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.JS ZZ LOIT Questions Ken Walter > Class 4.16 kV > Flashcards

Class 4.16 kV Flashcards

1
Q 
Which of the following components IS NOT supplied by power from PBA-S03?
A.  'A' Normal Chiller
B.  'A' Auxiliary Feed Pump
C.  'A' Essential Spray Pond Pump
D.  'A' Essential Cooling Water Pump
A

B

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2
Q

Describe the ESF Service Transformers.

A

NBN-X03 and NBN-X04 receive 13.8 KV power from NAN-S03 and NAN-S04 and supply 4.16 KV power to PBA-S03 and PBB-S04

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3
Q

What are the three Load Centers supplied by Train A PBA-S03?

A

PGA-L31
PGA-L33
PGA-L35

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4
Q

The ‘A’ DG is running with its output breaker PBA-S03B closed, loaded to 5.2 MW. PBA-S03 normal supply breaker PBA-S03L is closed. The CO places PBA-S03 alternate supply breaker PBA-S03K synch switch PBA-SS-S03K to ON and then places the breaker switch PBA-HS-S03K to CLOSE. Alternate supply breaker PBA-S03K will:
A. close. The DG supply breaker will open when the switch is released.
B. close. The normal supply breaker will open when the switch is released.
C. not close, because the normal supply breaker is closed.
D. not close, because the DG supply breaker is closed.

A

D

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5
Q

What loads directly powered from PBA-S03 are SIAS load shed?

A

‘A’ Normal Chiller

‘N’ Aux Feed Pump

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6
Q

What is different about ‘B’ train components and why?

A

‘B’ Train components necessary for safe shut down of the pant have local/local+remote switches to remove control room circuitry in the event of a control room fire. This is done to prevent spurious operations due to the fire.

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7
Q

What are the purposes of an anti-pumping relay?

A

1) Anti-Pumping

2) Prevent closure attempt of the breaker of closing springs are not charged.

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8
Q

PBA-S03 is currently being powered from DGA and the CO is going to parallel across the breaker to NBN-X03. After the sync selector switch is enabled, which voltages are indicated by “running” and “oncoming?”

A

“Running” is the PBA-S03 voltage, “Oncoming” is the voltage at the output of NBN-X03. This often leads to confusion when performing this operation. Remember that PBA-S03 and PBB-S04 are always considered “Running” and never “oncoming.”

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9
Q

PBA-S03 is being powered from the ‘A’ Diesel. The control room instructs the AO to close the PBA-S03 feeder breaker from NBN-X03. What will happen when the AO takes the CS-1 switch on the breaker cubicle to “shut?”

A

The breaker will not close as interlocks prevent paralleling power supplies locally.

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10
Q

List the ESF transformer trips.

A

1) Sudden pressure
2) Phase and ground overcurrent
3) Transformer differential

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11
Q

What indication do PBA and PBB under voltage relays provide in the Control Room?

A

Under their respective busses there are 8 white lights representing status of the relay. If the relay is actuated the light will be out. All 8 lights should normally be lit.

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12
Q

The CR has approved a clearance to remove the PT fuses for PBA-S03 during an outage. What will happen as soon as the fuse drawer is removed?

A

All 8 UV relays will detect an under voltage condition.

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13
Q

How is a LOP detected, and what coincidence is required for actuation?

A

Instantaneous undervoltage at 75% rated voltage, Time delay undervoltage at 90% for 30 seconds. 2/4 signals required for BOP ESFAS actuation.

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14
Q

What supplies control power for PBA-S03(PBB-S04)?

A

PKA-D21(PKB-D22)

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15
Q

Upon a SIAS signal, what is NOT load shed from PBA-S03 and PBB-S04?
A) AFN-PO1
B) Class Load Centers
C) NHN-M19, M20, M71, and M72

A

B.

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16
Q

Upon a SIAS load shed, what does not sequence back onto PBA-S03?

A

AFN-P01 and WCN-E01A

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17
Q

What are the protective features of the ESF transformers?

A

Sudden Pressure Relay
Transformer Differential
Phase and Ground Over-current

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18
Q

Explain degraded voltage vs. under-voltage with regards to 4.16kV Class buses. What coincidence will cause a LOP signal for the bus?

A

Degraded voltage: Below 90% rated voltage for ~30 seconds.
Under-voltage: Voltage drops below 75%.

2 out of 4 (for either condition) will initiate a LOP signal.

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19
Q

How does the operation of the Unit 1 class load center feeder breakers differ from those in the other two Units?

A

Due to initial plant design in Unit 1 where a SIAS load shed opened the LC feeder breaker and then sequenced it back on, an issue resulted in the breaker where the springs would not be sufficiently charged. Therefore, a jumper was installed to ensure the closing springs were charged under all conditions (vice just charging when the breaker opens).

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20
Q

Given the following Class (PG) Load Centers, list all the Class (PH) MCCs powered from each:
PGB-L36
PGB-L34
PGB-L32

A

PHB-M36 powered from PGB-L36
PHB-M34 powered from PGB-L34
PHB-M32 powered from PGB-L32
PHB-M38 powered from PGB-L32

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21
Q

Which MCC’s are SIAS Load Shed?

