Static Ex System

gGE Industrial Systems

GEI-100488

EX2100Static Excitation System

These instructions do not purport to cover all details or variations in equipment, norto provide for every possible contingency to be met during installation, operation,and maintenance. If further information is desired or if particular problems arisethat are not covered sufficiently for the purchaser�s purpose, the matter should bereferred to GE Industrial Systems.

This document contains proprietary information of General Electric Company, USA,and is furnished to its customer solely to assist that customer in the installation,testing, operation, and/or maintenance of the equipment described. This documentshall not be reproduced in whole or in part, nor shall its contents be disclosed to anythird party without the written approval of GE Industrial Systems.

Section Page

Introduction..................................................................................................................3Hardware......................................................................................................................3

Digital Controller (Thyristor-Based Controls)......................................................6Application Control Layer Board (ACLA)...........................................................7Digital Signal Processor Control Board (DSPX)..................................................8Exciter ISBus Board (EISB).................................................................................8Exciter Selector Board (ESEL).............................................................................8Exciter PT/CT Board (EPCT)...............................................................................8Exciter Contact Terminal Board (ECTB) .............................................................9Exciter Terminal Board (EXTB) ..........................................................................9Excitation Power Supply Module (EPSM and EPBP)..........................................9Exciter Power Distribution Module (EPDM) .....................................................10Gate Pulse Amplifier Board (EGPA)..................................................................10Exciter DC Feedback Board (EDCF) .................................................................11Exciter AC Feedback Board (EACF) .................................................................11Exciter De-Excitation Module (EDEX)..............................................................11Power Control Module (Thyristor � SCR)..........................................................13DC Interrupting Device ......................................................................................13AC Isolation Device ...........................................................................................13Shaft Voltage Suppressor....................................................................................14Crowbar Module.................................................................................................14Field Flashing Module ........................................................................................14Field Ground Detector (EGDM).........................................................................14Redundancy (Power Bridge � Warm Back-Up) .................................................15Operator Console (Remote/Local)......................................................................15Diagnostic Interface (Keyboard) ........................................................................16Cabinet................................................................................................................16Standards Supported ...........................................................................................17

________Ethernet is a trademark of Xerox Corporation.SPEEDTRONIC is a trademark of General Electric Company, USAVersaMax is a trademark of GE Fanuc Automation North America, Inc.

2 •••• EX2100 Static Excitation System GEH-100488EX2100

Software .................................................................................................................... 18Overview............................................................................................................ 18Software Transducers......................................................................................... 18Auto Regulator Reference (AUTO REF)........................................................... 19Manual Regulator Reference (MANUAL REF) ................................................ 19Automatic and Manual Reference Follower (Tracking) ................................... 20Exciter AVR Setpoint (EXASP) ........................................................................ 21Under Excitation Limiter (UEL)........................................................................ 21Reactive Current Compensation (RCC/ARCC)................................................. 21Volts per Hertz Limiter (V/Hz Lim) .................................................................. 21Automatic Voltage Regulator (AVR) ................................................................ 21Power System Stabilizer (PSS).......................................................................... 22Stator Current Limit (SCL)................................................................................ 22Manual Regulator (FVR or FCR) ...................................................................... 22Over-excitation Limiter (OEL) .......................................................................... 23Hydrogen Pressure / Temperature Limiter Compensation................................ 23Manual Restrictive Limiter ................................................................................ 23VAR/PF Control ................................................................................................ 23Generator Simulator (GEN SIM)....................................................................... 24Unit Data Highway Interface (UDH)................................................................. 24DCS Interface (ModBus) ................................................................................... 24Volts per Hertz Protection (24G)....................................................................... 24Over-Excitation Protection (OET)..................................................................... 24Generator Overvoltage Trip (59G) .................................................................... 24Potential Transformer Fuse Failure Detection (PTFD)...................................... 25Transfer to Manual Regulator upon Loss of PT................................................. 25Loss of Excitation Protection (40) ..................................................................... 25Exciter Phase Unbalance (EUT) ........................................................................ 25OffLine Over Excitation Protection (OLOT)..................................................... 25Generator Field Temperature Calculation.......................................................... 25

Testing ...................................................................................................................... 26Routine Factory Tests ........................................................................................ 26Customer Witness Testing ................................................................................. 26Option A � Customer Witness ........................................................................... 27Option B - Customer Witness ............................................................................ 27

GEH-100488EX2100 EX2100 Static Excitation System •••• 3

IntroductionThe EX2100 Excitation System is GE�s latest state-of-the-art control offering forboth new and retrofit steam, gas, or hydro generation. GE has supplied more than6,000 static excitation systems in over 70 countries during the last 40 years. EX2100is GE�s third generation of digital excitation systems. There are approximately 1,000first and second-generation GE digital excitation controls operating in 27 countries.Hardware and software design is closely coordinated between GE�s system engi-neering and controls engineering to ensure you receive a true �system� solution.

HardwareThe EX2100 is available in several configurations to provide flexibility for full staticexcitation systems. These systems can support potential (voltage only) or compound(voltage and current) source.

The architecture is one control rack, the customer interface sub-system, operator in-terface device, control power input module and the power module. The power mod-ule consists of a bridge interface sub-system, power bridge, ac and dc filter networks,and ac and/or dc isolation devices.

The EX2100 supports Ethernet� local area network (LAN) communication to:

• Control System Toolbox (toolbox)

• Mark VI turbine control system and HMI using the Ethernet Global Data (EGD)protocol

• Static Starter

• OnSite center

It can also support a RS-232 ModBus interface to a customer Distributed ControlSystem (DCS).

The EX2100 incorporates a powerful diagnostic system and a control simulator tosupport fast installation, tuning of control constants, and training.

The following two figures include a one-line diagram overview of the EX2100 sys-tem, and all the printed wiring boards (PWBs) in the EX2100, along with major in-terconnections.


