Model REF542plus: Multifunction Protection and Switchgear Control Unit

IT
Protect
Multifunction Protection and Switchgear Control Unit
Model REF542plus
Protection Functions
Configuration and Settings
ABB
Multifunction Protection and Switchgear Control Unit Model REF542plus
Protection Functions: Configuration and Settings
Table of Contents
1 About this manual ............................................................................................13
IT
1.1 Industrial ....................................................................................................13
1.2 REF542plus Network address ....................................................................13
2 Safety Information ............................................................................................13
3 Acronyms and definitions................................................................................14
3.1 Acronyms.....................................................................................................14
3.2 Definitions....................................................................................................14
3.3 Document information ................................................................................14
4 REF542plus analog measurement ..................................................................15
4.1 Measured-value processing .......................................................................15
5 Analog Inputs ...................................................................................................16
5.1 Terminals .....................................................................................................16
5.1.1 Analog Inputs ............................................................................16
5.1.1.1 Analog Board selection................................................................17
5.1.1.2 Current Transformer....................................................................17
5.1.1.3 Current Rogowski........................................................................18
5.1.1.4 Voltage Transformer....................................................................18
5.1.1.4.1 Phase-Voltage Transformer ........................................................19
5.1.1.4.2 Line Voltage Transformer ............................................................20
5.1.1.4.3 Residual Voltage Transformer (open delta) .................................21
5.1.1.5 Voltage Sensor............................................................................22
5.1.2 General constraints...................................................................22
5.1.3 Network characteristics ............................................................23
5.1.4 Calculated values ......................................................................23
6 Control and monitoring....................................................................................24
6.1 Analog Objects ............................................................................................24
6.1.1 Measurement supervision NPS and PPS.................................24
6.1.1.1 Input/Output description ..............................................................24
6.1.1.2 Configuration ...............................................................................25
6.1.1.2.1 General .......................................................................................25
6.1.1.2.2 Sensors .......................................................................................25
6.1.1.2.3 Parameters..................................................................................26
6.1.1.2.4 Events .........................................................................................26
6.1.1.2.5 Pins .............................................................................................27
6.1.1.3 Measurement mode ....................................................................27
6.1.1.4 Operation criteria.........................................................................27
6.1.1.5 Setting groups .............................................................................27
6.1.1.6 Parameters and Events ...............................................................27
6.1.1.6.1 Setting values..............................................................................27
6.1.1.6.2 Events .........................................................................................28
6.1.2 Power Factor Controller............................................................28
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Valid beginning since version V4D02

6.1.2.2 Configuration ...............................................................................30
6.1.2.2.1 General .......................................................................................30
6.1.2.2.2 Capacitor banks ..........................................................................30
6.1.2.2.3 Control Data ................................................................................31
6.1.2.2.4 Time ............................................................................................31
6.1.2.2.5 Events .........................................................................................32
6.1.2.2.6 Pins .............................................................................................32
6.1.2.4 Operating modes and requirements ............................................34
6.1.2.5 Time settings ...............................................................................35
6.1.2.6 Indications ...................................................................................35
6.1.2.7 Automatic power factor controlling...............................................36
6.1.2.8 Setting Example ..........................................................................39
6.1.2.9 Parameter and Events.................................................................40
6.1.2.9.1 Setting values..............................................................................40
6.1.2.9.2 Events .........................................................................................40
7 Protection Functions........................................................................................42
7.1 Current protection functions ......................................................................42
7.1.1 Inrush blocking..........................................................................42
7.1.1.2 Configuration ...............................................................................43
7.1.1.2.1 General .......................................................................................43
7.1.1.2.2 Sensors .......................................................................................43
7.1.1.2.3 Parameters..................................................................................44
7.1.1.2.4 Events .........................................................................................44
7.1.1.2.5 Pins .............................................................................................45
7.1.1.5 Setting groups .............................................................................47
7.1.1.6.1 Setting values..............................................................................47
7.1.1.6.2 Events .........................................................................................47
7.1.2 Inrush Harmonic........................................................................48
7.1.2.2 Configuration ...............................................................................49
7.1.2.2.1 General .......................................................................................49
7.1.2.2.2 Sensors .......................................................................................49
7.1.2.2.3 Parameters..................................................................................50
7.1.2.2.4 Events .........................................................................................50
7.1.2.2.5 Pins .............................................................................................51
7.1.2.5 Steady-state detection.................................................................52
7.1.2.6 Setting groups .............................................................................53
7.1.2.7.1 Setting values..............................................................................53
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7.1.2.7.2 Events .........................................................................................53

7.1.3 Directional overcurrent protection...........................................54
7.1.3.2 Configuration ...............................................................................55
7.1.3.2.1 General .......................................................................................55
7.1.3.2.2 Sensors .......................................................................................55
7.1.3.2.3 Parameters..................................................................................56
7.1.3.2.4 Events .........................................................................................56
7.1.3.2.5 Pins .............................................................................................57
7.1.3.5 Current direction..........................................................................57
7.1.3.6 Voltage memory ..........................................................................58
7.1.3.7 Setting groups .............................................................................58
7.1.3.8.1 Setting values..............................................................................58
7.1.3.8.2 Events .........................................................................................59
7.1.4 Overcurrent Protection .............................................................60
7.1.4.2 Configuration ...............................................................................61
7.1.4.2.1 General .......................................................................................61
7.1.4.2.2 Sensors .......................................................................................61
7.1.4.2.3 Parameters..................................................................................62
7.1.4.2.4 Events .........................................................................................62
7.1.4.2.5 Pins .............................................................................................63
7.1.4.5 Setting groups .............................................................................64
7.1.4.6.1 Setting values..............................................................................64
7.1.4.6.2 Events .........................................................................................64
7.1.5 Overcurrent IDMT ......................................................................65
7.1.5.2 Configuration ...............................................................................66
7.1.5.2.1 General .......................................................................................66
7.1.5.2.2 IDMT Type ..................................................................................66
7.1.5.2.3 Sensors .......................................................................................67
7.1.5.2.4 Parameters..................................................................................67
7.1.5.2.5 Events .........................................................................................68
7.1.5.2.6 Pins .............................................................................................68
7.1.5.5 Setting groups .............................................................................69
7.1.5.6.1 Setting values..............................................................................69
7.1.5.6.2 Events .........................................................................................69
7.1.6 Earth fault protection ................................................................70
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7.1.6.2 Configuration ...............................................................................70

7.1.6.2.1 General .......................................................................................70
7.1.6.2.2 Sensors .......................................................................................71
7.1.6.2.3 Parameters..................................................................................71
7.1.6.2.4 Events .........................................................................................72
7.1.6.2.5 Pins .............................................................................................72
7.1.6.5 Setting groups .............................................................................73
7.1.6.6.1 Setting values..............................................................................73
7.1.6.6.2 Events .........................................................................................73
7.1.7 Directional earth fault protection .............................................74
7.1.7.2 Configuration ...............................................................................75
7.1.7.2.1 General .......................................................................................75
7.1.7.2.2 Sensors .......................................................................................75
7.1.7.2.3 Parameters..................................................................................76
7.1.7.2.4 Events .........................................................................................76
7.1.7.2.5 Pins .............................................................................................77
7.1.7.5 Setting groups .............................................................................79
7.1.7.6.1 Setting values..............................................................................79
7.1.7.6.2 Events .........................................................................................79
7.1.8 Sensitive earth fault protection ................................................80
7.1.8.2 Configuration ...............................................................................81
7.1.8.2.1 General .......................................................................................81
7.1.8.2.2 Sensors .......................................................................................81
7.1.8.2.3 Parameters..................................................................................82
7.1.8.2.4 Events .........................................................................................82
7.1.8.2.5 Pins .............................................................................................83
7.1.8.5 Setting groups .............................................................................85
7.1.8.6.1 Setting values..............................................................................85
7.1.8.6.2 Events .........................................................................................85
7.1.9 Earth fault IDMT.........................................................................86
7.1.9.2 Configuration ...............................................................................87
7.1.9.2.1 General .......................................................................................87
7.1.9.2.2 IDMT Type ..................................................................................87
7.1.9.2.3 Sensors .......................................................................................88
7.1.9.2.4 Parameters..................................................................................88
7.1.9.2.5 Events .........................................................................................89
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7.1.9.2.6 Pins .............................................................................................89

7.1.9.5 Setting groups .............................................................................90
7.1.9.6.1 Setting values..............................................................................90
7.1.9.6.2 Events .........................................................................................90
7.2 Voltage Protection.......................................................................................91
7.2.1 Overvoltage Protection .............................................................91
7.2.1.2 Configuration ...............................................................................92
7.2.1.2.1 General .......................................................................................92
7.2.1.2.2 Sensors .......................................................................................92
7.2.1.2.3 Parameters..................................................................................93
7.2.1.2.4 Events .........................................................................................93
7.2.1.2.5 Pins .............................................................................................94
7.2.1.5 Setting groups .............................................................................95
7.2.1.6.1 Setting values..............................................................................95
7.2.1.6.2 Events .........................................................................................95
7.2.2 Undervoltage Protection...........................................................96
7.2.2.2 Configuration ...............................................................................97
7.2.2.2.1 General .......................................................................................97
7.2.2.2.2 Sensors .......................................................................................97
7.2.2.2.3 Parameters..................................................................................98
7.2.2.2.4 Events .........................................................................................98
7.2.2.2.5 Pins .............................................................................................99
7.2.2.5 Behavior at low voltage values ..................................................100
7.2.2.6 Setting groups ...........................................................................101
7.2.2.7 Parameters and Events .............................................................101
7.2.2.7.1 Setting values............................................................................101
7.2.2.7.2 Events .......................................................................................101
7.2.3 Residual Overvoltage Protection ...........................................102
7.2.3.1 Input/Output description ............................................................102
7.2.3.2 Configuration .............................................................................103
7.2.3.2.1 General .....................................................................................103
7.2.3.2.2 Sensors .....................................................................................103
7.2.3.2.3 Parameters................................................................................104
7.2.3.2.4 Events .......................................................................................104
7.2.3.2.5 Pins ...........................................................................................105
7.2.3.3 Measurement mode ..................................................................105
7.2.3.4 Operation criteria.......................................................................105
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7.2.3.5 Setting groups ...........................................................................106

7.2.3.6.1 Setting values............................................................................106
7.2.3.6.2 Events .......................................................................................106
7.3 Motor Protection........................................................................................107
7.3.1 Thermal Overload Protection .................................................107
7.3.1.2 Configuration .............................................................................108
7.3.1.2.1 General .....................................................................................108
7.3.1.2.2 Sensors .....................................................................................108
7.3.1.2.3 Parameters................................................................................109
7.3.1.2.4 Events .......................................................................................110
7.3.1.2.5 Pins ...........................................................................................110
7.3.1.4 Operation Criteria ......................................................................111
7.3.1.5 Thermal model ..........................................................................111
7.3.1.6 Thermal memory at power-down ...............................................112
7.3.1.7 Setting groups ...........................................................................113
7.3.1.8.1 Setting values............................................................................113
7.3.1.8.2 Events .......................................................................................113
7.3.2 Motor Start Protection.............................................................114
7.3.2.2 Configuration .............................................................................114
7.3.2.2.1 General .....................................................................................114
7.3.2.2.2 Sensors .....................................................................................115
7.3.2.2.3 Parameters................................................................................115
7.3.2.2.4 Events .......................................................................................116
7.3.2.2.5 Pins ...........................................................................................116
7.3.2.5 Setting groups ...........................................................................117
7.3.2.6.1 Setting values............................................................................117
7.3.2.6.2 Events .......................................................................................117
7.3.3 Blocking Rotor.........................................................................118
7.3.3.2 Configuration .............................................................................119
7.3.3.2.1 General .....................................................................................119
7.3.3.2.2 Sensors .....................................................................................119
7.3.3.2.3 Parameters................................................................................120
7.3.3.2.4 Events .......................................................................................120
7.3.3.2.5 Pins ...........................................................................................121
7.3.3.5 Setting groups ...........................................................................122
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7.3.3.6.1 Setting values............................................................................122

7.3.3.6.2 Events .......................................................................................122
7.3.4 Number of Starts .....................................................................123
7.3.4.2 Configuration .............................................................................124
7.3.4.2.1 General .....................................................................................124
7.3.4.2.2 Parameters................................................................................124
7.3.4.2.3 Events .......................................................................................125
7.3.4.2.4 Pins ...........................................................................................125
7.3.4.5 Setting groups ...........................................................................126
7.3.4.6.1 Setting values............................................................................126
7.3.4.6.2 Events .......................................................................................126
7.4 Distance Protection...................................................................................127
7.4.1 Distance Protection.................................................................127
7.4.1.2 Configuration .............................................................................128
7.4.1.2.1 General .....................................................................................128
7.4.1.2.2 Start Values...............................................................................128
7.4.1.2.3 Zones ........................................................................................129
7.4.1.2.4 Phase selection .........................................................................133
7.4.1.2.5 Parameters Earth factors...........................................................133
7.4.1.2.6 Events .......................................................................................134
7.4.1.3 Operation Mode.........................................................................134
7.4.1.3.1 Start ..........................................................................................135
7.4.1.3.2 Phase selection .........................................................................138
7.4.1.3.3 Calculation of the impedance ....................................................138
7.4.1.3.4 Directional voltage memory .......................................................140
7.4.1.3.5 Tripping logic .............................................................................140
7.4.1.3.6 Adaptation to Autoreclosure ......................................................141
7.4.1.3.7 Signal comparison scheme .......................................................143
7.4.1.3.8 Switching onto faults .................................................................145
7.4.1.4 Switchover to Emergency Overcurrent Protection .....................145
7.4.1.5 Setting the Impedance Zone .....................................................145
7.4.1.6 Setting groups ...........................................................................147
7.4.1.7.1 General parameter ....................................................................147
7.4.1.7.2 Start values ...............................................................................147
7.4.1.7.3 Choose zone .............................................................................148
7.4.1.7.4 Zone 1, 2, 3, Zone Overreach, Autoreclose (border) .................148
7.4.1.7.5 Drectional backup......................................................................148
7.4.1.7.6 Non-directional backup..............................................................148
7.4.1.7.7 Phase selection .........................................................................148
7.4.1.7.8 Earth factor................................................................................149
7.4.1.7.9 Events .......................................................................................149
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7.5 Differential protection ...............................................................................150

7.5.1 Transformer Differential Protection .......................................150
7.5.1.2 Configuration .............................................................................151
7.5.1.2.1 General .....................................................................................151
7.5.1.2.2 Sensors .....................................................................................151
7.5.1.2.3 Transformer...............................................................................152
7.5.1.2.4 Current ......................................................................................152
7.5.1.2.5 Harmonics .................................................................................153
7.5.1.2.6 Events .......................................................................................154
7.5.1.2.7 Pins ...........................................................................................154
7.5.1.5 Transformer ratio compensation................................................156
7.5.1.6 Vector group adaptation ............................................................156
7.5.1.7 Tripping characteristic ...............................................................160
7.5.1.8 Inrush stabilization.....................................................................161
7.5.1.9 Setting groups ...........................................................................161
7.5.1.10.1 Setting values............................................................................162
7.5.1.10.2 Events .......................................................................................162
7.5.2 Restricted Differential Protection...........................................163
7.5.2.2 Configuration .............................................................................164
7.5.2.2.1 General .....................................................................................164
7.5.2.2.2 Sensors .....................................................................................164
7.5.2.2.3 Parameters................................................................................166
7.5.2.2.4 Events .......................................................................................166
7.5.2.2.5 Pins ...........................................................................................167
7.5.2.5 Tripping characteristic ...............................................................168
7.5.2.6 Directional Criterion for stabilization against CT saturation........169
7.5.2.7 Setting groups ...........................................................................171
7.5.2.8.1 Setting values............................................................................171
7.5.2.8.2 Events .......................................................................................171
7.6 Other Protections ......................................................................................172
7.6.1 Unbalanced Load Protection ..................................................172
7.6.1.2 Configuration .............................................................................173
7.6.1.2.1 General .....................................................................................173
7.6.1.2.2 Sensors .....................................................................................173
7.6.1.2.3 Parameters................................................................................174
7.6.1.2.4 Events .......................................................................................174
7.6.1.2.5 Pins ...........................................................................................175
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7.6.1.4.1 Thermal memory .......................................................................176
7.6.1.5 Setting groups ...........................................................................176
7.6.1.6.1 Setting values............................................................................176
7.6.1.6.2 Events .......................................................................................176
7.6.2 Directional Power Protection..................................................177
7.6.2.2 Configuration .............................................................................177
7.6.2.2.1 General .....................................................................................177
7.6.2.2.2 Parameters................................................................................178
7.6.2.2.3 Events .......................................................................................178
7.6.2.2.4 Pins ...........................................................................................179
7.6.2.5 Setting groups ...........................................................................180
7.6.2.6.1 Setting values............................................................................180
7.6.2.6.2 Events .......................................................................................180
7.6.3 Low Load Protection ...............................................................181
7.6.3.2 Configuration .............................................................................181
7.6.3.2.1 General .....................................................................................181
7.6.3.2.2 Sensors .....................................................................................182
7.6.3.2.3 Parameters................................................................................182
7.6.3.2.4 Events .......................................................................................183
7.6.3.2.5 Pins ...........................................................................................183
7.6.3.5 Setting groups ...........................................................................184
7.6.3.6.1 Setting values............................................................................184
7.6.3.6.2 Events .......................................................................................184
7.6.4 Frequency supervision ...........................................................185
7.6.4.2 Configuration .............................................................................186
7.6.4.2.1 General .....................................................................................186
7.6.4.2.2 Sensors .....................................................................................186
7.6.4.2.3 Parameters................................................................................186
7.6.4.2.4 Events .......................................................................................187
7.6.4.2.5 Pins ...........................................................................................187
7.6.4.5 Setting groups ...........................................................................188
7.6.4.6.1 Setting values............................................................................188
7.6.4.6.2 Events .......................................................................................188
7.6.5 Synchronism check ................................................................189
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7.6.5.2 Configuration .............................................................................190
7.6.5.2.1 General .....................................................................................190
7.6.5.2.2 Sensors .....................................................................................190
7.6.5.2.3 Parameters................................................................................191
7.6.5.2.4 Events .......................................................................................192
7.6.5.2.5 Pins ...........................................................................................192
7.6.5.5 Setting groups ...........................................................................193
7.6.5.6.1 Setting values............................................................................193
7.6.5.6.2 193
7.6.5.6.3 Events .......................................................................................194
7.6.6 Switching Resonance Protection...........................................194
7.6.6.2 Configuration .............................................................................195
7.6.6.2.1 General .....................................................................................195
7.6.6.2.2 Sensors .....................................................................................195
7.6.6.2.3 Parameters................................................................................196
7.6.6.2.4 Events .......................................................................................196
7.6.6.2.5 Pins ...........................................................................................197
7.6.6.5 Setting groups ...........................................................................198
7.6.6.6.1 Setting values............................................................................198
7.6.6.6.2 Events .......................................................................................198
7.6.7 High Harmonic Protection ......................................................199
7.6.7.2 Configuration .............................................................................199
7.6.7.2.1 General .....................................................................................199
7.6.7.2.2 Sensors .....................................................................................200
7.6.7.2.3 Parameters................................................................................200
7.6.7.2.4 Events .......................................................................................201
7.6.7.2.5 Pins ...........................................................................................201
7.6.7.5 Setting groups ...........................................................................202
7.6.7.6.1 Setting values............................................................................202
7.6.7.6.2 Events .......................................................................................202
7.6.8 Frequency Protection..............................................................202
7.6.8.2 Configuration .............................................................................203
7.6.8.2.1 General .....................................................................................203
7.6.8.2.2 Trip Logic ..................................................................................204
7.6.8.2.3 Sensors .....................................................................................204
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7.6.8.2.4 Parameters................................................................................205
7.6.8.2.5 Events .......................................................................................205
7.6.8.2.6 Pins ...........................................................................................206
7.6.8.5 Setting groups ...........................................................................208
7.6.8.6.1 Setting values............................................................................208
7.6.8.6.2 Events .......................................................................................208
7.7 Autoreclose................................................................................................209
7.7.1 Autoreclose .............................................................................209
7.7.1.2 Configuration .............................................................................210
7.7.1.2.1 General .....................................................................................210
7.7.1.2.2 Parameters................................................................................210
7.7.1.2.3 Events .......................................................................................211
7.7.1.2.4 Pins ...........................................................................................212
7.7.1.3 Operation Mode.........................................................................212
7.7.1.3.1 Start and Trip Controlled ...........................................................212
7.7.1.3.2 Start Controlled .........................................................................212
7.7.1.4 Setting groups ...........................................................................215
7.7.1.5.1 Setting values............................................................................216
7.7.1.5.2 Events .......................................................................................216
7.8 Fault recorder ............................................................................................218
7.8.1 Fault recorder ..........................................................................218
7.8.1.2 Configuration .............................................................................219
7.8.1.2.1 General and setting parameters ................................................219
7.8.1.2.2 Pins ...........................................................................................219
7.8.1.3 Operation ..................................................................................220
7.8.1.4.1 Setting values............................................................................221
7.9 Appendix A – Connection Diagram..........................................................222
7.9.1 Directional protections Connection Diagram........................222
7.9.2 Differential and Restricted differential protections Connection
Diagram....................................................................................224
7.9.3 Synchro Check Connection Diagram.....................................225
7.10 Appendix B –IDMT Protection Curve Characteristics.............................226
7.10.1 IDMT Protection Functions.....................................................226
7.10.1.1 Overcurrent IDMT......................................................................226
7.10.1.2 Earth fault IDMT ........................................................................226
7.10.1.3 Operating time calculation .........................................................227
7.11 Appendix C: Product Information ............................................................233
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1 About this manual

This manual describes how to use the protection functions available in the
REF542plus.
This manual is addressed to engineering personnel and to anyone who needs to
configure the REF542plus.
1.1 IndustrialIT
IT
This product has been tested and certified as Industrial Enabled. All product infor-
mation is supplied in interactive electronic format, compatible with ABB Aspect Ob-
IT
jectTM technology. The Industrial commitment from ABB ensures that every enter-
prise building block is equipped with the integral tools necessary to install, operate,
and maintain efficiently throughout the product lifecycle.
IT
Detailed information on Industrial is available at <http://www.abb.com/industrialit>.
1.2 REF542plus Network address

The network address can be found in "Field bus address" parameter in the
“General tab” dialog window of every protection module.
The SPA registers reference is reported in the "REF542 plus network address.xls",
version V4D02 table.
2 Safety Information
There are safety warnings and notes in the following text. They are in a different for-
mat to distinguish them from normal text.
Safety warning
The safety warnings should always be observed. Non-observance can result in death,
personal injury or substantial damages to property. Guarantee claims might not be
accepted when safety warnings are not respected. They look like below:
Do not make any changes to the REF542plus configuration unless you are fa-
Warning! miliar with the REF542plus and its Operating Tool. This might result in disoper-
ation and loss of warranty.
Note
A note contains additional information worth noting in the specific context, and looks
like below:
The selection of this control mode requires caution, because operations are allowed
Note both from the HMI and remotely.
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3 Acronyms and definitions

3.1 Acronyms
CT Current Transformer
PFC Power Factor Controller
HMI Panel (Remote) Human Machine Interface
ROA Relay Operating angle
VT Voltage Transformer
3.2 Definitions
Active signal A signal is active when high, e.g. “1”
Inactive signal A signal is inactive when low, e.g.”0”
3.3 Document information

Revision History
Version Date Comment
1VTA0002 15.07.2003 1st release, valid since SW V4C01

nd
1VTA10002 Rev02 10.12.2003 2 release, valid since SW V4D02
Applicability
This manual is applicable to REF542plus Release 2.0, software version V4D02.
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4 REF542plus analog measurement

4.1 Measured-value processing
The eight available Analog Input channel measures are acquired and processed ac-
cording to the following flowchart:
AA LP Filter HP Filter ADC

(2.2 KHz) (0,720 Hz) 19.2KHz
LP1 Filter
(1.5 KHz)
Down sampling
4.8 KHz
LP2 Filter LP3 Filter

(380 Hz) 8th order IIR (100 Hz) 3th order IIR
DFT / RMS & Math
Protection & Control

