GEA-S1301A

EX2100e Excitation Control

35 A and 120 A Regulator Systems
Product Description

These instructions do not purport to cover all details or variations in equipment, nor to provide for every possible
contingency to be met during installation, operation, and maintenance. The information is supplied for informational
purposes only, and GE makes no warranty as to the accuracy of the information included herein. Changes, modifications,
and/or improvements to equipment and specifications are made periodically and these changes may or may not be reflected
herein. It is understood that GE may make changes, modifications, or improvements to the equipment referenced herein or to
the document itself at any time. This document is intended for trained personnel familiar with the GE products referenced
herein.
This document is approved for public disclosure.
GE may have patents or pending patent applications covering subject matter in this document. The furnishing of this
document does not provide any license whatsoever to any of these patents.
GE provides the following document and the information included therein as is and without warranty of any kind, expressed
or implied, including but not limited to any implied statutory warranty of merchantability or fitness for particular purpose.
For further assistance or technical information, contact the nearest GE Sales or Service Office, or an authorized GE Sales
Representative.

Revised: Jul 2014

Issued: Nov 2013

Copyright © 2013 General Electric Company, All rights reserved.

___________________________________
* Indicates a trademark of General Electric Company and/or its subsidiaries.
All other trademarks are the property of their respective owners.

We would appreciate your feedback about our documentation.

Please send comments or suggestions to controls.doc@ge.com

For public disclosure

 Contents
1 Overview ....................................................................................................................................................3
1.1 Acronyms and Abbreviations ....................................................................................................................4
2 Control Hardware .........................................................................................................................................5
2.1 Digital Controller (IGBT-based Systems) ....................................................................................................7
2.2 Dual Control (Power Bridge Warm Backup).................................................................................................7
2.3 Control Cabinet ......................................................................................................................................8
2.4 Power Conversion Module...................................................................................................................... 10
3 Control Software ........................................................................................................................................ 12
4 Specifications and Standards......................................................................................................................... 15
5 Testing...................................................................................................................................................... 16
5.1 Routine Factory Tests ............................................................................................................................ 16
5.2 Customer Witness Tests ......................................................................................................................... 16

2 GEA-S1301A EX2100e Excitation Control 35 A and 120 A Regulator Systems

For public disclosure
1 Overview
GE has supplied more than The EX2100e Excitation Control Regulator system is GE’s most recent state-of-the-art
6,000 thyristor and regulator control system for steam, gas, or hydro generators for both new and retrofit units. Control
systems in over 70 countries hardware and software design is closely coordinated between GE’s system and controls
during the last 40 years. The engineering to ensure delivery of a true system solution. Integration is seamless between
EX2100e Control Regulator Excitation Control systems, Turbine Control systems, Static Starter Control systems,
system is GE’s fourth Integrated Control Systems (ICS), and the Human-machine Interface (HMI). For
generation digital excitation stand-alone retrofit applications, integration with customer distributed control systems
control system. (DCS) through serial or Modbus® Ethernet is supported. This document specifically
addresses applications for the 35 A and 120 A (nominal) series of EX2100e Control
There are over 4,000 first and Regulator systems.
second generation GE digital
excitation controls operating in
60 countries.

EX2100e Control Cabinet (35 A Regulator System)

Product Description GEA-S1301A 3

For public disclosure
 1.1 Acronyms and Abbreviations
ARCC Active reactive current compensation
AVR Automatic Voltage Regulator
COI Control Operator Interface
CT Current Transformer
DCS Distributed Control System
ECTX EX2100e CT Expansion Board
EDFF EX2100e dc Fanned Feedback Board
EGD Ethernet Global Data
EMC Electromagnetic Compatibility
EMI Electromagnetic Interference
ESYS EX2100e System Interface Board for Customer I/O
EXAM Exciter Attenuator Module
FCR Field Current Regulator
FPGA Field programmable gate array
FVR Field Voltage Regulator
HMI Human-machine Interface
HSLA High-speed Serial Link Interface Board for Host Application Boards
HSSL High-speed Serial Link
ICS Integrated Control System
IGBT Insulated Gate Bipolar Transistor
I/O Input and output
PCM Power Conversion Module
PF Power Factor
PI Plus Integral
PMG Permanent Magnet Generator
PPT Power potential transformer
PSS Power System Stabilizer
PT Potential transformer
PWM Pulse-width Modulator
RCC Reactive Current Compensation
RFI Radio frequency interference
SCM Shunt Contactor Module
SCR Silicon-controlled rectifier
SCT Saturable current transformer
SOE Sequence of events
TCM Transfer Control Module
TMR Triple Modular Redundant
UBC Universal Building Code
UCSB Universal Controller Stand-alone Board
UDH Unit Data Highway
UEL Underexcitation Limit control
V ac Volts ac (alternating current)
VAR Volt-amperes reactive
V dc Volts dc (direct current)
WBU Warm Backup