FlashingControl

DC CB orContactor

Shunt

Shaft Voltage Suppression

Active FieldGround Detector

Bridge I/O

Line Filter

Generator

AC

ACLoad

I/O

Customer I/O

Gating Selector(Bridge 1 or 2)

ControlM2

ControlM1

ControlC

AC AC CBAuxSource

PT

CT

DC

AC CB orDisconnect

PPT

PowerConversionModules(Bridge #1)

Current

Voltage

DiagnosticInterface(Keypad)

ControlPower

Supplies

AC DC

UnitData

Highway

Deexcitation

Crowbar

PT: Potential TransformerCT: Current TransformerCB: Circuit BreakerI/O: Input/OutputPPT: Power Potential Transformer

PowerConversionModules(Bridge #2)

To Bridge#1 only

To Bridge#2 only

One-line Diagram of EX2100, Showing Major Functional Components


PT

CT

TRIPTRIPTRIPTRIP86868686

PT

PT

PT

CT

To Flashingpanel

41 Device

ACLA

DSP

X

EPCT

EMIO

Mas

ter I

/0ES

EL

Fan-outcircuits

2nd2nd2nd2ndTRIPTRIPTRIPTRIP

ECTB

Brid

ge 1

ACLA

DSP

X

DSP

X

EMIO

Mas

ter I

/O

EMIO

Mas

ter I

/0

Brid

ge 2

Brid

ge 3

Brid

ge 4

Brid

ge 5

Brid

ge 6

70V

De-excitation

-125Vdc

Crowbar

Gate Pulse Amplifiers

EISB

ESEL

EISB

EISB

EDCF

EDCF

EDCF

EGPA

125Vdc

EGPA

125Vdc

PowerSupply

EPDM Coil Power

125 V dcBattery

125 Vdc

P24V

PN24V70V

EDEXDe-excitation

EACF

PPT and air core CT (AC) Feedbacks

FieldGroundDetectorEGDM

EXTB

53Apilot

41trip

41trip

41trip

53Bpilot

53Bpilot

53Bpilot

53Apilot

53Apilot

41close

41close

41close

Opt

ion:

Fie

ld B

reak

er

70V

70V

De-expilot

Tool

EETB

Ethernet Data Highway to Turbine Control and HMI

EBKPBackplane

Keypad Keypad

M2M1 C

PowerSupply

70V P24V

PN24V

PowerSupply

70V P24V

PN24VEGDM

EGDM

EGDM

Fiber-optic FieldV & I feedback

EPSM EPSM EPSM

EPBPbackplane

Option:DACA

Rectified ac

Optional:Crowbar

EXAMAttenuatorGPA power

EX2100 PWB and Interconnection Overview


Digital Controller (Thyristor-Based Controls)The control module, M1 or M2, contains two processor boards with associated I/Oboards to process the application software. The control board rack can have one(M1), or three (M1, M2, and C) controllers. M1 and M2 are identical. The C con-troller only has one processor board.

The controller module assembly contains up to six boards:

• The main processor board (ACLA)

• The digital signal processor board (DSPX)

• ISBus communication board (EISB)

• Three I/O boards (EEIO, EMIO, and ESEL)

These boards are interconnected through the Versa Module Eurocard (VME) back-plane and cabled to their associated I/O terminal boards.

ACLAM1

DSPXM1

ACLAM2

DSPXM2

DSPXC

Ethernet Data Highway (EGD, Modbus)

ISBus

Communicationwith Mark VI, HMI,and LCI Static Starter

Communication acrossVME backplane

SerialModbus

SerialModbus

DPM DPM HMI: Human Machine Interf aceLCI: Load Commutated Inv erter

(Static Starter)M1: Control Module Master #1M2: Control Module Maser #2C: Control Module ProtectionDPM: Dual-Ported MemoryEGD: Ethernet Global Data

Processor Boards and Communications Paths in the EX2100 Control Assembly


Application Control Layer Board (ACLA)The ACLA is a scaleable microprocessor-based controller, used for communicationand control in the exciter. The ACLA mounts in a VME rack and occupies two half-slots. The other is the DSPX board. The ACLA is based on a 486 processor operatingat 100 MHz, supporting 8 MB of dynamic random access memory (DRAM) and a 4MB flash memory BIOS. The ACLA is used as a communication gateway to exter-nal machines and as an outer loop controller/regulator.

ENET

CO

M21

OKACTIVEENETFLASH

RST

STATUS

ACLAH1A

g GE Industrial Systems

Serial Ports, RS-232C

Ethernet Port, RJ-45

Status Lights:OK - Watchdog timer enabledACTIVE - Microprocessor accessing memoryENET - Ethernet ActivityFLASH - Flash memory write operation in progress

Status Lights, Diagnostics

The communication gateway functions are:

• Ethernet such as, EGD to Mark VI turbine controls, Human Machine Interfaces(HMI), static starters, etc.

• Serial RS-232

• Dual Port Memory (DPM)

The outer loop control/regulator functions are:

• Setpoint controller for the auto and manual regulators

• Generator Voltage Regulator (Auto Regulator)• Var or PF control• Limiter functions• Power system stabilizer• Field temperature calculation• Balance meter


Digital Signal Processor Control Board (DSPX)The DSPX is the primary controller for inner loop control/regulators and local op-erator interface control supporting testing and setup. The board is based on a highspeed, 60 MHz, digital signal processor chip supporting 248 kilobytes of high speedstatic random access memory and a 512 kilobytes flash memory BIOS.

Inner loop control/regulator function are:

• Field voltage regulator

• Field current limiter

• Sequencing of start-stop, field flashing, alarms and trips

• Generator instrumentation processing

• Generator simulator

Local operator interface control functions use a serial interface to a keypad and dis-play unit mounted on the door of the control enclosure and supports:

• Display and changing of internal control data and alarm and status informationfrom the DSPX or its paired ACLA controller

• Display and change of live data to support commissioning, tuning, and trouble-shooting

Exciter ISBus Board (EISB)The EISB is a special communication interface board for the M1, M2, and C controlmodules. ISBus is a proprietary, high-speed communication bus used in many GEsystems. The EISB is used to provide communication among the 3 DSPSs in M1,M2, and C. EISB receives and transmits fiber-optic feedback signals through thebackplane connector. It transmits them over the control backplane to the DSPX con-troller and also communicates between the DSPX and the tool and keypad ports us-ing RS-232C. EISB is a single-slot, 3U high module that is located in the controlrack under the DSPX. From six fiber-optic connectors on the front panel it acceptscurrent and voltage signals from the generator field (and from the exciter if required)using EDCF boards, and receives and transmits signals to the Ground DetectionModule (EGDM).

Exciter Selector Board (ESEL)The Exciter Selector board receives six logic level gate pulse signals from its corre-sponding EMIO. These pulse signals drive up to six sets of cables which are distrib-uted to the exciter gate pulse amplifier (EGPA) boards. The EGPA boards aremounted in the power conversion cabinet. If there are redundant controls, two ESELare used, one driven by M1 and the other by M2. The active ESEL, selected by con-troller C, sends the necessary control signals to the EGPA boards.

