOGIC (01) FOR PERIPHERAL UNITS
Input-Opto Couplers
Opto Label 01 Reset Latches

DDB #032 DDB #103
Opto Label 02 Reset Lockout

DDB #033 DDB #099
Opto Label 03 Q1 Closed

DDB #034 DDB #073
Opto Label 04 Q1 Open

DDB #035 DDB #072

DDB #036 DDB #075

DDB #037 DDB #074
Opto Label 07 CB Aux. 3ph (52a)

DDB #038 DDB #091
Opto Label 08 CB Aux. 3ph (52b)

DDB #039 DDB #092

DDB #040 DDB #077

DDB #041 DDB #076
Opto Label 12 Ext. 3 ph Trip

DDB #043 DDB #084
Opto Label 13 CB not available

DDB #044 DDB #089
Opto Label 14 Ext. CB Fail

DDB #045 DDB #090
Opto Label 15 Man.CB Close Cmd

DDB #046 DDB #088
Dead Zone Fault

DDB #229
20
Fault_REC_TRIG
Dwell DDB #408
0
Any Trip
DDB #326
P3721ENa
MiCOM P740 Page C-5
MiCOM P742 & P743

Output Contact
Ext. Retrip Ph A
DDB #136
Ext. Retrip Ph B
DDB #137 0
Relay Label 06
Pick-Up DDB #005
Ext. Retrip Ph C
0
DDB #138
Int retrip 3 ph
DDB #139
0
CB Fail Alarm Relay Label 04
0
0
Relay Label 05
Opto Label 13
Pick-Up DDB #004
DDB #044 0
Internal Trip
DDB #224 0
Relay Label 07
Pick-Up DDB #006
Dead Zone Fault 0
DDB #229
CB Status Alarm 0
DDB #320 Relay Label 08
Pick-Up DDB #007
Opto Label 03 0
DDB #034
Opto Label 04
DDB #035
& 5000
Dwell
Opto Label 03
0
DDB #034
Opto Label 04
DDB #035
Opto Label 05
DDB #036
Opto Label 06
DDB #037
& 5000
Dwell User Alarm 1
Opto Label 05 DDB #104
0
DDB #036
Opto Label 06
DDB #037
Opto Label 09
DDB #040
Opto Label 10
DDB #041
& 5000
Dwell
Opto Label 09
DDB #040 0
Opto Label 10
DDB #041
Page C-6 MiCOM P740
MiCOM P742 & P743

Leds Front Panel
Q1 Closed Output_led_01
DDB #288 Latching DDB #064 Isolator 1
Q2 Closed Output_led_02
DDB #290 Latching DDB #065 Isolator 2
Q3 Closed
DDB #066 Isolator 3
CB Fail Alarm
DDB #142
Output_led_05
Latching DDB #068 Breaker Fail
Opto Label 13
DDB #044
Internal Trip
DDB #224
Busbar Trip
Trip 87BB
& Latching Output_led_06
DDB #069
DDB #225
Dead Zone Fault Output_led_07

DDB #229 Latching DDB #070 Dead Zone
Menu Content Tables P740/EN HI/D11
MiCOM P740
MENU CONTENT TABLES

abcd
MiCOM P740 Page 1
MiCOM P741 - Central Unit
PU CONF &
SYSTEM DATA VIEW RECORDS MEASUREMENTS 1 MEASUREMENTS 2 TOPOLOGY 1 TOPOLOGY 2 DATE AND TIME
STATUS
Language Last Record IA bias IA Diff CZ Zx1: IA diff Current Node 01 Current Node 01 PU in service Date/Time
English 0 0 0 A 0 0 0 0
Password Menu Cell Ref IB bias IB Diff CZ Zx1: IB diff Current Node 02 Current Node 02 PU connected Time
AAAA (From Record) 0 0 A 0 0 0 0
Description Time & Date IC bias IC Diff CZ Zx1: IC diff Current Node 03 Current Node 03 PU topo valid IRIG-B Sync
MiCOM P741 (From Record) 0 0 A 0 0 0 Disabled
Plant Reference Record Text IN bias IN Diff CZ Zx1: IN diff Reset Circt Flt IRIG-B Status
ALSTOM 0 0 0 A 0 0
Serial Number Record Value IA CZ diff Zx1: IA bias Current Node 16 Current Node 16 CircuitryFfault Battery Status
Serial Number 0 0 0 0 0 0
Frequency Active Group IB CZ diff Zx1: IB bias Circ Fault Phase Battery Alarm
50 0 0 0 Enabled
Relay Address Faulted Phase IC CZ diff Zx1: IC bias