The analog signal entering the Analog Input board goes through two hardware filters
to reduce noise and is then sampled and converted to digital information by a sigma-
delta Analog/Digital converter with an acquisition rate of 19.2kHz.
The acquisition is performed in parallel on all 8 analogue channels, so the data sam-
ples of the network currents and voltages are contemporary (i.e. no phase shift/time
delay is introduced between network quantities).
The digital data is then processed by a digital filter LP1 to reduce the information
bandwidth to 1,5 kHz.
This information is then provided directly to the DFT/ RMS and Math block, perform-
ing the Discrete Fourier Transformation and RMS value analysis for the protection
working on the full RMS harmonic content up to the 25th harmonic (Switching Reso-
nance, High Harmonic) and to the Frequency protection for higher discrimination of
zero crossing.
For all the other protection function the digital data are down sampled (.i.e. one sam-
ple each 4 is used to 4800 samples/s , maintaining the same information bandwidth).
This signal is furthermore digitally filtered by LP2 and LP3 (HSTS function analogue
quantities only) and provided to the DFT/ RMS and Math block, performing the Dis-
crete Fourier Transformation and RMS value analysis.
All protection functions are based on the RMS value at the network rated frequency.
In addition the following functions utilize:
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Overcurrent instantaneous:
The function the peak value of the measured current under transient condition
for a faster response: when the instantaneous peak value is higher then three times
SQRT (2) the RMS value, ( I x _ peak 2 > 3 ⋅ I x _ RMS ).
Inrush Harmonic:
The function evaluates the ratio between current values at 2nd harmonic and at
fundamental frequency.
Differential Protection:
The function evaluates the measured amount of differential current at the fun-
damental, 2nd and 5th harmonic frequencies.
5 Analog Inputs
The Analog Inputs dialog windows allow the user to configure:
analog input channels
network characteristics (REF542plus can handle currents/voltages from
two different networks)
calculated values (power, THD, mean and maximum current values over
the desired time interval)
5.1 Terminals
5.1.1 Analog Inputs
To ease the input of analog input channels, the user can push the button labeled “Get
group data” in Inputs tab of Analog Inputs dialog and then select the used board from
the list. This automatically configures used analog input channels to the proper sen-
sor type and sets default values for each sensor type.
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5.1.1.1 Analog Board selection
To complete the configuration of each analog input channel (e.g. setting the appropri-
ate Rated Primary and Secondary Values) the user must double-click on the line in
Inputs tab of Analog Inputs dialog.
5.1.1.2 Current Transformer
Board Input Rated Value (IRV) at present can be 0.2, 1 or 5 A only (depending on the
type of CT mounted on Analog Input Board).
In case of mismatch between Rated Secondary Value (RSV) and Board Input Rated
Value, REF542plus automatically compensates protection function thresholds.
Default direction of the polarity for the CT is “Line”. If “Bus” is selected, the polarity of
analog signal will be inverted to preserve directions in directional protections. Ampli-
tude and phase corrections can be introduced.
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5.1.1.3 Current Rogowski
Board Input Rated Value (IRV) at present can be only 0.150 V (depending on the
Rogowski sensor input on Analog Input Board)
Value, REF542plus automatically compensates protection function thresholds.
Default direction for the polarity of the Rogowski current sensors is “Line”. If “Bus” is
selected, the polarity of analog signal will be inverted to preserve directions in direc-
tional protections. Amplitude and phase corrections can be introduced.
5.1.1.4 Voltage Transformer

Voltage Transformers can be phase, line or residual (open delta) voltage transform-
ers.
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5.1.1.4.1 Phase-Voltage Transformer
Phase-voltage transformers normally refer rated phase-voltage at primary sidewith

20kV 100V
rated phase voltage on the secondary side, e.g. : . This is shown below
3 3
RSV line in “Transformer ratio” dialog window. When entering VT rated voltage data,
it is therefore not necessary to perform division by 3.
Board Input Rated Value (IRV) at present can be100 V only (depending on the input
transformer mounted on Analog Input Board)
Value, REF542plus automatically compensates protection function thresholds. If “In-
vert phase” is selected, the polarity of analog signal will be inverted. Amplitude and
phase corrections can be introduced.
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5.1.1.4.2 Line Voltage Transformer
Line voltage transformers normally refer rated line voltage at primary side with rated
voltage on secondary side, e.g. 20kV : 100V . This is shown below RSV line in
“Transformer ratio” dialog window.
Board Input Rated Value (IRV) at present can be 100 V only (depending on the input
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5.1.1.4.3 Residual Voltage Transformer (open delta)
Residual voltage transformers normally refer rated phase-voltage at the primary side
with secondary side rated voltage of each winding in the open delta, e.g.
20kV 100
: . This is shown below RSV line in “Transform ratio” dialog window.
3 3
When entering VT rated voltage data, it is not necessary for the user to perform any
division. Simply, the user must select in “VT type” dialog window the corresponding
secondary winding denominator.
Board Input Rated Value (IRV) at present can be 100 V only (depending on the input
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5.1.1.5 Voltage Sensor
Voltage sensors can be connected as phase-voltage only, but the Rated Primary
Value (RPV) to be insertedis the rated line (phase to phase) voltage at primary side
When entering the sensor rated voltage data, it is therefore not necessary to perform
division by 3.
Board Input Rated Value (IRV) at present can be 2 V only (depending on the voltage
sensor input on Analog Input Board)
5.1.2 General constraints

• Channels 1-6 can be used only for phase currents, phase voltages or line volt-
ages
• Channels 7 and 8 can be used also either for earth currents or residual volt-
ages
• Current and voltage sensors inside the triples 1-3 and 4-6 must have the same
characteristics (RPV, RSV and IRV)
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5.1.3 Network characteristics
REF542plus can handle two different networks or network parts having the same fre-
quency. By default only one network is used.
If the second network is needed it must be enabled in Networks tab of Analog Inputs
dialog window.
For each network the Rated Nominal Voltage and Current can be configured. These
values are used by HMI led bars to scale displayed quantities.
5.1.4 Calculated values
The preferred reference system (i.e. load or generator) and some calculations can be
enabled in REF542plus:
Power (either three-phase or Aaron)
Mean and maximum current values
Total Harmonic Distortion (on voltage sensors only)
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6 Control and monitoring

6.1 Analog Objects
6.1.1 Measurement supervision NPS and PPS
The REF542plus provides two types of measurement supervision functions. Each of
them can be independently activated:
Positive Phase Sequence (PPS)
Negative Phase Sequence (NPS)
6.1.1.1 Input/Output description

Input
Name Type Description
BS Digital signal (active high) Blocking signal
When BS signal becomes active, the measurement supervision function is reset (no
matter its state), i.e. all output pins go low generating the required events (if any) and
all internal registers and timers are cleared. The protection function will then remain in
idle state until BS signal goes low.
Output
Warning Digital signal (active high) Warning signal
Failing Digital signal (active high) Failing signal
Warning is the start signal. Warning signal will be activated when the start conditions
are true (negative phase sequence value exceeds the setting threshold value for
NPS; positive phase sequence value falls below the setting threshold value for PPS).
Failing signal will be activated when the start conditions are true and the operating
time has elapsed.
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6.1.1.2 Configuration
6.1.1.2.1 General
6.1.1.2.2 Sensors
The measurement supervision functions operate on all sensors in a triple (analog

channels 1-3 or 4-6 can be used to supervise phase currents, phase voltages or line
voltages).
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6.1.1.2.3 Parameters
Start Value: Positive/Negative phase sequence threshold for Start condition

detection.
Time: Time delay for Trip condition detection.
6.1.1.2.4 Events
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6.1.1.2.5 Pins
6.1.1.3 Measurement mode

Measurement supervision functions evaluate the measured amount of positive and
negative phase sequence values at the fundamental frequency.
6.1.1.4 Operation criteria

If the negative phase sequence value exceeds the setting threshold value (Start
value) (in the NPS-based functions), or if the positive phase sequence value falls
below the setting threshold (Start value) the function enters the START status
and raises the warning. After the preset operating time (Time delay)has elapsed,
the failing signal is generated.
The measurement function will come back in passive status and the warning signal
will be cleared if the negative phase sequence value falls below 0.95 the setting
threshold value for NPS or if the positive phase sequence value exceed 1.05 the set-
ting threshold value for PPS.
The measurement function will exit the Failing status and the failing signal will be
cleared when the negative phase sequence value falls below 0.4 the setting threshold
value for NPS or if the positive phase sequence value exceed 1.05 the setting thresh-
old value for PPS.
6.1.1.5 Setting groups

Two parameter sets can be configured for each of the measurement supervision func-
tions.
6.1.1.6 Parameters and Events
6.1.1.6.1 Setting values

Parameter Values Unit Default Explanation
Start value (PPS) 0.30 .. 0.90 In/Un 0.85 PPS threshold to undergo.
Time delay 30 .. 30000 ms 1000 Time delay from start condition (warning signal)
to failing signal.
Start value (NPS) 0.05 .. 0.40 In/Un 0.10 NPS threshold to be exceeded.
Time delay 30 .. 30000 ms 1000 Time delay from start condition to failing signal.
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6.1.1.6.2 Events
Code Event reason
E0 Warning signal is active
E1 Warning signal cancelled.
E6 Failing signal is active
E7 Failing signal is back to inactive state
E18 Function block signal is active
E19 Function block signal is back to inactive state
By default all events are disabled.
6.1.2 Power Factor Controller

The power factor controller is a control function in the REF542plus. Due to the com-
plex setting parameter, this function is also described in this protection part.
The power factor controller is designed to control reactive power compensation in
power systems. The magnitude of the reactive power in the network is derived from
the measured power factor. Consequently the power factor controller permanently
monitors the power factor, which is defined as the ratio of the effective power to the
active power. The PFC then controls the switching ON/OFF of the available capaci-
tors banks to reach the set power factor target.

Input
BL Digital signal (active high) Blocking signal
DISCONNECT Digital signal (active high) Disconnect all capacitor banks
RESET Digital signal (active high) Reset the function
OVERTEMP. Digital signal (active high) Overtemperature
VMIN / VMAX Digital signal (active high) Voltage out of range
VA MAX Digital signal (active high) Overload due to overvoltage
MODE: MAN. Digital signal (active high) Mode manual
SET NIGHT Digital signal (active high) Set night parameter
MANUAL CON- Digital signal (active high) Switch bank 0 manually
TROL BANK 0
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TROL BANK 0
TROL BANK 1
TROL BANK 2
TROL BANK 3
CHECKED Digital signal (active high) Status on indication bank 0
BACK BANK 0
BACK BANK 1
BACK BANK 2
BACK BANK 3
When BS signal becomes active, the protection function is reset (no matter its state),
i.e. all output pins go low generating the required events (if any) and all internal regis-
ters and timers are cleared. The protection function will then remain in idle state until
BS signal goes low.
Output
Q ALARM Digital signal (active high) Alarm indication Q
COS ϕ ALARM Digital signal (active high) Alarm indication cos ϕ
OPERAT. ALARM Digital signal (active high) Operation Alarm (reset only by power off)
GENERAL ALARM Digital signal (active high) General alarm
SWITCH ON/OFF Digital signal (active high) Bank 0 on (high), off (low)
BANK 0
BANK 1
BANK 2
BANK 3
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6.1.2.2.1 General
6.1.2.2.2 Capacitor banks
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6.1.2.2.3 Control Data
6.1.2.2.4 Time
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6.1.2.2.5 Events
6.1.2.2.6 Pins

When a reactive power consumer is switched into the network, the current variable
increases. Simultaneously the phase displacement increases in relation to the related
voltage quantity. As a result, the reactive power increases and the power factor is re-
duced correspondingly. Because of the increase in the current measured quantity and
the angle of the phase displacement, an increased voltage drop in the power system
must be taking into account.
The following figure shows the reason of the increased voltage drop. The section on
the left shows the single line diagram of the power system. In this case U 1 is the
source voltage, which is assumed to be constant, U 2 is the voltage in the network
with a motor, that requires as well as the active power as also the reactive power. To
simplify the explanation, the transformation ratio of the transformer is assumed to be
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1. The center of the diagram shows the case where only pure active power is con-
sumed. The current and voltage quantities are in phase. As shown in the vector dia-
gram, the amplitude of the voltage U 2 is virtually uninfluenced by this. However, if
additional inductive reactive power is used, as shown in the vector diagram on the
right, the amplitude of the voltage U 2 in the network can be substantially reduced.
U1 U2 U1
U1
U2
U2
I I
Figure 1: Increase in voltage drop resulting from inductive reactive power
To maintain the voltage drop within a certain limits in the event of a high consumption
of reactive power, capacitors must be used for compensation. The power factor con-
troller function is implemented in the REF542plus, that offers the option of regulating
the demand for capacitive reactive power to compensate the inductive reactive power
in medium voltage system by switching of the required capacitor banks optimally.
If a power factor control function is applied, it is recommended to provide the

Warning! resonance protection function, switching resonance protection and high har-
monic resonance protection too, in order to protect the capacitor banks against
overloading by the possible appearance of harmonics.
The principle of compensation of the reactive power is explained in Figure 2. P is the

active power and Q the reactive power. As in the vector diagram in the previous illus-
tration, the active power P is shown on the vertical axis and the reactive power Q on
the horizontal axis. The power factor cos ϕ1 , which is shown as a straight line in the
diagram, shows the relationship between the active power P1 and the apparent
power S1. The apparent power S1 is again dependent on the magnitude of the con-
sumed reactive power Q1 . This enables the consumption of reactive power to be
compensated with the aid of the measured power factor so that the voltage drop in
the network always remains within the allowable tolerance limits.
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Q1 S1
ϕ1
P
P1
Figure 2: Reactive power diagram
The capacitor output required to compensate the reactive power consumption can be
determined as shown in the power diagram in the Figure 3. In this case cos ϕ1 is the
setting value for limitation of the power factor, which is generally referred to as the re-
versal point in the power factor controlling. The resulting apparent power is S1 , active
power P1 and reactive power Q1. Furthermore, S2 is the actual apparent power, P2
the actual active power and Q2 the actual reactive power in the power system.
Q2 S2
Q1 S1
ϕ1
P
P1 = P2
Figure 3: Determining the capacitor output for compensation
To determine the required capacitor output, the active power P1 at the reversal point
or at the set power factor cos ϕ1 is set to be equal to the instantaneous active power
P2. The associated or the allowable reactive power Q1 can then be calculated with
the following equation:
1 − cos 2 ϕ1
Q1 =
cos ϕ1
The reactive power ∆Q that must be compensated is calculated from the difference of
the instantaneous and the allowable reactive power.
As a result, the value of the capacitance for the capacitor banks that are to be
switched on or off to compensate for the reactive power can be determined.
6.1.2.4 Operating modes and requirements

The power factor controller has the following operating modes:
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Manual
Automatic
During manual operation every individual capacitor bank can be switched on or off via
the inputs provided for the purpose. This requires the signals for switching on and off
to be pulse-type signals.
If a capacitor bank is switched on, a logical signal 1 will show at the associated out-
put. When it is switched off, the output will show a logical signal 0.
To ensure that the controller is always informed of the switch status of the capacitor
banks, checked confirmations of the switch settings must be fed back via the binary
inputs (checked back inputs, bank 0-3).
The reactive power compensation should normally only be required when the power
system is in operational status. Therefore, the power factor controller's activities are
made dependent on the voltage status of the power system. For this reason the
power factor controller shall always includes the overvoltage (U>>) function and the
undervoltage (U<<) function for monitoring the voltage status in the system. If one of
the set voltage limits, either overvoltage or undervoltage, is exceeded and the associ-
ated time delay has expired, all active capacitor banks are immediately switched off.
This function is independent of whether the power factor controller is in manual or
automatic operating mode. The binary input VMIN/MAX is used for this function.
The binary input DISCONNECT also has the capacity to disconnect all active capaci-
tor banks on receiving the logical signal 1.
6.1.2.5 Time settings

After the auxiliary voltage supply has been activated, the function of the power factor
controller is first blocked by the initialization period. It is in operation again only after
expiry of this initialization period. The initialization period is also started when the sys-
tem voltage recovers after a system fault, e.g. when the undervoltage protection is re-
set from the operating position, the binary input DISCONNECT is active. Reasonably,
the initialization period should always be set to be greater than the blocking time for
discharging the capacitor banks.
If a capacitor bank is switched on to compensate for reactive power during a control
process, transient phenomena will generally be initiated in the network. Determining
of the power for the power factor control must therefore be delayed until the transient
process has mostly subsided. The dead time required for this must be set in the
power factor controller. Further switching of the capacitor group will only be enabled
when the dead time has expired. However, this requires the capacitor bank in ques-
tion to be already fully discharged.
When a capacitor bank is switched off, the stored electrical energy must first
Warning! be discharged before it shall being switched on again (capacitor discharge
must be provided by internal resistors or by external voltage transformers), to
avoid high inrush current phenomena.
The power factor controller foresees a discharge blocking period set. This ensures
that a capacitor bank has sufficient time to discharge the accumulated power before
being switched on again.
6.1.2.6 Indications
As noted in the previous section, control is started only when the input of reactive
power in the system falls below the power factor cos ϕ set as the reversal point. In
addition, to be able to supervise the input of reactive power in the network continu-
ously, the power factor controller has an additional setting for power factor cos ϕ to
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generate an alarm message (binary output ALARM COS ϕ). It makes sense for the
setting value for cos ϕ alarm to be set to less than the setting value for cos ϕ reversal
point for starting the control process. This enables the cos ϕ warning to be generated
only if the power factor controller cannot switch on a capacitor bank because of oper-
ating conditions.
However, if all capacitor banks are already switched on and the reversal point still has
not been reached, the alarm Q (binary output ALARM Q) will be generated. This sig-
nals that the needed reactive power can no longer be compensated, because all ca-
pacitor banks are already switched on.
In the event of a power system fault, such as when the overvoltage protection or un-
dervoltage protection function is activated (binary input V MIN/V MAX is used for this
function), all switched-on capacitor banks will be switched off. Then the General
Alarm (binary output ALARM GENERAL) is generated.
The power factor controller also has inputs that will generate the General Alarm mes-
sage when they receive a signal. In this case information on Over-temperature (binary
input OVERTEMP.) in the capacitor banks or the upper limit of the operation voltage
U> (binary input V A MAX) on the relevant inputs being exceeded is present. As soon
as the General Alarm is generated, the power factor controller functions are blocked
in the automatic mode. The power factor controller can only be reactivated after this
indication has been reset.
If the general alarm is set, the power factor controller is blocked until a reset is per-
Note formed.
The number of switchgear switching cycles for switching the individual capacitor
banks on or off is monitored and compared with the set value for the switching cycles.
If this value is exceeded, an alarm is sent (binary output ALARM OPERAT.)
Operation Alarm can only be reset by power off.

Note
6.1.2.7 Automatic power factor controlling

In automatic operating mode the power factor and its required reactive power in the
network is continuously monitored. The sign of the difference of the reactive power
∆Q, which is determined from the current and allowed reactive power, enables the
capacitor banks to be switched on or off with reference to compensation for the reac-
tive power. If the sign is positive, a capacitor bank must be switched on. In the event
of a negative sign, an appropriate bank must be switched off.
To switch on a capacitor bank, a reactive power must first be defined as the activating
threshold QON . The activating threshold here must be set by multiplying an adjustable
factor KON in percent by the smallest installed reactive power of a capacitor bank QCO.
QON = K ON QC0
Then capacitor bank 0 (C0) is set as the smallest bank. The controller is enabled for
the reversal point set as power factor cos ϕ as soon as the relationship between the
compensating reactive power ∆Q in the network and the smallest installed capacitor
output QC0 is greater than the set activating threshold QON in percent. This is shown
by the following equation:
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 ∆Q K 
 − ON  > 0
 QC0 100% 
The number NON (QCO) of the capacitor banks to be switched on can be determined
with the following relationship:
 ∆Q K 
N ON (QC 0 ) =  − ON  + 1
 QC0 100% 
Once a capacitor bank is switched on, a set dead time sequence starts. It should be
delayed until the transient processes in the network have somewhat subsided. Power
calculation will only be resumed after expiry of this dead time and only then a control
process will be permitted to start again.
However, if the inductive reactive power decreases, the current power factor cos ϕ in
the network may become capacitive. In this case, the reactive power ∆Q, which is
generated from the difference between the current and the resulting reactive power
corresponding to the reversal point, will naturally have a negative sign. This capaci-
tive state is also not desirable for system operation, because in these circumstances
overvoltages could be expected in the system. As a result, in this case at least one
capacitor bank must be switched off. A criterion for the switch-off threshold must also
be defined, similar to that above for switching on.
QOFF = (K OFF − K ON ) QC0

In this case QOFF is the switch-off threshold defined here to switch off the capacitor
bank, KOFF is the so called neutral zone in percent (hysterisis) that can be set on the
power factor controller, KON is the adjustable factor for the activating threshold in per-
cent and QC0 is again the smallest installed power of a capacitor bank. But please
note, that the condition has to be fulfilled:
(K OFF − K ON ) > 1
Otherwise the capacitor bank will always be switch on and off all the time.
The power factor controller will enable the control for switching off the capacitor bank
if the ratio of the negative reactive power difference ∆Q to the smallest installed ca-
pacitor output is greater than the switch-off threshold QOFF in percent. This is shown
by the following equation:
 ∆Q K OFF 
 −  > 0
 QC0 100% 
The number NOFF (QC0) of the capacitor units that are to be switched off can be de-
termined. with the following relationship:
 ∆Q K OFF 
NOFF (QC 0 ) =  −  − 1
 QC0 100% 
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cos ϕ
Figure 4: Configuration of the capacitor banks for reactive power compensation in the network
The figure above shows an example of the configuration of the capacitor banks for
compensating reactive power in a single-line view. Capacitor banks must be switched
on and off depending on the power intake of the inductive consumer, so that the
power factor does not drop below the allowable limit.
The REF542plus bay control and protection unit enables a control process to be run
with a maximum of 4 capacitor banks. The various capacitor banks are referred to as
bank C0, bank C1, bank C2 and bank C3. The individual capacitor banks can be de-
fined separately or differently with the same reactive power. In the case of different
power ratings, bank C0 must be configured with the smallest capacitor output. Then
the recommended power rating based on C0 is listed in the following table.
Table 1: Definition of the capacitor banks
C0 / C0 C1 / C 0 C 2 / C0 C3 / C 0
1 1 1 1
1 1 2 2
1 2 2 2
1 2 4 4
1 2 4 8
If all capacitor banks are defined equally, it is possible to switch them on and off in
accordance with a linear or a circular switching program. With a linear switching pro-
gram the capacitor banks are switched on in ascending order and switched off in de-
scending order of indices. In contrast, with a circular switching program the capacitor
banks are always switched on and off in ascending order.
The capacitor banks are switched on or off in accordance with the calculated number
NON or NOFF . Only the calculated whole number before the decimal point is taken into
account. For example, if it is assumed that the calculated number of capacitor banks
to be switched on is equal to 3 and if the configuration of the capacitor banks is set to
1:2:4:8, the controller first attempts to switch on the next lower bank C1 with 2QC0 . If
it is known from the reconfirmation of the switch that bank C1 is already switched on,
the next smaller bank C0 will be addressed with QC0 . However, if bank C1 is already
switched on, the next free bank, for example bank C2 with capacitor output 4 QC0 ,
will be selected and switched on.
After bank C2 has been switched on, the control function is first blocked for the dura-
tion of the set dead time. The reactive power controller only becomes active again af-
ter expiry of the dead time. Because the switched-on capacitor output is too big in the
event of unchanged network conditions, the power factor controller will have to detect
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that a capacitor bank with power QC0 should be switched off. If the switch-off condi-
tions, which must be determined from the setting of the neutral zone, are met, the
switch-off process for bank C0 will be started. Switching off the capacitor banks is in
principle similar to switching them on.
6.1.2.8 Setting Example

A capacitor banks of each 6.36 µF shall be applied to compensate the reactive power
in 10kV power system. Consequently each capacitor bank is able to compensate a
reactive power of:
QCO = 200 kVAr

which is also equal to the value of the smallest capacitor bank.
If it is required, that one of the capacitor bank shall be switch on at a certain apparent
power, e.g. 250 kVAr and a power factor 0.7. The portion of the reactive power can
be calculated as following:
QON = sin (arc cos 0.7) x 250 kVAr = 178.5 kVAr

Accordingly the pick up value of the power factor controller shall be set to:.
178.5
Pick Up = 100% = 89.2%
200
From the difference of the reactive power the threshold for the setting for the neutral
zone for switching off can be determined.
QOFF = (178.5 − 200) = 21,5 kVAr

∆Q 21,5 kVAr
= 100% = 10,75%
QC0 200 kVAr
One of the same capacitor bank will be switch off again, if the reactive power be-
comes negative. To avoid continuously switching on and off of the capacitor bank, the
setting of the neutral zone has to be higher than the following:
Neutral Zone ≥ (100 + 10.75)% = 110.75%

The setting for the neutral zone is selected to be 115%. Consequently the reactive
power at the switch off moment can be check as following:
Q OFF = − 0.15 × 200 kVAr = - 30 kVAr

The next setting parameter is dedicated for the capacitor banks. As mentioned in the
calculation above, each capacitor bank has a reactive power of 200 kVAr. The banks
are equal to each other and the number is 2. The maximum switching cycles shall be
limited to a number, that is to be confirmed by the manufacturer of the circuit breaker,
e.g. 10,000.
The parameter of the control data give the limitation of control activities. The control-
ler shall be activated, if the power factor is less than 0.7. The switching on of a spe-
cific capacitor banks can only be initiated, if the condition of the pick up value, is ful-
filled.
The time setting has to be adapted to the system operation condition. The discharge
blocking time is the blocking duration of a capacitor bank after it is switched off. After
switching on a capacitor bank the power factor control is deactivated as long as the
dead time is not expired. After a complete switch off of all banks and recovery of the
1VTA10002 Rev02 PTMV, 2003.12.10 39 / 234

power supply for the power factor controller no capacitor banks can be switched on
before the power on delay time is elapsed.
6.1.2.9 Parameter and Events

Neutral zone 105… 200 % QCO 115
Pickup zone 0…100 % QCO 0
Reactive power of 1…20000 kVA 100
smallest QCO
Number of banks 1…4 1
Maximum switch- 1…10000 2500
ing cycles
Set point cos phi 0.7..1.0 Ind/cap 0.9 ind
Limiting value cos 0…1 Ind/cap 0
phi
Discharge blocking 1…7200 s 900
time
Dead Time 1…120 s 10
Power on delay 1…7200 s 900
Duration of integra- 1…7200 s 900
tion
6.1.2.9.2 Events
Code Event reason
E0 Bank 0 on
E1 Bank 1 on
E2 Bank 2 on
E3 Bank 3 on
E4 Bank 0 off
E5 Bank 1 off
E6 Bank 2 off
E7 Bank 3 off
E8 Overtemperature started
E9 Overtemperature back
E10 Va max started
E11 Va max back
E12 Vmin/Vmax started
E13 Vmin/Vmax back
E14 Command DISCONNECT started
E15 Command DISCONNECT back
E16 Cos phi warning started
E17 Cos phi warning back
E18 Alarm Q started
1VTA10002 Rev02 PTMV, 2003.12.10 40 / 234

Code Event reason

E19 Alarm Q back
E20 Warning switching cycle
E21 Alarm reset
E22 Block signal started
E23 Block signal back
E24 Manual operating mode
E25 Automatic operating mode
E26 Night mode
E27 Day mode
1VTA10002 Rev02 PTMV, 2003.12.10 41 / 234

7 Protection Functions
7.1 Current protection functions
7.1.1 Inrush blocking
REF542plus has one inrush blocking protection function. This function is replaced
from the Inrush Harmonic function and it has to be preferred when very fast response
time is required only.
The following current protection functions are blocked by the inrush blocking protec-
tion function without the need of additional wiring in the FUPLA (i.e. the block to the
protection functions is implicit).
Overcurrent instantaneous
Overcurrent high
Overcurrent low
Directional overcurrent high
Directional overcurrent low
IDMT
Earthfault IDMT

Input
BS signal goes low.
Output
S L1 Digital signal (active high) Start signal of IL1
TRIP Digital signal (active high) Trip signal
S L1-3 are the start signals phase selective. The phase starting signal will be acti-
vated when respective phase current start conditions are true and the overcurrent
protection will be implicitly blocked until the operating time (Time) has elapsed.
1VTA10002 Rev02 PTMV, 2003.12.10 42 / 234

The TRIP signal will be activated when the start conditions are true (inrush detection)
the maximum measured current exceeds the threshold (limit N·I>>) an the relevant
overcurrent protection operating time has elapsed.
7.1.1.2.1 General
Output Channel different from 0 means direct execution of the trip command (i.e.
skipping FUPLA cyclic evaluation).
7.1.1.2.2 Sensors
The protection function operates on any combination of current phases in a triple,

e.g., it can operate as single phase, double phase, three-phase protection on phase
currents belonging to the same system.
1VTA10002 Rev02 PTMV, 2003.12.10 43 / 234

N: Threshold I>> multiplier for fault detection and inrush protection trip
M: Threshold I> multiplier for inrush detection
Time: Overcurrent protection blocking Time at inrush detection
7.1.1.2.4 Events
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7.1.1.2.5 Pins

Inrush blocking function evaluates the current at the fundamental frequency.