Three groups of ESEL boards are available supporting increasing redundancy levels;ESELH1 contains a single bridge driver, ESELH2 contains three bridge drivers, andESELH3 contains six bridge drivers.

Exciter PT/CT Board (EPCT)The EPCT contains isolation transformers for critical generator voltage and currentmeasurements. Two three-phase generator PT voltage inputs are input to EPCT. Twogenerator CT current inputs, with current levels of 1 A or 5 A, are input. In addition,one analog input, which can be either 0-10 V or 4-20 mA, is brought into EPCT. Allthe signals are interfaced to the EMIO board.


Exciter Contact Terminal Board (ECTB)The ECTB board supports excitation contact outputs and contact inputs. There aretwo versions; the ECTBG1 board which is only used in the redundant mode, and theECTBG2 board which is only used in the simplex mode. Each board contains twotrip contact outputs driving a customer lockout, and four general purpose Form-Crelay contact outputs, controlled by the EMIO board. Six auxiliary contact inputs arepowered (wetted) with 70 V dc by ECTB. Also, the 52G and 86 G contact inputs arepowered and monitored by ECTB. In the redundant case, power comes from the M1and M2 power supplies.

Exciter Terminal Board (EXTB)The EXTB board supports pilot relay contact outputs, contact inputs, and signal con-ditioning circuits. EXTB cables to the EMIO board through the EBKP backplane.

Pilot relays for the breaker/contactor close 41, and flashing contactors 53A, and 53Bare located on the board, plus pilot relays for the trip relay 41T and the de-excitationrelay KDEP. Crowbar status signals and de-excitation status signals from the EDEXboard are conditioned on EXTB and sent to EMIO. Three contact inputs from 41,53A, and 53B are powered (wetted) by 70 V dc on EXTB. Power for the contacts isfrom the M1 and M2 power supplies (redundantly), and the resulting status signalsare sent to EMIO in the control rack. Different groups of EXTB are available forcontrolling either a field breaker or a contactor in the field circuit.

Excitation Power Supply Module (EPSM and EPBP)The Exciter Power Supply Module converts 125 V dc from the Power DistributionModule (EPDM) into the voltages required for the Exciter Control System�s boardrack. This module is made from two boards:

• The EPSM board has two main sections:

• A buck regulator that takes the 125 V dc input and supplies the input side ofa multi-tapped switching isolation transformer. And,

• The converter section that generates the +5, +15, -15, 24, and 70 V dcpower outputs.

• The EPBP power supply backplane board that is used to mount and distributesthe input and outputs to the EPSM board as well as house the field ground de-tector modules.

Each of the control sections M1, M2, and C have an independent power supply mod-ule. These modules are located in a power supply rack assembly mounted below thecontrol rack in the control panel.

The control backplane (EBKP) rack holds the control boards and is supplied with +5V dc, ±15 V dc, and +24 V dc by the EPSM. Power is also supplied to modules ex-ternal to the EBKP as follows:

• ±24 V dc to power the De-Excitation module, Crowbar module, Ground Detec-tor, and the Field Voltage/Current module (EDCF).

• Isolated +70 V dc for "contact wetting" to the EXTB and ECTB boards.

The EPSM is a 6U VME form-factor board. Backplane connectors P1 and P2 carrypower from the power supply board to its board rack which then support the cablesneeded to source the Excitation Control System board rack backplane (EBKP).


Exciter Power Distribution Module (EPDM)Control power can be acquired from a 125 V dc source and one or two 115 V acsources. The ac source is passed through an external ac/dc converter module. The re-sulting 125 V dc is diode coupled with the other dc sources onto a dc bus on theEPDP board. This Power Distribution Module (EPDM) feeds the control modulesand gate pulse amplifier boards. Outputs from the EPDM are fused, pass throughswitches, and have LED status indicators.

AC power for the bridge cooling system comes from breakers included in the exciter.

Gate Pulse Amplifier Board (EGPA)The EGPA Gate Pulse Amplifier board interfaces the control to the Power Bridge.EGPA takes the gate commands from the ESEL and controls the gate firing of up tosix SCRs (Silicon Controlled Rectifiers) in the Power Bridge. It also is the interfacefor current conduction feedback, and the bridge airflow and temperature monitoring.

The EGPA functional model with the major I/O is shown in the following figure. Anominal 130 V dc power source supplies an on-board DC/DC converter, which pro-vides the isolated power for SCR gating over the full range of input supply voltage.LEDs provide visual indication of the status of the output firing, currents into thebridge, power supply, line filter, cooling fan rotation, bridge temperature, and alarmor fault conditions.

1 3 5

4 6 2

Discrete HallEffect Sensors

1 4 3 6 5 2

5 feedbacks to control (redundantfeedbacks to M1 and M2)

- 3 cond sensors - 1 ALARM - 1 Temp/FAULT(VCO)

PSOK

DC Power Source130 V dc (nominal)

80 - 140 V dc

Disable coolant trip

Single cable

6 Gate Commands from Controller

RTD Coolant Temp

Fan Rotation Sensor 2

Klixon (T=170F, Alarm)

Klixon (T=190F, Fault)

Fan Rotation Sensor 1

ALARM

FAULT

6X GatesFan Rotation Sensor 3

Line Filter Sensor


Exciter DC Feedback Board (EDCF)The EDCF board measures field current and field voltage at the SCR bridge, and in-terfaces to the EISB board in the control panel over a high-speed fiber-optic link.The fiber-optics provides voltage isolation between the two boards, and high noiseimmunity. Field current is measured using a shunt in the dc field circuit. The fieldvoltage feedback circuit provides seven selector settings to scale down the bridgevoltage, depending on the type of bridge application.

Exciter AC Feedback Board (EACF)The EACF board measures the exciter PPT ac supply voltage and current. The EACFterminal board contains transformers for a 3-phase voltage measurement, and termi-nals for two Flux/Air core coils. The outputs of the voltage and current circuits arefanned out to three DB9 connectors for cables to controllers M1, M2, and C. Thesecables can be up to 90 m in length. There are two versions of this board, EACFG1 isfor inputs up to 480 V rms, and EACFG2 is for inputs up to 1000 V rms.