1 0 0 0
Plant Status Start Elements IN CZ diff Zx1: IN bias

0 0 0
Control Status Trip Elements Faulted Zone Zx16: IA diff

0 0 0
Active Group Time Stamp Select Report Zx16: IB diff

0 0 0
Software Ref. 1 Fault Alarms Report Text Zx16: IC diff

0 0 0
Opto I/P Status System Frequency Type Zx16: IA bias

0 0 0
Relay O/P Status Fault Duration Data Zx16: IB bias

0 0 0
Alarm Status IA diff Reset Indication Zx16: IC bias

0 No 0
Access Level IB diff Zx16: IN bias

0 0
Password Control Password Level 1 IC diff

2 AAAA 0
Password Level 2 IN diff

AAAA 0
abcd
MiCOM P740 Page 2
MiCOM P741 - Central Unit
OPTOS DIFF BUSBAR PROT INPUT LABELS OUTPUT LABELS Idem GROUP
CONFIGURATION RECORD CONTROL DISTURB RECORDER MEASURE'T SETUP COMMISSION TESTS
SETUP GROUP 1 GROUP 1 GROUP 1 2,3 & 4
Restore Defaults Clear Events Duration Default Display Opto I/P Status Global nominal V Current Is Opto Input 1 Relay 1
No Operation No 1.2 0 0 2 0,1*Ibp Opto Label 01 Relay Label 01
Setting Group Clear Faults Trigger Position Local Values Relay O/P Status Opto Input 1 Phase Slope k Opto Input 2 Relay 2
Select via Menu No 50 Secondary 0 2 40 % Opto Label 02 Relay Label 02
Active Settings Clear Maint Trigger Mode Remote Values Test Port Status Opto Input 2 ID>2 Current Opto Input 3 Relay 3
Group 1 No Single Primary 0 2 1,2*Ibp mA Opto Label 03 Relay Label 03
Save Changes Analog Channel 1 Ibp Base Cur Pri LED Status Opto Input 3 ID>1 Current Opto Input 4 Relay 4
No Operation IA diff 1000 0 2 0,05*Ibp mA Opto Label 04 Relay Label 04
Copy From Analog Channel 2 Monitor Bit 1 Opto Input 4 ID>1 Alarm Timer Opto Input 5 Relay 5
Group 1 IB diff Relay 1 2 5 s Opto Label 05 Relay Label 05
Copy to Analog Channel 3 Opto Input 5 Diff Earth Fault Opto Input 6 Relay 6
No Operation IC diff Monitor Bit 8 2 Enabled Opto Label 06 Relay Label 06
Relay 8
Setting Group 1 Analog Channel 4 Opto Input 6 IBiasPh> Cur. Opto Input 7 Relay 7
Enabled IN diff Test Mode 2 2*Ibp mA Opto Label 07 Relay Label 07
Disabled
Setting Group 2 Analog Channel 5 Opto Input 7 Earth Cur. IsN Opto Input 8 Relay 8
Disabled IA bias Test Pattern 2 0,1*Ibp mA Opto Label 08 Relay Label 08
0
Setting Group 3 Analog Channel 6 Opto Input 8 Earth Slope kN Virtual Opto 1 Virtual Relay 1
Disabled IB bias Contact Test 2 20 mA Virtual Opto 01 Virtual Relay 01
No Operation
