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Operator Knowledge > BOP/ESS Electrical > Flashcards

BOP/ESS Electrical Flashcards

1
Q

Why are the EP breakers to the T-bus interlocked to prevent closure unless all other feeder breakers are open?

A

EP is 30 degrees out of phase with reserve feed and unit auxiliaries.

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2
Q

What is the maximum loading per unit and why?

A

600 amps
This coincides with the temp limit for the aluminum feeder cables.

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3
Q

What is the power source for the SDG output breaker trip coils and closing coils?

A

-48 VDC battery
-230 VAC powers the breaker closing coils

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4
Q

What is the power source for the 345kV yard breaker trip coils?

A

125 VDC battery (with two chargers) in the 345kV control house.

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5
Q

What is the power source for the 765kV yard breaker trip coils?

A

Two 125 VDC batteries (with two chargers) in the 765kV control house.

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6
Q

What is the power source for the 34.5kV breakers?

A

125 VDC battery (with two chargers) in the 345kV control house.

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7
Q

What is the power source for the EP breakers?

A

48 VDC in the SDG switchgear house.

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8
Q

What is the power source for the EP motor operated disconnect?

A

48 VDC in the SDG switchgear house.

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9
Q

What is the power source for the 4kV breakers (RCP bus feeder breakers)?

A

The associated train 250 VDC battery.

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10
Q

What is the power source for the 600V breakers (BMC and CMC)?

A

The associated train 250 VDC battery.

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11
Q

When will the 600V non-vital bus tie-breaker automatically close?

A

For a fault located on either transformer feeding the associated 600V non-vital bus.

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12
Q

When will the 600V non-vital bus tie-breaker NOT automatically close?

A

For a fault located on either associated 600V non-vital bus.

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13
Q

When would knife switches be openned to prevent the auto closure (fast-transfer) of the RAT’s?

A
  • When a standing close signal from fast transfer exists and you want to control when the breaker closes.
  • Conditions in which the anti-pumping circuit is energized without breaker closure and conditions now allow it to close.
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14
Q

What actions are required for a loss of U1 Main Transformer Cooling?

A

-Rapid Power Reduction to 50%.
- If cooling cannot be restored within 2 hours, TRIP the RX.

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15
Q

What actions are required if U1 Main Transformer Cooling is lost AND winding Hi-Hi temp is received?

A
  • Rapid Power Reduction to 50%
  • RX TRIP if >P-8 and winding temp >140C
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16
Q

What actions are required for a loss of U2 Main Transformer Cooling?

A
  • Restore one cooling group immediately
    OR
  • TRIP the RX
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17
Q

What is the power source for Main Transformer Cooling?

A

Train A 600V buses
(11/21C and 11/21D)

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18
Q

What are the SDG’s sized for electrically?

A
  • For a SINGLE Units RCS inventory control, using a SINGLE train of equipment. (ESW, CCW, NESW, CCP, and CAC)
  • Support RCS inventory control for 24 hours.
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19
Q

What is the SDG auto-start sequence?

A
  • Powerlynx sense undervoltage on the 69kV EP system, and waits 150 seconds.
  • Sends open signal to the MDS
  • Verifies MDS is open and sends start signal to the SDG’s
  • The first SDG to reach speed and voltage closes its output breaker.
  • The remaining SDG auto synchronizes to the bus and closes its output breaker.
  • Powerlynx then closes the tie-breaker to the station EP bus.
  • Operator must manually close the EP breaker(s) to the T-buses.
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20
Q

Why must the SDG’s be in MANUAL when 69kV EP is being used to power the 4kV safety buses?

A
  • Prevents overloading the SDG’s should 69kV EP be lost.
  • If EP is powering the T-buses, then the EDG output breakers would be in PTL (defeats the load shed circuit).
  • If EP is lost when load shed is defeated, the EP feeder breakers and all of the loads will remain on the T-bus(es).
  • With the SDG’s in auto, they would start and tie to the T-bus(es) and overload.
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21
Q

What are the conditions required to get a Degraded Bus Voltage sequence?

A
  • 2/3 sensors < 113V
  • On either T11(21)A or T11(21)D
22
Q

What is the Degraded Bus Voltage Sequence?

A
  • 9 seconds from DBV sensed on T-A or D bus will give the alarm.
  • If during the 9 seconds a S/G Lo-Lo or SI signal exists then that TRAIN T-bus feeder breakers open and the EDG starts.
  • 90 seconds to transfer that TRAIN from UAT’s to the RAT’s.
  • 21 seconds on the RAT’s with load tap changers attempting to adjust voltage. IF voltage is still low, then that TRAIN T-bus feeder breakers will open and the EDG starts.
  • Total time of 120 seconds.
23
Q

What is the impact on Tech Specs for EDG’s if SDG(s) are unavailable?

A
  • With both SDG’s available, the allowed outage time for an inoperable EDG is 14 days.
  • With both SDG’s unavailable, the allowed outage time for an inoperable EDG lowers to 72 hours.
24
Q

What is the Anti-Pumping Relay?