Exciter De-Excitation Module (EDEX)The EDEX board is the main board in the de-excitation module. EDEX provides de-excitation SCR firing, conduction sense feedback, and voltage retention to ensureoperation in the event of a power failure. EMIO initiates de-excitation on the EXTBboard. The EXTB board opens the 41 dc contactor (41A/41B) or breaker, and thentransfers de-excitation signals from the auxiliary contacts to SCR firing circuits onthe EDEX.


41A

125VDC

41B

J2/3M

1

4

+ -

Control Encl.PDMJ7A1 2

FILT1

1

2

3

4

3

4

To Bridge 2

41ATo Bridge 2

SCR1

SCR4

SCR2

SCR5

SCR3

SCR6

41B

J1 J2 J5 J3 J6J4 Gen. Field -

Auxiliary Encl.

Gen. Fld +21 + -

BK WH

53B (Y)

53B (W)FieldFlash

De-Excit.HS +

FDI-1

TB1-2

TB1-1 ShaftVoltage

J505

J508

J515

EXTB

ControlEnclosure

K41_M1 K41_M2

K41_M2

K41_M1

K41_C

K41_C

Feedback 70V Ret

J6

1

4

2

5J505

J508

J515

EMIO

C

M2

M1

EMIO

EMIO

Control Rack 2

5

P70V

EISB M1

AuxiliaryE l

2

1

P1

E1VCO

VCO

EDCF-1

2

1

P2

P24VDC

-

++-

BK

BK

WH

VFOFCFOF

VoltsCurrent

ControlE l

GeneratorField

Duplex Fiber-OpticLink

2

1PSM1

Voltage

Current

PPTScaling

Shunt (mv)

L1L2L3

Power Control Module and Interfaces


Power Control Module (Thyristor � SCR)Negative forcing can not besupported when the freewheel-ing diode form of de-excitationof the generator field is sup-plied.

The 3- phase, full-wave, inverting thyristor (SCR), used as the standard power con-version module for EX2100 digital exciters, meets or exceeds the performance re-quirements for most applications. The inverting bridge can provide both positive andnegative forcing voltage for optimum performance. Negative forcing provides fastresponse for load rejection and de-excitation. Software changes of the firing circuitscan be made to suppress negative forcing, if it is not required for the system applica-tion. Each rectifier bridge includes thyristor protection circuitry, such as snubbers,filters, and fuses.

The thyristor bridge assembly is normally forced-air cooled with convection coolingavailable for lower current applications. For most applications, redundant cooling as-semblies are used, all normally energized during operation. Thermostats monitor thepower conversion module temperature. A set of alarm and trip contacts can triggeran alarm at a high temperature level, and a trip at an even higher temperature level.

A software-based conductionsensing circuit monitors eachSCR bridge for blown fuses,missing gate pulses, oropen/shorted SCRs.

Reactors are located in the ac legs feeding the SCRs. The snubbers are a RC circuitfrom the anode to the cathode of each SCR. The cell snubbers, line-to-line filters andline reactors together perform the following functions to maintain proper operationof the SCRs.

• Limit the rate of change of current through the SCRs, and provide a current�dump� to aid in starting conduction.

• Limit the rate of change in voltage across each cell, and during cell commutationlimit the reverse voltage that occurs across the cell.

DC Interrupting DeviceFor most applications a field interrupting dc contactor in the rectifier bridge dc-positive output is used to connect the exciter to the generator field leads. The dccontactor and the de-excitation module (SCR or diode-based) together form the in-ternal field breaker function found in previous excitation systems used to removestored energy in the generator field during shutdown or trip events. Often, two dccontactors are provided to interrupt both the positive and negative field leads.

For some applications, an external exciter field breaker is offered. DC field breakersinterrupt the output of the exciter and use a shorting contact to de-excite the genera-tor field through a discharge resistor. Some dc field breakers may use a static de-excitation device in place of the shorting contractor, which is functionally the sameas the combination of a dc contactor and static de-excitation module.

AC Isolation DeviceAn internal manual ac disconnect switch is offered for small to medium size systems,below 600 V ac. This switch serves as a disconnect device between the secondary ofthe power potential transformer and the power bridge in the static exciter. In mostcases, it is a molded case, 3-phase, non-automatic, panel-mounted switch, which ismanually operated. This switch permits the customer to close and open the ac-inputsupply.

An external ac disconnect breaker can be offered for larger systems. This breakerserves as a disconnect device between the secondary of the power potential trans-former and the static exciter. It may be a molded-case or a vacuum breaker support-ing remote control. This breaker permits the customer to close and open the ac-inputsupply.


Shaft Voltage SuppressorThe shaft voltage suppressor isa filter that conducts the highfrequency components of volt-ages to ground.

The shaft voltage suppressor limits shaft voltage to ground (caused by thyristorcommutation) to less than 5 - 7 V zero to peak. Shaft voltage, if not effectively con-trolled, can damage both journals and bearings. Static excitation systems cause rip-ple and transient voltages at the exciter output. Due to their rapid rise and decaytimes, these voltages are capacitively coupled from the field winding to the rotorbody. This creates a voltage on the shaft relative to ground.

The shaft voltage suppressor is shipped loose (for mounting at the collector of thegenerator) in most large applications. For smaller applications, the shaft voltage sup-pressor is part of the main exciter lineup.

Crowbar ModuleA crowbar circuit is applied for most hydro applications (salient pole generators) andsome steam or gas applications (wound rotor generators). During a pole slip event(when the generator loses synchronism with the power grid), high voltages can beinduced from the generator stator back on the generator field. This high voltage candamage the excitation system and/or the generator field if the induced voltage risesabove destructive levels. The crowbar safely limits the induced voltage below the de-structive level for the excitation system and the generator field.

The hardware used to implement the crowbar function is the de-excitation modulewith the thyristor direction changed. The load for the crowbar must be a resistor, butthe resistor can be shared with the de-excitation function. The functionality of thecrowbar, thyristor with snubber, and conduction sensor, are the same as for the de-excitation module. The crowbar�s thyristor is turned on when the anode to cathodevoltage of the SCR exceeds a certain value. Once the crowbar conducts, the reversecurrent induced by the pole slip event has a conduction path thus limiting the voltageon the generator field and exciter output.

Field Flashing ModuleThe field flashing module supplies approximately 15 to 20% of no-load field currentAFNL to the generator field during the startup sequence. Field flashing from a dcpower source is the standard method of flashing, however an ac field flashing mod-ule is also available.