An inrush is detected if the maximum measured current exceeds the threshold M·I>
within 60 ms after it exceeded 10% of current threshold I>.
Here I> is the threshold (Start value I>) of the overcurrent low protection func-
tion. If this protection function is not installed, the threshold of IDMT protection func-
tion (Base current Ieb:, if installed) is used or a standard value of 0.05·IN (if
IDMT also is not installed).
If an inrush is detected, the above-listed protection functions are blocked until the end
of inrush has been detected or the maximum preset inrush duration (i.e. Time) has
elapsed.
The end of inrush condition is detected when the maximum measured current falls
below M·0.65·I>. A counter is then started and 100 ms later the end of inrush is as-
sumed. The current protection functions are then released from the block.
Note At feeder start-up, with current zero, the implicit block of the overcurrent protection
function is already active. Only as the current increase the inrush condition is evalu-
ated and the block can be released if an inrush is not present.
The inrush blocking itself becomes a protection function, if the maximum measured
current exceeds the limit N·I>> after the inrush detection. The operating time is that of
the overcurrent instantaneous (if installed) or 80 ms.
Here I>> is the threshold (Start value I>>) of the overcurrent high protection
function. If this protection function is not installed, the threshold of overcurrent instan-
taneous protection function (if installed) is used or a standard value of 0.10·IN (if over-
current instantaneous also is not installed).
The following three diagrams are not scaled and are provided solely for a better un-
derstanding of the explanations of how the inrush blocking works.
1VTA10002 Rev02 PTMV, 2003.12.10 45 / 234
Tesb is the operation counter that is compared to the set overcurrent protection block-
ing Time (i.e. Time).
Fig. 5: Inrush is detected within the 60ms window, then the end of inrush condition is
detected and the block released before protection-blocking Time ex-
I [A]
Inrush Tripping Overcurrent
high-set tripping
N I>> Inrush
detected
M I>
I>>
Overcurrent
0.65 M I> low-set tripping
I>
0.1 I>
t
60 ms 100 ms
pires. tESB
Figure 5: Current-time characteristic of the detected inrush process
Fig. 6: Inrush is detected within the 60ms window, then the end of inrush condition is
detected and the block released before protection-blocking Time expires. The current
value is over the I> threshold and that protection function will start timing and trip in
due time.
I [A]
high-set tripping
N I>> Inrush
detected
M I>
I>>
Overcurrent
I>
0.1 I>
t
60 ms 100 ms
tESB
Figure 6: Current-time characteristic of the detected overload
Fig. 7: Inrush is detected within the 60ms window, no end of inrush condition is de-
tected and the protection-blocking Time expires. The current value is over the I>>
threshold and that protection function will start timing and trip in due time.
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I [A]
high-set tripping
N I>> Inrush
detected
M I>
I>>
Overcurrent
I>
0.1 I>
t
60 ms
Blocking time expires
Figure 7: Current-time characteristic of the detected fault

Two parameter sets can be configured for the inrush blocking protection function.

N 2.0 .. 8.0 2.0 Threshold I>> multiplier for fault detection and trip
M 3.0 .. 4.0 3.0 Threshold I> multiplier for inrush detection
Time 200 .. 100000 ms 250 overcurrent protection blocking Time after inrush
detection
7.1.1.6.2 Events
Code Event reason
E0 Start L1 started
E1 Start L1 back
E2 Start L2 started
E3 Start L2 back
E4 Start L3 started
E5 Start L3 back
E6 Trip started
E7 Trip back
E18 Protection block started
E19 Protection block back
1VTA10002 Rev02 PTMV, 2003.12.10 47 / 234

7.1.2 Inrush Harmonic

REF542plus has one Inrush Harmonic function, which can be used to temporarily
block other protection functions.
The following current protection functions are blocked by the Inrush Harmonic protec-
tion function without the need of additional wiring in the FUPLA (i.e. the block to the
protection functions is implicit).
Overcurrent instantaneous
Overcurrent high
Overcurrent low
Directional overcurrent high
Directional overcurrent low
IDMT
Earthfault IDMT

Input
BS signal goes low.
Output
Start Digital signal (active high) Start signal
Start signal can be wired in the FUPLA to signal inrush condition status or to protec-
tion functions BS input pins (different from those listed above and implicitly blocked)
to temporarily block during an inrush transient (i.e. the block to the protection func-
tions is explicit).
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7.1.2.2.1 General
7.1.2.2.2 Sensors
The protection function operates on any set of phase currents in a triple.
1VTA10002 Rev02 PTMV, 2003.12.10 49 / 234

Minimum current threshold: Current threshold for inrush detection.
Fault current threshold: Current threshold for fault detection.
Harmonic ratio threshold: 2nd/fundamental current ratio threshold for in-

rush detection.
7.1.2.2.4 Events
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7.1.2.2.5 Pins

Inrush harmonic protection function evaluates the ratio between current values at 2nd
harmonic and at fundamental frequency.

If for at least one phase current:
the current is not in steady-state condition,
AND the current value at fundamental frequency is above the preset minimum
current threshold (i.e. Min current threshold),
AND the current value is below the preset maximum current threshold (i.e.
Fault current threshold),
AND the Harmonic ratio between current values at 2nd harmonic and at funda-
mental frequency exceeds the preset threshold (i.e. Harmonic ratio
threshold)
then the protection function is started and the start signal will be activated.
The start criteria are illustrated in the following flowchart:
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Min current Thr

0.05 .. 40.00 In
Fundamental
Frequency
Start Fault current Thr

0.05 .. 40.00 In & Start
Steady State
detection
0.95 .. 105%
Second I2H/Fundamental
Harmonics
5% .. 50%
The protection function will remain in START status until at least for one phase the
above conditions (steady state excluded) are true. It will come back in passive status
with a 10ms delay when:
for all the phases at least one condition falls below 0.95 the setting threshold
value (i.e Min Current threshold or Harmonic ratio threshold re-
spectively),
OR at least for one phase the current value exceeds the preset maximum cur-
rent threshold (i.e. Fault current threshold).
7.1.2.5 Steady-state detection

Steady-state condition is detected if:
the current value at fundamental frequency falls below the preset minimum cur-
rent threshold (i.e. Min current threshold) for at least 10ms,
OR the current value at fundamental frequency is between 95% and 105% of

the previous period for at least one period.
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Two parameter sets can be configured for the harmonic inrush protection function.

Minimum current 0.05 .. 40.00 In 0.5 Current threshold for inrush detection, if ex-
threshold ceeded the inrush conditions are evaluated
Fault current 0.05 .. 40.00 In 2
Current threshold for fault detection, if exceeded
threshold
the inrush start is set to low.
Harmonic ratio 5 .. 50 % 10
threshold 2nd/fundamental current ratio threshold for in-
rush detection.
7.1.2.7.2 Events
Code Event reason
E0 Protection has started timing
E1 Timing is cancelled
E18 Protection block signal is active started
E19 Protection block signal is back to inactive state
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7.1.3 Directional overcurrent protection

The REF542plus has two directional definite time functions, each of which can be in-
dependently activated:
Overcurrent directional high set (I>> )
Overcurrent directional low set. (I> )

Input
BS signal goes low.
Outputs
BO Digital signal (active high) Block output signal
vated when respective phase current start conditions are true (current exceeds the
setting threshold value and the fault is in the specified direction).
The TRIP signal will be activated when at least for a phase current the start condi-
tions are true and the operating time has elapsed.
The Block Output (BO) signal becomes active when the protection function detects a
current exceeding the preset value and the fault direction opposite to the specified di-
rection.
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7.1.3.2.1 General
7.1.3.2.2 Sensors
The protection function operates on any combination of current phases in a triple,

The faulty phase current is combined with the voltage of the corresponding sound
phases. The required voltage measure is automatically selected and displayed in the
“General” dialog window.
1VTA10002 Rev02 PTMV, 2003.12.10 55 / 234

Direction: Directional criteria to be assessed together to overcurrent condition

for START detection.
Start Value: Current threshold for overcurrent condition detection.
Time: Time delay for overcurrent Trip condition detection.
(An example the typical connection diagram of current and voltage transformers for a
generic feeder and the convention used to define Forward and Backward direction of
the power flow is provided in the Appendix - Connection Diagram).
7.1.3.2.4 Events
1VTA10002 Rev02 PTMV, 2003.12.10 56 / 234

7.1.3.2.5 Pins

The directional overcurrent protection function evaluates the current and voltage at
the fundamental frequency.

If the measured current exceeds the setting threshold value (Start Value), and the
fault is in the specified direction (backward/forward), the protection function is
started. The start signal is phase selective; i.e. when at least for one phase current
the above conditions are true then the relevant start signal will be activated.
If the preset threshold value (Start Value) is exceeded and the fault is in the op-
posite direction to the specified one, the Block Output signal becomes active. The
protection function will remain in START status until there is at least one phase
started. It will come back in passive status and the start signal will be cleared if for all
the phases the current falls below 0.95 the setting threshold value (or the fault current
changes direction).
After the protection has entered the start status and the preset operating time (Time)
has elapsed, function goes in TRIP status and the trip signal is generated.
The protection function will exit the TRIP status and the trip signal will be cleared
when the measured current value falls below 0.4 the setting threshold value.
To determine the fault direction the REF542plus must be connected to the three-
phase voltages. The protection function has a voltage memory, which allows a direc-
tional decision to be produced even if a fault occurs in the close up area of the volt-
age transformer/sensor (when the voltage falls below 0.1 x Un).
7.1.3.5 Current direction

Detection of the current direction is obtained by calculating the reactive power, which
is computed combining the faulty phase current with the voltage of the corresponding
sound phases. The reactive power calculation uses voltage and current measure-
ments at the fundamental frequency. Before the calculations, the voltages are shifted
to a lagging angle of 45°.
The reactive power is calculated like the following:
1VTA10002 Rev02 PTMV, 2003.12.10 57 / 234

Q = (IL1 x U 23 x sin ϕ1 ) + (IL2 x U 31 x sin ϕ 2 ) + (IL3 x U12 x sin ϕ 3 )

Where is:
Q Reactive power
IL1,2,3 Current of phase 1, 2 and 3
U12,23,31 Line voltages between phases 1-2, 2-3 and 3-1 after shifting -45°
ϕ1,2,3 Angles between the currents and the corresponding voltages

Only the phases whose current exceeds preset threshold are used in the calculation.
If the result of the calculation leads to a negative reactive power, which is greater than
5% of the nominal apparent power, the fault is in forward direction. Otherwise, the
fault is in backward direction.
A directional signal can be sent to the opposite station using the output (trip) and/or
the Block Output (BO) signal. The content of a directional signal from the opposite
station (BO output) can be used to release tripping of its own directional protective
function. This enables a directional comparison protection to be established.
The following figure shows the forward and backward direction in the impedance
plane in case of a balanced three-phase fault.
Error! Objects cannot be created from editing field codes.
Figure 8: Diagram of the directional overcurrent protection in case of balanced three-phase
faults
Because the application of the fault-current is in combination with the sound voltages,
the directional decision area can change. This change depends on the power system
parameters in case of non-symmetrical fault condition. The criteria for forward and
backward direction is derived from the calculated reactive power.
7.1.3.6 Voltage memory

The directional overcurrent protection function includes a voltage memory feature.
This allows a directional decision to be produced even if a fault occurs in the close up
area of the voltage transformer/sensor.
At a sudden loss of voltage, a fictive voltage is used for direction detection. The fictive
voltage is the voltage measured before the fault has occurred, assuming that the volt-
age is not affected by the fault. The memory function enables the function block to
operate up to 300 seconds after a total loss of voltage.
When the voltage falls below 0.1 x Un, the fictive voltage is used. The actual voltage
is applied again as soon as the voltage rises above 0.1 x Un for at least 100 ms. The
fictive voltage is also discarded if the measured voltage stays below 0.1 x Un for more
than 300 seconds.

Two parameter sets can be configured for each of the overcurrent directional definite
time protection functions.

Start Value 0.05 .. 40 In 0.2 Current threshold for fault detection.
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Time 40 .. 30000 ms 80 Operating Time between start and trip.

Direction forward/backward - backward Direction criteria.
7.1.3.8.2 Events
Code Event reason
E0 Protection started timing on phase L1
E1 Timing on phase L1 cancelled.
E6 Trip signal is active
E7 Trip signal is back to inactive state
E16 Block signal is active
E17 Block signal is back
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7.1.4 Overcurrent Protection

The REF542plus provides three overcurrent definite time protection functions. Each
of them can be independently activated:
Overcurrent definite time instantaneous (I>>>)
Overcurrent definite time high set (I>>)
Overcurrent definite time low set. (I>)

Input
BS signal goes low.
Outputs
vated when respective phase current start conditions are true.
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7.1.4.2.1 General
7.1.4.2.2 Sensors
The protection functions operate on any combination of phase currents in a triple,

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Start Value: Current threshold for overcurrent condition detection.
Time: Time delay for overcurrent Trip condition detection.
7.1.4.2.4 Events
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7.1.4.2.5 Pins

All overcurrent definite time functions evaluate the current RMS value at the funda-
mental frequency. In case of the overcurrent definite time instantaneous, the peak
value of the measured current is also used under transient condition for a faster re-
sponse: when the instantaneous peak value is higher then three times SQRT (2) the
RMS value ( I x _ peak 2 > 3 ⋅ I x _ RMS ).

If the measured current exceeds the setting threshold value (Start Value), the
overcurrent protection function is started. The start signal is phase selective; i.e. when
at least the value of one phase current is above the setting threshold value then the
relevant start signal will be activated.
The protection function will remain in START status until there is at least one phase
the phases the current falls below 0.95 the setting threshold value. After the protec-
tion has entered the start status and the preset operating time (Time) has elapsed,
function goes in TRIP status and the trip signal is generated.
All overcurrent definite time functions can be used in parallel to generate a current
time-step characteristic, as shown in the following figure.
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tI>
tI>>
tI>>>
I> I>> I>>> I

Figure 9: Schematic view of the definite time tripping steps

Two parameter sets can be configured for each of the overcurrent definite time pro-
tection functions.

Start Value I >, I >> 0.05 .. 40.00 In 0.50 Current threshold for overcurrent condi-
tion detection.
Time 20 .. 300000 ms 80 Time delay for overcurrent Trip condition.
Start Value I >>> 0.1 .. 40.00 In 0.50 Current threshold for overcurrent condi-
tion detection.
Time 15 .. 30000 ms 80 Time delay for overcurrent Trip condition.
7.1.4.6.2 Events
Code Event reason
E18 Protection block signal is active
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7.1.5 Overcurrent IDMT

The REF542plus makes available an IDMT function in which one at the time of the
four current-time characteristics can be activated:
Normal inverse,
Very inverse,
Extremely inverse and
Long-term inverse.

Input
BS signal goes low.

vated when respective phase current start conditions are true (phase current value is
above 1.2 times the setting threshold value).
tions are true and the calculated operating time has elapsed.
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7.1.5.2.1 General
7.1.5.2.2 IDMT Type
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7.1.5.2.3 Sensors

Base current (Ieb): Current threshold for overcurrent condition detection.
Time multiplier (k): Parameter to vary time delay for Trip condition
The trip time is calculated according to British Standard (BS 142) when the time mul-
tiplier k is used. When the time multiplier k is set to one (k=1) the IDMT curve is in ac-
cordance to IEC 60255-3.
1VTA10002 Rev02 PTMV, 2003.12.10 67 / 234

7.1.5.2.5 Events
7.1.5.2.6 Pins

IDMT protection function evaluates the RMS value of phase currents at the funda-
mental frequency.

If the measured current exceeds the setting threshold value (Base current Ieb),
by a factor 1.2 then the protection function is started. The start signal is phase selec-
tive; i.e. when at least one phase current is above 1.2 times the setting threshold
value then the relevant start signal will be activated.
the phases the current falls below 1.15 the setting threshold value. When the protec-
tion enters the start status the operating time is continuously recalculated according
1VTA10002 Rev02 PTMV, 2003.12.10 68 / 234

to the set parameters and measured current value. If the calculated operating time is
exceeded, the function goes in TRIP status and the trip signal becomes active.
The operating time depends on the measured current and the selected current-time
characteristic. The formulas for the trip time according to British Standard (BS 142)
and IEC 60255-3 are reported in the Appendix – IDMT Protection Curve Characteris-
tics.The protection function will exit the TRIP status and the trip signal will be cleared

Two parameter sets can be configured for the IDMT protection function.

Type NI/VI/EI/LTI - NI Tripping characteristic according to
the IEC 60255-3 curve definition.
Base current (Ieb): 0.05 .. 40 In 0.5 Fault current factor threshold for start
condition detection.
Time multiplier (k): 0.05 .. 1.50
- 0.50 Time multiplier to vary time delay for
Trip condition according to BS 142
7.1.5.6.2 Events
Code Event reason
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7.1.6 Earth fault protection

The REF542plus has two earth fault definite time protection functions, which can be
activated and the parameters set independently of each other:
Earth fault low and
Earth fault high.

Input
BS signal goes low.
Outputs
The Start signal will be activated when the measured or calculated earth current ex-
ceeds the setting threshold value (Start Value).
The TRIP signal will be activated when the start conditions are true and the operating
time (Time) has elapsed.
7.1.6.2.1 General
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7.1.6.2.2 Sensors
The protection functions can operate on measured or calculated (on any set of phase
currents in a triple) earth current.
Start Value: Current threshold for earth fault condition detection.
Time: Time delay for earth fault Trip condition detection.
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7.1.6.2.4 Events
7.1.6.2.5 Pins

All earth fault definite time protection functions evaluate the measured residual cur-
rent or the calculated neutral current at the fundamental frequency.

If the measured or calculated earth current exceeds the setting threshold value
(Start Value), the earth fault protection function is started.
The protection function will come back in passive status and the start signal will be
cleared if the earth current falls below 0.95 the setting threshold value.
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when the earth current value falls below 0.4 the setting threshold value.

Two parameter sets can be configured for each earth fault protection function.

Start value 0.05 .. 40.00 In 0.10 Current threshold for earth fault condition detection.
Time 40 .. 30000 ms 200 Time delay for earth fault Trip condition detection.
7.1.6.6.2 Events
Code Event reason
E0 Start started
E1 Start back
E6 Trip started
E7 Trip back
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7.1.7 Directional earth fault protection

REF542plus has two directional earth fault protection functions, each of which can be
independently activated and configured:
Earth fault directional low
Earth fault directional high.

Input
BS signal goes low.
Output
ceeds the setting threshold value (Start Value) and the fault is in the specified di-
rection.
rection.
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7.1.7.2.1 General
7.1.7.2.2 Sensors
The protection functions can operate on earth current and residual voltage quantities
measured through dedicated sensor(s) or calculated from the current and voltage
phase components in a triple.
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Net Type: Parameter defining the connection to ground network typology.
Direction: Directional criteria to be assessed together to earth fault condition

for START detection.
Start Value: Current threshold for earth fault condition detection.
Time: Time delay for earth fault Trip condition detection.
Voltage U0: Residual or neutral voltage threshold.
(An example the typical connection diagram of current and voltage transformers for a
generic feeder and the convention used to define Forward and Backward direction of
the power flow is provided in the Appendix - Connection Diagram).
7.1.7.2.4 Events
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7.1.7.2.5 Pins
aggiornare pin ou nuova bitmap

All directional earth fault definite time protection functions evaluate the measured or
calculated amount of neutral current I0 and voltage V0 at the fundamental frequency.

The direction is determined (hence the protection function is active) only if the neutral
voltage is above the preset threshold (i.e. Voltage U0).
The way the direction is determined depends on the selected network type (iso-
lated/earthed).
If parameter “Net type” is set to isolated, then the “significant” component of neutral
current is its projection on a line orthogonal to neutral voltage.
Earthfault in forward direction
U0
I0
Block Passive Trip
Figure 10: Vector diagrams of the directional earth fault protection (isolated networks sin ϕ)
If parameter ”Net type” is set to earthed, then the “significant” component of neutral
current is its projection parallel to neutral voltage.
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Earthfault in forward direction
Block U0
Passive
Trip
I0
Figure 11: Vector diagrams of the directional earth fault protection (grounded networks cos ϕ)
If the following conditions are true:
Neutral voltage value is above the preset threshold (i.e. Voltage U0)
AND “significant” component of neutral current value exceeds the setting

threshold value (Start Value)
AND the direction is as selected (i.e. backward/forward),
then the protection function is started.
When the preset threshold values (Start Value and Uo) are exceeded and the
first two conditions are true but the fault is in the opposite direction to the specified
one, the Block Output signal becomes active.
cleared if the earth current “significant” component value falls below 0.95 the setting
threshold value OR if the conditions on Neutral voltage value OR direction are not
true.
when the earth current “significant” component value falls below 0.4 the setting
threshold value.
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Two parameter sets can be configured for each directional earthfault protection func-
tion.

Net type Isolated/earthed - Isolated Network grounding typology.
Direction Forward/backward - Backward Directional criteria.
Start value 0.05 .. 40.00 In 0.10 “Significant” component threshold
Voltage U0 0.02 .. 0.70 Un 0.10 Neutral or residual voltage threshold.
7.1.7.6.2 Events
Code Event reason
E0 Protection started timing
E7 Trip signal is back to inactive
E16 Block output signal is active
E17 Block output signal is back to inactive
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7.1.8 Sensitive earth fault protection

REF542plus has one sensitive directional earth fault protection function (67S).
With respect to the two directional earth fault protection functions (67N), the 67S pro-
tection can be configured so to set the maximum sensitivity direction at a user defined
angle (Angle delta). The only additional requirement it to acquire the neutral cur-
rent I0 through a dedicated earth transformer in order to have the proper precision.

Input
BS signal goes low.
Outputs
The Start signal will be activated when the measured earth current exceeds the set-
ting threshold value (Start Value) and the fault is in the specified direction.
rection.
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7.1.8.2.1 General
7.1.8.2.2 Sensors
The protection functions can operate on earth current and residual voltage quantities.
The neutral current I0 is acquired through the dedicated transformer in order to have
the proper precision. The Residual voltage U0 can be either measured through a
dedicated sensor or calculated from the voltage phase components a triple.
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Current I0: Current threshold for dir. earth fault condition detection.
Time: Time delay for dir. earth fault Trip condition detection.
Angle alpha: Parameter to improve the discrimination of the directional decision.
Angle delta: Angle between U0 vector and the direction of maximum sensitivity
Voltage U0: Residual or neutral voltage threshold.
7.1.8.2.4 Events
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7.1.8.2.5 Pins

Sensitive earth fault direction protection function evaluates the amount of residual
current I0 and voltage U0 at the fundamental frequency.