A

NHN-M19 and NHN-M71 (Load Group A)

NHN-M20 and NHN-M72 (Load Group B)

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22
Q 
(ANNUNCIATOR)
XFMR
HI TEMP
BUS UNDV
125VDC
FAILURE
A

Alarm is generated by:
A high temp condition in the x-fmr
Bus UV -or-
Control Power Failure

Note: Alarm is only associated with PGA-L33

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23
Q

What are the three Load Centers supplied by PBB-S04?

A

PGB-L32
PGB-L34
PGB-L36

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24
Q

Name the Train A MCC’s.

A

PHA-M31
PHA-M33
PHA-M35
PHA-M37

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25
Q

Name the Train B MCC’s.

A

PHB-M32
PHB-M34
PHB-M36
PHB-M38

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26
Q 
Which of the following components IS NOT supplied by power from PBB-S04?
A.  'B' Normal Chiller
B.  'B' Auxiliary Feed Pump
C.  'B' Essential Spray Pond Pump
D.  'B' Essential Cooling Water Pump
A

A

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27
Q

Describe the cooling system of the ESF transformers.

A

The ESF transformers are FA/OA (Forced Air/Oil Air) meaning air is blown across cooling fins filled with oil, causing natural circulation of the oil. The four fans turn on at a winding hot spot temperature of 70 C, when in AUTO.

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28
Q

What are the SIAS Load Shed MCCs and their respective power sources?

A

NHN-M71 receives power from PGA-L33
NHN-M19 receives power from PGA-L35
NHN-M20 receives power from PGB-L36
NHN-M72 receives power from PGB-L34

29
Q

If a loss of PBA-S03 occurs and the associated D/G starts but is unable to power PBA-S03, what must be perfomed?

A

With a loss of power to the Essential Spray Pond System power the associated D/G can NOT be operated due to the lack of cooling. DGA must be emergency tripped by the AO in the field.

30
Q

Which of the following is required for an automatic closure of ‘A’ DG output breaker PBA-S03B but not required for a manual closure from B01?
A. Normal supply breaker PBA-S03L is open
B. Alternate supply breaker PBA-S03K is open
C. Synch Switch PEA-SS-S03B is in ON
D. DG ‘A’ is at rated speed and voltage

A

A

31
Q

List the Train ‘B’ Class Load Centers.

A

PGB-L32
PGB-L34
PGB-L36

32
Q

What are the Train ‘A’ Class Load Centers?

A

PGA-L31
PGA-L33
PGA-L35

33
Q

Where can you reset the 86 lockouts for PBA-S03(S04) breakers?

A

Locally & from the Control Room.

34
Q

Typically in Class 480V Load Center Main Feeder Bkrs, the closing spring charges when the bkr is _____. However in U1, explain why a jumper was installed to charge the spring under all conditions.

A

Opened
The jumper is a holdover from early operation in U1. In the original design, the Class IE Load Centers were load shed on a SIAS and were then immediately sequenced back on. This resulted in the springs not being fully charged when called upon to reclose and restore power to the Class LCs.
(Class IE LCs no longer load shed)

35
Q

What are the conditions required to locally close the PBB-S04 normal supply breaker?

A

The ‘B’ DG output breaker and the PBB-S04 alternate supply breaker must both be open
No lockout on any of the three supply breakers (Normal and Alternate supplies and the ‘B’ DG output breaker)

36
Q

List all the ‘A’ Train Class IE (PH) MCCs and their respective power sources.

A

PHA-M31 powered from PGA-L31
PHA-M33 powered from PGA-L33
PHA-M35 powered from PGA-L35
PHA-M37 powered from PGA-L33

37
Q

What protective relaying do the Class 4.16kV buses have?

A 
Bus Under-voltage
Negative Sequence
Motor Phase Over-current
Motor Ground Fault Over-current
Bus Feeder Phase Over-current
Bus Feeder Neutral Residual Over-current
Lockout
38
Q

What will trip the Normal Supply Breaker to PBB-S04?

A

BOP-ESFAS load shed on a LOP.
The Alt supply breaker is closed with the SYNC switch on.
ESF transformer fault.
Bus over-current generated by lockout.

39
Q

What are the required condition to close the PBA-S03 normal supply breaker remotely?

A

Sync switch is ON

No lockout on any of the three supply breakers (Norm. and Alternate supplies and ‘A’ DG output breaker)

40
Q

How does the Class 1-E system support Safety Injection and Shutdown Cooling System?

A
  • 4.16 KV power to operate the pump motors

- 480 VAC power for motor operated valves and essential room cooling units (ACUs)

41
Q

How does the Class 1-E system support Chilled Water System?

A
  • Out of four normal chillers, the ‘A’ Chiller receives classpower from PBA-S03.
42
Q

A station blackout has just occurred, the SBOG has been started and placed on the class ‘A’ bus; 10 minutes later NBN-X03 suffers a ‘Sudden Pressure’ fault. Which bkrs immediately attached to the transformer would you expect to trip OPEN?