The dc field flashing module can be powered from either a 125 or a 250 V dc stationbattery and has a maximum rating of 350 A dc for 15 seconds.

The ac field flashing control is almost identical to the dc field flashing control, how-ever the ac voltage is rectified by a diode bridge and filtered. The diode bridge alsoserves as a freewheeling diode circuit. This panel accepts a 460 V ac single-phaseinput that is then stepped down to 27 V ac through a transformer. The panel is ratedfor a maximum of 350 A dc for 15 seconds.

Field Ground Detector (EGDM)The field ground detector detects leakage resistance to ground from any point in thefield circuit starting at the ac secondary windings of the input transformer throughthe excitation system and on the generator field. The active detection system appliesa low voltage with respect to ground and monitors current flow through a high im-pedance ground resistor. When PRV resistors are present, grounds anywhere in thesystem can be detected even while the exciter is not running (gating SCRs). WithoutPRV resistors the grounds on the ac side of the power bridges can only be detectedwhen the system is running.


This field ground detector (patent pending) has three other improvements:

The ground detector voltage issent over a fiber-optic link tothe EISB board for monitoring.

• Constant sensitivity to grounds independent of operating voltages on the gen-erator field

• Constant sensitivity to grounds without regard to ground location in the genera-tor field

• Location detection of field ground

Redundancy (Power Bridge � Warm Back-Up)For small to medium sized static exciters, where the customer requires power bridgeredundancy and the total power needs of the generator field can be supported withinone power conversion module, the GE EX2100 excitation system Warm Backup op-tion is available. This option uses redundant controls (three controllers, M1, M2, andC) with two full wave SCR bridges that share common ac input and dc output cir-cuits.

The Warm Backup configura-tion is a cost-effective way toobtain N + 1 bridge redun-dancy when N = 1.

The active power bridge receives the gating commands from the active control (M1or M2) and supports the full field voltage and current needs of the generator fieldwhile the backup power bridge�s gating circuit is inhibited. The operator has fullcontrol to select which of the redundant power bridges is active or inactive. Bi-directional bumpless transfer between active and inactive bridges is supported. So-phisticated monitoring and protection circuits detect a failure or mis-operation of theactive power bridge, delay transfer (if needed to clear and SCR leg fuses), and acti-vate the inactive power bridge without operator intervention.

Operator Console (Remote/Local)Remote (control console) or lo-cal (exciter door)control aresupported.

The operator console is embedded PC based using an LCD display that supportsgraphical and character displays using a touch-screen interface. Configuration willbe supported using the same GE Control System Toolbox (toolbox) software thatinterfaces with the exciter control hardware and software. Multiple displays for run-ning and displaying data, alarm, status, diagnostics, and such are supported.


Diagnostic Interface (Keyboard)The keypad is a local operator interface mounted on the cabinet door. Start/stopcommands, regulator transfer commands, and regulator selection can be issued fromthe keypad. The keypad also includes meter displays indicating system conditions,such as generator MW and Mvars, field current and voltage, and regulator balance.Diagnostic displays such as the alarm history, setup, application data, and I/O inter-face displays provide system information for service personnel.

Exciter Health& State Icons

Run (Green)

Stop (Red)

ResetFaults

CommandMenu

Voltage Level

Exciter Control

Status

Menu

EnterEscape

Navigation

FVR Feedback

0.0 Volts

FldCurrAmps

0.00 Amps

EX2100 ExcitationC t lg

-30% 0% 150%

Auto

Man

On

Off

100%

Vmag

Freq_Hz

Imag Watts

Bal Meter Vars00.00

0.000.00

60.00

0.00

0.00

-30% 0% 150%100%

Display:

Status screens provide analog and digitalrepresentation of exciter functions and values.Menu screens provide text-based access toparameters, wizards, and faults.

Pushbuttons:

Organized into functional groups:Navigation buttons for using the menuExciter Control buttonsRun and Stop buttons

CabinetThe exciter lineup is supplied in a NEMA 1 / IP20 freestanding, indoor-type metalcabinet for floor mounting installation. The lineup consists of several cabinets boltedtogether, with cable entry through the top or bottom. The equipment is designed tooperate in an ambient temperature range of 0° C to 40° C, but custom applicationsmay support up to 50° C.

Each cabinet consists of a rigid, self-supporting, enclosed panel with a full-lengthdoor to provide easy access to the equipment. The panel back serves as the rear ofthe cabinet. Each door is equipped with a suitable handle, three-point latch, and pro-visions for locking. The power bridge doors do not have handles, but are boltedclosed to support code requirements. The standard cabinet color is ANSI-70 (lightgray) on both exterior and interior surfaces.


Standards SupportedSafety

• UL508A Safety Standard Industrial Control Equipment• CAN/CSA 22.2 No. 14 Industrial Control Equipment• UL 796 Printed Circuit Boards• ANSI IPC guidelines• ANSI IPC/EIA guidelines

Electromagnetic Compatibility (EMC) Directive 89/336/EEC• EN50081-2 General Emission Standard

- EN 55011:1991 ISM equipment emissions (CISPR 11)• EN 50082-2:1994 Generic Immunity Industrial Environment

- EN 61000-4-2 Electrostatic Discharge Susceptibility- ENV 50140:1993 Radiated RF Immunity- EN 50141 Conducted RF Immunity- EN 61000-4-4 Electrical Fast Transient Susceptibility- EN 61000-4-5 Surge Immunity

CE � Low Voltage Directive 72/23/EEC• EN 50178 Electronic equipment for use in power installation 1995• EN 60439-1 (Panel Program)

CE � Machinery Directive 89/392/EEC• EN 60204-1 Electrical Equipment for Machines• EN 292-1 Basic Terminology, Methodology• EN 954-1 General Design Principals

IEEE• 421.1 Standard Definitions for Excitation Systems for Synchronous Ma-

chines• 421.2 Guide for Identification, Testing, and Evaluation of the Dynamic Per-

formance of Excitation Control Systems• 421.3 High-Potential Test Requirements for Excitation Systems for Syn-

chronous Machines• 421.4 Guide for the preparation of Excitation Systems Specifications• 421.5 Recommended Practice for Excitation Systems for Power Stability

Studies• C57.12.01 General Requirements for Dry-Typ Distribution & Power Trans-

formers including those with Solid Cast and/or Resin-Encapsulated Wind-ings

• C57.110 Recommended Practice for Establishing Transformer Capabilitywhen Supplying Non-Sinusoidal Load Currents

• C57.116 Guide for Transformers Directly Connected to Generators• C37.90.1 Surge Withstand Capability (SWC) tests for Protective Relays &

Relay Systems• C57.18.10 Practices and Requirements for Semiconductor Power Rectifier

Transformers

Seismic

• Universal Building Code (UBC) � Seismic Code section 2312 Zone 4


Software

OverviewThe EX2100 software is designed to support high performance and structured to helpthe customer and field engineers to understand, install, commission, tune, and main-tain the excitation system. The following sections define major software functionsshown in the software overview block diagram below.