If the following conditions are true:
Residual voltage value is above the preset threshold (i.e. Voltage U0)
AND Neutral current value is in the trip area of the protection function, then the
protection function is started.
If the condition of the voltage U0 is true but the neutral current value is in the block
area, then the protection function remains idle and the Block Output signal becomes
active. When the neutral current value is in the passive area both Start and Block sig-
nals are inactive.
cleared if the earth current OR residual voltage value fall below 0.95 the setting
threshold value.
when the earth current OR residual voltage value fall below 0.4 the setting threshold
value. To ensure the required sensitivity and discrimination for the earth fault detec-
tion, in its implementation in the REF542plus the operating characteristic is formed
with additional adjustability. The following diagram shows the shape of the operating
characteristic.
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Trip
UN UN
IN IN
Passive
Block
Block Passive Trip
δ=0° δ=90°
Figure 12: Operating characteristic of the earth fault directional sensitive protection function
The value of δ (i.e. Angle delta between U0 vector and the direction of maximum sen-
sitivity) can be configured in the range –180° to 180°. This provides the option of us-
ing the earth fault directional sensitive protection for every type of network grounding
situation (isolated, earthed or compensated).
The “significant” component of neutral current is its projection on the direction of
maximum sensitivity. Neutral current value is in the trip or block area when the “sig-
nificant” component exceeds the setting threshold value (Current I0).
The other parameter α (i.e. Angle alpha) is used to improve the discrimination of the
directional decision.
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Two parameter sets can be configured for the sensitive directional earthfault protec-
tion function.

Current I0 0.05 .. 2.00 In 1.00 Earth fault current threshold.
Angle alpha 0.0 .. 20.0 ° 20.0 Discrimination of the directional decision.
Angle delta -180.0 .. 180.0 ° 0.0 Angle between U0 and maximum sensitivity direction
Voltage U0 0.05 .. 0.70 Un 0.50 Neutral or residual voltage threshold.
7.1.8.6.2 Events
Code Event reason
E0 Protection is timing
E16 Block output is active
E17 Block output is back to inactive
E18 Protection block is active
E19 Protection block is back to inactive
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7.1.9 Earth fault IDMT

The dependent earth fault current timer protection, like the IDMT, is a time-delay func-
tion with a set of hyperbolic current-time characteristics. An earthfault IDMT function
in which four current-time characteristics may be selected, can be activated in the
REF542:
Normal inverse,
Very inverse,
Extremely inverse and
Long-term inverse.

Input
BS signal goes low.
Outputs
ceeds the setting threshold value (Base current Ieb) by a factor 1.2.The TRIP
signal will be activated when the start conditions are true and the calculated operating
time has elapsed.
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7.1.9.2.1 General
Output Channel different

from 0 means direct execution of the trip command (i.e. skipping FUPLA cyclic
evaluation).
7.1.9.2.2 IDMT Type
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7.1.9.2.3 Sensors
The protection function can operate on measured or calculated (on any set of phase
currents in a triple) earth current.
Base current (Ieb): Current threshold for overcurrent condition detection.
Time multiplier (k): Parameter to vary time delay for Trip condition
The trip time is calculated according to British Standard (BS 142) when the time mul-
tiplier k is used. When the time multiplier k is set to one (k=1) the IDMT curve is in ac-
cordance to IEC 60255-3.
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7.1.9.2.5 Events
7.1.9.2.6 Pins

Earth fault IDMT function evaluates the measured amount of residual current at the

If the measured or calculated earth current exceeds the setting threshold value (Base
current Ieb) by a factor 1.2 then the protection function is started.
cleared if the earth current falls below 1.15 the setting threshold value.
When the protection enters the start status the operating time is continuously recalcu-
lated according to the set parameters and measured current value. If the calculated
operating time is exceeded, the function goes in TRIP status and the trip signal be-
comes active.
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characteristic.
The formulas for the trip time according to British Standard (BS 142) and IEC 60255-3
are reported in the Appendix – IDMT Protection Curve Characteristics.
when the measured or calculated earth current value falls below 0.4 the setting
threshold value.

Two parameter sets can be configured for Earthfault IDMT protection function.

Type NI/VI/EI/LTI - NI Tripping characteristic according to the
IEC 60255-3 curve definition.
Base current (Ieb): 0.05 .. 40 - 0.5 Fault current factor threshold for start
Time multiplier (k): 0.05 .. 1.50 - 0.50 Time multiplier to vary time delay for Trip
condition according to BS 142
7.1.9.6.2 Events
Code Event reason
E0 Protection is timing
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7.2 Voltage Protection

7.2.1 Overvoltage Protection
There are three overvoltage definite time protection functions in the REF542plus,
which can be independently activated and parameterized:
Overvoltage low,
Overvoltage high,
Overvoltage instantaneous.

Input
BS signal goes low.
Outputs
vated when respective phase (line) voltage start conditions are true (voltage exceeds
the setting threshold value).
The TRIP signal will be activated when at least for a phase voltage the start condi-
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7.2.1.2.1 General
7.2.1.2.2 Sensors
The protection functions can operate on any combination of phase (or line) voltages
in a triple, e.g., it can operate as single phase, double phase, three-phase protection
on voltages belonging to the same system.
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Start Value: Voltage threshold for overvoltage condition detection.
Time: Time delay for overvoltage Trip condition detection.
7.2.1.2.4 Events
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7.2.1.2.5 Pins

Overvoltage protection functions evaluate the phase or line voltage RMS value at the

If the measured voltage exceeds the setting threshold value (Start Value), the
overvoltage protection function is started. The start signal is phase selective; i.e.
when at least the value of one phase voltage is above the setting threshold value then
the relevant start signal will be activated.
the phases the voltage falls below 0.95 the setting threshold value. After the protec-
when the measured voltage value falls below 0.4 the setting threshold value.
The overvoltage protective functions, like the overcurrent protective functions, are
used in a time graded coordination. An example of grading is shown in the following
diagram.
Figure 13: Overvoltage response grading.
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Two parameter sets can be configured for each of the overvoltage protection func-
tions.

Start Value U >, U >> 0.1 .. 3.00 Un 0.50 Voltage threshold for Start condition de-
tection.
Time 40 .. 30000 ms 80 Time delay for Trip condition.
Start Value U >>> 0.1 .. 3.00 Un 0.50 Voltage threshold for Start condition de-
tection.
7.2.1.6.2 Events
Code Event reason
E19 Block signal is back to inactive state
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7.2.2 Undervoltage Protection

There are three undervoltage protection functions in the REF542plus, which can be
activated and parameters set independently of one another:
Undervoltage low.
Undervoltage high.
Undervoltage instantaneous.

Input
BS signal goes low.
Outputs
vated when respective phase (line) voltage start conditions are true (voltage falls be-
low the setting threshold value).
The TRIP signal will be activated when at least for a phase voltage the start condi-
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7.2.2.2.1 General
7.2.2.2.2 Sensors
The protection functions can operate can operate on any combination of phase (or
line) voltages in a triple, e.g., it can operate as single phase, double phase, three-
phase protection on voltages belonging to the same system.
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Start Value: Voltage threshold for undervoltage condition detection.
Time: Time delay for undervoltage Trip condition detection.
7.2.2.2.4 Events
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7.2.2.2.5 Pins

Undervoltage protection functions evaluate the phase or line voltage RMS value at
the fundamental frequency.

If the measured voltage falls below the setting threshold value (Start Value), the
undervoltage protection function is started. The start signal is phase selective; i.e.
when at least the value of one phase voltage is below the setting threshold value then
the relevant start signal will be activated.
the phases the voltage raises above 1.05 the setting threshold value. After the protec-
The undervoltage protection functions are used in a graded coordination. An example
of staging is shown in the following diagram.
Figure 14: Undervoltage protection response stages
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7.2.2.5 Behavior at low voltage values
Because a de-energized feeder has no voltage, an undervoltage protection function

remains activated. It is not be possible then to switch the feeder on again.
Therefore, the “Under Voltage” configuration dialog provides the option of deactivat-
ing the undervoltage protection functions when the voltage is in the range of 0 to 40%
of the setting voltage threshold (Start Value).
The diagrams below shows how this feature works when the “lowest voltage = 0” flag
is checked:
Figure 15: Configuration of the undervoltage limit = 0
If 40% is considered too high, the undervoltage function can also be blocked, e.g.
through the circuit-breaker auxiliary contact, by connecting a signal (high at CB open)
to the BS input pin inside the FUPLA.
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Two parameter sets can be configured for each of the undervoltage protection func-
tions.

lowest voltage = 0 used/not used - not used When “used” the U< functions are ac-
used tive below the 0.4 Start Value
Start Value U <, U << 0.1 .. 1.20 Un 0.50 Voltage threshold for Start condition
detection.
Start Value U <<< 0.1 .. 1.20 Un 0.50 Voltage threshold for Start condition
detection.
7.2.2.7.2 Events
Code Event reason
E18 Protection block signal is active state
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7.2.3 Residual Overvoltage Protection

There are two residual overvoltage protection functions in the REF542plus, which can
be independently activated and parameterized:
Residual overvoltage high and
Residual overvoltage low.

Input
BS signal goes low.
Outputs
The Start signal will be activated when the measured or calculated residual voltage
exceeds the setting threshold value (Start Value).
The TRIP signal will be activated when the start condition is true and the operating
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7.2.3.2.1 General
Output Channel different

from 0 means direct execution of the trip command (i.e. skipping FUPLA cyclic
evaluation).
7.2.3.2.2 Sensors
The protection functions can operate on residual voltage measured through a dedi-
cated sensor (e.g. open delta connected voltage transformers) or calculated from the
voltage phase (line) components in a triple.
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UNe Voltage threshold for residual overvoltage condition detection.
Time: Time delay for residual overvoltage Trip condition detection.
7.2.3.2.4 Events
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7.2.3.2.5 Pins

Residual overvoltage protection functions evaluate the residual voltage at the funda-
mental frequency.

If the measured voltage exceeds the setting threshold value (UNe), the residual over-
voltage protection function is started.
cleared if the voltage falls below 0.95 the setting threshold value.
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Two parameter sets can be configured for each of the residual overvoltage protection
functions.

UNe 0.10 .. 3.00 Un 0.50 Voltage threshold for Start condi-
tion detection.
Time
20 .. 300000 ms 50 Time delay for Trip condition.
7.2.3.6.2 Events
Code Event reason
E0 Start started
E1 Start back
E6 Trip started
E7 Trip back
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7.3 Motor Protection

The protection functions described in the following subsections are provided for pro-
tection of the motor from overloads and faults.
7.3.1 Thermal Overload Protection

REF542plus has one thermal overload protection function.

Inputs
RST Trigger signal (active low-to- Reset signal
high)
BS signal goes low.
When the reset input pin (RST) is triggered, the estimated motor temperature is set to
the parameter value Trst (Reset Temperature Trst).Outputs
Warn Digital signal (active high) Warning signal
Overheat Digital signal (active high) Overheat signal
Sensor Error Digital signal (active high) Error on RTD (used with 0..20ma input)
The Warn signal will be activated when the calculated temperature exceeds the set-
ting threshold value (Twarn).
The Trip signal will be activated when the calculated temperature exceeds the setting
threshold value (Ttrip).
The Overheat signal will be activated when the calculated temperature exceeds the
setting threshold value Nominal Motor Temperature (TMn).
The Sensor Error signal will be activated the external environment temperature
(Tenv) sensor use is set and its failure is detected.
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7.3.1.2.1 General
7.3.1.2.2 Sensors
The protection function operates on any combination of phase currents in a triple,

An external sensor connected to the 4-20mA Analog Input can directly measure the
environment temperature. When it is used it is automatically selected and displayed in
the “General” dialog window.
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Nominal Motor Temperature (TMn): Nominal Motor Temperature, asymptoti-

cally reached at IMn with environment temperature Tenv.
Nominal Motor Current (IMn): Nominal Motor current for operational
Initial Temperature (Tini): Initial motor temperature at protection ini-

tialasing.
Time Constant Off: Time constant for cooling down.
Time Constant Normal: Time constant for motor operational condition.
Time Constant Overheat: Time constant for overload condition.
Trip Temperature (Ttrip): Temperature threshold for trip condition.
Warning Temperature (Twarn): Temperature threshold for warning condition.
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Environment Temperature (Tenv): Ambient temperature.
Reset Temperature (Trst): Initial (i.e. after reset by RST input PIN)
motor temperature.
7.3.1.2.4 Events
7.3.1.2.5 Pins

Thermal overload protection function evaluates the square average of phase currents
at the fundamental frequency.The instantaneous temperature estimation is based on
the average of the phase currents monitored.
The environment temperature can either be set in the “Parameter” dialog window
(Tenv) or measured through and external sensor and a 4-20mA Analog Input. In case
of external measure failure the set parameter Tenv is used as back-up.
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7.3.1.4 Operation Criteria

The Thermal Overload protection function estimates the instantaneous value of motor
temperature.
If the estimated instantaneous temperature exceeds the first setting threshold value
(Twarn), then the protection function enters the START status and generates a
WARNING signal.
If the estimated instantaneous temperature exceeds the second setting threshold
value (Ttrip), then the protection function generates a TRIP signal.
If the estimated instantaneous temperature exceeds the setting threshold value
(Nominal Motor Temperature TMn), then the protection function generates a
OVERHEAT signal.
The protection function will exit START status, come back in passive status and the
start signal will be cleared if the estimated temperature falls below the setting thresh-
old value Twarn.
when the estimated temperature falls below the setting threshold value Ttrip.
The protection function avoids also reconnection after a trip of overheated machines
until estimated motor temperature has fallen below the below the warning tempera-
ture Twarn (according to calculated motor cooling process, based on Time Constant
OFF).
When the Thermal Overload protection is instantiated the motor temperature can be
estimated. Therefore, after a trip for maximum number of starts, an overheated motor
cannot be reconnected until its temperature has fallen below the warning temperature
(Twarn). Therefore the time to decrement the number of start counters will be the
maximum between the setting time interval (Reset Time, t rst) and the motor
cooling-down time estimation.
If the protection function is reset by means of the reset input pin (RST), then the esti-
mated motor temperature will be set to value Trst (Reset Temperature).
7.3.1.5 Thermal model

It is assumed the heating (or cooling) process works according to the following equa-
tion
 −
t
 −
t
T = T f ⋅ 1 − e τ  + Tini ⋅ e τ

 
Tf
where: is the final (asymptotical) temperature Tini is the initial motor temperature τ
is the thermal constant of the heating (or cooling) process t is the actual time,
counted from t=0 starting at Tini
It is also assumed that at nominal environment temperature (i.e. Environment

Temperature Tenv) and at nominal current (i.e. Nominal Motor Current IMn)
the motor will reach (asymptotically) its nominal temperature (i.e. Nominal Motor
Temperature TMn), i.e.
T f = TMn = ∆Tn + Tenv
where
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∆Tn is the nominal (asymptotical) temperature increment of motor
Tenv is the environmental temperature
The value of ∆Tn is related to the thermal energy dissipation in the motor, and is
proportional to the squared value of current
∆Tn ∝ I 2
In general, the value of (asymptotical) temperature increment when the generic cur-
rent I is flowing into the motor is then given by
I2
∆T = ∆Tn ⋅ 2
I Mn
According to the above considerations, the estimated instantaneous temperature T of
the motor, taking into account the environment temperature and the actual motor cur-
rent, is calculated according to:
2
−
t
 I   −
t

T = Tenv + (Tini − Tenv ) ⋅ e τ
+ (TMn − Tenv )  1 - e τ



 I Mm   
To better approximate different motor operational conditions, the time constant τ can
assume three different values, depending on the on the actual motor current I ,
namely:Time Constant OFF, when I < 0.1⋅ I Mn
Time Constant NORMAL, when 0.1 ⋅ I Mn ≤ I ≤ 2 ⋅ I Mn
Time Constant OVERHEAT, when I > 2 ⋅ I Mn
7.3.1.6 Thermal memory at power-down

At power-down, REF542plus saves the estimated motor temperature (T) and at sub-
sequent power-up is able to estimate the new motor temperature, under the hypothe-
sis that the motor was cooling in the meantime (i.e. the timeconstant OFF is used).
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Two parameter sets can be configured for the thermal overload protection function.

Nominal Motor Temperature (TMn) 50 .. 400 °C 100 Motor temp. @ IMn and Tenv
Nominal Motor Current (IMn) 0.1 .. 5.0 In 1.0 Current for operational mode (τ) detection
Initial Temperature (Tini) 10 .. 400 °C 50 Initial (e.g. after reset by BS PIN) temperature
Constant Off (I < 0.1 IMn) 10 .. 100000 s 500 Cooling time constant.
Time Constant Normal 10 .. 20000 s 500 Time const. used in Normal operation.
Time Constant Overheat (I > 2 IMn) 10 .. 20000 s 500 Overheating time constant.
Trip Temperature (Ttrip) 50 .. 400 °C 100 Temperature threshold for Trip condition.
Warning Temperature (Twarn) 50 .. 400 °C 100 Temperature threshold for Start condition.
Environment Temperature (Tenv) 10 .. 50 °C 20 Ambient Temperature.
Reset Temperature (Trst) 10 .. 400 °C 100 Initial (i.e. after reset by RST PIN) motor tem-
perature.
7.3.1.8.2 Events
Code Event reason
E1 Warning signal is back to inactive state
E16 Overheat signal is active
E17 Overheat signal is back to inactive state
E20 Reset input signal is active
E21 Reset input signal is back to inactive state
E22 Sensor error is active
E23 Sensor error is back to inactive state
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7.3.2 Motor Start Protection

REF542plus has one motor start protection function.

Input
BS signal goes low.
Outputs
The Start signal will be activated when the current exceeds 10% motor nominal cur-
rent value IMn and within 100 ms the setting threshold value (Motor Start IMs).
The TRIP signal will be activated when the start conditions are true and the calculated
current-time integration (Is2 x Time) is exceed.
The Block Output (BO) signal becomes active at protection initialization until when the
current exceeds 10% motor nominal current value IMn.
7.3.2.2.1 General
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7.3.2.2.2 Sensors
Nominal Motor Current (IMn): Nominal Motor current for operational con-
dition detection
Start Value (Is): Motor start current for Trip condition detection (start energy
integral I2t).
Time: Time for Trip condition detection.
Motor Start (IMs): Current threshold for motor start condition detection.
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7.3.2.2.4 Events
7.3.2.2.5 Pins

Motor start protection function evaluates the current at the fundamental frequency.
The maximum measured motor current I RMS _ max is used to detect Start and Trip
conditions.
The motor start behavior depends on the switching torque of the specific machine
load. The manufacturer assigns an allowable current-time start integral I2t for motors
or, as an alternative, information on the maximum allowable start current and the
maximum allowable start time is provided.

A motor start is detected if:
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the maximum measured motor current exceeds 0.10 the setting threshold value
nominal motor current (i.e. Nominal Motor Current IMn)
AND within 100 ms later the measured motor current exceeds the setting motor
start detection (Motor Start IMs).When a motor start is detected the protection is
∫
2
started, the start signal is activated and the current-time integral ( i (t ) dt ) is calcu-
lated.
cleared if the maximum motor current falls below 0.95 the setting motor start detec-
tion threshold value (IMs). At that time calculation of current-time integral is stopped.
After the protection has entered the start status and the calculated current-time inte-
gration exceeds the default I s ⋅ T value, where:
2
• I s is Start current parameter (Start Value Is).
• T is Time parameter (Time),

the function goes in TRIP status and the trip signal is generated.
when the measured current value falls below 0.95 the setting motor start detection
threshold value (IMs).

Two parameter sets can be configured for the motor start protection function.

Nominal Motor Current (IMn) 0.20 .. 2.00 In 1.00 Motor nominal current for Start condition.
Start Value (Is) 1.00 .. 20.00 IMn 1.00 Trip condition detection (integral I2t).
Time 40 .. 300000 ms 10000 Time for integral Trip condition.
Motor Start (IMs) 0.20 .. 0.80 Is 0.70 Current threshold for Start condition.
7.3.2.6.2 Events
Code Event reason
E1 Timing cancelled.
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7.3.3 Blocking Rotor

Input
BS signal goes low. This input can be assigned to the speed indicator signal (ta-
chometer generator or a speed switch).
Outputs
vated when respective phase current start conditions are true (one phase current ex-
ceeds Start Value Is).
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7.3.3.2.1 General
7.3.3.2.2 Sensors
The protection function operates on any combination of phase currents in a triple,

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Nominal Motor Current (IMn): Nominal Motor current
Start Value (Is): Current threshold for motor start condition

detection.
7.3.3.2.4 Events
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7.3.3.2.5 Pins

Blocking Rotor protection function evaluates the current at the fundamental fre-
quency. It operates like an overcurrent protection function.
The Blocking Rotor protective function is utilized to detect a locked rotor condition by
sensing the current increase arising from the loss of synchronism between the rotor
revolving and phase voltages.
It can be used to monitor the starting characteristics of three-phase asynchronous
motors to check whether the rotor braking is on and other conditions preventing the
motor to speed up. If this malfunction occurs, the starting current would flow perma-
nently and the motor would be thermally overloaded.

The Blocking Rotor protection function can be blocked on the BS input. The blocking
input can be provided by a speed switch or by the start signal output from the Motor
Start protection function.
A tachometer generator or a speed switch is used to send a defined signal at a speci-
fied speed. If the rotor of the monitored motor is locked, the missing speed signal will
ensure that the overcurrent function in the protective function will continue to remain
active.
The protection function can also be used without a speed signal using the start signal
output from the Motor Start protection function to block it during motor starting phase.
When the motor start condition is detected the Blocking Rotor function is blocked by
the BS input.
If the measured current exceeds the setting motor starting threshold value (Start
Value, Is), the protection function is started. The start signal is phase selective; i.e.
when at least the value of one phase current is above the setting threshold value then
the relevant start signal will be activated (SL 1-3).
the phases the current falls below 0.95 the setting threshold value. After the protec-
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Two parameter sets can be configured for the blocking rotor protection functions.

Nominal Motor Current IMn 0.20 2.00 In 1.00 Nominal Motor current
Start Value Is 1.00..20.00 Imn 1.00 Current threshold for motor start condi-
tion detection.
Time 40 .. 30000 ms 10000 Time delay for Trip condition detection.
7.3.3.6.2 Events
Code Event reason
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7.3.4 Number of Starts

REF542plus has an additional motor protection function that supervises the number
of motor starts. It distinguishes between cold starts and warm starts, the allowable
number of which is generally provided by the motor manufacturer. The starting signal
(Start output) of the Motor Start protection function is used to count the starts.

Inputs
SI Trigger signal (active high) Motor start signal
BS signal goes low.
SI signal is used to provide to the Number of Start function the Start signal output
from the Motor Start protection function by wiring the connection in the FUPLA. It is
used to count the motor number of starts. Outputs
Warn Digital signal (active high) Warning signal
The Warn signal will be activated when the cold (OR warm) starts counter reaches
the setting threshold value maximum number of starts (Ncs and Nws respectively).
The TRIP signal will be activated when the cold (OR warm) starts counter exceeds
the setting threshold value maximum number of starts (Ncs and Nws respectively).
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7.3.4.2.1 General
Max Num. of Warm Starts (Nws): Motor manufacturer declared N° of starts

above temperature threshold Tws.
Max Num. of Cold Starts (Ncs): Motor manufacturer declared N° of starts

below temperature threshold Tws.
Reset Time (t rst): Cooling down motor time; time to dissipate

the heat of a motor start.
Warm Start Temp. Threshold (Tws): Above Tws temperature thereshold a

start is assumed to be “warm”.
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7.3.4.2.3 Events
7.3.4.2.4 Pins

Number of starts protection function supervises the Motor number of starts. The start-
ing signal of Motor Start protection function is used to count starts.
It is also important to distinguish between cold starts and warm starts, the allowable
number of which is generally provided by the motor manufacturer.
Motor temperature estimated by the Thermal Overload function is used to determine
whether a start is cold or a warm. When the Thermal Overload function is not instan-
tiated, a cold start is assumed.

If Thermal Overload protection is not enabled the estimated machine temperature
isn’t available and the Warm counter is not increased (the Warm counter is frozen to
zero). In this case all counted starts are classified as cold.
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When the Thermal Overload protection is enabled the estimated motor temperature is
compared with the setting temperature threshold (Warm Start Temp. Threshold
Tws). Above Tws temperature thereshold a start is assumed to be “warm”, below it is
assumed to be a cold start.
At every motor start (detected by the Motor Start protection function), depending on
the type of start (i.e. warm or cold start) the related counter is incremented by one
unit. At every warm start both the warm counter and the cold counter are incre-
mented. Cold starts increment only the cold counter.
If no start has occurred after the setting time interval (Reset Time, t rst) it is as-
sumed that the motor had time to cool down and both cold and warm start counters
are decremented by one unit.
If the preset number of warm (Max Num. of Warm Starts, Nws) OR respec-
tively of cold starts (Max Num. of Cold Starts, Ncs) is reached, then the pro-
tection function is started and the relevant Warning signal will be activated. If there is
another start, the protection function will enter the TRIP status and the trip signal will
be activated.
If the protection function is in TRIP status and the above condition is satisfied, then
the protection function will exit the trip status and the trip signal will be cleared.The
protection function is in TRIP status and the trip signal remains active until the reset
period t rst has expired; then both cold and warm start counters are decremented
and the trip signal will be cleared.
The protection function will exit START status, come back in passive status and the
start signal will be cleared if the cold AND warm counters falls below the respective
maximum setting values Ncs and Nws, i.e. after the reset period t rst has expired.

Two parameter sets can be configured for the number of starts protection functions.

Max Num. Of Warm Starts (Nws): 1 .. 10 - 1 Number of starts above Tws.
Max Num. Of Cold Starts (Ncs): 1 .. 10 - 1 Number of starts below Tws.
Reset Time (t rst): 1.00.. s 30.00 Time to cool down after a start.
7200.00
Temperature threshold to define a
Warm Start Temp. Threshold (Tws): 20 .. 200 °C 80 warm start.
7.3.4.6.2 Events
Code Event reason
E15 Warning signal is back to inactive state
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7.4 Distance Protection

7.4.1 Distance Protection
The distance protection is dedicated to protect a meshed medium-voltage system or a
simple high-voltage system.

