ML20211E284

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Trip & Monitoring Unit
ML20211E284
Person / Time
Site: Seabrook  NextEra Energy icon.png
Issue date: 06/11/1986
From:
GENERAL ELECTRIC CO.
To:
Shared Package
ML20211E267 List:
References
GEK-46488, NUDOCS 8606130302
Download: ML20211E284 (13)
v • d • e


Text

INSTRUCTI-@NS CEx-48488 em TRIP & MONITORING UNIT GENERAL The 125V Trip Eus trips the IMTSV directly by

' The Trip and Monitoring Unit (T&M) is a part of energizing its solenold, while the 24V Trip Circuit trips the ETSV directly by de-energiz-(- the Turbine Protective System, andconsists of logic ing its two solenoids.

circuits locatedin theEHCcabinet, andpushbuttons, indicating lights, and meters on the Control Panel and on the System Monitoring Panel of the EHC When activated, the 125V Trip Bus trips the Cabinet. 24V Trip Circuit, resulting in an indirect trip of the ETSV. (Crosstrip action.) In some The principal function of the Trip and Monitor- cases of 24V Trip Circuitactivation, depending ing Unit is to receive signals corresponding to on the cause, the 24V Trip Circult trips the 125V Trip Bus, resulting in an indirect trip of various undesirable ord2ngerous turbine-generator the MTSV. (Crosstrip action.)

operating conditions, perform suitable logic opera-tions on these signals, and relay them as tripping Each trip signal, through its individual trip signals to either or both the Mechanical Trip Sole- circuit, energizes one of the two fundamental noid Valve (MTSV) or the Electrical Trip Solenoid trip circuits. In general, signals external to Valve (ETSV). These valves are independently the EHC cabinet energize the 125V Trip Bus, capable of tripping the Emergency Trip System while signals internal to the EHC cabinet ener-(ETS) which trips the turbine; in mostcases both of gize the 24V Trip Circult. In some cases, a these valves operate and provide redundancy at this trip signal energizes both fundamental trip C level, circults; this in conjunctionwith the crosstrips provides the redundancy mentioned previously.

The Trip and Monitoring Unit provides display signals for Protective System status, signals for Each of the two trip circuits is electrically annunciation and First Hit Detection of tripping or latched a short time interval (typically 30 msec) otherabnormalconditions, signals for control func- a.~ier a trip of the circuit. The 125V Trip Bus tions by other EHC units, and signals for customer has an additional "hydraullc" latch circuit that use.

is established when the followingconditions are met:

8

( a. The ETS is tripped (as detectedby two pres-A. FUNDAMENTAL TRIP CIRCUITS sure switches)

Figure I shows an elementary diagram of the b. The Mechanical Trip Valve is tripped (as trip circuits. Here and elsewhere in the Trip detected by a pressure switch).

& Monitoring Unit, relays andcircuits are often C arranged in a two-out-of-three logic scheme. c. The Generator Circuit Breaker is open, This improves by manyordersof magnitude the reliability of both failure modes. A standard The four TRIP VALVES indicating lights two-out-of-three relay arrangement is shown (" MECHANICAL RESET, " " MECHANICAL in Figure 2. TRIPPED", " ELECTRICAL RESET", and

" ELECTRICAL TRIPPED"), located on the The Trip and Monitoring Unit has two funda- Control Panel, provide indication of the status mental tripcircuits, the 125V Trip Bus and the of these devices, as detected by pressure and 24V Trip Circuit. limit switches.

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TRIP & MONITORING UNIT, GE K-46488

( a. Speed Control Unit.

b. Load Control Unit.

The circuits accomplishing the functions de ,

scribed in sections A, B, C, and D are located on 125V/24V TRIP SYSTEM circuit board un-less otherwise stated.

B. 125V TRIP SIGNALS

( b KAT l

KCT

1. CUSTOMER TRIP The Customer can provide a parallel com-SA - S8 " Sc~ Ka b Ka bins. tion of any number of contacts, corres-ponding to any undesirable conditions of his Kg Kg KC - -

choice. Closureof any oneof these contacts KT KsT energizes the 125V Trip Bus and, in addi-tion, provides a signal to FH and PC. The 4 o customer has the option of providing a two-TOTRIP BUS out-of-three logic circuitinstead of a single Figure 2 contact for some of the tripping conditions.