4 GEA-S1301A EX2100e Excitation Control 35 A and 120 A Regulator Systems

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2 Control Hardware
The EX2100e Regulator system is available in several configurations to provide control
flexibility for Thyristor and Regulator systems. For small Regulator systems, two
pulse-width modulated (PWM) power converter modules use Insulated Gate Bipolar
Transistors (IGBT) to provide up to 35 A or 120 A nominal output. These systems can
support the following applications:

• Saturable Current Transformers / Power Potential Transformers (SCT/PPT) regulator

• Brushless exciter regulator
• Direct current (dc) rotating exciter regulator
In the SCT/PPT regulator and dc rotating exciter regulator applications, the EX2100e
Regulator system can de-sensitize the effect of the exciter time constant. It incorporates
direct measurement of the generator field voltage and field current to enhance speed of
response to system transients.
The architecture is a single control with a single Power Control Module (PCM) or dual
control with dual PCM, including a customer interface sub-system, optional diagnostic
local operator interface (touchscreen), optional control operator interface (COI) remote
touchscreen interface, control power input module, and PCM. The PCM consists of a
bridge interface sub-system, power bridge, optional ac and dc filter networks, and
alternating current (ac) and/or dc isolation devices. For expanded input and output (I/O)
capability, either VersaMax® or Mark* VIe control IONet I/O modules may be added.
The EX2100e Regulator system supports Ethernet local area network (LAN)
communication to the following:

The EX2100e Regulator system • Turbine controls and ICS, HMI, Proficy*-based Historian, Programming Interface
incorporates a powerful (PI-based) Historian, Onsite Monitoring System (OSM), and COI
diagnostic system and a • Extended I/O modules using the Ethernet Global Data (EGD) protocol
control simulator to support
rapid installation, tuning of • Customer DCS through Ethernet or Modbus Ethernet remote terminal unit (RTU)
control constants, and training. • ToolboxST* application
• GE Onsite Support* for monitoring and diagnostics

Product Description GEA-S1301A 5

For public disclosure
 EGD or Control
Modbus Power

Customer I/O
CT Current
I/O
PT-1
Voltage
Bridge I/O
PT-2
PT-2 (Optional)
[Optional ]
AUX
Aux AC
AC Source
Source(Optional)
(Opt.) Control Control
M2 M1
AC Circuit
Breaker
Generator Terminals (Optional ) Dual
Selector

PPT
PMG (Optional )
G 1-phase or
Line Filter (Optional ) 3-phase
Input Power

AC CB AC CB
DC CB

Brushless or
DC Rotating
DC CB Full Wave
Exciter
Rectifier
125-250 V dc
Battery Input

IGBT PCM
IGBT PCM (Bridge #2)
(Bridge #1)
(Optional )