Generator

Voltage/CurrentSensing

DCRegulator

ACRegulator

ExciterBridge

ACVoltageadjust

DC Voltageadjust

Exciter SystemStabilizer Circuits

Over-excitationLimiter

Under-excitationLimiter

V/Hz Limiter &Protection

Voltage Sensing &Load Compensation

Power SystemStabilizer

Software TransducersIntegral to the high performance of the EX2100 is the sophisticated software trans-ducering system. The generator Potential Transformers (PTs) and Current Trans-formers (CTs) are the source of the control signals needed by the automatic(generator terminal voltage) regulator, most limiters, and protection functions. Thesystem simultaneously samples the ac waveform at high speed and in software usesadvanced mathematical algorithms to digitally generate the variables needed.


The output of the software transducer system include 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 outputs above to calculate the following:

• Generator power and vars.

• Magnitude of generator flux (V/Hz).

• Phase angle and power factor

Auto Regulator Reference (AUTO REF)This block can be configuredwith upper and lower limits,presets, and up/down ramptimes.

This block generates the auto control (AC) setpoint variable for the Automatic Volt-age Regulator (AVR). Operator commands, (raise and lower inputs) come in fromdirect inputs or over a data link from an HMI operator station or from a plant DCS orremote dispatch system.

Manual Regulator Reference (MANUAL REF)This block can be configuredwith upper and lower limits,presets, and up/down ramptimes.

This block generates the manual setpoint variable for the Manual Voltage Regulator(MVR). Operator commands, (raise and lower inputs) come in from direct inputs orover a data link from an HMI operator station or from a plant DCS or remote dis-patch system.


AUTOREF

PSS

UEL AVR

PowerSystem

Stabilizer

UnderExcitation

Limit

GeneratorTerminalVoltage

Watts

AVRSetpointandTracking

(VMAG)

AutomaticVoltage

RegulatorFVRTrackValueSetpoint

EXASP

Exciter AVRSetpoint.

Setpoint

V/Hz Limit;ReactiveCurrent

Compen-sation.

Frequency

VMAG

VMAG

Slip

ExternalRaise/Lower

MANUALREF

FVR

Field Voltage

Regulator

FCR

Field Current

Regulator

Min.

Field Voltage Regulator Setpoint

FiringCommdtoBridge

Field Volts from Bridge OutputFCR Setpoint(User Input)

Field Current from Bridge DC Shunt

ExternalRaise/Lower

Watts

VARs

ReactiveCurrent

Automatic and Manual Reference Follower(Tracking)These software implemented ramp functions adjust the non-active regulator output toautomatically track the active regulator. That is, when the auto regulator is control-ling the generator, the manual regulator tracks, and when the manual regulator iscontrolling, the generator the auto regulator tracks. This provides for smooth transi-tion when a transfer occurs from one regulator to the other.


Exciter AVR Setpoint (EXASP)The exciter AVR setpoint block combines a number of functions to produce the ref-erence input to the AVR and the variables to support regulator tracking. The refer-ence output from this block is a summation of:

• stabilizing signal from the PSS block

• output of the AVR REF block

• limiter signal from the UEL block

• output from the RCC/ARCC block

• combination of frequency and generator voltage to generate the V/Hz limitersignal

• external test signal to support injection of white noise and step test signals

Under Excitation Limiter (UEL)The UEL is an auxiliary control to limit the automatic voltage regulator demand forunderexcited reactive current. The UEL prevents reductions of the generator fieldexcitation to a level where the small-signal (steady state) stability limit, or the statorcore end-region heating limit is exceeded. Performance is specified by identifyingthe region of the limiter action on the generator capability curve.

Reactive Current Compensation (RCC/ARCC)This function, when in the Reactive Current Compensation (RCC) mode permitssharing reactive current between paralleled machines. When in the Active ReactiveCurrent Compensation (ARCC) mode, it enables line drop for regulating at somepoint remote from the generator terminals.

Volts per Hertz Limiter (V/Hz Lim)This function acts to limit the generator volts per hertz ratio to the programmed set-ting in the EX2100. This functions uses two inputs from the software transducer, av-erage generator voltage and generator frequency, and it's V/Hz ratio is configurable.Typically, the generator is considered to be operating acceptably within ±5% of ratedterminal voltage at rated frequency.

Automatic Voltage Regulator (AVR)The function of the AVR is to maintain the generator terminal voltage constant overchanges in load and operating conditions. The error value (average generator voltageminus the composite reference output from the EXASP block) is the input to a pro-portional plus integral (PI) regulator with integrator windup protection. In most ap-plications, AVR control output directly controls the firing command generator whichcontrols the gating of the power bridge SCRs when the AVR is enabled.

On some applications that require an inner loop regulator, such as compound (volt-age and current sourced) exciters and some high ceiling exciters, the manual regula-tor uses the control output from the AVR as a setpoint input.


Power System Stabilizer (PSS)The PSS provides an additional input to the automatic regulator to improve powersystem dynamic performance. Many different quantities may be used by a PSS, suchas shaft speed, frequency, synchronous machine electrical power, acceleratingpower, or some combination of these signals. The PSS offered in the EX2100 is amulti-input system using a combination of synchronous machine electrical powerand internal frequency (which approximates rotor speed) to arrive at a signal propor-tional to rotor speed. This comes from the integral of accelerating power, but withshaft torsional signals greatly attenuated.

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

Manual Regulator (FVR or FCR)The function of the manual regulator is to control the generator field voltage or cur-rent, letting the generator output voltage. The manual regulator, like the AVR, use aproportional plus integral (PI) regulator with integrator windup protection and itscontrol output directly controls the firing command generator that controls the gatingof the power bridge SCRs when enabled.