The individual trip circuits are described in 2. LOSS OF STATOR COOLANT TRIP the following sections B and C. These circults are connected to the 125V Trip Bus or the 24V This trip is initiated by a contact closure in Trip Circult throughdiodes, providing isolation the Generator protection system. An input

( between circuits and permitting each signal t be used for purposesother than tripping. They provide inputs to the First Hit Detection Clr-is provided to FH and PC.

cult (FH), the Electrical Malfunction Circuit 3. LOW SHAFT PUMP DISCHARGE PRES-(EM), and Plant Communications (PC). FH SURE TRIP and EM are parts of the T&M andare described in sections F and G. Unless otherwise stated, When the ctated condition occurs, three the signals to PC are relayed to the Customer pressure switches using the two-out-of-three through isolation relays for optional annuncia- logic arrangement provide a switching signal tion or other uses. to T&M. The trip circult is armed only when the speed of the turbine exceeds 75%

The two fundamental trip circuits have the fol- of rated; this is accomplished with a second lowing auxillary outputs: two-out-of-three logic contact chain, in series with thefirst. These contacts belong

1. 24V applied when the 125 Trip Bus is ener- to three T&M relays which are energized j gized, to Speed Control Unit. Independently by signals from Auxiliary Speed Sensor Unit. This is an example of l
2. 24V applied when the 125 Trip Bus is ener- two-out-of-three logic encompassing more l

l { gized, or the 24V Trip Circuit is energized than onelevelof devices. Eachpath consists j and latched, to: of a Speed Sensor, a Frequency to Voltage Converter, a Voltage Comparator, and a

{

a. Standby Control Unit. relay. Duringthis trip, an input is provided
b. Flow ControlUnit. (Inturbines with slave to FH and PC.

valves)

4. TURBINE SUPERVISORY INSTRUMENTS j c. Plant Communications. (TSI) TRIP (HIGH VIBRATION)
3. 24Vremovedwhen the 125 Trip Bus is ener-gized, to Plant Communications. This trip is inttlated by a contact closure in the Tu rbine Supervisory Instruments System.
4. 24Vremoved whenthe 125 Trip Bus is ener- An input is provided to FH and PC. The i ( gized, or when the circuit breaker is open, the ETS tripped, and no Trip Anticipator Customer may choose not to connect this trip; however, itis recommendedby General l

Action has taken place, to: Electric that the trip be connected.

i 3

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1 GEK-46488, TRIP & MONITORING UNIT

5. HIGH EXHAUST HOOD TEMPERATURE There are three vacuum switches on each l TRIP hood, with their contacts connected in a two-

- out-of-three arranget sent. These two-out-This trip protects the last stage of the tur- of-three contact chars are connected in bine from damage due to overheating. There parallel, and energize the 125V Trip Bus. +

is one thermostat contact for each hood; all contacts are connectedin parallel. An input An input is provided to FH and PC, and an is provided to FH and PC. auxiliary relay is energized during this ,

. trip. Its function is to light the " VACUUM

6. LOW HYDRAULIC PRESSURE TRIP TRIPPED" indicating light during this trip and the" VACUUM RESET"when the vacuum This protects the turbine against operation under abnormally low hydraulic pressure.

Three pressure switches areusedwith their.

is normal.

)

contacts connected in a two-out-of-three 11. THRUST BEARING WEAR DETECTCR arrangement. An input is provided to FH (TBWD) TRIP & TEST CIRCUIT and PC, and an auxillary relay is energized h pr s ps s, d the DA IC L ID RE S di- ted WEp P ER ,e 9 cating light on the Control Panel when the ing to one of the two thrust plates.

hydraulle pressure is low.

Excessive wear of one thrust plateactivates

7. REMCTTE OPERATION TRIP two pressureswitches set atdLiferent levels of pressure, which correspond to different (Applicable to turbines equipped with the shaft displacements, the first representing Remote Operationoption). A tripping signal an alarm level, and the second a trip.

from PC permits tripping the Turbine through remote operation. During this trip an input The pressure switch contacts are connected is provided to FH and PC. In series, constituting a two-out-of-two logic ,) ,

arrangement. A third series contact, be- ~

I nging to a relay, permits the trip line to

8. MOISTURE SEPARATOR HIGH LEVEL be opened for the testing of the TBWD.

TRIP i '

Three high impedance meter-relays are (Applicable only to Nuclear Turbines with connected across the three contacts, mont-Moisture Separators su;' plied by General toring the contact states. If there is suffi-Electric)* cient wear toactivate only the first pressure switch, or if the pressure switch contact In each separator three "high level trip" de- fails in the closed mode, the respective vices have theircontactsconnectedin a two- " WEAR" lamp on the System Monitoring out-of-three arrangement. All of these two- Panel will light, and an input will be pro-out-of-three contact chains (one for each vided to EM and PC.,

separator) are connected in parallel and energize through timers (with 10 seconds If there is wear exceeding the setpoints of i pick-up delay) three relays. A ,'high level , both pressure switches, in addition to the signal must remainformore than 10 seconds above a trip will occur, the respective

' to cause a trip and tMs prevents spurious , TRIP" lamp on the System Monitoring trips due to level translents. When a trip Panel Willlight, and an input to FH and PC occurs, an input is provided to FH and PC. will be provided.