Transfer switch

DC Contactor

Shunt

EX2100e Control 35 A and 120 A Regulator Systems Functional Diagram

6 GEA-S1301A EX2100e Excitation Control 35 A and 120 A Regulator Systems

For public disclosure
 2.1 Digital Controller (IGBT-based Systems)
The control and PCMs are The EX2100e Excitation control products offer a Regulator control system in a 800 mm
panel-mounted. (32 in) enclosure with supporting hardware based on the particular application. Other
packaging options are available. The Regulator system can be purchased as part of a
finished cabinet, or individual components can be shipped separately for onsite mounting
to better serve retrofit applications.
Power conversion consists of an input section, a dc link, and the converter output section.
The input section is a 3-phase diode bridge with input filters. The system accepts a
An input PPT is not required primary ac input range of 90 to 280 V rms, nominal for the 35 A system, and up to 480 V
for the PMG input, but it is rms for the 120 A system. The ac input is 480 Hz (maximum), which can be supplied as
required for an auxiliary bus 1-phase or 3-phase from a permanent magnet generator (PMG), auxiliary bus, or
or generator terminal feed. generator terminals.
As a backup, the system accepts a secondary power input from a dc battery bank (125 to
250 V dc nominal). The dc secondary input is diode-isolated and combined with the
3-phase diode bridge output. These sources energize the dc link, which is an unregulated
source voltage for the control output power through the IGBTs. The dynamic discharge
(DD) circuit limits the dc link voltage level during events such as load rejection or unit
trip.
The converter output section uses IGBTs to pulse-width modulate the dc link source
voltage to its final value. The chopping frequency of the IGBTs is approximately 1,000
Hz. This output is fed to the exciter field as a regulated voltage or current. An output
shunt monitors the field current. Continuous dc output is provided up to 100% rating with
temporary forcing capabilities up to 210%. Regulated output flows through a dc contactor
to the exciter field.
The EX2100e Regulator system contains interface boards that are interconnected through
a high-speed serial link (HSSL) and cabled to their associated I/O terminal boards.

2.2 Dual Control (Power Bridge Warm Backup)

The EX2100e Regulator system is available in a warm backup (WBU) configuration,
which includes dual exciter control I/O and protection. The control includes M1 (Master
One) and M2 (Master Two), with two IGBT bridges that can accept separate or shared ac
input power. The control configuration can also share a common dc output circuit to the
exciter field through the transfer module. M1 and M2 are independent controls, each with
automatic and manual regulator functions. Either M1 or M2 can control bridge firing, as
determined by the operator. In the WBU configuration, M1 controls bridge #1, and M2
controls bridge #2.
To process application software, two independent Universal Controller Stand-alone Board
Version B (UCSB) controllers, with separate PCMs and an output selector module (SCM
or TCM), provide the dc output current for the exciter field (or SCT control winding).
The active power bridge receives the gating commands from the active control (M1 or
M2), and supports the full-field voltage and current needs of the exciter field while the
backup power bridge’s gating circuit is inhibited. The operator has full control to select
which of the dual power bridges is active or inactive. Bi-directional, bumpless transfer
between active and inactive bridges is standard. The active master can also self-diagnose
a failure or missed operation and activate the backup control and power bridge without
operator intervention.

Product Description GEA-S1301A 7

For public disclosure
 AC DC

PPT

UDH
Touchscreen
ToolboxST Ethernet
ENET Local Control
VersaMax Switch
SWITCH
COI

UCSB
CPU PCM1
IONet e1

HSLA
UCSB ERSD or IGBT
ERAX

hsla
CPU t M1
ERBI PCM
IONet Ethernet M1 M1 M1 SCM /
I/O Switch TCM
s r
EXAM / ERGT Transfer
Ground Relay K5 , To
86 Lockout Detector K41 , & DC Exciter
Shunt Field

r
fib e
PCM2
e1 r
UCSB ERAX ERSD or IGBT

HSLA
hsla
CPU t M2 ERBI PCM
HSLA M2 M2
PTs & CTs ESYS M2
External HSLA s
Customer I/O
I/O er EDSL
Transducers fi b Dual
GEN Field EDFF Select
Feedbacks

28 V dc Control Power Distribution

= HSSL

24 , 125 V dc PWR SUP PWR SUP

120, 240 V ac M1 M2

EX2100e Regulator Dual Control System Block Diagram

2.3 Control Cabinet

EX2100e Regulator system The EX2100e Regulator system is encased in a NEMA® 1/IP20 or IP21 freestanding,
modules may be shipped as a indoor metal cabinet for floor-mounting installation. An IP54 option for the cabinet is
parts kit for retrofit into also available. The standard cabinet color is ANSI-70 (light gray) on exterior surfaces
existing control systems. (other colors are available). Interior surfaces are galvanized steel. The equipment is
designed to operate in an ambient temperature range of 0 to 40°C (32 to 104 °F).
Depending upon the specific application, a current derating factor may apply at 50°C
(122 °F).