Inputs

SIGNAL COMP Digital signal (active high) Signal comparison scheme
When BL signal becomes active, the protection function is reset (no matter its state),
BL signal goes low.
Output
< Z1 Digital signal (active high) Z1 signal used for signal comparison
START L1 Digital signal (active high) Start signal in L1
EARTH START Digital signal (active high) Start Earth signal
GENERAL Digital signal (active high) General start signal
START
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7.4.1.2.1 General
Output channel different from 0 means direct execution of the trip command (i.e.
skipping FUPLA cycle evaluation).
7.4.1.2.2 Start Values
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7.4.1.2.3 Zones
Zone 1
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Zone 2
Zone 3
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Zone Overreach
Zone Autoreclose (control)
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Directional Backup
Non-directional Backup
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7.4.1.2.4 Phase selection
7.4.1.2.5 Parameters Earth factors
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7.4.1.2.6 Events
7.4.1.3 Operation Mode

The distance protection comprises the following subordinate functions:
Start
Impedance determination
Directional memory
Tripping logic
To run the protection function, phase currents and the phase voltages measurement
quantities are required. The phase currents and the phase voltages are arranged in
consecutive groups of three. The following combinations can be configured:
Measuring input 1,2,3: current signals; measuring input 4,5,6: voltage signals in
phase L1, L2, L3,
Measuring input 1,2,3: voltage signals; measuring input 4,5,6: current signals in
phase L1, L2, L3
The start function is intended to check for the presence of a system failure and to de-
tect the type of the fault. The appropriate measured quantities for determining the im-
pedance and the directional decision are selected depending on the type of system
fault. Once the direction and the zone of the system fault have been determined, the
tripping logic is used to determine the trip time in accordance with the set impedance
time characteristic.
A signal comparison protection scheme, which enables to protect a very short line se-
lectively, is also integrated. This requires pilot wires for signal exchange.
For network operation, it is important to localize the fault as soon as possible after
system fault has been switched off in order to repair the damage. Because medium-
voltage networks are usually spread over wide areas, fault-tracking information in km
or in reactive ohm is desirable for network operation after the system fault has been
tripped. For this reason, the fault locator, which can derive the fault distance from the
measured fault impedance, is also implemented in the distance protection. It calcu-
lates the distance in km to the fault from the nominal value of the cable reactance.
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Caution The requirement of current transformers for distance protection must be ful-
filled. Otherwise the proper function behavior can not be assure. Beside that
the fault locator would not be in position to display the correct value.
Once the system fault has been switched off, it may also be of interest for the system
operator to carry out a fault analysis from a disturbance recorder and the sequences
of the appearance of the signaling events. The fault recorder function can be started
either by an external signal (via a binary input) or by a signal from the distance
protection. The general start or the trip signal can be used for this purpose.
If the fault recorder is started by the general start signal, the system quantities will be
recorded. However, a correct fault reactance can only be detected if the fault is in the
first protection zone. Therefore it is recommended to start the fault recorder by a trip
signal.
The option of switching the distance protection over to the overcurrent protection shall
normally be provided. This procedure is generally referred to the so-called emergency
overcurrent protection and is required if the voltage measurement quantities do not
exist anymore, for example due to an MCB failure. Using the FUPLA (FUnction block
Programming Language) to program the configuration, a related scheme must be de-
signed to block the distance protection by binary input signal.
7.4.1.3.1 Start
The start function in the distance protection is used to detect the system faults selec-
tively and shall enable the distance protection to function properly in different system,
either with high-resistance grounding or in networks with low-resistance grounding.
Here, the high-resistance grounding means that the network is operated with an iso-
lated neutral point or with earth fault compensation coil. The distance protection must
also work properly, if the system is switched over from earth fault compensation to
low-resistance grounding for a short time for the purpose of earth fault tripping.
The start function must also be able of adapting to the variable short circuit power in
the related electrical system. During the day for example the minimum fault current is
normally much greater than the maximum occurring load current because of the
availability of the short circuit power. During this time period a normal overcurrent
starting is sufficient to detect the fault fast and selectively.
However, at night time the short circuit power of the system can decrease, that the
maximum fault current may be less than the above-mentioned load current. Under
these circumstances reliable fault detection is not possible without processing the
voltage information.
To ensure a proper function for the distance protection in all situations, the start func-
tion consists of:
Overcurrent starting I>,
Earth fault current starting IE> and
Undervoltage controlled overcurrent starting UF</ IF>
The overcurrent starting I> is used to monitor the line currents exceeding the thresh-
old values. The following diagram shows the associated signal processing.
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I>
IL1 START L1
IL2 START L2
IL3 START L3
IE>
IE START E
With START E
P
1 G-START
Figure 16: Logic diagram of overcurrent starting
If the set overcurrent threshold value is exceeded, the starting signals Start L1, Start
L2 and Start L3 for the corresponding phase appear. The Start E signal is derived
from the earth current supervision, which is calculated from the sum of the phase cur-
rents. Then the General Start signal is generated with the OR Gate of all starting sig-
nals (optionally also with the Start E signal).
Note The Start E value shall be set in such a way, that a starting by an earth fault current
occurring in a system with isolated neutral point or with earth fault compensation can
be prevented.
IF>
With High Ohmic Grounding:
IL1 IF1>
IL2 IF2> Start L1 = (IFL1> Λ IFL2> Λ UF12<) v

(IFL3> Λ IFL1> Λ UF31<) v
IL3 IF3> (IFL1> Λ IE> Λ UF12<) v
(IFL1> Λ IE> Λ UF31<)
UF<
Start L2 = (IFL2> Λ IFL3> Λ UF23<) v
U1 UF1<
U2 UF2< (IFL2> Λ IE> Λ UF23<) v
U3 UF3<
U12 UF12< Start L3 = (IFL3> Λ IFL1> Λ UF31<) v

U23 UF23< (IFL3> Λ IE> Λ UF31<) v
U31 UF31<
Figure 17: Undervoltage-controlled overcurrent starting in case of high - ohmic grounding
The undervoltage voltage controlled overcurrent starting is formed from the logical
scheme between the current threshold value IF> and the setting value of the under-
voltage UF<, as shown in above figure. The phase voltage in this case must be less
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than undervoltage UF< setting and the corresponding phase current must exceed the
current threshold value IF>. As shown in above logical scheme, the start signals for
the two or three phase fault without earth are formed from the combinations of two
phase currents, each with the corresponding phase voltage. Only a start signal is
generate, if the current threshold value IF> are exceeded in two phases and the un-
dervoltage condition of the related line voltage is fulfilled.
In system with low ohmic grounding the signal of the residual (earth) current is logi-
cally combined to the signals of the phase voltages. In contrary, in system with high
ohmic grounding the signal of the residual current is combined with the signals of cor-
responding line voltages. The combination with the line voltages shall enable the cor-
rect starting in case of a cross-country fault (earth fault on two different places).
IF>
With Low Ohmic Grounding:
IL1 IF1>
IL2 IF2> Start L1 = (IFL1> Λ IFL2> Λ UF12<) v

IL3 IF3> (IFL1> Λ IE> Λ UF1<)
UF<
Start L2 = (IFL2> Λ IFL3> Λ UF23<) v
U1 UF1<
U2 UF2< (IFL2> Λ IE> Λ UF2<)
U3 UF3<
U12 UF12< Start L3 = (IFL3> Λ IFL1> Λ UF31<) v

U23 UF23< (IFL3> Λ IE> Λ UF3<) v
U31 UF31<
Figure 18: Undervoltage-controlled overcurrent starting in case of low - ohmic grounding
The entire logical scheme (Boolean algebra) of the signals to form the corresponding
start signals can be seen as following:
For system with high – ohmic grounding:
Start L1 = IL1> ∨ {(IFL1 > ∧ IFL2> ∧ UF12<) v (IFL3> ∧ IFL1> ∧ UF31<)}

∨ {(IFL1> ∧ IE> ∧ UF12<) v (IFL1> ∧ IE> ∧ UF31<)}
Start L2 = IL2> ∨ {(IFL2 > ∧ IFL3> ∧ UF23<) v (IFL1> ∧ IFL2> ∧ UF12<)}

∨ {(IFL2> ∧ IE> ∧ UF23<) v (IFL2> ∧IE> ∧ UF12<)}
Start L3 = IL3> ∨ {(IFL3> ∧ IFL1> ∧ UF31<) v (IFL2> ∧ IFL3> ∧ UF23<)}

∨ {(IFL3> ∧ IE> ∧ UF31<) v (IFL3> ∧ IE> ∧ UF23<)}
and for system with low – ohmic grounding:
Start L1 = IL1> ∨ {(IFL1> ∧ IFL2> ∧ UF12<) v (IFL3> ∧ IFL1> ∧ UF31<)}

∨ (IFL1> ∧ IE> ∧ UF1<)
Start L2 = IL2> ∨ {(IFL2 > ∧ IFL3> ∧ UF23<) ∧ (IFL1> ∧ IFL2> ∧ UF12<)}

∨ (IFL2> ∧ IE> ∧ UF2<)
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Start L3 = IL3> ∨ {(IFL3> ∧ IFL1> ∧ UF31<) ∧ (IFL2> ∧ IFL3> ∧ UF23<)}

∨ ( IFL3> ∧ IE> ∧ UF3<)
∨: OR Gate
∧: AND Gate
Note In system with short time low resistance grounding the setting "High Ohmic Ground-
ing" shall be selected.

System with isolated neutral point or with earth fault compensation, for reasons of
power supply availability, shall not be disconnected in case of an earth fault. If the
earth fault becomes to a cross-country fault, then one of the two earth fault footing
points shall be disconnected.
To coordinate the disconnection of the earth fault footing point, a phase selection can
be programmed into the distance protection. This enables the distance protection to
disconnect the corresponding phase with the earth fault according to a certain set se-
quence. The following phase selection setting can be selected:
Acyclical: L3 before L1 before L2
Cyclical: L3 before L1 before L2 before L3
Acyclical: L1 before L3 before L2
Anticyclical: L1 before L3 before L2 before L1
For example, if the acyclical phase setting L3 before L1 before L2 is selected in the
distance protection, in case of a cross-country fault between the phases L3 and L1 to
earth, the earth fault footing point in phase L3 will be disconnected. The earth fault in
phase L1 will remain until it is disconnected by the system control center after appro-
priate switchover action in the system.
Note To ensure correct functioning of the conductor preference, the measured quantities of
the phase voltages must be correctly connected (correct phase sequence).
7.4.1.3.3 Calculation of the impedance
After the starting has correctly detected the system fault, the fault impedance will be
calculated by applying the discrete Fourier transformation (DFT). The DFT is used
because the measured quantities are mostly superimposed by transient phenomena
or harmonic disturbances of varying frequency. By applying the DFT high harmonic
disturbances can be eliminated effectively that the fault impedance can be calculated
properly.
The fault impedance is determined with the following equation for the phase-to-phase
fault:
U L −L
ZL − L =
I L −L
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ZL-L is the fault impedance to be determined. UL-L and IL-L are the corresponding line
voltage and the calculated line current variable.
The following equation shall then be used in case of an earth fault or two phase to
ground fault:
U L −E
ZL − E =
IL + k ⋅ IE
ZL-E is again the fault impedance to be determined. UL-E and IL are the corresponding
voltage or current measurement quantities of the relevant phase current and IE is the
earth current respectively the residual current resulting from the sum of all phase cur-
rents.
I E = I R + I S + IT
However, for the final calculation of the impedance, the earth current must first be
corrected with the complex earth factor k as follows:
1  Z0 
k = ⋅  − 1
3  Z1 
In this case Z0 is the impedance of the zero sequence and Z1 is the impedance of the
positive-sequence. Positive-sequence, negative-sequence and zero sequence are
defined in the theory of the symmetrical components.
To calculate all fault types correctly, six impedance loops must be calculated; three l
for faults between the phases and three for faults between phase and earth. Because
of various influencing quantities the fault impedance may deviate from the theoretical
impedance value of the line unit. A typical example for this is a short circuit with arc-
ing. In this case, the fault impedance is overlain with the non-linear arc characteristic.
To avoid the non tripping, a tripping area need to be defined. For the distance protec-
tion function a polygonal tripping characteristic is foreseen.
The following figure shows this polygon tripping characteristic for the distance protec-
tion.
Im
X
δ2
R
δ1 Re
Figure 19: Tripping characteristic for the distance protection
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The first quadrant the tripping characteristic is set by a horizontal and a vertical line.
The reactance setting X defines the value of the horizontal line and the resistor set-
ting R for the vertical line. The tripping area is finally closed by another two lines in
the second and the fourth quadrants. The angle of rotation for the line is δ2 in the
second quadrant and δ1 in the fourth quadrant.
7.4.1.3.4 Directional voltage memory
The directional decision is normally derived from the result of the complex fault im-
pedance value. Therefore, the voltage measured related to the fault is used to deter-
mine the direction. However, if the fault occurs in the close up area where the voltage
transformers or the voltage sensors are installed, the generation of the directional de-
cision can be seriously affected because of the small value of the voltage measured
quantity. For this reason a directional voltage memory is always used to form the di-
rectional decision. All voltages (phase and line voltages) that were measured before
the fault occurred are saved in the directional voltage memory. After the fault occurs a
phase displacement angle of approximately ± 30° may occur. For example, this may
occur on the transition to a cross-country fault. This fact should be taken into account
when setting the tripping characteristic.
The tripping characteristic should be set as follows to obtain a correct directional de-
cision permanently:
In the second quadrant at
δ2 = 90° + 30° = 120°

and in the fourth quadrant at
δ1 = 0° – 30° = – 30°.
7.4.1.3.5 Tripping logic
The tripping logic generates from the distance and directional decision in logical com-
bination with the timer function the different zone characteristics. In total, three im-
pedance zones, one directional zone, one non-directional zone and the correspond-
ing five timer functions are available. The adjustable zone characteristics can be seen
in the following diagram.
As can be seen in the next figure, every impedance zone and the directional zone can
be set either backwards or forwards. The timer functions are assigned as follows:
Time t1 of impedance zone Z1,
Time t4 of impedance-independent directional zone as directional backup and
Time t5 of impedance and direction-independent zone as non-directional backup.
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t t
t5 t5
t4 t4
t3 t3
t2 t2
t1 t1
Z1 Z2 Z3 Z Z3 Z1 Z2 Z
t
t5 t5
t4 t4
t3 t3
t2 t2
t1 t1
Z1 Z2 Z3 Z Z2 Z1 Z3 Z
Figure 20: Impedance-timer characteristics
Every single zone can be deactivated. Which of the impedance zone characteristics
should be selected depends on one hand by the network topology and on the other
hand by the design of the protection scheme.
Moreover, the tripping logic provide also the interface to the autoreclose function
(AR), signal comparison protection scheme and switching onto fault scheme. For that
reason, the function of the first impedance zone Z1 is superimposed by another two
special zones, the "overreach zone" and the autoreclosure blocking zone. The corre-
sponding setting parameters must accordingly adapt.
7.4.1.3.6 Adaptation to Autoreclosure
The figure below shows the principal view of the impedance-time characteristic in
conjunction with autoreclose function. The line that is to be protected is between sta-
tions A and B. The impedance-time characteristic is shown for the distance protection
with autoreclosure in station A.
Station A Station B
t2
t1
DP
Z1 Zov
Figure 21: Zone characteristics for autoreclosure on overhead line
DP Distance Protection
Z1 First impedance zone
Zov Overreach zone
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In system with overhead line the overreach zone Zov is generally set approximately in
the range of 120 to 150% of the line impedance ZL. The timer setting tov should, in
this case, be set equal to the time t1 of the first impedance zone Z1. The autoreclo-
sure zone ZAR must be set to inactive.
When the General-Start signal occurs, the specified time is started. The setting of this
specified time should be set higher or equal to the time setting of the overreach zone
tov. In case that a trip is generated that is longer than the specified time, the autore-
closure is blocked. Only for a trip, which appears within this time, the autoreclosure is
started. On the expiry of the specified time the overreach zone Zov will be deactivated
again.
If a multi shot autoreclosing is set, another autoreclose cycle is released if the first
one is unsuccessful. Here also, similarly to the first autoreclosure, the specific time is
activated by the General-Start signal. This should be adjusted to the time setting t2 of
the second impedance zone Z2. The second impedance zone should be set in this
case in forward direction immediately above the first impedance zone Z1.
In the event that a mixed line, comprising cable and overhead line, need to be pro-
tected, an autoreclosing is allowed only in the area of the overhead line. From the dis-
tance protection point of view, if the line connection starts with an overhead cable and
ends with a cable, in principle the same setting as described above with the standard
autoreclosure is valid. The autoreclosure zone ZAR will only be set to approximately
90% of the impedance of the overhead line of the first section. The following figure
shows the corresponding zone characteristic.
Station A Station B
t2
t1
DP
ZAR Z1
Overhead Line Cable

Figure 22: Zone setting for autoreclosure on overhead line –cable
ZAR Autoreclose zone to release or block the autoreclosing
In this case, the autoreclosing blocking zone operates to release the autoreclosure
within the set zone. If the fault occurs in the second cable area, the autoreclosure will
be blocked.
The restriction on the reach of the overreach zone is required because it is known
that faults of approximately 5% must be expected with the current and voltage meas-
urement. If the current and voltage measurement is more precise, the reach of the
overreach zone should be set correspondingly.
From the distance protection point of view, if in the first section of the line connection
a cable is installed and behind it the overhead line, the autoreclosing blocking zone
ZAR is used to block the autoreclosing in case of system fault in the first section with
cable. The following figure shows the impedance-time characteristic that must be set.
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Station A Station B
t2
t1
DP
ZAR Z1
Cable Overhead Line

Figure 23: Zone setting for autoreclosure on cable-overhead line
ZAR Autoreclose zone to release or block the autoreclosing
If there is a fault on the cable the autoreclosure need to be blocked by the autoreclos-
ing zone ZAR. The autoreclosing zone ZAR, due to the above-mentioned faults with
current and voltage measurement, should be set to approximately 110% of the total
cable impedance. The reach of the overreach zone Zov with the associated time tov
sets the range for activating the autoreclosure on the overhead cable side.
7.4.1.3.7 Signal comparison scheme
If the zone for the protection reach is less than the smallest possible impedance set-
ting value, the distance protection can be supplemented with a signal comparison
scheme. This enables the relative selective protection with time discrimination to func-
tion as a absolute selective protection. With the signal comparison scheme, the dis-
tance protection becomes a protection system with data transmission link. However,
there are no specific requirements on the signal connection and transmission as this
would be the case with the line differential protection. A part of the protection system,
in this case the distance protection, will also works properly without the communica-
tions link. The following figure illustrates the principle of distance protection with the
signal comparison scheme by using a pair of pilot wires.
Station A Station B
DP Pilot wire DP
Z1
Z1
Figure 24: Zone characteristic of the distance protection with signal comparison scheme
Z1 First impedance zone of the corresponding distance protection
As noted above, the impedance of the line to be protected is so small that the dis-
crimination by applying of the first impedance zone Z1 can not be guaranteed. There-
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fore the zone can only be set greater than the impedance of the entire line. To ensure
the selective tripping, a signal comparison scheme must be added. The time t1 of the
first impedance zone need in this case to be increased, for example to 0.2 to 0.3 s. In
this way, a fault can always be tripped by distance protection in the increased base
time independent of the status of the link.
The two distance protection units at each end of the line unit are connected to each
other with a pair of pilot wires to form a comparison protection scheme. This enables
the General-Start and impedance Z1< protection signals occurring during the fault to
be compared with each other. The following figure shows an example of the function-
ing of the signal comparison protection with the aid of simple relay contacts.
L+ L-
G Start G Start
Z < Z1 Z < Z1
REF542plus REF542plus
Figure 25: Principle of the distance protection with signal comparison scheme
The two distance protection units are connected with the pair of pilot wires. This forms
a loop over the two protection devices. An auxiliary voltage is applied at one end of
the loop. The auxiliary voltage is assigned to the two binary inputs in use. It can also
be used to monitor the pair of pilot wires. If the auxiliary voltage is down an indication
signal can be generated after the expiry of a configurable time delay of, for example,
5 s. If necessary, this will then be forwarded to the upper level control system. As de-
scribed above, also in the case of a failure of the pilot wire the line will continue to be
protected by distance protection, but with the slightly increased operation time.
If a fault occurs in the power system, both distance protection units (at each line
ends) will be tripped. Each of them will send a General-Start signal. The General-
Start N/C (normally closed) contacts and with them the pilot wire loop will be opened.
The connection to the signal comparison is broken for a while. Because the loop is
only open for a fraction of time, less than 5 s, an indication signal is not sent.
The tripping of the distance protection is only possible if both protection units ac-
knowledge a fault impedance within the first impedance zone Z1. In this case, the sig-
nal Z1< appears, which is used to close the comparison loop again. The closed state
of the loop means that the fault is within the protection zone of both distance protec-
tion units. In the event of a fault outside the protection zone, the loop cannot be
closed due to the missing signal Z1<. Therefore, a trip does not occur.
The signal comparison protection also functions if the line unit is fed from only one
side after for example a switchover actions in the power system. A quasi-echo circuit
is implemented within the signal comparison scheme. The loop remains closed be-
cause the distance protection at the other end of the line is and remains in idle status,
if a fault is occurred within the protection zone. The tripping is then generated on the
side of the distance protection, which detect the system fault.
A fault within the protection zones can be tripped quickly and selectively with the sig-
nal comparison scheme. However, when making the settings, the propagation time of
the signals must be taken into account. It is important that the General Start signal
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always appears before the signal Z1< to ensure that the loop is opened at the right
time.
In addition, the fact that the signals required for the signal comparison protection are
not always received simultaneously at both ends of the line unit must be considered.
Sufficient time delays must be defined at the binary inputs.
7.4.1.3.8 Switching onto faults
The distance protection consist also the function of the so-called “switching onto
faults”. With this setting activated, the tripping response of the distance protection can
be remotely or locally influenced by the closing command of the circuit-breaker as fol-
lows:
Standard operation
In this case the function "switching onto fault“ is not activated. The distance protection
ignores the closing command of the circuit-breaker. A fault is only tripped in accor-
dance with the zone characteristic. This means that a fault will be tripped in the first
impedance zone with the time t1 and in the second impedance zone with the time t2.
Use overreach zone
With this setting the overreach zone will be activated for about 200 ms by the closing
command of the circuit-breaker. The protection zone is given by the setting of the
overreach stage ZOR. This is normally about 120 … 150% of the line impedance ZL.
The tripping then will occurs with the corresponding time tOV. When the circuit-breaker
is closed by the autoreclosure function, the overreach zone will not be activated any-
more.
Tripping after general starting:
In this setting the General-Start signal will define the behaviour of the protection trip-
ping. If the general starting signal occurs when the circuit-breaker is closed, the dis-
tance protection trips with a fixed operation time of 50ms. The impedance measure-
ment will not be used.
Note If the switching onto fault shall be used, the distance protection must be connected to
a function block 2-2 switch object, which is defined as a circuit breaker. Otherwise the
switching on process of the circuit breaker will not be recognized.
7.4.1.4 Switchover to Emergency Overcurrent Protection

In the event of an MCB failure in the voltage instrument transformer the distance pro-
tection will be unable to function correctly because of missing the voltage measured
quantities. For this reason it is necessary to block the distance protection and to
switch over to the so-called emergency overcurrent protection functions. The auto-
matic switchover scheme to the emergency definite time overcurrent protection must
be designed in the FUPLA.
7.4.1.5 Setting the Impedance Zone

Distance protection is a non-unit protection (relative selectivity). In order to get the re-
quired selectivity, time-grading is used for this purpose. The individual ranges are lim-
ited by means of impedance zones.
After generating the trip, the fault impedance and the reactance are indicated on the
LCD screen for fault-locating purposes. The values of the fault impedance and of the
reactance, as usual for fault-locator, are indicated as primary values.
1VTA10002 Rev02 PTMV, 2003.12.10 145 / 234

In contrary the impedance zones have to be set as secondary values. These values
need to be calculated, depending on the transducers or sensors used. The secondary
setting of the impedance zone is normally based on current and voltage transformers
with secondary nominal values 1A and 100 V. By default, the input transformers for
converting current and voltage values are nominal at 1A and 100 V. Therefore, the
conversion is based on the following relation:
Ti
Zsec = Zpri
Tu
where Zsec is the secondary impedance quantity, Zpri is the primary impedance
quantity, Ti is the transformation ratio for the current transformer, and Tu is the trans-
formation ratio for the voltage transformer.
If the secondary nominal value of the current transformers deviates from 1A, the
equation needs to be extended as follows:
Ti Isn
Zsec = Zpri
Tu 1A
where, as before, Zsec is the secondary impedance quantity, Zpri is the primary im-
pedance quantity, Ti is the transformation ratio for the current transformer, and Tu is
the transformation ratio for the voltage transformer. Furthermore, the nominal current,
Isn, and the nominal voltage, Usn, on the secondary side of the transducers have to
be taken into consideration.
The following example of distance protection illustrates how the primary impedance is
converted for setting the respective impedance value. For this purpose, a series of
data from the transducers and sensors are used.
CT 100/1 A and VT 20,000/100 V

The above-mentioned data for the current and voltage transformers can be used to
calculate the secondary impedance value for the protection by using the first equa-
tion:
100
Zsec = Zpri = 0.5 Zpri
200
The primary impedance values can be converted into the secondary impedance val-
ues by applying factor 0.5.
CT 100/5 A and VT 20,000/100 V
With this transducer, the calculation must be made using the second equation which
looks like this:
20 5 A
200 1A
Note Please note that the input transformer for the nominal current of 5A must be used for
connecting.
1VTA10002 Rev02 PTMV, 2003.12.10 146 / 234

CT 100/1 A and VT 20,000/110 V
Since the voltage transformer transforms the primary line voltage to 110V, the refer-
ence quantity for the calculation in distance protection needs to be adapted. For this
purpose, the calibration factors for the voltage inputs have to be adjusted from 100V
to 110V, by setting them to 1.1. For converting, the same relation is used:
100
181.81
Sensor 80A/150mV and 20,000V/2V
The sensors transform the primary measured quantities directly to the reference
quantity for signal processing in the REF 542plus. The current quantity is then con-
verted to 150 mV and the voltage quantity is converted to 2V. In principle, the first
equation can be used for calculation. However, this is based on the assumption that
the primary measured quantities are converted to secondary quantities of 1A and
100V. Moreover, it must be assumed that the nominal quantities for the interposing
transformers are 1A and 100 V as well. Consequently, the secondary setting is de-
termined as follows:
80
200
Note The same voltage sensor that is used for 20 kV nominal voltage with a divider ratio of
10,000:1 is also used for systems with nominal voltages below 20 kV. Therefore the
calculation of impedance values must be based on the same nominal voltage 2V x
10.000 = 20 kV. The nominal voltage must always be based on the actual divider ra-
tio. For example, a sensor with a divider ratio of 20,000 : 1 corresponds to a resulting
nominal voltage of 2V x 20,000 = 40 kV.