It has two inputs:

Setpoint or reference

For most applications, the manual regulator setpoint or reference input onlycomes from the MANUAL REF block and is only in control of the power bridgewhen selected by the operator or after a control transfer. For applications thatrequire an inner loop regulator to be used with the AVR, when the AVR is incontrol of the generator, the setpoint input comes from the AVR control output.

Generator field feedback (indicates the type of manual regulator)

• Field Voltage Regulator (FVR) is the typical manual regulator supplied onmost applications and uses the generator field voltage as the feedback input.While FVR�s do permit the current to vary as a function of the field resis-tance, GE has selected the FVR as its standard manual regulator to make themanual regulator completely independent from the over excitation limiter.

• The Field Current Regulator (FCR) is a special application of the manualregulator and uses the generator field current as the feedback input. While itdoes regulate constant field current over varying field temperature, GE hasnot selected the FCR as its standard manual regulator because it inhibits thesignal independence from the over excitation limiter.


Over-excitation Limiter (OEL)This function protects the generator field from damage by events that require abnor-mally high field currents. These high currents, over an extended time, can overheatthe field and cause damage. Generator fields are designed to ANSI Standard C50.13,which specify the over voltage as a function of time that the field is designed to fol-low. This standard uses curves to describe the field overheating as a function of timeand current. The OEL design approximates the curve of field voltage versus time.

The current limit values areselectable base on the operat-ing mode of the generator.When the generator is offline,the offline limits are used, andwhen the generator is online,the online limits are used.

The OEL interfaces directly with the power bridge firing command generator, there-fore it can protect the generator field from damage in either automatic or manualregulator mode. The function is not active under normal operation condition. Thisallows the exciter to respond to any generator fault condition without current limitfor a time period of about one second. After this, a two stage current limiter is acti-vated. The first stage normally limits the current to a high value. The thermal loadinto the field is integrated, using the known heating time constant of the field, untilreaching the field limit. At this time, the current limiter transfers to the lower limit.When the event is over, the integrator discharges based on the cooling time constantof the field, which is slower than the heating time constant.

Hydrogen Pressure / Temperature LimiterCompensation

The intent of this function is tocorrelate limiter action to thevalid generator capabilitycurves.

This feature compensates the configuration parameters of key generator limiters andprotection functions based on generator cooling. For hydrogen cooled generators, thecorrect parameter is the internal hydrogen pressure, and for air-cooled generators, itis air temperature. In ether case, the exciter uses a 4-20 mA input to capture the pa-rameter.

The three limiters affected by pressure/temperature compensation are:

• Under Excitation Limiter (UEL)

• Over Excitation Limiter (OEL)

• Stator Current Limiter

Entering the parameters of three generator capability curves configures compensa-tion. Sophisticated software in the exciter extrapolates this data into an infinite num-ber of curves needed to translate the present operation condition of the generator intothe correct limiter configuration parameters.

Manual Restrictive LimiterThis feature limits the under-excited operation of the EX2100 while the manualregulator is selected (FVR or FCR). It also does not allow the manual regulator totrack the Automatic regulator when the unit is operating below the field voltage limitcalled for by the manual restrictive limiter.

VAR/PF ControlThis function is accomplished by slow ramping of the AVR reference setpoint. TheVAR/PF is selected by operator command and the var/pf value is controlled usingthe raise/lower pushbuttons. When the exciter interfaces with a Mark VI turbinecontrol system, this function is typically included in the Mark VI system.


Generator Simulator (GEN SIM)A detailed generator model is included as part of the excitation system software. Itcan be configured to closely match the operation of the real generator. It can also beused for operator training, and can support the checkout of regulators, limiters, andprotection functions while the unit is shut down.

Unit Data Highway Interface (UDH)The Unit Data Highway (UDH) connects the exciter with the turbine control system,Human-Machine Interface (HMI) or HMI Viewer/Data Server, and GE Fanuc PLCcontrols. The UDH is based on Ethernet Global Data (EGD) protocol.

The UDH provides a digital window into the exciter where variables can be moni-tored and controlled. It also supports the GE Control System ToolBox (toolbox) con-figuration and maintenance tool for the exciter.

DCS Interface (ModBus)The exciter can support a ModBus RTU slave data link to interface with customerDCS systems. This link can be based on RS-232C or use TCP/IP support overEthernet 10baseT hardware. Both commands and data can be supported.

Volts per Hertz Protection (24G)This function serves as a backup to the Volts/Hertz limiter and can be supported withor without the C (protection) controller. The protection scheme consists of two levelsof volts per hertz protection. One level is set at 1.10 per unit over volts per hertz withan inverse time period, and the other level is set at 1.18 per unit with a 2 second timeperiod. In operation, this means:

Both trip and time setpoints areadjustable.

• From 1.0 to 1.10 per unit no alarm or trip occurs

• From 1.10 to, but not exceeding, 1.18 per unit an alarm is activated with triptime inversely proportional to the magnitude of the over volts per hertz

• At 1.18 per unit trip time is 45 seconds (adjustable from 6-60 seconds)

• If over volts per hertz exceeds 1.18 per unit, either initially or during the inversetime period, trip activation occurs in 2 seconds (adjustable from 1.7 to 2.8 sec-onds)

Over-Excitation Protection (OET)This function serves as backup to the over excitation limiter and can be supportedwith or without the C (protection) controller. If an over-excitation condition shouldoccur which the limiter can not correct, then a trip signal is produced. This functionapproximates the curve of field voltage versus time defined in ANSI Std. C50.13.

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


Potential Transformer Fuse Failure Detection(PTFD)This function detects loss of PT feedback voltage to the voltage regulator. If thesensing voltage is lost or if it is single-phased, there is a transfer to the manual regu-lator and an alarm output is provided. If the Power Potential Transformer (PPT) isfed from an auxiliary bus instead of the generator terminals, then a second set of PTsignals must be supplied to independently monitor the generator terminal voltage.

Transfer to Manual Regulator upon Loss of PTThis function detects loss of PT feedback voltage to the ac voltage regulator. If thesensing voltage is lost, the regulator forces its output to ceiling for 0.5 seconds andthen transfers to manual. This is distinctly different from the PTFD function, whichdoes not force the regulator to ceiling before transferring.

Loss of Excitation Protection (40)This function detects a loss of excitation on synchronous machines. It can providethe GE-recommended settings, which require two separate relay characteristics. Thefunction is performed within software code and can accommodate offset settings andtwo diameter settings. The recommended offset settings are both equal to one-halfthe machine transient reactance (X'd/2). The small diameter setting is equal to 1.0 perunit on the machine base, and the large diameter setting is equal to the machine syn-chronous reactance (Xd). The small diameter setting has no time delay and the largediameter setting has an adjustable time delay.