A

Prevents the breaker from attempting a second closure with a standing close signal when the first attempt was followed by a trip open signal.

25
Q

What is the 600V non-vital bus tie-breaker auto closure sequence?

A
  • Overcurrent is sensed on the feeder transformer.
  • Low side breaker opens first, then current is assessed for 30 cycles.
  • If the overcurrent condition is no longer sensed, then the fault is on the bus and no further action occurs.
  • If the overcurrent condition still exists, then the low side breaker gets a backup open signal, high side breaker opens, and the tie-breaker will close.
  • The fault is on the transformer and the bus will be powered via the tie-breaker.
26
Q

What is the RCP bus fast transfer sequence?

A
  • Occurs when the main generator lockout relays are actuated.
  • Open signal is sent to the RCP bus normal feeder breakers. This takes 5 cycles to open.
  • Close signal is sent to the RCP bus reserve feed breakers, this takes 7 cycles to close.
  • 2 cycle dead time minimizes RCP motor “stall”
27
Q

What is the preferred Offsite Power Line-Up?

A

Split Bus Line-Up
- Train A from TR9
- Train B from TR5

28
Q

What is the alternate Offsite Power Line-Up?

A

Split Bus Line-Up
- Train A from TR4
- Train B from TR9

29
Q

How is the Anti-Pumping Circuit Reset?

A

Take the control switch to TRIP/RESET

30
Q

How long is the delay for a Fast Transfer if there is a Main Generator Trip?

A

Instant, no delay.

31
Q

How long is the delay for a Fast Transfer if there is a Main Turbine Trip?

A

30 second delay.

32
Q

What is the design capacity of EP?

A

Designed to handle a concurrent Station Blackout in both Units with a CTS in one of the units.

33
Q

What is the power source for the Unit Differential (HEA) Relays?

A

Train B

34
Q

What is the power source for 33VED?

A

Train A

35
Q

What is the power source for the OVERALL Differential (HEA) Relays?

A

Switchyard Cabinet

36
Q

What is the backup Offsite Power Line-Up?

A

Split Bus Line-Up
- Train A from TR5
- Train B from TR4

37
Q

What are the effects of NOT having control power available to a breaker?

A
  • Cannot operate remotely.
  • Protection scheme not available (auto trip unavailable).
38
Q

Where are the 480V PZR Heater Buses power from?

A

PHA from T11(21)A
PHC from T11(21)D

39
Q

What is the Load Shed Sequence?

A
  • 2/3 undervoltage relays sense loss of voltage (U1: 94V, U2:93V) to ANY T-bus for 2 seconds:
    -> Trips open all feeder breakers to the T-Bus
    -> Trips open all feeder breakers to loads powered from the bus.
    -> Starts the EDG and connects EDG to dead bus
    -> Sequences on required loads.
40
Q

What conditions will generate a Load Conservation?

A
  • SI followed by a Load Shed. (Standing SI signal, EDG running but not connected to bus, and a load shed occurs)
  • CTS followed by a Load Shed. (Standing CTS signal, EDG running but not connected to bus, and a load shed occurs)
  • LOOP followed by an SI (EDG running connected to either T-A or D bus, and SI occurs)
  • LOOP followed by a CTS (EDG running connected to T-A or D bus, and CTS occurs)
41
Q

What occurs on a Load Conservation signal?

A
  • Trips and locks out selected non-essential vital bus loads.
  • Prevents restarting any stripped loads until the 75 second timer runs out OR SI is reset after the 60 second SI timer runs out.
  • Trips the NESW pump.
42
Q

What size of loads are on the T-buses?

A
  • Greater than or equal to 400 HP motors.
  • 600V ESF transformers
  • PZR heater buses
43
Q

What size of loads are on the 600V vital buses?

A

Motors from 100 HP to 400 HP

44
Q

What pumps do the SDG’s power for RCS inventory control?

A
  • ESW
  • CCW
  • CCP
  • AFW
  • NESW
45
Q

When is the Loss of Voltage function (Load Shed) required?

A
  • MODES 1-4
  • MODES 5, 6, and Defueled: When the EDG is required to be OPERABLE
46
Q

When is the Degraded Bus Voltage function required?

A

MODES 1-4

47
Q

What is the power source for Reserve Aux Transformer (RAT) Cooling?

A

T11(21)D

48
Q

What is the power source for the Main Generator Output Breakers?

A

125 VDC Switchyard
(Each unit has its own)

49
Q

What is the switch positions required to close the 34.5kV breakers?

A
  • 3 switches total (control switches in each control room AND in the U1 switchyard control house)
  • All three must be in the CLOSE (red flag) position.
50
Q

What is the switch positions required to close the Main Generator Output Breakers?

A
  • A1 and A2: Two switches total. One in U2 control room and one in the 765kV switchyard. Both must be in CLOSE
  • O and O1: Two switches total. One in the U1 control room and one in the 345kV switchyard. Both must be in CLOSE.

Operator Knowledge (17 decks)

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