8 GEA-S1301A EX2100e Excitation Control 35 A and 120 A Regulator Systems

For public disclosure
 EX2100e Control 120 A Regulator Cabinet

EX2100e Control 35 A Regulator Cabinet (Right Side Floor Hidden, Left Side Wall and Roof Hidden)

Product Description GEA-S1301A 9

For public disclosure
 2.4 Power Conversion Module
The Power Conversion Module (PCM) consists of an integrated IGBT inverter module
that contains six IGBTs connected in a 3-phase inverter configuration. Two of the six
IGBTs are used to create the PWM dc output for field excitation. A third IGBT is used to
discharge the dc link capacitors into an external DD resistor to prevent overvoltage.
Input power is either rectified ac, dc from a station battery, or both.
In the dual redundant application, there is a primary control and PCM (M1) and a backup
control and PCM (M2), which are identical. A transfer module evaluates the health of the
primary and backup controls and selects which control is active to provide maximum
reliability and availability.

35 A Regulator PCM

10 GEA-S1301A EX2100e Excitation Control 35 A and 120 A Regulator Systems

For public disclosure
 120 A Regulator PCM

Product Description GEA-S1301A 11

For public disclosure
3 Control Software
The EX2100e control software supports high performance and helps the customer and
field engineers understand, install, commission, tune, and maintain the excitation control
system. The exciter software is configured and loaded from the ToolboxST application
and resides in the controllers. The software is represented on the ToolboxST Component
Editor screen by control blocks that are linked together to display the signal flow.
The generator voltages and currents from the PTs and CTs are the source of the control
signals needed by the automatic (generator terminal voltage) regulator, most limiters, and
protection functions. They are wired to the ESYS, which acts as a signal conditioner to
isolate and scale the signals. The conditioned signals are fed to the controller. The system
simultaneously samples the ac waveform at high speed and uses advanced mathematical
algorithms to digitally generate the needed variables.
The output of the software transducer system includes the following:

• Generator voltage
• Generator active current (average in phase with watts)
• Generator reactive current (average in phase with reactive power, VARs)
• Generator frequency (current)
• Slip (signal representing the change in the rotor speed)
The transducer system uses the output to calculate the following:

• Generator power and VARs

• Magnitude of generator flux (V/Hz)
• Phase angle and power factor

12 GEA-S1301A EX2100e Excitation Control 35 A and 120 A Regulator Systems

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 The following figures provide a simplified overview of the exciter control system,
displaying the main control functions. Both the generator field and stator currents and
voltages are measured and input to the control system. In normal operation, the ac
regulator is selected.

Software Overview Block Diagram (1 of 2)

Product Description GEA-S1301A 13

For public disclosure
 Software Overview Block Diagram (2 of 2)

14 GEA-S1301A EX2100e Excitation Control 35 A and 120 A Regulator Systems

For public disclosure
4 Specifications and Standards
Item Description
Physical Characteristics

Enclosure NEMA 1/IP20 or IP21 freestanding, indoor metal cabinet, floor mounted
Optional IP54 available

Cabinet dimensions Standard cabinet: 800 x 2290 x 830 mm (32 x 90 x 32.5 in)
(W x H x D) 35 A Simplex cabinet: 610 x 2286 x 508 mm (24 x 90 x 20 in)

Paint Exterior: ANSI®-70 (light gray) (other colors available)

Interior: Galvanized steel
Environmental Characteristics
Ambient temperature 0 to 40°C (32 to 104 °F); current derating at 50°C (122 °F)

Ac input range 35 A: 90-280 V rms, nominal

120 A: Up to 480 V rms

Ac input frequency 480 Hz maximum

Nominal continuous 35 A: 250 V dc at 35 A dc

output 120 A: 250 V dc at 120 A dc

Supported Standards

Safety UL508C Standard for Power Conversion Equipment

CSA 22.2 No. 14 Industrial Control Equipment
OSHA 29 CFR Part 1910 Subpart S, Electrical Safety Requirements

CE Electromagnetic Compatibility (EMC) Directive 2004/108/EC:

EN 55011: ISM equipment emissions (CISPR 11)
EN 6100-6-4 & -6-2 Emissions and Immunity, Industrial Environment

• EN 61000-4-2 Electrostatic Discharge Susceptibility

• EN 61000-4-3 Radiated RF Immunity

• EN 61000-4-6 Conducted RF Immunity

• EN 61000-4-4 Electrical Fast Transient Susceptibility

• EN 61000-4-5 Surge Immunity

Low Voltage Directive 2006/95/EC:

EN 50178 Electronic equipment for use in power installations 1997

IEEE™ 421.1 Standard Definitions for Excitation Systems for Synchronous Machines (2007)
421.2 Guide for Identification, Testing, and Evaluation of the Dynamic Performance of Excitation
Control Systems (1990)
421.3 High-Potential Test Requirements for Excitation Systems for Synchronous Machines (2004)
421.4 Guide for the preparation of Excitation Systems Specifications (2004)
421.5 Recommended Practice for Excitation Systems for Power Stability Studies (2005)
C57.12.01 General Requirements

Seismic IBC 2006/Universal Building Code (UBC) – Seismic Code section 2312 Zone 4

Product Description GEA-S1301A 15

For public disclosure
5 Testing
The following section is a brief description of the quality assurance tests performed on
each exciter.