Each of the two relay characteristics are independently adjustable (offset - diameter -time delay) and can be used to initiate a TRIP signal. GE recommends the use of tworelay characteristics since there is some concern about the performance of the volt-age regulator when it is operating on the under excited limit. The regulator may un-dershoot while trying to maintain the limit and cause the apparent impedance tomomentarily enter the relay characteristic. If only one relay characteristic is used(small diameter), there may be undesired operation as a result of any regulator un-dershoot. Using the large diameter setting with time delay helps to avoid this prob-lem with undershoot.

Exciter Phase Unbalance (EUT)This function monitors the secondary voltage from the 3-phase input power potentialtransformer. If a voltage phase unbalance condition exists, an alarm is generated, anda trip signal is initiated after a time delay.

OffLine Over Excitation Protection (OLOT)This function serves as backup to the over excitation limiter when the generator isoffline. If the generator field current exceeds 120% of no-load field current whileoperating offline, in either the automatic regulator or manual regulator mode, and thelimiter can not correct an over-excitation condition, this function will initiate a tripsignal after a time delay.

Generator Field Temperature CalculationThis function measures the resistance by dividing the field voltage by the field cur-rent. From the known field resistance at 25°C and the linear resistance temperaturechange in copper, the algorithm calculates operating temperature. An adjustable hightemperature alarm output contact is also included.


TestingThe GE Salem facility is ISO-9001 and Ticket certified. Below is a brief descriptionof the quality assurance tests performed on each exciter.

Routine Factory TestsEach exciter is subjected to routine factory tests, including but not restricted to thefollowing:

• Circuit continuity check

• Dielectric (Hi-Pot) tests in accordance with IEEE Std. 421B

• Functional check of all components and devices for proper operation

• Most other electrical parts, such as power supply, transformers, reactors, com-pensators and similar devices, are tested individually in accordance with appli-cable ANSI Standards or IEEE Standards. If, however, the parts are in quantityproduction and routine tests are made, and such routine tests are in accordancewith the above noted standards, individual tests of such parts will not be con-ducted

• An engineering inspection for conformance to purchaser specs

The transformer tests are in general accordance with ANSI Std. C57.91 for dry typetransformers and ANSI Std. C57.90 for liquid filled transformers. The tests include:

• Resistance measurements by any of the methods described in the applicableANSI standard

• No-load loss and excitation test

• Applied potential test

• Induced potential test

• Losses and impedance tests

• Ratio tests

• Phase relation test

Customer Witness TestingAll equipment goes through extensive testing with appropriate reviews and sign-offsas described in the section Routine Factory Tests above. After that, the customer canselect either of two options for a customer witness test.

• Option A lets the customer examine the appearance and workmanship of theequipment, then review the engineering and test paperwork. This is a standardservice for no additional charge.

• Option B lets the customer witness a demonstration of the hardware and soft-ware. This is an added-cost item to the customer.

Customers who desire some form of witness test other than Option A or Option Bmust contact GE Salem upon placing their order to discuss the feasibility and cost ofconducting such a test.

Our customers are always welcome to visit the Salem factory to see how theirequipment is engineered and manufactured.


Option A � Customer WitnessThis normal production inspection, performed immediately prior to shipment, veri-fies the mechanical integrity, conformance to special purchaser hardware require-ments, appearance, and design completeness of the enclosure. The purchaser canelect to participate in this inspection at no charge. This inspection lasts approxi-mately two hours, and includes:

• Inspection of appearance and mechanical integrity

• Review for completion:

− Test instructions

− Test log

− Test defect record

− Check Engineering Log

− Inspection defect records

− Shortages

• Audit �T� check (i.e. labeling/nomenclature)

• �As-shipped� prints

• Purchaser special requirements

The customer usually inspects the hardware the day before the unit is sent to ship-ping. At this point, the unit will have been completely tested and inspected. Thecustomer can inspect the unit to ensure that its appearance meets his expectation be-fore it is shipped. Generally, the customer reviews the quality of workmanship,looking at paint, wiring, crimping, assembly, etc. The duration of this witness pointis two hours.

The second part of this option is a review with the engineer. The customer can re-view all paperwork relevant to the engineering and testing of the requisition. Thiswould include the elementary, I/O list, alarm list, layouts, outlines, test sign-offsheets, etc. This documentation provides the basis for certification that the customer'shardware and software went through the proper engineering, verification, and testprocesses. The duration of this witness point is approximately two hours.

The customer should advise GE Salem eight weeks prior to shipment of their intentto visit the factory to inspect his equipment. GE will inform the customer two weeksprior to the inspection date so that the customer can make travel arrangements. Thereis no additional cost associated with this option.

Option B - Customer WitnessThis customer witness option consists of two demonstrations:

• hardware demonstration

• software demonstration

The hardware demonstration is an audit of those tests previously performed as de-scribed in the section Routine Factory Tests. The duration of this witness point istypically two to four hours.


For the software demonstration, the customer's application software is downloadedto a simulator panel at a convenient workstation area (not the customer's equipment)to verify its integrity, functionality, and conformance to the specifications. Thesimulator panel uses the same printed wiring boards and software as are used in thecustomer�s equipment to model the specific application, or a typical generator and itsfield.

The software simulates a normal startup and control sequence:

• emulating the necessary contactor(s) and relays

• checking feedback echoes for closing verifications

• activating regulators in both the manual and automatic modes

• displaying any faults

The engineer uses the simulation method to check out the integrity of the system byalso exercising any special functions. The duration of this witness demonstration isapproximately four hours.

Option B, if selected, should be included as part of the initial purchase order. If acustomer decides to purchase this option after the initial ordering drawing release, anamendment to the PO will be required. If option B was not initially purchased, thennotification of a change order is required at least eight weeks prior to shipment of theequipment. GE will inform the customer two weeks prior to the test date so that thecustomer can make travel arrangements. There is an additional cost associated withthis customer witness point.

gGE Industrial Systems

General Electric Company1501 Roanoke Blvd.Salem, VA 24153-6492 USA

Issue date: 2000-12-04 2000 by General Electric Company, USA.All rights reserved.+ 1 540 387 7000www.GEindustrial.com

Documents

Static Ex System