7.4.1.7.1 General parameter

Net type: high ohmic, low ohmic
Used sensors: I: 1-3; U: 4-6 or I: 4-6; U: 1-3
Earth start: IE> used or IE> unused (residual current)
Switching onto faults: normal behavior, overreach zone used or trip after occur-
rence of general start signal
Signal Comp. Time: 30 … 30,000 ms (set 1/set 2), default 30 ms
7.4.1.7.2 Start values

I> 0.05..4.00 In 1.00 Phase current high set
IN> 0.05..4.00 In 0.20 Residual current
1VTA10002 Rev02 PTMV, 2003.12.10 147 / 234

UF 0.05..0.90 Un 0.50 Phase or line voltage (net type)
IF> 0,05..4 In 0.50 Phase current low set
7.4.1.7.3 Choose zone

Cable reactance 0.05 .. 120 Ohm/km 1
OH line reactance 0.05 .. 120 Ohm/km 1
Border OH/cable 0.05 .. 120 Ohm 1
Type of transmission line only cable, only OH line, OH line before cable or
cable before OH line
7.4.1.7.4 Zone 1, 2, 3, Zone Overreach, Autoreclose (border)

Resistance R 0.05 .. 120 Ohm 1
Reactance X 0.05 .. 120 Ohm 1
Angle delta 1 -45 .. 0 ° 0
Angle delta 2 90 .. 135 ° 90
Time 20 .. 10000 ms 20
Direction forward, - zone un-

backward or used
zone unused
7.4.1.7.5 Drectional backup

Angle delta 1 -45 .. 0 ° 0
Angle delta 2 90 .. 135 ° 90
Time 20. 10000 ms 20
Direction forward, - zone un-

backward or used
zone unused
7.4.1.7.6 Non-directional backup

Time 20. 10000 ms 20
Normal acycle L3-L1-L2

Normal cycle L3-L1-L2-L3
Inverse acycle L1-L3-L2
Inverse cycle L3-L2-L1-L3
1VTA10002 Rev02 PTMV, 2003.12.10 148 / 234

7.4.1.7.8 Earth factor

Parameter Code Values Unit Default Explanation
Factor k 0 .. 10
Angle k -60 .. 60 °
7.4.1.7.9 Events
Code Event reason
E0 Start L1 started
E1 Start L1 back
E2 Start L2 started
E3 Start L2 back
E4 Start L3 started
E5 Start L3 back
E6 Trip started
E7 Trip back
E16 Z1< started
E17 Z1< back
E22 General start started
E23 General start back
E24 Earth start started
E25 Earth start back
E28 Signal comparison started
E29 Signal comparison back
1VTA10002 Rev02 PTMV, 2003.12.10 149 / 234

7.5 Differential protection

7.5.1 Transformer Differential Protection
Differential protection can be used to protect power transformers, motors and genera-
tors. The protection function has the following properties:
Differential protection of two windings power transformer
Amplitude and vector group adaptation
Zero sequence current compensation
Three-fold tripping characteristic
Inrush stabilization by 2nd and 5th harmonics
Stabilization during through-faults also in case of current transformers (CT) satu-
ration

Inputs
BS signal goes low.
Outputs
nd
BH2 Digital signal (active high) Block by 2 harmonic signal
BH5 Digital signal (active high) Block by 5th harmonic signal
GB Digital signal (active high) General Block output signal
The TRIP signal will be activated when at least one of the calculated differential cur-
rents Id exceeds the bias-dependent setting threshold value AND if the harmonic sta-
bilization is enabled, the harmonic content of differential current is below the set
thresholds (2nd ,5th Threshold).
When the harmonic stabilization is enabled, the Block Output (BH2, BH5) signals be-
come active if the protection function detects a differential current exceeding the pre-
set threshold and the harmonic content of differential current is above the set thresh-
olds (2nd ,5th Threshold).
1VTA10002 Rev02 PTMV, 2003.12.10 150 / 234

7.5.1.2.1 General
7.5.1.2.2 Sensors
Transformer differential protection requires 6 current sensors; it operates on two sets

of phase currents in a triple on primary and secondary side of the transformer.
1VTA10002 Rev02 PTMV, 2003.12.10 151 / 234

7.5.1.2.3 Transformer
7.5.1.2.4 Current
Primary nominal current Nominal transformer current on primary side.
Secondary nominal current Nominal transformer current on secondary

side, to be used for power transformer ratio
compensation.
All the Differential protection thresholds are referred the Rated power transformer cur-
Note rent Ir (p.u) in per unit; i.e. normalized on the primary or secondary nominal power
transformer current (Primary, Secondary nominal current). In this way all
differences due to CT ratios and board transformer analog input are automatically
normalized.
Threshold current First region Id threshold.
1VTA10002 Rev02 PTMV, 2003.12.10 152 / 234

Unbiased region limit First region Ib threshold.
Slightly biased region threshold Second region Id threshold.
Slightly biased region limit Second region Ib threshold.
Heavily biased slope Third region slope.
Trip by Id> Upper Id threshold for Trip condition de-

tection.
7.5.1.2.5 Harmonics
2nd, 5th Harmonic
Threshold Threshold value for 2nd, 5th harmonic content detection.
Block Flag enabling the harmonic content detection. When threshold

value is exceeded it blocks the protection function and generates a
blocking signal.
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7.5.1.2.6 Events
7.5.1.2.7 Pins

Differential protection function evaluates the measured amount of differential current
at the fundamental, 2nd and 5th harmonic frequencies.

Transformer differential protection is a current comparison scheme for the protection
of a component with two sides, like e.g. two windings power transformer, therefore
the incoming and outgoing currents through the component to be protected are com-
pared with each other.
If no fault exists in the protection zone, the incoming current and the outgoing current
are identical.
1VTA10002 Rev02 PTMV, 2003.12.10 154 / 234

Therefore the difference between those currents, the differential current Id, is used as
criteria for fault detection. The protection zone of transformer differential protection is
limited by the place where the current transformers or current sensors are installed.
The signals path and the measurement processing to obtain the differential current Id
sed as criteria for fault detection are described in the following flowchart:
Protected
Object
Primary Secondary
currents currents
Analog Analog
A/D A/D
Input Input
Transformation
Ratio
Compensation
Vector Group Bias Currents

Compensation Calculation
Differential Ib
Currents
Calculation
DFT
∆I(f 0)
∆I(2f 0)
∆I(5f 0)
After transformer ratio compensation and vector group adaptation the bias and differ-
ential currents are calculated on the three phases.
If harmonic stabilization is enabled (in “Harmonic” dialog window), 2nd and/or 5th har-
monic contents of differential currents are calculated.
If at least one of the calculated differential currents Id is above the bias (of the con-
sidered phase) dependent setting threshold (given by the tripping characteristic,
Threshold current, Slightly biased region threshold, Heavily
biased slope or Trip by Id>), then (if required) the check for harmonic stabi-
lization is performed.
If harmonic content of differential current Id is above the set threshold (2nd ,5th
Threshold), then the protection function will be blocked and the relevant Block sig-
1VTA10002 Rev02 PTMV, 2003.12.10 155 / 234

nal will be activated, else it goes in TRIP status and the trip signal is generated. The
Block is released If the Id harmonic content falls below 0.4 the setting threshold value
(for 2nd ,5th. Threshold respectively). .
The protection function will remain in TRIP status until there is at least one differential
current above the threshold. It will come back in passive status and the Trip signal will
be cleared if for all the phases the differential current falls below 0.4 the setting
threshold value.
7.5.1.5 Transformer ratio compensation

To perform the current comparison, it is necessary to correct the amplitude of the cur-
rents to compensate the transformer ratio. The amplitude correction is done by soft-
ware. In the case of power transformer protection for example, the current measure-
ment quantities on the primary and the secondary side are corrected by taking into
account the different nominal values of the sensors and primary/secondary nominal
current parameters.
7.5.1.6 Vector group adaptation

The vector Adaptation table is shown below. PS is the primary side, SS the secon-
dary side of the power transformer, IL1 to IL3 the current in the phase L1 to L3 and the
indexes 1 and 2 represent the primary and the secondary side of the transformer re-
spectively. If a transformer is grounded on the primary or on the secondary side it
must also take into consideration that the earthing is carried out by grounding trans-
formers. The vector group adaptation is also in position to cover the situation, where
the grounding transformer is inside the protection zone.
Vector Grounding Calculation of the current comparison
group
PS SS PS SS
0 No No IL11 IL12
IL21 IL22
IL31 IL32
No Yes ( IL11 - IL21 ) / √3 ( IL12 - IL22 ) / √3
( IL21 - IL31 ) / √3 ( IL22 - IL32 ) / √3
( IL31 - IL11 ) / √3 ( IL32 - IL12 ) / √3
Yes No ( IL11 - IL21 ) / √3 ( IL12 - IL22 ) / √3
( IL21 - IL31 ) / √3 ( IL22 - IL32 ) / √3
( IL31 - IL11 ) / √3 ( IL32 - IL12 ) / √3
Yes Yes ( IL11 - IL21 ) / √3 ( IL12 - IL22 ) / √3
( IL21 - IL31 ) / √3 ( IL22 - IL32 ) / √3
( IL31 - IL11 ) / √3 ( IL32 - IL12 ) / √3
1 No No ( IL11 - IL31 ) / √3 IL12
( IL21 - IL11 ) / √3 IL22
( IL31 - IL21 ) / √3 IL32
No Yes IL11 ( IL12 - IL22 ) / √3

IL21 ( IL22 - IL32 ) / √3
IL31 ( IL32 - IL12 ) / √3
1VTA10002 Rev02 PTMV, 2003.12.10 156 / 234


group
PS SS PS SS
Yes No ( IL11 - IL31 ) / √3 IL12
( IL21 - IL11 ) / √3 IL22
( IL31 - IL21 ) / √3 IL32
Yes Yes ( IL11 - IL31 ) / √3 IL12 - IL02

( IL21 - IL11 ) / √3 IL22 -- IL02
( IL31 - IL21 ) / √3 IL32 - IL02
2 No No IL11 - IL22
IL21 - IL32
IL31 - IL12
No Yes ( IL11 - IL31 ) / √3 ( IL12 - IL22 ) / √3
( IL21 - IL11 ) / √3 ( IL22 - IL32 ) / √3
( IL31 - IL21 ) / √3 ( IL32 - IL12 ) / √3
Yes No ( IL11 - IL31 ) / √3 ( IL12 - IL22 ) / √3
( IL21 - IL11 ) / √3 ( IL22 - IL32 ) / √3
( IL31 - IL21 ) / √3 ( IL32 - IL12 ) / √3
Yes Yes ( IL11 - IL31 ) / √3 ( IL12 - IL22 ) / √3
( IL21 - IL11 ) / √3 ( IL22 - IL32 ) / √3
( IL31 - IL21 ) / √3 ( IL32 - IL12 ) / √3
3 No No ( IL21 - IL31 ) / √3 IL12
( IL31 - IL11 ) / √3 IL22
( IL11 - IL21 ) / √3 IL32
No Yes IL11 ( IL32 - IL22 ) / √3

IL21 ( IL12 - IL32 ) / √3
IL31 ( IL22 - IL12 ) / √3
Yes Yes ( IL21 - IL31 ) / √3 IL12
( IL31 - IL11 ) / √3 IL22
( IL11 - IL21 ) / √3 IL32
Yes Yes ( IL21 - IL31 ) / √3 IL12 - IL02

( IL31 - IL11 ) / √3 IL22 -- IL02
( IL11 - IL21 ) / √3 IL32 - IL02
4 No No IL11 IL32
IL21 IL12
IL31 IL22
No Yes ( IL11 - IL21 ) / √3 ( IL32 - IL12 ) / √3
( IL21 - IL31 ) / √3 ( IL12 - IL22 ) / √3
( IL31 - IL11 ) / √3 ( IL22 - IL32 ) / √3
1VTA10002 Rev02 PTMV, 2003.12.10 157 / 234


group
PS SS PS SS
Yes No ( IL11 - IL21 ) / √3 ( IL32 - IL12 ) / √3
( IL21 - IL31 ) / √3 ( IL12 - IL22 ) / √3
( IL31 - IL11 ) / √3 ( IL22 - IL32 ) / √3
Yes Yes ( IL11 - IL21 ) / √3 ( IL32 - IL12 ) / √3
( IL21 - IL31 ) / √3 ( IL12 - IL22 ) / √3
( IL31 - IL11 ) / √3 ( IL22 - IL32 ) / √3
5 No No ( IL21 - IL11 ) / √3 IL12
( IL31 - IL21 ) / √3 IL22
( IL11 - IL31 ) / √3 IL32
No Yes IL11 ( IL32 - IL12 ) / √3

IL21 ( IL12 - IL22 ) / √3
IL31 ( IL22 - IL32 ) / √3
Yes No ( IL21 - IL11 ) / √3 IL12
( IL31 - IL21 ) / √3 IL22
( IL11 - IL31 ) / √3 IL32
Yes Yes ( IL21 - IL11 ) / √3 IL12 - IL02

( IL31 - IL21 ) / √3 IL22 -- IL02
( IL11 - IL31 ) / √3 IL32 - IL02
6 No No IL11 - IL12
IL21 - IL22
IL31 - IL32
No Yes ( IL11 - IL21 ) / √3 ( IL22 - IL12 ) / √3
( IL21 - IL31 ) / √3 ( IL32 - IL22 ) / √3
( IL31 - IL11 ) / √3 ( IL12 - IL32 ) / √3
Yes No ( IL11 - IL21 ) / √3 ( IL22 - IL12 ) / √3
( IL21 - IL31 ) / √3 ( IL32 - IL22 ) / √3
( IL31 - IL11 ) / √3 ( IL12 - IL32 ) / √3
Yes Yes ( IL11 - IL21 ) / √3 ( IL22 - IL12 ) / √3
( IL21 - IL31 ) / √3 ( IL32 - IL22 ) / √3
( IL31 - IL11 ) / √3 ( IL12 - IL32 ) / √3
7 No No ( IL11 - IL31 ) / √3 - IL12
( IL21 - IL11 ) / √3 - IL22
( IL31 - IL21 ) / √3 - IL32
No Yes - IL11 ( IL12 - IL22 ) / √3

- IL21 ( IL22 - IL32 ) / √3
- IL31 ( IL32 - IL12 ) / √3
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group
PS SS PS SS
Yes No ( IL11 - IL31 ) / √3 - IL12
( IL21 - IL11 ) / √3 - IL22
( IL31 - IL21 ) / √3 - IL32
Yes Yes ( IL11 - IL31 ) / √3 - IL12 + IL02

( IL21 - IL11 ) / √3 - IL22 + IL02
( IL31 - IL21 ) / √3 - IL32 + IL02
8 No No IL11 IL22
IL21 IL32
IL31 IL12
No Yes ( IL11 - IL31 ) / √3 ( IL22 - IL12 ) / √3

( IL21 - IL11 ) / √3 ( IL32 - IL22 ) / √3
( IL31 - IL21 ) / √3 ( IL12 - IL32 ) / √3
Yes No ( IL11 - IL31 ) / √3 ( IL22 - IL12 ) / √3
( IL21 - IL11 ) / √3 ( IL32 - IL22 ) / √3
( IL31 - IL21 ) / √3 ( IL12 - IL32 ) / √3
Yes Yes ( IL11 - IL31 ) / √3 ( IL22 - IL12 ) / √3
( IL21 - IL11 ) / √3 ( IL32 - IL22 ) / √3
( IL31 - IL21 ) / √3 ( IL12 - IL32 ) / √3
9 No No ( IL21 - IL31 ) / √3 - IL12
( IL31 - IL11 ) / √3 - IL22
( IL11 - IL21 ) / √3 - IL32
No Yes - IL11 ( IL32 - IL22 ) / √3

- IL21 ( IL12 - IL32 ) / √3
- IL31 ( IL22 - IL12 ) / √3
Yes Yes ( IL21 - IL31 ) / √3 - IL12
( IL31 - IL11 ) / √3 - IL22
( IL11 - IL21 ) / √3 - IL32
Yes Yes ( IL21 - IL31 ) / √3 - IL12 + IL02

( IL31 - IL11 ) / √3 - IL22 + IL02
( IL11 - IL21 ) / √3 - IL32 + IL02
10 No No IL11 - IL32
IL21 - IL12
IL31 - IL22
No Yes ( IL11 - IL21 ) / √3 ( IL12 - IL32 ) / √3
( IL21 - IL31 ) / √3 ( IL22 - IL12 ) / √3
( IL31 - IL11 ) / √3 ( IL32 - IL22 ) / √3
1VTA10002 Rev02 PTMV, 2003.12.10 159 / 234


group
PS SS PS SS
Yes No ( IL11 - IL21 ) / √3 ( IL12 - IL32 ) / √3
( IL21 - IL31 ) / √3 ( IL22 - IL12 ) / √3
( IL31 - IL11 ) / √3 ( IL32 - IL22 ) / √3
Yes Yes ( IL11 - IL21 ) / √3 ( IL12 - IL32 ) / √3
( IL21 - IL31 ) / √3 ( IL22 - IL12 ) / √3
( IL31 - IL11 ) / √3 ( IL32 - IL22 ) / √3
11 No No ( IL21 - IL11 ) / √3 - IL12
( IL31 - IL21 ) / √3 - IL22
( IL11 - IL31 ) / √3 - IL32
No Yes - IL11 ( IL32 - IL12 ) / √3

- IL21 ( IL12 - IL22 ) / √3
- IL31 ( IL22 - IL32 ) / √3
Yes No ( IL21 - IL11 ) / √3 - IL12
( IL31 - IL21 ) / √3 - IL22
( IL11 - IL31 ) / √3 - IL32
Yes Yes ( IL21 - IL11 ) / √3 - IL12 + IL02

( IL31 - IL21 ) / √3 - IL22 + IL02
( IL11 - IL31 ) / √3 - IL32 + IL02
7.5.1.7 Tripping characteristic

The tripping characteristic of the transformer differential protection function is a three-
fold characteristic. In the following figure the characteristic is shown.
III - Heavily
biased
region
II - Slightly
biased
I - Unbiased region
region
Figure 26: Tripping characteristic of the transformer differential protection function
1VTA10002 Rev02 PTMV, 2003.12.10 160 / 234

The tripping characteristic is drawn on p.u. basis after normalization of I1 and I2 cur-
rents on on the primary or secondary nominal power transformer current (Primary,
Secondary nominal current). Therefore Id and Ib currents are expressed in p.u.
as multiples of the Rated power transformer current Ir (p.u).
The bias currents are defined as the average values (in p.u.) between primary and
secondary currents obtained after transformation ratio compensation and vector
group adaptation.
Due to the measurement error of the current quantities on both sides of the object to
be protected, a small differential current Id will occur during normal operation condi-
tion.
The first fold of the characteristic curve is given by the settable threshold value of the
differential current (Threshold current) and the bias current limit (Unbiased
region limit).
The second fold of the characteristic curve is defined by the threshold value of the dif-
ferential current (Slightly biased region threshold) and the bias current
limit (Slightly biased region limit).
Afterwards a line with a selectable slope (Heavily biased slope) continues the
characteristic.
In case of the occurrence of a high differential current, a direct tripping can also be
generated by the threshold value (Trip by Id>) as the third fold of the tripping
characteristic. The setting value should be selected in such a way, that no tripping
could happen during the energizing of the power transformer.
7.5.1.8 Inrush stabilization

When switching on a power transformer without connected loads high inrush current
might occur. As a consequence undesired tripping could happen.
nd
To stabilize this condition of the power transformer the presence of the 2 harmonic
in the differential current can be used as criteria. Therefore the ratio of the 2nd har-
monic current to the current at fundamental frequency is important. As soon as the
threshold value (threshold) is exceeded, the protection function is blocked and a
blocking signal is activated..
Also in case of switching on in parallel a power transformer without connected loads
the inrush current can also be generated in the transformer which is already in opera-
tion. In this case it is necessary to detect the 5th harmonic in the differential current to
avoid the undesired tripping.
For that reason the differential protection in REF542plus is foreseen with the 2nd and
the 5th harmonic blocking possibilities, which can be set separately from each other.

Two parameter sets can be configured for the transformer differential protection func-
tion.
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Transformer group 0 .. 11 - 0 Parameters for: vector group
adaptation and
Transformer Earthing:
transformation ratio compensa-
Primary side Yes/No - No
tion between primary - secon-
Secondary side Yes/No - No
dary currents.
Primary nominal current 10 .. 100000 A 100
Secondary nominal current 10 .. 100000 A 100
Threshold current 0.10 .. 0.50 Ir (p.u.) 0.20 First region Id threshold.
Unbiased region limit 0.50 .. 5.00 Ir (p.u.) 0.50 First region Ib threshold.
Slightly biased region 0.20 .. 2.00 Ir (p.u.) 0.20 Second region Id threshold.
threshold
Slightly biased region limit 1.00 .. 10.00 Ir (p.u.) 3.00 Second region Ib threshold.
Heavily biased region 0.40 .. 1.00 - 0.40 Third region slope.
slope
Trip by Id> 5.00 .. 40.00 Ir (p.u.) 6.00 Upper Id threshold for Trip.
Second Harmonic: Parameters for:
Threshold 0.10 .. 0.30 Id 0.30 inrush stabilization and
Block Enabled/Disabled - Enabled
Fifth Harmonic:
Threshold 0.10 .. 0.30 Id 0.30 No load transformer Inrush
Block Enabled/Disabled - Enabled stabilization
7.5.1.10.2 Events
Code Event reason
E19 Protection block signal back to inactive
E20 Block signal due to 2nd harmonic is active
E21 Block signal due to 2nd harmonic back to inactive
th
E24 Block signal due to 5 harmonic is active
E25 Block signal due to 5th harmonic is back to inactive
E26 General block harmonic start
E27 General block harmonic back
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7.5.2 Restricted Differential Protection

Restricted differential protection can be used as well restricted earth fault protection
to detect and disconnect of fault in grounding system of the transformer as also as
line differential protection with 2 pair of pilot wire.

Inputs
BS signal goes low.
Outputs
The Start signal will be activated when the differential current Id exceeds the setting
threshold value.
The TRIP signal will be activated when the start and trip conditions are true and the
operating time (Time) has elapsed.
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7.5.2.2.1 General
7.5.2.2.2 Sensors
The protection function operates on the comparison of two earth currents; the zero-
sequence current, calculated by means of current measures acquired from the lines
(on any set of phase currents in a triple), and the measured earth-fault current flowing
through the neutral conductor towards the ground. The protection is used in case of
star windings with earthed neutral transformers.
Example of a typical current transformers connection diagram for a transformer Re-
stricted Differential (earthfault) protection is provided in the Appendix - Connection
Diagram).
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In the application as line differential protection the earth currents from both line sides
shall be provided for each line side REF542plus to two dedicated Analog Inputs (AI 7
and AI8). The earth currents can be directly measured through dedicated sensors, by
star connecting the three phase CTs to provide the neutral current or with a matching
transformer on each end of the line in order to generate from the three phase currents
a measurement quantity proportional to the earth currents.
Line side 1 Line side 2
Earth current Earth current

I1 I2
Figure 27: Connection scheme of the application as line differential protection
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Rated current Rated current for CT ratio compensation

and currents normalization.
Unbiased region Threshold First region Id threshold.
Unbiased region limit First region Ib threshold.
Slightly biased region threshold Second region Id threshold.
Slightly biased region limit Second region Ib threshold.
Heavily biased slope Third region slope.
Relay Operate Angle Directional criteria.
Time Time delay for Trip condition detection.
7.5.2.2.4 Events
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7.5.2.2.5 Pins

The restricted differential protection function evaluates the differential current be-
tween two earth currents at the fundamental frequency.
The two currents can be the calculated or measured residual current I0 from the
phase currents compared with the neutral current IG in the transformer restricted
earthfault applicationor, in case of line differential protection, the earth currents of
each end of the line (I1.and I2).