5.1 Routine Factory Tests

Each excitation control is subjected to routine factory tests including, but not restricted to,
the following:

• Circuit continuity check

• Di-electric (hi-pot) tests in accordance with IEEE standard 421B
• Functional check of all components and devices for proper operation

5.2 Customer Witness Tests

All equipment goes through After routine factory tests are complete, the customer can participate in a witness test.
extensive testing with Two options are available:
appropriate reviews and
sign-offs. Refer to the section, • Option A: The customer examines the appearance and workmanship of the
Routine Factory Tests equipment, then reviews the engineering and test paperwork. This is a standard
service for no additional charge.
Customers are always welcome • Option B: The customer witnesses a demonstration of the hardware and software.
to visit the GE factory to see This is an added-cost item to the customer.
how their equipment is
engineered and manufactured.

16 GEA-S1301A EX2100e Excitation Control 35 A and 120 A Regulator Systems

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Glossary of Terms
Auto Regulator Reference (AUTO REF) generates the auto control (AC) setpoint
variable for the automatic voltage regulator (AVR). Operator commands, (raise and lower
inputs) come from direct inputs or over a data link from an HMI operator station, or from
a plant DCS or remote dispatch system.

Automatic and Manual Reference Follower (Tracking) are

software-implemented ramp functions that adjust the non-active regulator output to
automatically track the active regulator. That is, when the auto regulator is controlling the
generator, the manual regulator tracks, and when the manual regulator is controlling the
generator, the auto regulator tracks. This provides for smooth transition when a transfer
occurs from one regulator to the other.

Automatic Voltage Regulator (AVR) maintains the generator terminal voltage

constant over changes in load and operating conditions.

DCS Interface (ModBus RTU) slave data link is supported to interface with
customer DCS systems. This link uses TCP/IP support over Ethernet 10/100baseT
hardware. Both commands and data can be supported.

Exciter AVR Setpoint (EXASP) combines a number of functions to produce the

reference input to the AVR and the variables to support regulator tracking.

Generator Field Temperature Calculation measures the resistance by dividing

the field voltage by the field current. From the known field resistance at 25°C (77 °F) and
the linear resistance temperature change in copper, the algorithm calculates operating
temperature. An adjustable high temperature alarm output contact is also included.

Generator Overvoltage Trip (59G) monitors the generator armature voltage and
initiates a trip signal upon detecting an unacceptably high voltage.

Generator Simulator (GEN SIM) is a detailed generator model that is included as

part of the excitation control system software. It can be configured to closely match the
operation of the real generator. It can also be used for operator training, and can support
the checkout of regulators, limiters, and protection functions while the unit is shut down.

Hydrogen Pressure/Temperature Limiter compensates the configuration

parameters of key generator limiters and protection functions based on generator cooling.
For hydrogen-cooled generators, the correct parameter is the internal hydrogen pressure,
and for air-cooled generators, it is air temperature. The three limiters affected by
pressure/temperature compensation are:

• Underexcitation limiter (UEL)

• Overexcitation limiter (OEL)
• Stator current limiter

Loss of Excitation Protection (40) detects a loss of excitation on synchronous

machines using a two-zoned timed trip function that is based on resistance and reactance.

Manual Regulator (FVR) controls the generator field voltage or current, letting the
generator output voltage. The manual regulator, like the AVR, uses a PPI regulator with
integrator windup protection and its control output directly controls the firing command
generator that controls the gating of the power bridge when enabled.

GEA-S1301A Glossary of Terms 17

For public disclosure
 Manual Regulator (FCR) is a special application of the manual regulator and uses
the generator field current as the feedback input. While it does regulate constant field
current over varying field temperature, GE has not selected the FCR as its standard
manual regulator because it inhibits the signal independence from the over excitation
limiter.