Setting Group 4 Analog Channel 7 IDN>2 Current Virtual Opto 2 Virtual Relay 2
Disabled IC bias Test LEDs 0,1*Ibp mA Virtual Opto 02 Virtual Relay 02
No Operation
Diff Busbar Prot Analog Channel 8 IDN>1 Current
Enabled 0 87BB monitoring 0,05*Ibp mA
0xFFFF
Optos Setup Digital Input 1 IDN>1 Alarm Tim. Virtual Opto 16 Virtual Relay 16
Visible Unused 87BB&50BF disabl 5 s Virtual Opto 16 Virtual Relay 16
0xFFFF
Input Labels
Visible Digital Input 32 87BBTrip Pattern
Unused 0
Output Labels
Visible Manual Trigger 87BB Trip Order
No 0
Recorder Control Comms Settings
Visible Invisible Zone To Record DDB 0-31
0 0
Disturb Recorder Commission Tests
Visible Visible
DDB 480-511
Measure't Setup Setting Values 0
Visible Secondary
abcd
MiCOM P740 Page 3
MiCOM P742/3 - Peripheral Units
SYSTEM DATA VIEW RECORDS MEASUREMENTS 1 TOPOLOGY CB CONTROL DATE and TIME
Language Last Record IA Magnitude Link CT / zone Prot Trip Pulse Date
English 0 0 A 0 0.2 0
Password Menu Cell Ref IA Phase Angle Zx1: IA diff Trip Latched Time
AAAA (From Record) 0 A 0 Disabled 0
Description Time & Date IB Magnitude Zx1: IB diff Zx3: IA diff Reset Trip Latch Battery Status
MiCOM P742/P743 (From Record) 0 A 0 0 No 0
Plant Reference Record Text IB Phase Angle Zx1: IC diff Zx3: IB diff CB Control by Battery Alarm
ALSTOM 0 0 ° 0 0 Disabled Enabled
Model Number Record Value IC Magnitude Zx1: IN diff Zx3: IC diff Man Close Pulse
Model Number 0 0 A 0 0 0.5
Serial Number Select Fault IC Phase Angle Zx1: IA bias Zx3: IN diff Man Trip Pulse
Serial Number 0 0 ° 0 0 0.5
Frequency Active Group IN Magnitude Zx1: IB bias Zx3: IA bias Man Close Delay
50 0 0 A 0 0 10
Relay Address Faulted Phase IN Phase Angle Zx1: IC bias Zx3: IB bias
0 0 ° 0 0
Plant Status Start Elements IN Derived Magn Zx1: IN bias Zx3: IN bias
0 0 A 0 0
Control Status Trip Elements IN Derived Angle Zx2: IA diff Zx4: IA diff
0 0 ° 0 0
Active Group Time Stamp I1 Magnitude Zx2: IB diff Zx4: IB diff

0 0 A 0 0
CB Trip/Close Fault Alarms I2 Magnitude Zx2: IC diff Zx4: IC diff

No Operation 0 0 A Group 1 0
Software Ref. 1 Alarm Status System Frequency Select Report I0 Magnitude Zx2: IN diff Zx4: IN diff
0 0 0 A 0 0
Opto I/P Status Access Level Relay Trip Time Report Text Frequency Zx2: IA bias Zx4: IA bias
2 0 0 0 Hz 0 0
Relay O/P Status Password Control IA Type Zx2: IB bias Zx4: IB bias
0 2 0 0 0 0
Password Level 1 IB Data Zx2: IC bias Zx4: IC bias

