Main Feedwater Pump Speed Control

Question 1

What are the low power inputs and when do they go into effect?

Answer 1

NR and WR SG level
FW temperature
FW flow (used to determine if high power controller should be used)

15% FW flow and lowering

Question 2

What are the high power inputs and when do they go into effect?

Answer 2

NR SG level
FW flow
Steam flow
FW temperature

Question 3

How does overspeed protection work? What are the various speed setpoints?

Answer 3

Controlled by ovation.
3 speed probes
@5550 rpm, ovation issues priority lower command to 5300 rpm
Overspeed trip electronically at 5720 rpm
Signal opens both 20/OOT and 20/OOT-2

Question 4

High vibration alarm at ____ mils and manual trip criteria at ____ mils.

Answer 4

3 mils
5 mils

Question 5

FW stop valve permissives to open (3) Same as permissives to start the pump.

Answer 5

1. FW pp reset (latched)
2. Recirc valve open (FW12B/C)
3. Recirc isol open (FW27B/C)

Question 6

FW stop valve permissive to latch

Answer 6

1. speed setter light lit
2. HP stop valve closed light lit
3. LP stop valve closed light lit
4. HP governor valve closed light lit
5. LP governor valve closed light lit

Question 7

What is the critical pump speed?

Answer 7

250 rpm, minimize operations near critical speed

Question 8

Turbine FW pump trips (7)

Answer 8

Manual PM04j or local
P-14
SI
Low bearing oil pressure
Low exhaust vacuum 14” Hg
HP and LP stop valves closed
Overspeed 5720 RPM

Question 9

Stop valves are ___ to open ___ to close. Governor valves are ____ to open and ___ to close.

Answer 9

Hydraulic; spring
Hydraulic; hydraulic

Question 10

Turning gear start interlocks:

Answer 10

HP and LP stops closed
Bearing oil pressure >15 psig
L/C/S in normal

Question 11

Turning gear auto start

Answer 11

CS in auto
Turbine speed <3.4 rpm
Turbine trip signal actuated

Question 12

Standby oil pump auto starts (3)

Answer 12

75 psig at discharge of running PP
13 psig at bearings
running pump breaker opens

Question 13

Auto setpoint control is enabled____

Answer 13

at 3000 rpm, manually transferred by operator in ovation after 3200 rpm.

Question 14

Low vacuum turbine trip can be bypassed to allow______.

Answer 14

turbine to be latched without condenser vacuum for testing.

Question 15

If the _______ drops below 30% and FWI aux relay train B is actuated, then the _B FW pump speed setpoint will go to 3000 RPM.

Answer 15

_A or _B S/G NR level

Question 16

If the_______drops below 30% and FWI aux relay train A is actuated, then the _C FW pump speed setpoint will go to 3000 RPM.

Answer 16

_C or _D S/G NR level

Question 17

FW012A and C are powered from ____ and FW 012B is powered from ____. All 3 valves fail ____ on loss of air.

Answer 17

113
114
Open

Question 18

MD FW Pump recirc open/closed:

TDFW Pumps recircs open/closed:

Answer 18

2335 gpm begins to close
8800 gpm full closed

2335 gpm begins to close
4050 gpm full closed

Question 19

Purpose of the TURBINE LOSS OF DC TO TRIP light:
Power supplies:

How/Will the turbine driven feed pumps trip?

Answer 19

Indicates loss of 125 VDC to Turbine FPSC Trip Circuit.
_B TDFWP - DC Bus _14.
_C TDFWP - DC Bus _13.
No auto trip or trip using pushbuttons will occur (_PM04J or Local).
Can only be tripped using the Local EH Trip Valve.

Question 20

What does the VACUUM TRIP LOCKED OUT light indicate?

Answer 20

Indicates Condenser pressure between 3 psig and 20” Hg vacuum (10” Hg absolute) with the Turbine Driven Feedwater Pump reset.

Question 21

MDFWP trips:

Answer 21

High lube oil temp: 175°F.
Electrical (OC, Ground OC, Differential OC, UV).
Low lube oil pressure: 10 psig.
Low suction pressure: 282 psig.
No CD/CB pumps running.
SI
P‑14
Manual

Question 22

MDFWP starting interlocks:

Answer 22

1 CD/CB pump running.
Discharge valve open (_FW002A).
Recirculation isolation valve open (_FW027A).
Suction valve open (_CB005A).
Lube oil pressure up: 15 psig rising (Oil Pressure Up light LIT on _PM04J).

Question 23

MFWP recirc valves fail open on:

Answer 23

Fail open on:
Loss of Air.
Loss of DC (_FW012A/C - DC _13, _FW012B - DC _14).
Loss of Control Signal.

Question 24

In the low power mode, if Wide Range Level signal is lost:

Answer 24

The SLIMs will stay in auto but the system response will be sluggish. The Feed Forward signal must be manually reset when WR level is back in band between 50% and 100%

Question 25

FW pumps not required for safe shutdown. However, isolation is required on specific ESF actuation for the following three reasons:

Answer 25

a. To prevent excessive primary plant cooldown.
b. Limit S/G overfill.
c. Habitability concerns in Turbine Building.

Question 26

What are the differences between the Turbine Driven Feedwater Pump control system and the Motor-Driven Feedwater Pump control system?

Answer 26

The control systems for the turbine speed controllers use an EH controller to regulate turbine speed. The Motor Driven Feedwater Pump control system uses a current to pneumatic transducer to vary its discharge flow control valve position.