Manual Regulator Reference (MANUAL REF) generates the manual setpoint

variable for the manual voltage regulator (MVR). Operator commands, (raise and lower
inputs) come in from direct inputs or over a data link from an HMI operator station or
from a plant DCS or remote dispatch system.

Manual Restrictive Limiter limits the under-excited operation of the EX2100e

while the manual regulator is selected (FVR or FCR). It also does not allow the manual
regulator to track the automatic regulator when the unit is operating below the field
voltage limit called for by the manual restrictive limiter.

Overexcitation Limiter (OEL) and Offline Overexcitation Protection

(OLOT) protect the generator field from damage by events that require abnormally high
field currents. These high currents, over an extended time, can overheat the field and
cause damage. Generator fields are designed to ANSI standard C50.13, which specifies
the overvoltage as a function of time that the field is designed to follow. This standard
uses curves to describe the field overheating as a function of time and current.

Potential Transformer Fuse Failure Detection (PTFD) detects loss of PT

feedback voltage to the voltage regulator. If the sensing voltage is lost or if it is
single-phased, there is a transfer to the manual regulator and an alarm output is provided.

Power System Stabilizer (PSS) provides an additional input to the automatic

regulator to improve power system dynamic performance. The PSS offered in the
EX2100e control is a multi-input system using a combination of synchronous machine
electrical power and internal frequency (which approximates rotor speed) to arrive at a
signal proportional to rotor speed. This comes from the integral of accelerating power, but
with shaft torsional signals greatly attenuated.

Reactive Current Compensation (RCC/Line Drop) has two modes: RCC and
Line Drop. The RCC mode permits sharing reactive current between paralleled machines.
Line Drop mode allows for better regulation of voltage at some point down stream from
the generator terminals.

Stator Current Limit (SCL) determines the AVR/VAR control. When the generator
stator current exceeds the rated value, the exciter changes from AVR control to a VAR
control preset. Once the stator current is less than the rated value, the exciter returns to
AVR control.

18 EX2100e Excitation Control 35 A and 120 A Regulator Systems

For public disclosure
 Transfer to Manual Regulator upon Loss of PT detects loss of PT feedback
voltage to the ac voltage regulator. If the sensing voltage is lost, the regulator forces its
output to ceiling for 0.5 sec and then transfers to manual. This is distinctly different from
the PTFD function, which does not force the regulator to ceiling before transferring.

Underexcitation Limiter (UEL) is an auxiliary control to limit the AVR demand for
underexcited reactive current. The UEL prevents reductions of the generator field
excitation to a level where the small-signal (steady state) stability limit or the stator core
end-region heating limit is exceeded. Performance is specified by identifying the region
of the limiter action on the generator capability curve.

Unit Data Highway Interface (UDH) connects the exciter with the turbine control
system, HMI or HMI viewer/data server, and GE controls. The UDH is based on EGD
protocol. The UDH provides a digital window into the exciter where variables can be
monitored and controlled. It also supports the ToolboxST application configuration and
maintenance tool for the exciter.

VAR/PF Control is accomplished by slow ramping of the AVR reference setpoint.

The VAR/PF is selected by operator command and the VAR/PF value is controlled using
the raise/lower push-buttons. When the exciter interfaces with a Mark VIe turbine control
system, this function is typically included.

Volts per Hertz Limiter (V/Hz Lim) limits the generator V/Hz ratio to the
programmed setting in the EX2100e. This function uses two inputs from the software
transducer, average generator voltage and generator frequency (its V/Hz ratio is
configurable). Typically, the generator is considered to be operating acceptably within
±5% of rated terminal voltage at rated frequency.

Volts per Hertz Protection (V/Hz 24G) serves as a backup to the V/Hz limiter. The
protection scheme consists of two levels of V/Hz alarm and trip protection. Typically, one
level is set at 1.10 per unit over V/Hz with an inverse time period, and the other level is
set at 1.18 per unit with a two second time period.

When out-of-limit operation causes the exciter to trip, the controller stops gating the
power converter IGBTs. The field current flows back into the dc link and rapidly
collapses as its energy transfers into the dc link capacitors. To prevent overvoltage of the
dc link, the dynamic discharge (DD) resistor is automatically connected across the dc link
to dissipate the energy from the field.

1501 Roanoke Blvd.

Salem, VA 24153 USA
For public disclosure