AAAA 0 0 0 0
Password Level 2 IC Reset Indication Zx2: IN bias Zx4: IN bias

AAAA 0 No 0 0
abcd
MiCOM P740 Page 4
CONFIGURATION CT AND VT RATIOS RECORD CONTROL DISTURB RECORDER MEASUR'T SETUP COMMISSION TEST OPTOS SETUP
Restore Defaults Phase CT Primary Clear Events Duration Default Display Opto I/P Status Global Level
No Operation 1000 No 1.5 s 0 0 2
Setting Group Phase CT Sec'y Clear Faults Trigger Position Local Values Relay O/P Status Opto Input 1
Select via Menu 1 No 33.3 % Secondary 0 2
Active Settings CT Class Clear Maint Trigger Mode Remote Values Test Port Status Opto Input 2
Group 1 X No Single Primary 0 0
Save Changes RBPh / RBN Analog Channel 1 LED Status

No Operation 1 IA 0
Copy From Power Parameters Analog Channel 2 Monitor Bit 1 Opto Input 24
Group 1 0 IB Relay 1 2
Copy to Standard Input Analog Channel 3

No Operation British IC
Setting Group 1 Knee Voltage Vk Analog Channel 4 Monitor Bit 8

Enabled 250 IN Relay 8
Setting Group 2 Rated Burden VA Analog Channel 5 Test Mode

Disabled 25 Unused Disabled
Setting Group 3 Rated Burden Ohm Analog Channel 6 Test Pattern

Disabled 25 / I1^2 Unused 0
Setting Group 4 KSCC Analog Channel 7 Contact Test

Disabled 2 Unused No operation
BB Trip Confirm RCT Sec'y Analog Channel 8 Test LEDs

Enabled 0.5 No Trigger No Operation
Optos Setup CT & VT Ratios Eff. Burden Ohm Digital Input 1 Position Pattern
Visible Visible 25 / I1^2 Unused 0
Overcurrent Prot Recorder Control Eff. Burden VA Input 1 Trigger Position Test
Disabled Visible 25 No Trigger No Operation
Earth Fault Prot Disturb Recorder DDB 0-31

Disabled Visible 0
CB Fail & I< Measure't Setup Digital Input 32

Disabled Visible Unused
Input Labels Commission Tests Input 32 Trigger DDB element 480-511

Visible Enabled No Trigger 0
Output Labels Setting Values

Visible Secondary
abcd
MiCOM P740 Page 5

BACKUP INPUT OUTPUTS Idem
BB TRIP CONFIRM O/C EARTH FAULT CB FAIL SUPERVISION
OVERCURRENT LABELS LABELS GROUP
GROUP1 GROUP1 GROUP1 GROUP1
GROUP1 GROUP1 GROUP1 2,3 & 4
I>BB Current Set I>1 Function IN>1 Function Control by Opto Input 1 Relay 1
I0 SUPERVISION
1,2*I1 Disabled Disabled I< Opto Label 01 Relay Label 01
IN>BB Current I>1 Current Set IN>1 Current Set I< Current Set Error Factor Kce Opto Input 2 Relay 2
0,2*I1 3*I1 3*I1 0,05*I1 40 Opto Label 02 Relay Label 02
I>1 Time Delay IN>1 Time Delay I> Status Alarm Delay Tce
1 1 Disabled 5
I>1 TMS IN>1 TMS I> Current Set Opto Input 24 Relay 21
1 1 1,2*I1 Opto Input 24 Relay Label 21
I>1 Time Dial IN>1 Time Dial IN> Current Set Virtual Relay 01
7 7 0,2*I1 Virtual Relay 01
I>1 Reset Char IN>1 Reset Char