9. LOW BEARING OIL PRESSURE TRIP If the second pressure switch contact falls in the closed mode, the " TRIP" lamp will Three pressure switches are used with con- light but no trip will occur.

tacts connected in two-out-of-three logic.

An input is provided to FH and PC. Each channel, LOWER and UPPER, can be tested by depressingand holdingthe respec-tive ' TEST"pushbutton, located on the Con- .

10. VACUUM TRIP trol Panel. The following esents occur in s

)

sequence This trip protects the turbine against dam-age from high exhaust hoodpressure(or low vacuum). a. The trip circuit is interrupted 4

TRIP L MONITORING UNIT, GEK-46488

b. The respective ' TRIP OPEN" lamp on on loss of 24V power. In either case, an j C: the Control Panel lights and an input is input is provided to F.4 and PC.

provided to PC

c. The respective TBWD Solenoid Valve is 15. MECHANICAL OVERSPEED TRIP & y energized, simulating a thrustplate wear MANUAL HANDLE TRIP
d. The two pressure switches are depres- Both of these trips act directly on the Me-surized and their two contacts close chanical-Hydraulic Trip System, andnot the Trip and Monitoring.
e. The respective ' TEST OK" on the Con- ,

trol Panel lamp lights. However, after the trip has occurred and a

the Generator circuit breaker has opened, When the ' TEST" pushbutton is released, the hydraulic latch circuit energizes the the Solenoid Valve isde-energized, the con- 125V Trip Bus which in turn trips the 24V tacts of the pressure awitches open, and only Trip Circuit.

after this has occurred will the trip circuit recloseandthetestbecompleted. During the .

test the " WEAR" and " TRIP" lamps do not C. 24V TRIP SIGNALS light. '

The principal components of the 24V Trip Cir-Associated with the TBWD are two analog cult are:

circuit boards of the Trip & Monitoring Unit.

One is the TBWD POSITION INDICATOR a. Three Trip relays with contacts connected

  • DRIVER, which is a 400 HZ oscillator used in a two-out-of-three logic arrangement that
  • to excite the Linear Voltage Differential de-energize the ETSV Solenoids. The con-Transformer (LVDT) mounted on the TBWD. tacts are monitored by two meter-relays, The second is the TBWD POSITION INDI- connected in a way adapted to the particular CATOR, that demodulates the LVDT output nature (de-energize-to-trip) of the ETSV '

and provides a DC signal for the TBWD po-

{ sition meter located on the control panel.

trip. I This system provides an analog indication b. Three Latch timer-relaypairswith contacts

  • of the exact position of the turbine shaft. connected in a two-out-of-three logic that

' latch themselves and the Trip relayt .

  • For additional information see THRUST a BEARING WEAR DETECTOR in Volume I c. Three Crosstrip relays with contacts con- I of the Instruction Book. nected in a two-out-of-three logic arrange-ment that energize the 125V Trip Bus. The 2
12. MASTER TRIP BUTTON - 125V TRIP contacts are monitored by three meter- I relays connected across them. I A contact of the Master Trip Button on the i j Control Panel energizes the 125V Trip Bus, The individual 24V Trip Signals are the follow-
  • and provides an input to FH and PC. ing:

As a customer option, two Master Trip Buttons may exist, with their contacts in 1. LOSS OF BOTH SPEED SIGNALS TRIP t series. Both must be simultaneously de- i C pressed to cause a trip. This trip occurs when both speed signals I are lost while the Turbine is not in the I

13. 24V TO 125V CROS& TRIP Standby Control mode. When both of these conditions are met, the Speed Control Unit This Crosstripoccurs during a Loss of Both provides to Trip & Monitoring a switching i Speed Signals Trip or a Backup Overspeed signal which energizes the Trip, Latch and '

Trip, as described in Section C. Crosstrip relays, and provides a signal to FH.

During this Crosstrip an input is provided to FH and PC.

2. BACKUP OVERSPEED TRIP (BOST) r 14.125V TRIP BUS LA'ICH C- The BackupOverspeed Trip Circuit provides This circuit, in addition to the function im- protection against turbine overspeed as plied by its name, trips the 125V Trip Bus follows:

5

GEK-46488, TRIP & MONITORING UNIT

a. Normal Mode - Set to trip the turbine at 3. MASTER TRIP BUTTON - 24V TRIP approximately 1/2%above the Mechanical Overspeed Trip Setting. A contact of the Master Trip Button (or a

. series combination of two contacts if two When no tests are being conducted, it buttons exist) energizes the Trip and the Latch relays, and provides an input to FH provides redundantoverspeed protection. and PC. Although the Crosstrip relays are (Speed Control provides the first line of n t energized, a 125V Trip occurs through protection and Mechanical Overspeed Trip a separate contact of the Master Trip Button.

