detail (bu bus fed)

GE Power Systemsg

Revision Date: 02/10/2000Revision Date: 02/10/2000 Property of Power Systems University- Proprietary Information for Training Purposes Only!Property of Power Systems University- Proprietary Information for Training Purposes Only!

EX2000 Hardware Details

GE Power Systemsg


Objectives

• Identify all of the system components associated with “your” exciter.

• Follow the power signal and feedback signals on the EX2000 1-line.

• Be able to locate each component in the GE excitation elementary drawings.

• Understand the function of each system component.

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC F ilters

ShuntPCM

ACNA

RT B PCCA 3T BSDCC SLCC LT B

RCC UEL O EL V/HzM AN/AUT O PT Failure

Duel SourcePW R Supply

Protection PW RSupply

T CCB

PT CT

ACNA DCFB

LT B 3T B RT B SDCC SLCC

T ransfers

SHVI

64FFLD G RD

Shaft Vo ltsSuppressor

120 vacPPT

41 AC

T o Hot B /Uand Protection

Core

De-excitationM odule

M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Volta

ge F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

TB6-01

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD

Shaft VoltsSuppressor

120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

Power Potential Transformer (PPT )

GE Power Systemsg


Power Potential Transformer (PPT)

• The PPT steps down the AC input from a medium voltage AC source (4.16Kvac to 18Kvac) to a low voltage supply (300vac to 600vac).

• Supplies the AC input to the PCM.• How is the PPT connected for your plant?• What is the ratio of the PPT for you plant?

Sheet 1AA and OE

TB6-02

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

Power Conversion Module (PCM)

GE Power Systemsg


Power Conversion Module (PCM)

• Functions to convert AC power in DC.• 6 SCR’s fire at different angles to achieve the desired

DC output.• 12 identical fuses (2/SCR) protect the SCR’s and ensure

equal current division.• 6 Leg Reactors limit current changes through the SCR’s.• R/C Snubber circuits protect the SCR’s after conduction

has stopped.• Thermal Detectors are mounted on the SCR heat sinks.

Normally alarm at 170 oF and Trip at 190 oF (1BA)

TB6-03

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

Field Contactor MDA/B

GE Power Systemsg


Field Contactor MDA/B

• Also know as a Magnetic Disconnect (1BA).• Can be a 1 or 2 pole contactor which provides a

disconnect between the PCM and the Generator Field.• MDA will close at _______________ as sensed by the

MK V (Vl).• MDA will open at ________________ as sensed by

the MK V (Vl). • What would happen if MDA failed to open if speed

fell below 90%? _________________________

95% Speed

93% Speed

Overfluxing would occur

TB6-04

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

Control Core

GE Power Systemsg


Control Core

• Consists of 5 printed wiring boards that work as the “BRAIN” for the exciter. The wiring boards are interconnected through ribbon cables.

• Calculates the proper amount of excitation and delivers the gate firing signals to the SCR’s.

• The control core will also calculate generator volts, amps, MW’s, MVARS, operating point, V/Hz, and trip settings.

TB6-05

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

Mark V (Vl)

GE Power Systemsg


Mark V (VI)

• Provides the reference parameters to the EX2000• MK V (Vl), IOS, and EX2000 communicate on a LAN

via a coaxial (Ethernet) cable. The communication protocol is a GE proprietary system known as “Status_ S”.

TB6-06

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

PT’s and CT’s

GE Power Systemsg


PT’s and CT’s

• PT’s and CT’s convert the generator voltage and current into smaller signals which are used by the EX2000.

• What are the PT and CT Ratios for your exciter? _________________________________

• They are not typically used for any metering or relaying.

• Located outside of the EX2000 cabinet.• Isolation switches are provided for testing and

maintenance (OF).

Sheets OF and OE

TB6-07

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

PTCT Board

GE Power Systemsg


PTCT Board (1H)

• This board isolates and scales the voltage and current levels from the PT’s and CT’s.

• Isolated the Control Core from the PT’s and CT’s and attenuates these signals so that the Control Core only receives a very low voltage signals.

• The PT signal transformer has a ratio of 75:1 (120:1.6 vac)

• CT signal transformer has a ratio of 5:0.25 amps.• Test points (TP) 1-18 are located on the board to

measure analog signals on the output of the board.

TB6-12

GE Power Systemsg


PTCT Board (1H)

• The output of the PTCT Board is sent to the TCCP Board through a ribbon cable.

• The TCCB Board will process the signals and convert them from analog to digital and use these values to calculate generator volts, current, MW’s, MVARS, etc.

• If the PTCT Board fails, the exciter auto regulator would not work because the generator terminal volts feedback signal is lost.

TB6-12

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

SHVI Board

GE Power Systemsg


SHVI Board (GEK 6120 pg. 6-45)

• Provides attenuation of the 3-phase bridge voltage and DC isolation for the generator field voltage and current signals.

• The DC field current feedback comes from the DC shunt and is inputted into shunt isolators VCO (Voltage Controlled Oscillators) circuits where it is converted from millivolts to frequency (-500 mV to + 500 mV) (0 to 500 kHz).