The restricted differential protection is a current comparison scheme. Therefore the
incoming and outgoing currents through the object to be protected are compared with
each other. If no fault exists in the protection zone, the incoming current and the out-
going current are identical. That is why difference between those currents, the differ-
ential current I d = I 0 − I G = I 2 − I 1 , is used as criteria for fault detection.
The protection zone of the restricted differential protection is limited by the place
where the current transformers or current sensors are installed.
If the calculated differential current Id is above the bias-dependent setting threshold
(given by the tripping characteristic, Unbiased region threshold, Slightly
biased region threshold or Heavily biased slope), then protection
function is started and the Start signal will be activated.
cleared if the differential current Id falls below 0.95 the setting threshold value.
If the start conditions are true then the following conditions are checked:
Direction. The directional check is made only if I0 is more than 3 % of the rated cur-
rent (Rated current Ir). If the result of the check means “external fault”, then the
trip is not issued. If the directional check cannot be executed, then direction is no
longer a condition for a trip.
External fault. For as long as the external fault persists (flag enabled in passive con-
dition only, for Id< 0.5 the lower setting threshold and IG> 0.5 the Rated current
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Ir) an additional temporary condition is introduced, which requires, that IG has to be

higher than 0.5 Ir, for protection temporarily desensitization.
Bias. The bias current Ib is above 0.5 the maximum bias current calculated during the
start condition period. Ibtrip > 0.5 Ibmax (start period).
has elapsed, function goes in TRIP status and the trip signal is generated if all the
above conditions are true.
The protection function will exit TRIP status to come back in passive status and the
Trip signal will be cleared if the differential current Id falls below 0.4 the setting
threshold value.
7.5.2.5 Tripping characteristic

The tripping characteristic of the Restricted Differential protection function is a three-
fold characteristic. In the following figure the characteristic is shown.
Assumptions:
Id/Ir I1 > I2, then I1 = Ib
I1 = IG I2 = I0 Ib Biased current
Id Differential current
Id
III - Heavily
biased
region
Trip area
II - Slightly
biased
region
I - Unbiased
Id1/ Ir region
Ib1/ Ir Ib2/ Ir Ib/Ir

Figure 28: Tripping characteristic
The tripping characteristic is drawn on p.u. basis after normalization of I1 and I2 cur-
rents on power transformer Rated current (Rated current Ir).
The bias current is per definition always the one with the higher magnitude, Ib = max
(IG, I0) or Ib = max (I1, I2).
After compensation of different sensor nominal values the differential current Id and
the bias current Ib are calculated.
The first fold of the characteristic curve is given by the settable threshold value of the
differential current (Unbiased region threshold) and the bias current limit (Un-
biased region limit).
The second fold of the characteristic curve is defined by the threshold value of the dif-
ferential current (Slightly biased region threshold) and the bias current
limit (Slightly biased region limit).
Afterwards a line with a selectable slope (Heavily biased slope) continues the charac-
teristic.
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In case of an external fault characterized from a high fault current, it could happen
that the different CTs don’t transform the primary current in the same way (even if
they have the same characteristics), allowing the circulation of a differential current
through the protection.
The tripping characteristic allows facing CT introduced error (e.g. due to phase and
ratio error, different CT load or magnetic properties), without decreasing the sensitiv-
ity of the differential protection. In fact in case of high line currents and then high
ground current, even if there are differences about the I0 and IG transformation, the
higher differential current threshold compensates such an error.
7.5.2.6 Directional Criterion for stabilization against CT saturation

Earth faults on lines connecting the power transformer occur much more often than
earth faults on a power transformer winding. It is important therefore that the re-
stricted earth fault protection should remain secure during an external fault, and im-
mediately after the fault has been cleared by some other protection.
The directional criterion is applied in order to distinguish between internal and exter-
nal earth faults in case of CT saturation, to prevent misoperations at heavy external
earth faults. This criterion is applicable is the residual current I0 is at least 3% Ir.
For an external earth fault with no CT saturation, the residual current in the lines I0
and the neutral current IG are equal in magnitude and phase. The current in the neu-
tral IG is used as directional reference because it flows for all earth faults in the same
direction.
To stabilize the behavior against CT saturation, a phase comparison scheme is intro-
duced. In case of a heavy current fault with saturation of one or more CTs, the meas-
ured currents IG and I0 may no more be equal, nor will their positions in the complex
plane be the same, anda certain value of false differential current Id can appear.
If the fault is inside of the protection zone, the currents to be compared must have a
phase shift to each other. That is why a so-called relay operate angle ROA is intro-
duced, like shown in the next figure. The direction of neutral current is inside of the
ROA, if it is an internal fault. The direction of both current is outside of the ROA for
external faults.
Figure 29: Currents at an external earth fault with CTs saturation
In case of internal fault then the I0 lies into the operate area for internal fault and the
protection is allowed to operate, see:
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Figure 30: Currents at an internal earth fault
The ROA can be taken out of operation by setting it to 180° if no CT saturation has to
be considered.
In case the Restricted Differential is used for line application the same considerations
apply using I1 and I2 earth currents.
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Two parameter sets can be configured for the restricted differential protection func-
tion.

Reference nomi- 1 .. 100000 A 100 Reference current for CT ratio com-
nal current pensation/ currents normalization.
Unbiased region 0.05 .. 0.50 Ir 0.30 First region Id threshold.
threshold
Unbiased region 0.01 .. 1.00 Ir 0.50 First region Ib threshold.
limit
Slightly biased 0.01 .. 2.00 - 0.70 Second region Id threshold.
region slope
Slightly biased 0.01 .. 2.00 Ir 1.25 Second region Ib threshold.
region limit
Heavily biased 0.10 .. 1.00 - 1.00 Third region slope.
region slope
Relay Operate 60 .. 180 ° 75 Directional criteria.
Angle
Time 0.04 .. 100.00 s 0.05 Time delay for Trip condition detec-
tion.
7.5.2.8.2 Events
Code Event reason
E16 Block signal is active state
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7.6 Other Protections

7.6.1 Unbalanced Load Protection
REF542plus has one unbalanced load protection function.

Inputs
RST Trigger signal (active low-to-high) Reset signal
BS signal goes low.
When the reset input pin (RST) is triggered, the protection function is reset. Outputs
The Start signal will be activated when the calculated negative phase sequence cur-
rent exceeds the setting threshold value (Is).
time has elapsed.
The Block Output (BO) signal becomes active when the protection function exit TRIP
status and remains active for the setting delay time (Reset Time ).
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7.6.1.2.1 General
7.6.1.2.2 Sensors
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Is Current threshold for negative sequence condition detection.
K Heating parameter to vary time delay for Trip condition
Reset Time Time BO output is high (e.g. to block the re-closing possibility of a
motor).
Timer decreasing rate Parameter to vary thermal memory effect.
7.6.1.2.4 Events
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7.6.1.2.5 Pins

Unbalanced load protection function evaluates the measured amount of negative
phase sequence current at the fundamental frequency.
The negative-sequence three phase system L1 - L3 - L2 is superimposed on the
three-phase system that corresponds to the standard phase sequence. This results in
different field intensities in the magnetic laminated cores. Points with particularly high
field intensities, "hot spots“, lead to local overheating.

If the calculated negative phase sequence current exceeds setting threshold value
(Is), then the protection function is started and the start signal will be activated.
When the protection enters the START status the operating time is continuously re-
calculated according to the set parameters (K, Is) and the negative phase se-
quence current value.
If the calculated operating time is exceeded, the function goes in TRIP status and the
trip signal becomes active.
when the measured current value falls below 0.4 the setting threshold value. The op-
erating time depends on the calculated negative phase sequence as follows:
K
t= 2 2
I2 − Is
where:
t: time until the protective function trips under sustained overcurrent
K: heating parameter of the component
I2 : calculated negative phase sequence current expressed in In
IS : start threshold expressed in In
According to the standard the characteristic is only defined for I2/Is in the range up to
20. If the values of the mentioned ratio is higher than 20, the operation time remains
constant as the operation time calculated for Is/I2= 20.
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If a trip is generated, e.g. in case of a motor protection, the motor should be blocked
for re-closing. The signal BO is in this case dedicated to block the re-closing possibil-
ity of the motor. The signal BO remains active for the “reset time” after the functions
exit TRIP status.
7.6.1.4.1 Thermal memory
To avoid machine overheating in case of intermittent negative phase sequence cur-

rent, the internal time counter is not cleared when the negative phase sequence cur-
rent falls below the start threshold. Instead, it is linearly decremented with time, using
a user-configurable slope (i.e. Timer decreasing rate). 100% means full memory, 0%
means no memory.

Two parameter sets can be configured for the unbalanced load protection function.

Is 0.05 .. 0.30 In 0.10 Current threshold for negative seq. detection.
K 2.0 .. 30.0 - 10.0 Heating parameter.
Reset time 0 .. 2000 s 60 Time to reset BO after a trip.
Timer decreasing rate 0 .. 100 % 10 Parameter to vary thermal memory effect.
7.6.1.6.2 Events
Code Event reason
E18 Protection block is back to inactive state
E19 Protection block is back to inactive state
E20 Reset input is active
E21 Reset input is back to inactive state
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7.6.2 Directional Power Protection

Directional power protection function can be added as a supervision function with
generators, transformers and three-phase asynchronous motors.

Inputs
BI Digital signal (active high) Blocking signal
When BI signal becomes active, the protection function is reset (no matter its state),
BI signal goes low.
Outputs
The Start signal will be activated when the calculated active power exceeds the set-
ting threshold value (Max Reverse Load) and the power flow is in the opposite di-
rection to the specified one.
time has elapsed.
7.6.2.2.1 General
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Direction: Directional criteria to be assessed with Power flow for

START detection.
Nominal Real Power: Power reference Pn for quantities normalization.
Max Reverse Load: Power threshold in opposition to set direction for start
detection.
Operating Time: Time delay for Trip condition detection.
7.6.2.2.3 Events
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7.6.2.2.4 Pins

The directional power protection function evaluates the active power at the fundamen-
tal frequency.

The directional power supervision compares the calculated active power with a preset
nominal value (Pn, Nominal Real Power) and a set power flow direction (Direc-
tion).
If the calculated active power exceeds the setting threshold value (Max Reverse
Load), and the power flow is in the opposite direction to the specified one (back-
ward/forward), the protection function is started and the Start signal is generated.
cleared if the calculated active power falls below 0.95 the setting threshold value (or
the power flow changes direction).
After the protection has entered the start status and the preset operating time (Oper-
ating Time) has elapsed, function goes in TRIP status and the trip signal is gener-
ated.
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Two parameter sets can be configured for the directional power protection function.

Direction Forward / Backward Directional criteria for START detection.
Backward
Nom. Active Power 1 .. 1000000 kW 1000 Power reference for normalization.
Max Reverse Load 1 .. 50 % Pn 5 Power threshold for START detection.
Operating time 1.0.. 1000 s 10 Time delay for Trip condition.
7.6.2.6.2 Events
Code Event reason
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7.6.3 Low Load Protection

REF542plus has one Low load protection function.
Three-phase asynchronous motors are subject to load variations. The low load moni-
toring function is provided to supervise the motor operational conditions for operation
below the required load.

Inputs
BS signal goes low.
Outputs
The Start signal will be activated when the function is enabled (maximum phase cur-
rent above Min. Current) and the calculated active power falls below 0.95 the set-
ting threshold value (Min. Load).
time (Operating Time) has elapsed.
7.6.3.2.1 General
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7.6.3.2.2 Sensors

Nominal Real Power: Power reference Pn for quantities normalization.
Min. Load: Power threshold for start detection.
Min. Current: Current threshold for start detection.
Operating Time: Time delay for Trip condition detection.
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7.6.3.2.4 Events
7.6.3.2.5 Pins

The low load protection function evaluates the measured amount of current and of ac-
tive power at the fundamental frequency.

Low load protection function is enabled only if the maximum phase current of the con-
figured sensors is above the preset threshold value (Min Current). It then normal-
izes the active power on a preset nominal value (Pn, Nominal Real Power).
When enabled, if the calculated active power falls below 0.95 the preset threshold
value (Min. Load) the protection function is started and the Start signal is gener-
ated.
cleared if the calculated active power exceeds the setting threshold value.
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After the protection has entered the start status and the preset operating time (Oper-
ating Time) has elapsed, function goes in TRIP status and the trip signal is gener-
ated.
when the calculated active power exceeds 1.05 the setting threshold value.

Two parameter sets can be configured for low load protection function.

Nom. Real Power 1 .. 1000000 kW 1000 Power reference for normalization.
Min Load 5 .. 100 % Pn 10 Power threshold for start detection.
Min Current 2 .. 20 % In 5 Current threshold for start detection.
Operating time 1.0 .. 1000 s 10 Time delay for Trip condition detection.
7.6.3.6.2 Events
Code Event reason
E0 Start started
E1 Start back
E6 Trip started
E7 Trip back
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7.6.4 Frequency supervision

REF542plus has one frequency supervision function.
It is worthwhile checking the network frequency so it remains within set limits when-
time and frequency-dependent processes are involved. Frequency changes influence,
for example, the power dissipation, the speed (motors) and the firing characteristics
(converters) of equipment. The frequency supervision function is used to report fre-
quency variations in a configurable frequency range.

Input
BS signal goes low.
Outputs
The Start signal will be activated when the frequency exceeds the setting threshold
value (Start Value).
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7.6.4.2.1 General
7.6.4.2.2 Sensors
The supervision function selects automatically the best sensor. It operates preferably
on voltage sensor but it can work also on current sensor.
Start Value: Frequency threshold for start condition detection.
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7.6.4.2.4 Events
7.6.4.2.5 Pins

The frequency supervision function evaluates network frequency on the measured
value of the first available (voltage or current) sensor.

If the measured network frequency is outside the allowed range, then the supervision
function is started.
If the measured network frequency remains outside the allowed range for at least op-
erating time setting, a trip signal becomes active.
If the measured network frequency falls outside the allowed range, i.e the network
nominal frequency plus/minus the setting threshold value (Start Value), the fre-
quency supervision function is started and the Start signal is generated.
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The frequency supervision function will come back in passive status and the start sig-
nal will be cleared if the frequency difference to the nominal network frequency falls
below 0.95 the setting threshold value.
has elapsed, function goes in TRIP status and the Trip signal is generated.
when the measured frequency value falls back within the allowed range, i.e the net-
work nominal frequency plus/minus 0.95 the setting threshold value.

Two parameter sets can be configured for frequency supervision function.

Start value 0.04 .. 5.0 Hz 0.20 Frequency threshold for start condition
detection.
Time 1.0 .. 300.00 s 10.00 Time delay for Trip condition detection.
7.6.4.6.2 Events
Code Event reason
E0 Start started
E1 Start back
E6 Trip started
E7 Trip back
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7.6.5 Synchronism check

REF542plus has one synchronism check protection function.
Paralleling monitoring is required if two networks are interconnected whose voltages
may differ in quantity, phase angle and frequency as a result of different power sup-
plies. (SYN). The switching operation for coupling the separate systems can be en-
abled by the Synchronism Check SYN signal.

Input
BI Digital signal (active high) Blocking signal
When BI signal becomes active, the protection function is reset (no matter its state),
BI signal goes low.
Outputs
SYN Digital signal (active high) Sync signal
The Start signal will be activated when both differential voltage ∆U and phase differ-
ence ∆ϕ between corresponding line voltages of two networks fall below the setting
threshold values (Delta Voltage AND Delta Phase respectively).
The SYN signal to parallel networks will be activated when the start conditions are
true and the operating time (Time) has elapsed.
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7.6.5.2.1 General
7.6.5.2.2 Sensors
The protection function operates on the combinations of phase (or line) voltages re-
ported in the following table. Two phase voltages belonging to the two networks (or a
line voltage belonging to the second network) are needed.
In table the comparison of corresponding line1-2 voltages of two networks is reported
as example; the third phase voltage U1 L3 is indicated (in gray, as additional earth
sensors) to complete the three-phase voltage system. An indication of possible board
list part number is provided.
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AI 750170 750170
Channel /811 /804
/814 /819
AI1 U1L1 U1L1 U1L1 U1L1 CT CT
AI2 U1 L2 U1 L2 U1 L2 U1 L2 CT CT
AI3 U2 L1 U1 L3 U1 L3 U2 L1 CT CT
AI4 U1 L1 U1 L1 U1 L1 U1 L1
AI5 U1 L2 U1 L2 U1 L2 U1 L2
AI6 U2 L1 U1 L3 U2 L1 U1 L3 U1 L3
AI7 U2 L2 U2 L2 U2 L12 U2 L12 U2 L2 U2 L2 U2 L12 CT
AI8 CT U2 L12
(Example of a typical voltage transformers connection diagram for the Synchro check
function is provided in the Appendix - Connection Diagram).
Delta Voltage: Maximum allowed amplitude difference between two syn-

chronous networks.
Delta Phase: Maximum allowed phase difference between two synchro-

nous networks.
Time: Time delay for Synchro condition detection.
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7.6.5.2.4 Events
7.6.5.2.5 Pins

Synchronism check protection function evaluates the measured amplitude and rate of
change of differential voltage between two networks corresponding line voltages.

The synchronism check protection function monitors the differential voltage ∆U be-
tween corresponding line voltages of two networks and their phase difference ∆ϕ.
If the measured differential voltage and phase difference fall below the setting thresh-
old values (Delta Voltage AND Delta Phase respectively), the Synchro
Check protection function is started.
cleared if differential voltage and phase difference exceed 1.05 the setting threshold
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value. After the protection has entered the start status and the preset operating time
(Time) has elapsed, the signal for parallel switching of networks (SYN) is generated.
The protection function will exit the Synchro status and the SYN signal will be cleared
when the start conditions on differential voltage and phase difference values become
false.Delta Voltage: Maximum allowed amplitude difference between two syn-
chronous networks.
V1
V2
Figure 31: Delta Voltage condition not satisfied. The gray circle radius is the Delta Voltage
value set in the ”Parameters” dialog window.
V1 V2
Figure 32: The Delta Voltage condition AND Delta Phase condition are satisfied, after the op-
erating time is expired, the synchronism condition is fulfilled and the SYN signal is generated.

Two parameter sets can be configured for the synchronism check protection function.

Delta Voltage 0.02 .. 0.40 Un 0.05 Max amplitude difference.
Delta Phase 5 .. 50 ° 10 Max phase difference.
Time 0.2 ... 1000 s° 100.00 Time delay to Syncro detection.
7.6.5.6.2
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7.6.5.6.3 Events
Code Event reason
E6 Synch is present
E7 Synch is not present
7.6.6 Switching Resonance Protection

REF542plus has one Switching Resonance protection function, to be used preferably
together with the Power Factor Controller.

Inputs
PFC OP Trigger signal (active low-to- PFC operation trigger
high)
BS signal goes low.
PFC OP trigger is provided by the PFC function block to temporarly enable the reso-
nance protection function at switching-in, switching-out of PFC controlled capacitor
banks.
Outputs
Start L1 Digital signal (active high) Start signal of IL1
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7.6.6.2.1 General
7.6.6.2.2 Sensors
The protection function operates on any combination of line or phase voltages in a tri-
ple, e.g., it can operate as single phase, double phase, three-phase protection on
voltages belonging to the same system.
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Voltage THD Startvalue: THD amplitude threshold.
Delta Voltage THD Startvalue: THD amplitude difference threshold.
Voltage THD Time Delay: Time delay for THD detection.
PFC OP Time: Enabling time at PFC trigger.
Rms Voltage Startvalue: Function enabling Voltage threshold condition.
7.6.6.2.4 Events
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7.6.6.2.5 Pins

Switching Resonance protection function evaluates the amount of voltage RMS with
th
harmonic content up to 25 harmoinic and THD (Total Harmonic Distortion).

Operation of switching resonance protection function is triggered by an external signal
connected to input pin ‘PFC OP’ (provided by the PFC function SwitchON/OFF output
pins) and remains enabled for the preset time (i.e. PFC OP Time).
At PFC OP trigger instant, voltage THD values are saved.

While enabled, if for at least one phase voltage (respectively line voltage, depending
on the configuration):
RMS value is above the preset threshold (i.e. Rms Voltage Start value)
AND THD value is above the preset threshold (i.e. Voltage THD Start value)
for at least the preset detection time (i.e. Voltage THD Time Delay)
AND the variation of THD value with respect to the saved value (i.e. THD value at
trigger time) is above the preset threshold (i.e. Delta Voltage THD Start
value) for at least the preset detection time (i.e. Voltage THD Time Delay)
then the protection function is started. The start signal is phase selective; i.e. when at
least the for one phase voltage the above conditions are true, then the relevant start
signal (S L1-3) will be activated.
the phases the voltage falls below 0.95 one of the setting threshold values (Rms OR
Voltage THD OR Delta Voltage THD).
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Two parameter sets can be configured for the switching resonance protection func-
tion.

Voltage THD Start 5 .. 50 % 5 THD amplitude threshold.
value
Delta Voltage 1 .. 50 % 2 THD amplitude difference threshold.
THD Start value
Voltage THD 0.01 .. 60.00 s 0.03 Stabilizing delay for THD detection.
Time Delay
PFC OP Time 0.01 .. 120.00 s 0.06 Function enabling time at PFC trigger.
Rms Voltage Start 0.10 .. 1.00 Un 0.50 Function enabling Voltage threshold
value condition
7.6.6.6.2 Events
Code Event reason
E16 Block output signal is active
E17 Block output signal is back to inactive
E20 PFC operation started
E21 PFC operation back
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7.6.7 High Harmonic Protection

REF542plus has one High Harmonic protection function.

Input
BS signal goes low.
Outputs
7.6.7.2.1 General
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7.6.7.2.2 Sensors
The protection function operates on phase or line voltages in a triple.
Voltage THD Startvalue: THD amplitude threshold.
Voltage THD Time Delay: Time delay for THD detection.
Rms Voltage Startvalue: Function enabling Voltage threshold condition.
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7.6.7.2.4 Events
7.6.7.2.5 Pins

High Harmonic protection function evaluates the measured amount of voltage RMS
and THD (Total Harmonic Distortion).

If for at least one phase voltage (respectively line voltage, depending on the configu-
ration):
RMS value is above the preset threshold (i.e. Rms Voltage Start value)
AND THD value is above the preset threshold (i.e. Voltage THD Start value)
for at least the preset detection time (i.e. Voltage THD Time Delay)
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then the protection function is started. The start signal is phase selective; i.e. when at
least the for one phase voltage the above conditions are true, then the relevant start
signal (S L1-3) will be activated.
the phases the voltage falls below 0.95 one of the setting threshold values (Rms OR
Voltage THD OR Delta Voltage THD).

Two parameter sets can be configured for the high harmonic protection function.

Voltage THD Start 1 .. 50 % 10 THD amplitude threshold.
value
Voltage THD 0.01 .. 360 s 0.50 Stabilizing delay for THD detection.
Time Delay
Time 0.05 .. 360 s 0.50 Time delay for Trip condition detection.
Rms Voltage Start 0.10 .. 1.00 Un 0.50 Function enabling Voltage threshold
value condition
7.6.7.6.2 Events
Code Event reason
E0 Start L1 started
E1 Start L1 back
E2 Start L2 started
E3 Start L2 back
E4 Start L3 started
E5 Start L3 back
E6 Trip started
E7 Trip back
E16 Block signal started
E17 Block signal back
7.6.8 Frequency Protection

REF542plus can install up to 6 frequency protection functions per protected net.
The Frequency protection function is used to detect frequency variations in a config-
urable amplitude and rate of change frequency range.
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Input
BS signal goes low.
Outputs
BLOCK Digital signal (active high) Block output signal
The Start signal will be activated when the current exceeds 10% motor nominal cur-
rent value IMn and within 100 ms the setting threshold value (Motor Start IMs).
current-time integration (Is2 x Time) is exceed.
The Block Output (BO) signal becomes active at protection initialization until when the
current exceeds 10% motor nominal current value IMn
7.6.8.2.1 General
1VTA10002 Rev02 PTMV, 2003.12.10 203 / 234
7.6.8.2.2 Trip Logic
7.6.8.2.3 Sensors
The protection functions can operate on any combination of phase or line voltages in
a triple, e.g., it can operate as single phase, double phase, three-phase protection on
voltages belonging to the same system. The default setting is to use the line voltage.
1VTA10002 Rev02 PTMV, 2003.12.10 204 / 234

Start Value: Delta frequency amplitude threshold, with respect to

rated network frequency fr. If set below fr it behaves
as under-frequency, otherwise as over-frequency.
Frequency gradient: Rate of frequency change threshold.
Undervoltage threshold: Minimum voltage threshold to be exceed for protec-

tion enabling, otherwise it is blocked.
7.6.8.2.5 Events
1VTA10002 Rev02 PTMV, 2003.12.10 205 / 234

7.6.8.2.6 Pins

Frequency protection functions evaluate the frequency and/or the frequency gradient
of voltage signals through the zero-crossing detection of the voltage measurement
quantity. The measure is performed on the first voltage measure available above the
minimum voltage amplitude (Undervoltage threshold).