Device the second).

4. CUSTOMER TRIPS OPERATED WITH i During Mechanical Overspeed Trip Test STATION BATTERY q or PistonTrip Test it provides the second ,)

line of protection. The customercan provideswitching signals, powered by thestation battery, representing any number of undesirable conditions of his

b. Standby Mode - Set to trip the turbine at choice. The signals enter the Trip and 105% of rated speed, and provides the Monitoring Unit through three relays located first line of protection, on CUSTOMER TRIP STATION BATTERY circuit board. These relays are connected in a two-out-of-three logic. Thus, each When the speed setting of the BOST is ex- undesirable condition must energize all ceeded, the Auxiliary Speed Sensor unit three relays. These relays energize the (where most of the EOST circuitry is 10- Trip and Latch relays of the 24V Trip Cir-cated) provides to the Trip & Monitoring Unit cult, but not the Crosstrip relays. It is three independent switching signals which recommended that the Customerprovide the energize the Trip, the Latch and the Cross- 125V EHC Trip as well as the Station Bat-triprelays. Three auxiliary relays arealso tery Trip for the same undesirable condi-energized, providing a two-out-of-three in- tions, to trip both fundamental trip circuits.

put to FH. In this case, the 125V Trip Bus will also be energized.

The Trip & Monitoring Unit contains logic for testing each of the three BOST channels An input to FH and PC during this trip is separately at rated speed. This logic is lo- provided.

cated on BOST TEST circuit board. De-pressing one of the three test pushbuttons 5. LOSS OF 125V POWER TRIP on the Control Panel ("NO.1", "NO. 2", or "NO. 3") applies a switching signal to the This trip is armed when the speed of the Auxiliary Speed Unit lowering the BOST turbine is below 75% of rated. When the r

setting of the respective channel to about 125V EHC power is lost, a relay contact l

99% of rated speed. This path is activated, closes and providing the above condition is l

and energizes the respective Trip, Latch met, energizes the Trip and Latch relays.

and Crosstriprelays. Noactualtrip occurs, The Crosstriprelaysarenot energized: with but the meter-relayswhichmonitor the Trip the 125V power lost, a 125V trip is impos-and Crosstrip relay contacts cause the light- sible.

ing of the "125 VOLT DC" and "24 VOLT T DC" lamps (Upper and lower half of the test When 125V power is lost, an input is pro- s/

button). De lamps light via magnetically vided to FH and two to PC. The second in-latched relays, and in order to be turned put to PC is a command to go to the Manual off, the adjacent " RESET" button or alter- operating mode.

nately, the Master P.eset button, must be depressed. 6. TRIP ANTICIPATOR ACTION The Trip Anticipator (TA) is used on tur-l An " ACTUAL 105% TRIP OF BOST OFF bines having a low inertia-to-power ratio to LINE" button on the Control Panel reduces reconcile the following two opposing re-the BOST reference to 105% of rated when quirements:

the Generator Circuit Breaker is open. If a. De second line-of-defenseagainst over-both this button and the 'OVERSPEED test speed must operateat a speedlow enough }

pushbutton are simultaneously depressed to keep the maximum speedbelow 120% of and held, the Turbine will overspeed and rated speed should the first line-of-de-trip by BOST action.

f id 6 mm W4 6

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1 TRIP & MONITORING UNIT, GEK-46488

b. A latching tripmustoccur ata speed high a. The electricallatching circuits of the 125V enough so that if the firstline-of-defense Trip Bus and the 24V Trip Circuit unlatch.

operates properly during an overspeed, This immediately resets the 24V Trip Cir-there is no unnecessary trip. cult, but not the 125V Trip Bus, the MTSV, c This is accomplishedby separating the fune- or the ETSV, which remain latched by the ,

tion of fastvalve closure, which is delegated hydraulic latching circuit.

to TA and is set low enough to satisfy (a), b. The Oil Reset Solenoid Valve is energized, i

  • from the function of latching this closure, operating the reset mechanism, and reset- .l which is left with the Mechanical Overspeed ting the Mechanical Trip Valve. This opens e Trip device, and set high enough to satisfy the hydraulle latching circuit, which in turn '

resets the 125V Trip Bus, the MTSV, and

(

(b). l The TA consists of three independent chan- the ETSV. The Oil Reset Solenoid Valve nels, located in the Auxiliary Speed Sensor remains energized for about 5 seconds, no Unit. When the turbine speed exceeds the matter whether the Master Reset Button is s' TA reference (which is load-dependent and released quickly or slowly, in the upper load region is lower than the The Master Reset Button should be released .

