BOP/ESS Electrical Flashcards
Why are the EP breakers to T-bus interlocked to prevent closure unless all other feed breakers to that bus are open?
EP is 30° out of phase with other grid connections through reserve power and unit auxiliaries
What is the maximum loading per unit due to the temperature limitation on the aluminum feeder cables?
600 amps
What is the voltage SDG output breaker trip coil?
48 VDC
When will 11BCMC automatically close?
For a fault located on either TR11BMC or on TR11CMC
When will 11BCMC not automatically close?
For a fault located on either bus (11BMC or 11CMC)
When would you pull open knife switches to prevent automatic closure of the reserve feed breaker?
-When a standing close signal from fast transfer exists and you want to control when the breaker closes
OR
-Conditions in which anti-pumping circuit is energized without breaker closure and conditions now allow breaker to be closed
What do you have to do with both power sources lost to U1 Main Transformer cooling?
- Power is reduced to 50% using the RAPID POWER REDUCTION procedure.
- If cooling cannot be restored within 2 hours, TRIP the Reactor.
If winding temperature Hi-Hi is received accompanying loss of cooling on U1 Main Transformer, what must you do?
Rapid power reduction to 50%
Reactor trip if temperature not lowering (140 degrees C) if > P8
What do you have to do with both power sources lost to U2 Main Transformer cooling?
Restore one group immediately or Trip Reactor
How do you reset the Anti-Pumping Circuit?
Take the control switch to trip/reset
Where is transformer Cooling powered from for the Main Transformer?
Train A 600V Buses (11/21C and 11/21D)
Both SDGs are sized to support?
Sized to power one unit/one train of vital equipment needed to ensure RCS inventory control following a Station Blackout.
(For 24 hours to provide a reduction in PRA risk)
What is the SDG auto start sequence on a loss of EP?
- Senses the undervoltage on the 69kV EP bus, waits 150 seconds.
- Sends the open signal to the MDS.
- Verifies the MDS is open, and then sends the start signal to the SDGs
- 1st SDG to reach speed and voltage (25 secs) closes its breaker (12-52-SDGS-2 or 12-52-SDGS-3) onto the dead bus.
- The remaining SDG auto synchronizes to the bus and closes its output breaker.
- PowerLynx then closes the tie breaker (12-52-SDGS-4) to the station EP bus.
Per TS 3.8.1 B (AC Sources - Operating), if you have 1 required EDG inop (within1 hour actions)
WITHIN 1 hr:
- Verify both SDGs are available and perform SR 3.8.1.1 (STP21)
Per TS 3.8.1 H (AC Sources - Operating), If you have 3 or more required AC sources INOP,
IMMEDIATELY:
- Enter L.C.O. 3.0.3
Load Shed is sensed on which buses and at what voltage is it caused by in both units?
2/3 sensed on EACH T-Bus (T11/21 A, B, C and D)
And it has to sense 94V on Unit 1, and 93V on Unit 2 for 2 sec on 2/3 sensors
What buses are degraded bus voltage sensed on?
T11/21A and T11/21D (pump buses)
2/3 sensors
What will happen if your T11A Bus is at 113v for 8 sec?
Nothing yet, At 9 seconds, an alarm will come in for degraded bus voltage
What will happen if T11D is at 113v for 99 sec?
It will cause a fast bus transfer to associated RAT
What will happen if T11A Bus is at 113v for 120 sec?
It will trip the A and B RCP Bus x-tie bkrs and cause a load shed. AB EDG will start and load to the T11A and T11B bus and ESF equip will sequence on. Rx does not trip unless RCP bus is lost
Which transformer normally provides power to the AB RAT (Train B)?
Transformer 5
Which transformer normally provides power to the CD RAT (Train A)
Transformer 9
How long is the wait for the fast bus transfer to RAT if you have a generator trip?
Instant
How long is the wait for the fast bus transfer to RAT if you have a Turbine trip?
30 Sec
If an overcurrent is sensed on TR11B, what happens first?
It trips the low side breaker (11B11)