The start condition and trip logic is selected by user and can be
Frequency only (only frequency value is considered)
Frequency AND frequency gradient (both values must exceed thresholds to have
start and trip)
Frequency OR frequency gradient (at least one of the values must exceed thresh-
old to have start and trip)
Depending on the set frequency threshold (Start Value) with respect to the net-
work rated frequency, the protection function behaves either as under-frequency or
over-frequency protection. (e.g. if the set frequency threshold is below rated fre-
quency value, the protection function behaves as under-frequency).
The condition on frequency gradient, when used, is in the same direction as the con-
dition on frequency (e.g. if the protection function is set as under-frequency, then fre-
quency gradient is significant only if it is negative and if actual frequency is below
rated value).
If the frequency cannot be measured,
OR the minimum voltage amplitude in the triple falls below 0.95 the preset
threshold value (i.e. Undervoltage threshold), then the protection function
is blocked and the Block signal is generated.
The protection function will exit Block status and clear the Block signal if mini-
mum voltage amplitude rises above the setting threshold value
If the frequency can be measured,
1VTA10002 Rev02 PTMV, 2003.12.10 206 / 234

AND the minimum voltage amplitude is above the preset threshold (Under-
voltage threshold),
AND the start condition is fulfilled (i.e. measured voltage frequency falls below
or rises above the setting threshold Start Value; AND/OR the frequency gra-
dient is negative or positive and exceeding the setting threshold Frequency
gradient when the protection is set as under-frequency or over-frequency re-
spectively), then the protection function is started and the start signal will be ac-
tivated.
cleared when at least the value of one of the needed conditions falls below 0.95 the
setting threshold value (Start Value AND/OR Frequency gradient).
After the protection has entered the start status, if the above conditions remain true
and the preset operating time (Time) has elapsed, function goes in TRIP status and
the trip signal is generated.
when the all the start conditions fall below 0.95 the setting threshold value (Start
Value AND/OR Frequency gradient).
1VTA10002 Rev02 PTMV, 2003.12.10 207 / 234


Two parameter sets can be configured for each of the frequency protection functions.

Trip Criteria f / f_AND_df/dt / - f Definition of start/trip criteria.
f_OR_df/dt
Start value 40.00.. 75.00 Hz 49.95 Delta frequency amplitude threshold.
59.95
Frequency gradient 0.10 .. 1.00 Hz/s 0.50 Rate of frequency change threshold.
Undervoltage thresh- 0.10 .. 1.00 Un 0.20 Minimum voltage threshold function
old block/enabling
7.6.8.6.2 Events
Code Event reason
E16 Block output signal is ii active state
E17 Block output signal is back to inactive state
1VTA10002 Rev02 PTMV, 2003.12.10 208 / 234

7.7 Autoreclose
7.7.1 Autoreclose
The autoreclose function can be used to reclose the circuit breaker automatically after
a protection function has tripped. This function block can be applied to all protection
functions available in REF542plus.

Input
1 SHOT Digital signal (active high) AR only performing single shot
CB OK Digital signal (active high) CB drive ready for the following AR
EX. TRIG Digital signal (active high) Triggering of AR by an external signal
INCR. Digital signal (active high) Increment the number of shots
STOP AR Digital signal (active high) Immediate stopping of the AR cycles
TEST Digital signal (active high) Test of AR cycle (O-CO-CO…)
BS signal goes low.
Output
CLOSE CB Digital signal (active high) CB close signal
OPEN CB Digital signal (active high) CB open signal
AR ACTIVE Digital signal (active high) High as long the AR is active
AR FAILED Digital signal (active high) High in case of unsuccessful AR
SHOT 1 Digital signal (active high) 1st Shot signal of the AR
nd
SHOT 2 Digital signal (active high) 2 Shot signal of the AR
rd
th
th
1VTA10002 Rev02 PTMV, 2003.12.10 209 / 234

7.7.1.2.1 General
1VTA10002 Rev02 PTMV, 2003.12.10 210 / 234

7.7.1.2.3 Events
1VTA10002 Rev02 PTMV, 2003.12.10 211 / 234

7.7.1.2.4 Pins
7.7.1.3 Operation Mode

The autoreclose function block can be operated in two different modes.
7.7.1.3.1 Start and Trip Controlled
In this operation mode the difference of the time duration between the start and the
trip signal of the related protection function is evaluated. Therefore different settings
of the specified time are provided. If the time difference between the protection start
and trip signal is within the specified time, the AR-cycle is released respectively con-
tinued. The corresponding CB shall be re-closed after the relating dead time is
elapsed. If the condition is not fulfilled, the AR function block will be blocked. To con-
tinue the operation of the feeder, the AR function block need to be released locally or
remotely via the station control system.
7.7.1.3.2 Start Controlled

This operation mode initiates the AR-Cycle only by a start signal of the related protec-
tion function. The tripping time for each shot can be delayed separately. This delayed
tripping is need in some application, e.g. to burn out a falling tree on the overhead
line. So the operation time of the protection function will now be controlled by the AR.
Normally, the first shot shall have a relatively short operation time in the range of 30
to 100 ms. The second and the following shot shall have longer operation time in the
range of 1 to 10s. If this mode is selected, the settings of the specified time are to be
used to control the operation time of the following shots.
The AR function can carry out maximal 5 shots. The corresponding scheme can be
configured using the General sheet, like shown in the following figure:
1VTA10002 Rev02 PTMV, 2003.12.10 212 / 234

Figure 33: Design of the AR scheme using the sheet General
As can be seen in above figure, the configuration can be done by a selection table. All
of the protection functions which can be connected are shown in table. The columns
is foreseen to define, which protection functions will activate a specific AR shots. By
selecting the related protection functions in each shot, the AR will be initiated accord-
ing to the operation mode is defined previously. The protection function can be re-
defined after each shot. In above example the AR will operate as following:
Note Due to dependency of the operation time on the fault current, the IDMT and Earth
Fault IDMT are not listed. If this protection shall be used to initiate the AR-cycle, the
relating trip signal shall be connected by a FUPLA wire to the input EX.TRIG of the
AR function block.
The number of the shots is limited to 3. The first shot can either be activated by the
Overcurrent High Set, the Earth fault high set or by the Overcurrent Instantaneous
protection function. The second and the third shots shall only be initiated by the Over-
current Instantaneous. If after the first AR shot only the protection function Overcur-
rent High Set will trip and the function Overcurrent instantaneous remains inactive, no
AR will be carried out anymore. The AR function will be blocked, because the AR cy-
cle is defined as not successful. As already mentioned before, a release command
from local – Alarm Reset Menu - or remote control is needed to have the AR in opera-
tion again.
The AR goes in ready condition again, if the CB is switch on and after the closed
command a 5 s fixed time has elapsed. In case of a protection trip, which is occurred
before the 5 s timer is elapsed, no AR cycle will be initiated. An unsuccessful AR will
be indicated and the AR function will be blocked again.
1VTA10002 Rev02 PTMV, 2003.12.10 213 / 234

Note The distance protection can only be used in start and trip control mode. If the AR
status is ready, the overreach zone of the distance protection will be activated. After
the first shot, the overreach zone will not be activated anymore. The trip will be done
according to the setting of the related impedance zone.
Note To ensure, the proper function of the AR, the trip of the protection shall be send di-
rectly to the so called 2-2 switch object, which controls and operates the CB. There is
no need to make a FUPLA wiring between the AR function block, 2-2 switch object
and the related protection functions.
The external trigger is to be selected, if the AR will be triggered by an external protec-

tion function. The trip must be connected to a binary input of the REF542plus. After-
wards the external trip signal need to be wired to the external trigger input EX. TRIG
of the AR function block.
Note If the AR-cycle is initiated by the input EX. TRIG, the same wire of this input signal
must also be used to open the CB via the 2-2 switch object. Otherwise, in case of
blocking the AR by a blocking signal, no opening of the CB by the external protection
will be possible.
Mode:
AR Ready Start and Trip Controlled
Protection x
Start
No If protection x trip,
t < spec. time CB definitively off,
AR blocked *
Yes
Loop for n < nmax
Protection x In case of Distance Protection,

trip
the overreach zone is released,
if AR Ready. After the first
Start dead time tp, at the specified time is ellapsed, the
end of tp, CB on, then zone Z1 is deactivated.
start reclaim time trecl.
No Yes If n = nmax. and

t < trecl. protection x trips,
CB def. off, AR
blocked
Figure 34: Flow chart of the start and trip control mode
The flow chart of the start and trip controlled mode is shown in above figure. With the
protection start signal the specified time is released, provided the AR function is
ready. Before the specified time is elapsed, the CB must be switched off by a protec-
1VTA10002 Rev02 PTMV, 2003.12.10 214 / 234
tion trip. Only in this case, the CB will be re-closed after the dead time has run out.
Otherwise the CB will be switched off definitively and an indication AR failed will be
generated. Simultaneously the AR function block is blocked, until the CB is switched
on again.
The reclaim time is used to define an successful AR-cycle. After the CB is re-close,
the reclaim time is started. In case that another protection trip occurred during this
time, the AR-cycle will be continued. If the reclaim time is elapsed and no other pro-
tection trip is detected, the AR is define successfully and the AR-cycle will start again
from the status AR ready. If all number of shots has been performed and still a
protection trip is detected during the reclaim time, the AR function will be blocked and
AR failed will be indicated.
Mode:
AR Ready
Start Controlled
Protection x
Start
No
t > oper. time
Yes
Loop for n < nmax

Protection x
trip
Start dead time tp, at the

end of tp, CB on, then
start reclaim time trecl.
No Yes If n = nmax and

t < trecl. protection x trips,
CB def. off, AR
blocked
Figure 35: Flow chart of the start control mode
The flow chart of the start controlled mode can be seen in above figure. The operation
principle is almost the same as the start and trip controlled. In this case, only the start
signal will operate the AR-cycle. The setting of the specified time is used to define a
delayed operation time of the protection, while the time setting in each protection
function blocks, which are connected to the AR function block, become during the
AR-cycle invalid.
Note A delayed operation time is carried out, if the start signal during this delayed opera-
tion remains active.

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Number of reclosure cycles 0 .. 5 1
Reclaim time 10 .. 30 s 30
Specific time first shot 0.04 .. 30 s 0.5
Dead time first shot 0,1.. 100 s 0.3
Specific time second shot 0.04 .. 30 s 0.5
Dead time second shot 0,1.. 100 s 0.3
Specific time third shot 0.04 .. 30 s 0.5
Dead time third shot 0,1.. 100 s 0.3
Specific time fourth shot 0.04 .. 30 s 0.5
Dead time fourth shot 0,1.. 100 s 0.3
Specific time fourth shot 0.04 .. 30 0.5
Dead time fourth shot 0,1.. 100 0.3
7.7.1.5.2 Events
Code Event reason
E8 AR active started
E9 AR active back
E10 General enable started
E11 General enable back
E12 Test enable started
E13 Test enable back
E14 AR failed started
E15 AR failed back
E18 Block AR started
E19 Block AR back
E20 AR 1. shot started
E21 AR 1. shot back
E22 CB OK started
E23 CB OK back
E24 CB OK internal drop delayed started
E25 CB OK internal drop delayed back
E26 External trigger started
E27 External trigger back
E28 Shot increment started
E29 Shot increment back
E30 Stop AR started
E31 Stop AR back
E32 Test started
1VTA10002 Rev02 PTMV, 2003.12.10 216 / 234

Code Event reason

E33 Test back
E40 Close CB started
E41 Close CB back
E42 Open CB started
E43 Open CB back
E48 Shot 1 started
E49 Shot 1 back
E50 Shot 2 started
E51 Shot 2 back
E52 Shot 3 started
E53 Shot 3 back
E54 Shot 4 started
E55 Shot 4 back
E56 Shot 5 started
E57 Shot 5 back
1VTA10002 Rev02 PTMV, 2003.12.10 217 / 234

7.8 Fault recorder

7.8.1 Fault recorder
This function block allows the eight REF542plus analog input signals to be recorded
for a period of at least 1 second and for a maximum of 5 seconds. It is also possible
to record up to 32 digital signals simultaneously from the FUPLA.

Inputs
1 … 32 Digital signal (active high) 32 Input for recording binary signal
START Digital signal (active high) Start of the fault recording
OVERFLOW Digital signal (active high) Overflow signal indication
When BL signal becomes active, the fault recorder function is reset (no matter its
state), i.e. all output pins go low generating the required events (if any) and all internal
registers and timers are cleared. The fault recorder function will then remain in idle
state until BL signal goes low.
1VTA10002 Rev02 PTMV, 2003.12.10 218 / 234

7.8.1.2.1 General and setting parameters
Name: User defined Analog Input meaning.
Factor: Analog input scaling factor, used for display.
time before fault: Recording duration before recorder start input trigger.
Recording time: Total allocated duration, it limits the number of records

(from 5 to 1) in the ring buffer.
time after fault: Recording duration after recorder start input trigger.
7.8.1.2.2 Pins
1VTA10002 Rev02 PTMV, 2003.12.10 219 / 234

7.8.1.3 Operation
The fault recorder is started within the application. The recording time of the fault re-
corder is a combination of the time before the fault and the time after the fault. The
time before the fault refers to the period recorded before the fault recorder is actually
started from a protection start signal. The time after the fault is the period after the
fault recorder has started. Dynamic recording of the fault record e.g. from start signal
to signal CB OFF) is not possible.
The ring buffer process saves the specific fault record, i.e. the oldest fault record is
always overwritten with a new one. The number of saved fault records depends on
the record time. The total duration of all saved fault records is 5 seconds maximum, if
it is set to a lower value it limits the number of records in the buffer:
n=int((recording time/(time before + time after).
For example, 5 fault records can be saved with a record time of 1 s, that is the mini-
mum settable record time (time before the fault + time after the fault).
The fault records are exported with the configuration software and then converted to
the COMTRADE format. The fault records can also be exported via the bus of the sta-
tion control system. The conversion to the COMTRADE format has to be carried out
in the station control system.
Note The following limitations must be taken into account on the use of the fault recorder:
At least one protective function must be configured and
The start signal for the fault recorder must be implemented in the FUPLA.
The analog signals are digitized and processed with a 1.2 kHz sampling rate, be-
cause they are decisive for the protection trips. They therefore within a time grid of
0.833 ms. Start and trip signals from protection functions are recorded and sent to the
binary outputs immediately.
In contrary, the digital signals are processed in accordance with the FUPLA cycle
time. The cycle time depends on the application in this case. The digital signals are
therefore in a grid that is significantly larger than the analog signal grid.
The fault recorder is dedicated for recording fault data during a short circuit in the
network. The data can be exported from the REF542plus later and displayed with
suitable program.
1VTA10002 Rev02 PTMV, 2003.12.10 220 / 234

Figure 36: Example showing the graphic display of fault record data of a two-pole short circuit
with the WINEVE program

Time before fault 100 .. 2000 ms 100 Recording duration before re-
corder start.
Recording time 1000 .. 5000 ms 2500 User defined limit to total duration
of the buffer, i.e. to records num-
ber.
Time after fault 100 .. 4900 ms 1000 Recording duration after recorder
start.
1VTA10002 Rev02 PTMV, 2003.12.10 221 / 234

7.9 Appendix A – Connection Diagram

7.9.1 Directional protections Connection Diagram
In the following figures are reported as an example the typical connection diagram of
current and voltage transformers for a generic feeder and the convention used to de-
fine Forward and Backward direction of the power flow.
The connection of earth current sensor and of residual voltage sensor (Analog Input 7
and 8) may be required depending from the directional protection used.
Figure 37: Generic feeder connection, directional earthfault (67N, 67S) and overcur-
rent protections can be instantiated, residual current can be directly measured
1VTA10002 Rev02 PTMV, 2003.12.10 222 / 234

Figure 38: Generic feeder connection, directional earthfault (67N, 67S) and overcur-
rent protections can be instantiated, both residual current and residual voltage (open
delta) can be directly measured
1VTA10002 Rev02 PTMV, 2003.12.10 223 / 234

7.9.2 Differential and Restricted differential protections

Connection Diagram
Figure 39: Differential transformer feeder connection, restricted differential protection

on grounded star side winding can be instantiated.
1VTA10002 Rev02 PTMV, 2003.12.10 224 / 234

7.9.3 Synchro Check Connection Diagram
Figure 40: Syncro Check feeder connection, network 2 line 1-2 voltage connection on
Analog Input 8
1VTA10002 Rev02 PTMV, 2003.12.10 225 / 234

7.10 Appendix B –IDMT Protection Curve Characteristics

7.10.1 IDMT Protection Functions
The REF542plus makes available two Overcurrent IDMT and Earth fault IDMT protec-
tion functions.
For each protection one at the time of the four current-time characteristics can be ac-
tivated:
Normal inverse,
Very inverse,
Extremely inverse,
Long-term inverse.
7.10.1.1 Overcurrent IDMT

IDMT protection function evaluates the RMS value of phase currents at the funda-
mental frequency.
vated when respective phase current start conditions are true (phase current value is
above 1.2 times the setting threshold value, Base current Ieb).
tions are true and the calculated operating time has elapsed.
7.10.1.2 Earth fault IDMT

Earth fault IDMT function evaluates the measured or calculated amount of residual
current at the fundamental frequency.
When the measured or calculated earth current exceeds the setting threshold value
(Base current Ieb), by a factor 1.2 then the protection function is started and the
start signal will be activated.
cleared if the earth current falls below the 1.15 the setting threshold value.
operating time has elapsed.
1VTA10002 Rev02 PTMV, 2003.12.10 226 / 234

7.10.1.3 Operating time calculation

characteristic.
The formulas for the trip time according to British Standard (BS 142) and IEC 60255-3
are the following:
kß k
t = t =
(I I EB )
α
−1 (G GS )α − 1
BS142 IEC60255-3
where:
t: Time to trip
k: Time multiplier to vary time delay (BS 142, 0.05 ≤ K ≤ 1.5)or time value
(IEC 60255-3, see table)
α: Constant according to the list below
ß: Constant according to the list below (BS 142)
I/I EB : Fault current factor
I = G: Actual measured current
IEB = GS : Base current setting value
The following table shows the two constants α and ß for the different current-time
characteristics.
Current-time characteristic α ß (BS142) k (IEC 255) [s]

Normal inverse 0.02 0.14 0.14
Very inverse 1.0 13.5 13.5
Extremely inverse 2.0 80.0 80.0
Long time inverse 1.0 120.0 120.0
REF542plus implements the formula in accordance with BS 142 and the k-factor
ranges from of 0.05 to 1.50. When the time multiplier k in the “parameters” dialog
window is set to one (k=1) the REF542plus IDMT protections operate in accordance
with IEC 60255-3.
The tripping characteristic of the four different IDMT-curves are shown in the next fig-
ures. According to the standard the characteristic is only defined for G/Gs or I/IEB in
the range up to 20. If the values of the mentioned ratio G/GS or I/IEB is higher than 20,
the operating time remains constant as the operation time at the border value of 20.
1VTA10002 Rev02 PTMV, 2003.12.10 227 / 234

IDMT IEC60255-3
1000
1
t=
100
(G GS )α − 1
Time [ s ]
10
Long time Inverse
Normal Inverse
1
Very Inverse
Extremely Inverse
0.1
1 1.2 10 20 100
G/Gs
Figure 41: Tripping characteristic according to the IEC 60255-3 curve definition.
1VTA10002 Rev02 PTMV, 2003.12.10 228 / 234

IDMT Normal Inverse

100
k × 0.14
t=
(I I EB )0.02 − 1
10
Time [ s ]
k=1.5
k=1
1 k=0.5
k=0.1
k=0.05
0.1
1 1.2 10 20 100
I/Ieb
1VTA10002 Rev02 PTMV, 2003.12.10 229 / 234

IDMT Normal Inverse

100
k × 0.14
t=
(I I EB )0.02 − 1
10
Time [ s ]
k=1.5
k=1
1 k=0.5
k=0.1
k=0.05
0.1
1 1.2 10 20 100
I/Ieb
1VTA10002 Rev02 PTMV, 2003.12.10 230 / 234

IDMT Extremely Inverse

1000
k × 80
t=
100
(I I EB )2 − 1
10
Time [ s ]
1
k=1.5
k=1
0.1 k=0.5
k=0.1
0.01 k=0.05
1 1.2 10 20 100
I/Ieb
1VTA10002 Rev02 PTMV, 2003.12.10 231 / 234

IDMT Long time Inverse

1000
k ×120
t=
100 (I I EB ) − 1
Time [ s ]
10 k=1.5
k=1
k=0.5
1
k=0.1
k=0.05
0.1
1 1.2 10 20 100
I/Ieb
1VTA10002 Rev02 PTMV, 2003.12.10 232 / 234

7.11 Appendix C: Product Information
Product Information
ABB Australia Pty Limited ABB Secheron SA
Medium Voltage Medium Voltage
Power Technology Products Division Rue des Sablieres 4-6
Bapaume Road, Moorebank NSW 2170, CH – 1217 Meyrin
Switzerland
Australia
Phone: +61 2 9821 0111 Phone: +41 22 306 2646

Fax: +61 2 9602 2454 Fax: +41 22 306 2682
E-mail: abbptmv.aus@au.abb.com E-mail: info.secheron@ch.abb.com
internet: http://www.abb.com/au Internet: http://www.abb.ch
ABB Xiamen Switchgear Co. Ltd. ABB s.r.o.
ABB Industrial Park MV Switchgear
Torch Hi-tech.Development Zone Videnska 117
Xiamen, Fujian, P.R.of China 61900 Brno
Czech Republic
Phone: +86 (0)592 6026033 Phone: +420 5 4715 2413
Fax: +86 (0)592 6030505 Fax: +420 5 4715 2190
E-mail: info.ejf@cz.abb.com
Internet: http://abbcndmx.com.cn
Internet: http://www.abb.com
ABB Calor Emag Mittelspannung GmbH ABB Arab S.A.E
Product Management Medium voltage department
Oberhausener Straße. 33 Industrial Zone - B1,
40472 Ratingen 10 th of Ramadan City ,
Germany
Egypt.
Phone: +49 2102 12 1901 Phone: +20 15 36 1288

Fax: +49 2102 12 1808 1901 Fax: +20 15 36 1642
E-mail: calor.info@de.abb.com Internet: http://www.abb.com/eg
Internet: http://www.abb.de/calor
ABB Limited - Design & Development
MV Switchgear Division
plot No. 79 Street No. 17
Nashik -PIN- 422007
India
Phone: +91 0253 2351095

Fax: +91 0253 2350644
ABB T&D S.p.A, Unita’ Operativa ABB Ltd.

SACE T.M.S. Power Technology Medium Voltage
Product Management 513 Sungsung-dong (Chonan Foreign In-
Via Friuli 4 vested-Enterprises Industrial Park)
I-24044 Dalmine (BG) Chonan, Chungchong-namdo, Post 330-300
Italy Korea
Phone: +39 035 395 710 Phone: +82 41 529 2458

Fax: +39 035 395689 Fax: +82 41 529 2500
E-mail: sacetms.tipm@it.abb.com E-mail: swgr.info@kr.abb.com
Internet: http://www.abb.com Internet: http://www.abb.com.kr
1VTA10002 Rev02 PTMV, 2003.12.10 233 / 234

Product Information
ABB Transmission & Distribution Sdn. Bhd. ABB Elektrik Sanayi A.S.
Manufacturing Medium Voltage Technology
Lot 608, Jalan SS 13/1K Power Technology Products Turkey
47500 Subang Jaya, Petaling Jaya Design&Order Handling
Selanggor Darul Ehsan Organize Sanayi Bölgesi 2. Cadde No:16
Malaysia Yukar Dudullu 81260 Istanbul
Turkey
Phone : +90 216 528 20 00

Phone: +603 5628 4888
Fax : +90 216 365 29 43
1VTA10002 Rev02 PTMV, 2003.12.10 234 / 234


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Multifunction Protection and Switchgear Control Unit

Configuration and Settings

6.1.2.1 Input/Output description ..............................................................28

1VTA10002 Rev02 PTMV, 2003.12.10 3 / 234

7.1.2.7.2 Events .........................................................................................53

7.1.6.2 Configuration ...............................................................................70

7.1.9.2.6 Pins .............................................................................................89

1VTA10002 Rev02 PTMV, 2003.12.10 6 / 234

7.2.3.5 Setting groups ...........................................................................106

1VTA10002 Rev02 PTMV, 2003.12.10 7 / 234

7.3.3.6.1 Setting values............................................................................122

1VTA10002 Rev02 PTMV, 2003.12.10 8 / 234

7.5 Differential protection ...............................................................................150

1VTA10002 Rev02 PTMV, 2003.12.10 9 / 234

7.6.1.4 Operation criteria.......................................................................175

7.6.5.1 Input/Output description ............................................................189

1VTA10002 Rev02 PTMV, 2003.12.10 12 / 234

1 About this manual

1.2 REF542plus Network address

1VTA10002 Rev02 PTMV, 2003.12.10 13 / 234

3 Acronyms and definitions

3.3 Document information

1VTA0002 15.07.2003 1st release, valid since SW V4C01

1VTA10002 Rev02 PTMV, 2003.12.10 14 / 234

4 REF542plus analog measurement

AA LP Filter HP Filter ADC

LP2 Filter LP3 Filter

DFT / RMS & Math

Protection & Control

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5.1.1.1 Analog Board selection

5.1.1.2 Current Transformer

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5.1.1.3 Current Rogowski

5.1.1.4 Voltage Transformer

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5.1.1.4.1 Phase-Voltage Transformer

Phase-voltage transformers normally refer rated phase-voltage at primary sidewith

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5.1.1.4.2 Line Voltage Transformer

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5.1.1.4.3 Residual Voltage Transformer (open delta)

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5.1.1.5 Voltage Sensor

5.1.2 General constraints

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5.1.3 Network characteristics

5.1.4 Calculated values

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6 Control and monitoring

6.1.1.1 Input/Output description

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The measurement supervision functions operate on all sensors in a triple (analog

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Start Value: Positive/Negative phase sequence threshold for Start condition

Time: Time delay for Trip condition detection.

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6.1.1.3 Measurement mode