peek speed reached in a load rejection .vith when the " HYDRAULIC FLUID PRESSURE" '

normal Speed Control function), the TA en- lamp lights.

ergizes the three Trip relays of the 24V Trip Circuit and depressurizes the ETS. E. TRIP TEST CIRCUITS This action is not a trip because it is not latched, and is automatically cleared when The Me chanical Trip test and the Ele ctrical Trip and if the speed drops below the TA reference test circults permit the following tests during without having exceeded the Mechanical normal operation at rated speed and any load, Overspeed Trip setting. without tripping the turbine:

During TA action an input is provided to FH and PC; also the hydraulle latch line is in- 1. MECHANICAL OVERSPEED TRIP TEST

(

terrupted. (OIL TEST)

7. ELECTRICAL TRIP TESTING SIGNAL During this test the following events occur in sequenm This signal energizes the trip relays, but not the Latchand the Crosstrip relays. The ectrical Trip Testing isdescribed in sec- a. The Mechanical Lockout Solenoid Valve is energized, locking out the Mechanical Trip System.
8. LOSS OF 24V POWER TRIP This trip does not activate the 24V Trip b. The Oil TripSolenoid Valveis energized, Circuit, but de-energizes the two ETSV tripping the Mechanical Overspeed Trip, solenoids and the 125V Trip Bus latch timer- and causing the Mechanical Trip System ,

relay pairs. R causes both 24V and 125V to trip. ,

trips.

c. The Oil Trip Solenoid Valve is de-ener-9.125V TO 24V CROSSTRIP gized. ,

This trip does not activate the24V Trip Cir- d. The OilReset Solenoid Valveis energized, cult, but de-energizes the two ETSV sole-

{ noids. R causes 24V trip. The same con-resetting the Mechanical Trip System.

tacts de-energize three timer-relay pairs and cause the latching of the 125V trip. e. He Mechanical Lockout Solenoid Valve is de-energized.

D. MASER RESET CIRM f. The Oil Reset Solenoid Valvels de-ener-Reset of the Trip and Monitoring System and gized.

ETS is initiated by depressing the Master

" RESET" button on the Control Panel. In tur- 2. MECHANICAL TRIP PISTON TEST

  • bines equipped with Remote Operation option, a reset signal may be given through PC. During this test the following events occur All trip signals must have been cleared for the I" 8'9"'"
  • reset to be successful.
a. De Mechanical Lockout Solenoid Valve The following actions take place during the re- is energized locking out the Mechanical set process: Trip System.

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GEK-46488, TRIP & MONITORING UNIT

b. The MTSV is energized, activating the formation about the status of the various Trip Piston and tripping the Mechanical components (RESETTING, LOCKED OUT, Trip System. etc.) is also provided to PC for Customer

. use.

c. The MTSV is de-energized. l If Tests 1 or 2 are unsuccessful, an input '
d. The OilReset Solenoid Valve is energized, is provided to PC, a ' TEST MALFUNCTION" resetting the Mechanical Trip System. lamp on the Control Panel lights, and, de-pending on the component that failed, one of
e. The Mechanical Lockout Solenald Valve a number of lamps on the Mechanical Trip is de-energized. Test Malfunction section of the Monitoring Panellights. If Test 3 is unsuccessful, an-
f. The Oil Reset Solenold Valve is de-ener-glzed.

other input is provided to PC and another

" TEST MALFUNCTION" lamp on the Con-

-)

trol Panel lights.

3. ELECTRIC AL TRIP TEST During the oil test or the piston test, the During this test the following events occur Electrical Trip Valve provides protactb to in sequence: the turbine. During the electMcal trip test, the Mechanical Trip System provides pro-
a. The Electrical Lockout Solenold Valve is tection to the turbine. The test circuits are energized, lockingoutthe Electrical Trip interlocked so that only one testcan be per-System. formed at a time.
b. The Electrical Trip Solenold Valves are The circults thataccomplish theabove func-de-energized, tripping the Electrical tions are located on the MECHANICAL /

Trip System. ELECTRICAL TRIP TEST circuit board.

c. The Electrical Trip Solenoid Valves are The Trip and Monitoring Unit contains also energized, resetting the Electrical Trip logic for testing the TBWD Trip circuit, System. described in Section B-11 and the BOST circuit, described in Section C-2.
d. The Electrical Lockout Solenoid Valve is de-energized. F. FIRST HIT DETECTION CIRCUIT Each test is initiated bydepressing the pro-per " START" pushbutton and holding it in The First Hit Detection circuit provides an in-until Lockout has occurred. The sequence dication of the cause for a trip by lighting ap-of each step is followed automatically; each propriate indicatinglights onthe First Hit see-step takes place only after the previous step tion of the System Monitoring Panel, was successful as acknowledged by operation of pressure and limit switches. Also, suf- The circuit receives input signals from three ficient time intervals between the steps are groups of circuits:

allowed to permit the damping of pressure transients. a. Electrical Tripping Circuits In case a malfunction occurs, the test se-quence stopsbeforecompletion. Depressing

b. Front Standard Tripping Circuits )

the proper "STOP GO NORMAL"pushbutton c. Non-Tripping Circuits will reset the test circuits back to normal.