TB6-13

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

Blowers

GE Power Systemsg


Blowers (1AC and 1BC)

• (3) motor driven fans provide cooling circulation air through the SCR heat sink.

• Power for the motors can come from customer preferred AC or the PPT secondary and stepped down to 120 vac.

TB6-14

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

AC Suppression Module

GE Power Systemsg


AC Suppression Module (1AB)

• The module protects the power conversion module from over frequency and voltage spikes.

• The module consists of MOV’s (Metal Oxide Varistors) connected line to line and line to ground across the PPT secondary to protect the PCM.

• The MOV is a varistor that changes impedance with the amount of current flow through it. If PPT secondary voltage raises above the rating of the MOV, the MOV “clamps” the voltage and will not allow the high voltage to applied to the SCR’s.

TB6-15

GE Power Systemsg


MOV’s

TB6-16

GE Power Systemsg


• The MOV protects the PCM from over voltage.

• During normal operation, the MOV appears like an open circuit and current flow is from the source (PPT) through the source impedance (Zs).

• If source voltage (Vsource) is too high, the MOV conducts.

MOV’s

TB6-17

GE Power Systemsg


• Voltage clamping results from the voltage drop across Zs.

• The MOV relies on the source impedance (Zs) to produce the clamping.

MOV’s

TB6-17

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

AC Line Filter

GE Power Systemsg


AC Line Filter (1AB)

• This is a low pass filter which attenuates the transient high frequency AC signals but allows low frequency signals to pass undisturbed to the PCM.

• The line filters consist of resistor and capacitors.

TB6-18

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

DC Power Supply

GE Power Systemsg


DC Power Supply (1J)

• Duel Power Supply: with one AC input from the Blower Motor Transformer and the other from the 125 vdc customer supplied DC system.

• During NORMAL operation, the DC output from the AC supply is greater than the DC from the customer 125 vdc system. The diode at J38 is reverse biased (does not conduct) and the customer DC supply supplies no current.

TB6-19

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

De-Excitation Module

GE Power Systemsg


De-Excitation Module (1BB)

• The De-Excitation Module provides a current path path to collapse the generator field when the generator breaker opens under load to prevent an over fluxing condition.

• During an abrupt trip, MDA are opened immediately and an SCR associated with the module is fired to provide at path for current flow either through a discharge resistor or inductor and dissipates the stored energy of the field.

TB6-20

GE Power Systemsg


De-Excitation Module (1BB)

• If the De-Excitation circuit is active and the exciter has not been issued a STOP command, a fault (FLT.715) occurs. If the generator is On-Line, the fault will issue a trip request.

TB6-20

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

Shaft Voltage Suppressor

GE Power Systemsg


Shaft Voltage Suppressor (1BB)

• Protects the generator journal bearings.• The PCM SCR’s produce spike voltages at the exciter

output. These voltages are capacitively coupled from the field winding to the rotor body. This creates a voltage on the shaft relative to ground,

• If the voltages are high enough, the voltage can cause an arc from the shaft through the oil and into the journal bearing babbit.

• The SVS is a low pass filter that conducts the high frequency components of the induced voltages to ground.

TB6-21

GE Power Systemsg


PT CT

SHVI

DCBFContro l

CoreT CCB

AC Filters

ShuntPCM

ACNA





T CCB

PT CT

ACNA DCFB


T ransfers

SHVI

64FFLD G RD


120 vacPPT

41 AC


Core


M DA & B

125 VDC

2 CT 's

G enPT 's

120 VAC

ProtectionCore

T o/FromHot B /U

andPrim ary

Core

G enerator

UC2000

B/U Core Prot. Core

M K 6

(3) BridgeBlow ers

O C 2000

6 SCR's

12 Fuses

DC

Vo

ltag

e F

DB

KD

C C

urr

en

t F

DB

K

AC Bridge FDBK

Ge

n F

DB

K

Field Ground Detector

GE Power Systemsg


Field Ground Detector (1BC)

• Detects a single field ground and will either creates an alarm or trip.

• One ground is not a problem however a second ground is.

• On most units, if the field resistance to ground is: > 5000 ohms -No Alarm, No Trip > 2000 ohms but < 5000 ohms - Alarm < 2000 ohms - Trip

• GE recommends tripping the unit with grounds < 2000 ohms.

TB6-22

GE Power Systemsg



m ax (+)

(-)

A B C

TB6-23

GE Power Systemsg



At this instant in time, B is max (+) and A is an intermediate (-)

TB6-23

GE Power Systemsg



Current will flow from B through SCR 1, through the field, back through SCR 5 and back to point A.

TB6-23

GE Power Systemsg



If the field winding insulation fail such that the winding touches the shaft, there is no current through the shaft back to the

source.

TB6-23

GE Power Systemsg



If a second ground appears, current flow is through the shaft and the field is bypassed which could result in a loss of field, loss of

synchronism, and create system instability.

TB6-23

detail (bu bus fed)

Education

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