INTERNAL TRIP
DT DT
I>1 tReset IN>1 tReset CB Fail Timer 1 Virtual Relay 16

0 0 0.05 Virtual Relay 16
I>2 Function IN>2 Function CB Fail Timer 2

Disabled Disabled 0.2
I>2 Current Set IN>2 Current Set

EXTERNAL TRIP
20*I1 20*I1
I>2 Time Delay IN>2 Time Delay CB Fail Timer 3

1 1 0.05
CB Fail Timer 4
0.2
Version Compatibility P740/EN VC/D11
MiCOM P740
VERSION COMPATIBILITY
P740/EN VC/D11 Version Compatibility
MiCOM P740
MiCOM P740
Version Compatibility
Relay type: P740
Backward Compatibility
Software Date of S1
Full Description of Changes
Version Issue Compatibility Menu Text
PSL Setting Files
Files
00 02/2003 First release to Production V2.07
Refer to manual P740/EN xx/B11 for software version 00 and hardware version B
01 07/2003 Update of default settings in the four languages V2.07
Refer to manual P740/EN xx/C11 for software version 01 and hardware version B
ABCDP740/EN VC/D11
Page 1/2
P44x/EN VC/D11
ABCD Menu Content Tables
Page 2/2 MiCOM P441, P442 & P444

Publication: P740/EN T/D11
AREVA T&D's Automation & Information Systems Business www.areva-td.com

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Micom P740: Numerical Busbar Protection

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What are the main topics covered in the safety section?

What are the main topics covered in the safety section?

What precautions should be taken when handling electronic modules?

What precautions should be taken when handling electronic modules?

MiCOM P740

Numerical Busbar Protection

1. HANDLING OF ELECTRONIC EQUIPMENT 3

3. INSTALLING, COMMISSIONING AND SERVICING 5

4. EQUIPMENT OPERATING CONDITIONS 6

5. DECOMMISSIONING AND DISPOSAL 7

1. HANDLING OF ELECTRONIC EQUIPMENT

Protective/safety earth * Functional earth terminal*

NOTE: This symbol can also be used for a

*NOTE: The term earth used throughout the product documentation is

3. INSTALLING, COMMISSIONING AND SERVICING

! product documentation should be consulted before installing, commissioning or

4. EQUIPMENT OPERATING CONDITIONS

5. DECOMMISSIONING AND DISPOSAL

Insulation class: IEC 601010-1: 1990/A2: 1995 This equipment requires a

MiCOM P740 Page 1/18

2. INTRODUCTION TO MiCOM GUIDES 4

3. USER INTERFACES AND MENU STRUCTURE 6

3.1.2 Relay rear panel 7

3.2 Introduction to the user interfaces and settings options 10

3.3.2 Peripheral Units settings 12

3.4 Password protection 13

3.6.2 Menu navigation and setting browsing 15

3.6.3 Password entry 15

3.6.4 Reading and clearing of alarm messages and fault records 16

3.6.5 Setting changes 16

3.7 Front communication port user interface 17

Page 2/18 MiCOM P740

MiCOM P740 Page 3/18

MiCOM is a comprehensive solution capable of meeting all electricity supply

Page 4/18 MiCOM P740

2. INTRODUCTION TO MiCOM GUIDES

MiCOM P740 Page 5/18

P740/EN IN Installation (includes a copy of publication P740/EN BR)

P740/EN GC Configuration / Mapping:

Page 6/18 MiCOM P740

3. USER INTERFACES AND MENU STRUCTURE

Serial N° and I*, V Ratings Top cover

FIGURE 1: RELAY FRONT VIEW (example for MiCOM P742 – 40 TE)

MiCOM P740 Page 7/18

Page 8/18 MiCOM P740

ANALOG INPUT MODULE 8 LOGICAL OUTPUTS

Figure 2a: P742 - Relay rear view 40TE case

24 LOGICAL INPUTS 21 LOGICAL OUTPUTS

ANALOG INPUT POWER SUPPLY

Figure 2b: P743 - Relay rear view 60 TE

MiCOM P740 Page 9/18

LOGICAL INPUT CONTACT BOARD

POWER SUPPLY MODULE

OPTIONAL IRIG-B BOARD

Figure 2c: P741 - Relay rear view 80 TE

Page 10/18 MiCOM P740

3.2 Introduction to the user interfaces and settings options

The relay has three user interfaces:

MiCOM P740 Page 11/18