The same pushbuttoncan beused in case the Each input corresponds to a latching relay.

operator decides to interrupt the test before The first signal received in each group at the completion. time of a trip energizes the corresponding re-lay which identifies the input by means of an For turbines equipped with Remote Opera- indicating Ilght. The relay also disconnects tion option, the three tests can be initiated the common of all relays of its group so that and a "STOP GO NORMAL" action can be subsequent signals received do not energize the provided by four remote signals through PC. corresponding relays.

The sequence of events during these tests The sequence in which the three signals (first can be observed from the Control Panel signal of each group) are received is identifled through a number of indicating lights. In- by a sequence logic circuit. For this purpose 8

TRIP & MONITORING UNIT, GEK-46488 there are two lights for each group, labeled TESTING

" HIT 1" and " HIT 2".

The following tests of the Trip and Monitoring "

Resettingof the Trip System doesnot erase the and the Protective System must be performed at the First Hit information. To reset the First Hit specified intervals:

circuit the two Resef buttons on the Monitoring Panel must be simultaneously depressed, after l

t the Trip System has been reset. A. MECHANICAL OVERSPEED TRIP TEST (OIL TEST)

The logic for the above function is located on the FIRST HIT DETECTION circuit board. 1. Frequency of Testing

a. Weekly (just after testing the Backup 8 I

G. ELECTRICAL MALFUNCTION INDICATION Overspeed Trip - Test D) 8 CIRCUIT

b. Each startup This circuit receives signals representing a number of abnormal, non-tripping conditions 2. Turb!ne Operation Status of the EHC, and provides indication by means 1 of lights located on the Electrical Malfunction a. NORMAL mode of operation. (Exception:  ?

sectionof the Monitoring Panel, as well as sig- If necessary this test can be performed 8 nals for optional use by the customer. The in the STANDBY mode; permissible only 8 i

circuit provides the following lamps and sig- if the Power / Load Unbalance circuit is nals, all of which remain lit after the removal operative).

of the inputs by means of magnetically latching relays corresponding to the inputs: b. Turbine at rated speed. ;8

3. Test Initiation and SuccessfulTest Sequence I
a. Individual lights f or identification of the in-( puts.
b. Two common lights and a switching signal
a. Observe that " NORMAL", "MECHANI-cal, WERSq,ED RESET", ' TRIP ems are ON, and an I

labeled " SYSTEM FAULT". other lights in this group are OFF.

c. Two common lights and a switching signal b. Depress and hold" START MECHANICAL labeled " ELECTRICAL MALFUNCTION . OVERSPEED TRIP TEST" pushbutton.

A & b can be cleared only after all inputs have c. Observe that the pushbutton light comes been removed, while e canbe cleared either be- ON, then " NORM AL"goes OFF," LOC KED fore or after input removal. This last function OUT" comes ON. 8 is accomplished by means of a relay which is momentarily energized by capacitor charging d. Release pushbutton.

3 currents and activates a magnetically latching relay. e. Observe that:

Two reset buttons on the Monitoring Panel, when 1. The " MECHANICAL OVERSPEED simultaneously depressed, clear this circuit. RESET" light goes OFF, and the "ME-4 C CH ANICAL OVERSPEED TRIPPED"

/ The logic for the above functions is located on light comes 04 i the ELECTRICAL MALFUNCTION circuit

! board. 2. The " RESETTING" light comes ON. ,

3. The " MECHANICAL OVERSPEED H. LAMP TEST CIRCUIT TRIPFED" light goes OFF and "ME- '

CHANICAL OVERSPEED RESET" Depressing the " LAMP TEST" pushbuttons on light comes ON. i the Control Panel and the System Monitoring ,

Panel, energizes the respective group of indl- 4. The " LOCKED OUT" and " START

( craing lights, as a check for burned-out bulbs. MECH O/S TRIP TEST" light goes OFF and " NORMAL" light comes ON.

I This is accomplished through a number of re- I lays located on the LAMP TEST circuit board. 5. The " RESETTING" light goes OFF.

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GEK-46488, TRIP & MCNITORING UNIT

4. Action following an unsuccessful test 4. " LOCKOUT" and " START MECHANI-CAL TRIP PISrON TESr" go OFF Deviation from the above indicates an un- and ' NORMAL" comes ON, successful test. Usually the test will stop at an intermediate point, and the ' TEST 5. " RESETTING" light goes OFF.

MALFUNCTION" light will come ON.

4. Action Following an unsuccessful test Follow the instructions inthe GEK " Periodic Test ifummary". After unloading the turbine Same as in A4.

and opening the generator breaker record event sequence. Record indications on the If Test B is unsuccessful, and tests A, C, EHC Cabinet MechanicalTrip Test Malfunc-tion Panel, and any other abnormal condi-tions. Shutdown to correct the problem.

and D (performed immediately prior to or after B) are successful, unloading and shut-down of the Turbinemay bepostponed for up to one week.

)

B. MECHANICAL TRIP PISTON TEST

1. Frequency of testing C. ELECTRICAL TRIP TEST
a. Weekly 1. Frequency of testing
b. Each start-up a. Weekly
2. Turbine Operation Status b. Each start-up
a. NORMAL mode operation (Exceptions: 2. Turbine Operation Status If necessary this test can be performed in the STANDBY mode; permissible only a. NORMAL or STANDBY mode operation if the Power Ioad Unbalance circuit is -

operative). b. Turbine at rated speed

b. Turbine at rated speed. 3. Test initiation and successful test sequence
3. Test Initiation and successful test sequence a. Observe that the ' NORMAL"and " RESET" lights are ON and all other lights in this
a. Observe that the ' NORMAL", MECHANI- group are OFF.

CAL OVERSPEED RESET", "rRIP PISTCN RESET" lights are ON, and all b. Depress and hold the " START TEST" other lights in this group are OFF. pushbutton

b. Depress and hold the " START MECHAN- c. Observe that the ' NORMAL" light goes ICAL TRIP PISTON TEST" pushbutton. off and " LOCKED OUT" light comes on.
c. Observe that the pushbutton light comes d. Release the pushbutton.

ON, then the ' NORMAL" goes OFF, and

" LOCKED OUT" comes ON. e. Observe that:

d. Release the pushbutton.
1. The " RESET" light goes off and the
e. Observe that: "rRIPPED" light comes on.
1. ' TRIP PISION RESET" and "ME- 2. The ' TRIPPED" light goes off and the
  • CHANICAL OVERSPEED RESET"go ' RESET" light comes on.

OFF, and the "rRIP PISTON TRIPPED"and" MECHANICAL OVER- 3. The " LOCKED OUT"lightgoes off and SPEED TRIPPED" come ON. the ' NORMAL" comes on.

2. " RESETTING" light comes ON. 4. Action following an unsuccessful test
3. "rRIP PISION TRIPPED" and "ME-CHANICAL OVERSPEED TRIPPED" goes OFFandtheircomplements come Same as in A4 If Test C is unsuccessful, and if tests A, B,

)

ON. and D (performed immediately prior to or 10

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TRIP & MONITORING UNIT, GEK-46488 b'

after C) are successful, unloading and shut- trip the turbine. Trouble shooting can e down of the Turbine may bepostponed for up be done on-line by replacing components to one week. of the BOST circuit that failed. After normal operation has been restored, pro-D. BACKUP OVERSPEED TRIP TEST ceed to the next (if any) test. De turbine may be kept operating at any load for up

1. Frequency of Testing to one week withdefectiveBOST circuits.

During this period transfer to STANDBY

a. Weekly (prior to testing the Mechanical and tests A, B, and C are prohibited.

Overspeed Trip - Test A)

( b. Prior to or imm ediately aiter transferring to STANDBY.

c. Each start-up.

E. THRUST BEARING WEAR DETECTOR TEST This weeklyon-line test is describedin " Thrust Bearing Wear Detector Testing" in Volume 1.

2. Turbine Operation Status The electrical sequence of the testing is de-
a. NORMAL or STANDBY mode of opera- scribed under the DESIGN, Section B-11 of tion. (It is preferable to perform this these instructions.

test while in the NORMAL mode).

b. Turbine at rated speed. F. AC1'UAL OVERSPEED TEST
3. Test initiation and successful test sequence
1. Frequency of testing
a. Depress and hold the"NO.1"pushbutton.

Every six to twelve months.

b. Observe that the "125 VOLT DC" and

(' "24 VOLT DC" lamps (upper and lower halves of pushbutton) light. 2. Turbine Operation Status

c. Release the pushbutton. De two lamps shall remain lit,
a. Turbine at rated speed.
d. Depress the " RESET" pushbutton. The
  • lamps shall go out. c. Rotor hot,
e. Repeat a, b, c, and d with "NO. 2" and "NO. 3" pushbuttons. 3. Test initiation and successful test sequence
4. Action following an unsuccessful test
a. Select the " FAST" Starting Rate.

Record observations includingindications of meter-relays on the System Monitoring

b. Depress and hold the "OVERSPEED Fanel. TEST" pushbutton.

i C a. If in STANDBY mode and more than one l, test is unsuccessful, unload immediately c. Observe that the " SPEED INCREASING" l following the instructions in Periodic Test lamp lights.

  • Summary and shutdown before trouble-s M ng.
d. At 50 RPM below rated trip speed select
b. If in STANDBY mode and only one test is the " MEDIUM" Starting Rate.

I unsuccessful unload as soon as possible

! (within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) following the instructions e. Observe that the turbine trips at rated in Periodic Test Summary and shutdown trip speed, plus or minus trip speed tol-before trouble-shooting. erance. TRIP VALVES " MECHANICAL TRIPPED" and " ELECTRICAL TRIP-C' c. If in NORMAL mode and one of the tests PED" lamps light. "CLOSE VALVES" is unsuccessful, do not proceed to the Speed Set lamp lights. Record the trip next (if any) BOST test, since this may speed.

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GEK-46488, TRIP & MONITORING UNIT

f. Release the 'OVERSPEED TEST" push- 4. Action following an unsuccessful test button.

If the Turbine failed to Trip by BOST action

g. Allow the Turbine to slow down to rated at 105% of rated speed, shut-down and cor-speed or less. - rect the prob 1cm before synchronizing the turbine to the system.
h. Reset the Turbine.

1.1 Perform the complete test twice more to H. ACTUAL TRIP ANTICIPATOR ACTION TEST check repeatability.

(applicable to units equipped with the Trip

4. Action following an unsuccessful test Anticipstor feature)

If the Turbinefailed totrip, or thetrip speed is not within tolerances, shut down and cor- 1. Frequency of testing rect the problem before synchronizing the turbine to the system. Six to twelve months.

G. ACTUAL 105% TRIP OF BOST OFF-LINE 2. Turbine Operation Status

1. Frequency of testing _ a. Turbine at rated speed Six to twelve months. b. Circuit breaker open
2. Turbine Operating Status c. Rotor hot
a. Turbine at rated speed d. NORMAL mode of operation
b. Circuit breaker open 3. Test initiation and successful test sequence ,
c. Rotor hot a. Select the " SLOW" Starting Rate
d. The BOST Test (Test D) was just per- b. (For Fossil Turbines equipped with Full formed and was successful. Arc & Partial Arc Admission Modes):

Momentarily depress the " HOLD" Ad-

3. Test Initiation and successful test sequence mission Mode Pushbutton and manually transfer to Partial Arc mode by slowly
a. Select the " FAST" Starting Rate rotatingthe AdmissionMode Potentiome-ter in the EHC Cabinet.

depress and hold the

b. Simultaneously

" ACTUAL 105 % TRIP OF BOST OFF- c. Increaae the Imad Set to 100% of rated LINE" and 'OVERSPEED TEST" push- load. Thespeedof the Turbinewill grad-buttons. Observe that the " SPEED IN- uallyincrease until105% or rated speed is CREASING" lamp lights. reached (5% Regulation is assumed).

d. Walt 3 to 5 minutes after the Turbine l
c. Observe that at 105% of rated speed, the turbine trips by BOST action. Trip Valves stops accelerating.
e. Select the " FAST" Starting Rate.

])

" MECHANICAL TRIPPED" and "ELEC-TRICAL TRIPPEI)"lampsligl#. "CLOSE VALVES" Speed Set lamp lights. On the f. Depress and hold the 'OVER. PEED First Hit Detectionpartof the Monitoring TEST" pushbutton. The Turbina will ac-Panel,the " BACKUP OVERSPEED TRIP" celerate.

lamp lights.

g. At the speed equalto the Trip Anticipator
d. Release 'OVERSPEED TEST"and "105% setting, indicated in the " Field Line-Up TRIP OF BOST OFF-LINE"pushbuttons. Diagram"of the Turbine, TA action must occur. Observe that or the First Hit De-
e. Allow the Turbine to slow down to rated speed or less.

tection part of the Monitoring Panel the

' TRIP ANTICIPATOR ACTION" and

" ELECTRICAL TRIP SOLENOID" lamps

'}

f. Reset the Turbine. light.

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TRIP & MONITORING UNIT, GEK-46488

h. Release the "OVERSPEED TEST" push- J. Momentarily depress the " TRANSFER button. Observe that the turbine speed FULL ARC" pushbutton. Observe that a returns toTJEf rated. transfer to FA takes place. ,

. 4. Action following an unsuccessful test

1. Decrease the Load Set to the no-load flow If Trip Anticipator Action failed to occur, point. Observe that the turbine returns shut down and correct the problem before to rated speed. synchronizing the turbine to the system.

C C

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