A

On a Sudden Pressure Relay (SPR), a lockout relay trips the x-former’s high side bkr at NAN-S03 and the low side bkr at PBA-S03 and PBB-S04 (tie bkr). If the SBOG is supplying the Unit, the supply bkr at NAN-S03AB would also trip.

43
Q

How does the Class 1-E system support Fuel Pool Cooling System?

A

480 VAC power is provided to the Fuel Pool Cooling pump motors.

44
Q

How does the Class 1-E system support CVCS?

A
  • 480 VAC power is provided to the charging pumps and various MOVS.
45
Q

How does the Class 1-E system support Essential Cooling Water System?

A
  • 4.16 KV power is provided to operate the pump motors.
  • Loss of power may affect the ability to remove decay heat when shutdown (Shutdown Cooling) and renders the Essential Chillers for the affected train inoperable.
46
Q

How does the Class 1-E system support Auxiliary Feedwater System?

A
  • 4.16 KV power is supplied to two motor driven Aux Feed Pump Motors. (AFN-P01 and AFP-P01).
  • 480 V power is supplied to the associated MOVs and essential ACUs.
  • Loss of power depends on the redundancy of the system (opposite train or Steam Driven Aux Feedwater Pump)
47
Q

How does the Class 1-E system support Essential Chilled Water System?

A
  • 4.16 KV and 480 VAC power is provided to operate the Essential Chillers.
  • Loss of power will prevent the safety related motors from operating indefinitely due to inadequate room cooling.
48
Q

How does the Class 1-E system support HVAC Equipment?

A
  • 480 VAC power is provided to:
    • ContainmentNormal Air Condition Unit (ACU) Fan
    • Control Element Drive Mechanism (CEDM) Normal ACU
      Fan.
    • Control Room Essential Air Handling Unit (AHU)
49
Q

How does the Class 1-E system support Pressurizer Pressure Control System?

A

480 VAC power is provided to two banks of class backup heaters.

50
Q

What does the “Phase and Ground Overcurrent” protection on the ESF Service Transformer monitor?

A

The secondary (wye connected) winding of the ESF transformers has a ground attached to its neutral. This ground is monitored for excessive current and, when detected, initiates a lockout.

51
Q

What are the trips for the LC Motor Feed Bkrs?

A

These bkrs are equipped with solid state overcurrent trip devices (long and instantaneous elements).
Solid state ground fault relays are also provided for ground fault protection.

NOTE: Both an overcurrent and ground fault will energize a lockout relay which will prevent re-closing this bkr until reset. The lockout relay can be reset locally (manually) and from the remote control location (i.e. CR or 120’ Fuel Bldg for a PC pump).

52
Q 
(ANNUNCIATOR)
UNDV
A(B)
CH
TRIP
A

Alarm is received when an UV or degraded voltage relay actuates.

BOP ESFAS will act accordingly to strip the bus and start the D/G

53
Q

The PHA-M31 supply bkr has tripped on a solid state overcurrent trip. Where can the lockout relay be reset from?

A

The lockout relay for an MCC Feed Bkr can only be reset manually at the LC.

NOTE: this differs slightly from LC Main and LC Motor Feed Bkrs; both of these bkrs can be reset from the CR (electrically) and locally at the LC (manually).

54
Q

Describe the method of cooling for the ESF Service Transformers (NBN-X03 and X04) and state the temperature at which all 4 fans turn on (if in AUTO).

A

FA/OA type (Forced Air/Oil Air), meaning air is blown across cooling fins filled with oil. This arrangement sets up a natural circulation of cooling oil.
Fans turn on when winding hot spot temp reaches 70C.

55
Q

The following description identifies what type of ESF Service Transformer Protection:
Monitors current leaving NAN-S03 and compares it to the value being supplied to PBA-S03 and PBB-S04 (tie bkr). A difference would indicate either a x-former OR bus differential condition.

A

Transformer Differential

56
Q

When excessive current is detected on the neutral of the Class 480VAC transformer, the overcurrent relay will trip …

A

BOTH the LC Main Feed and the 4160V supply bkr in order to isolate the transformer.

57
Q

Where can the lockout relay for the 480VAC LC Main Feed Bkrs be reset from?

A 
Locally (manually)
Control Room (electrically)
58
Q

How does the Class 1-E system support Diesel Generator support equipment?

A

480 VAC power is required to safely operate the D/Gs. Loads include fuel oil pumps, ventilation fans and lube oil pumps.

59
Q

A protective relay has just caused a lockout of the bus feeder bkr on PBB-S04, the ‘B’ DG has started but has failed to close in on the bus after 10 seconds. What is the most likely reason for the DG bkr failing to close on the bus?

A

The lockout relay on the bus feeder bkr not only trips that bkr, but also PREVENTS closing the other supply bkrs. This action prevents a D/G from closing in on a faulted bus.

60
Q 
(ANNUNCIATOR) - Green alarm window
4.16KV
IE TR A(B)
SPLY BKR
LKO TRIP
A

Generated by a lockout actuation on the supply bkr.

NOTE: In response to this, the D/G will start BUT will not have a SP pump operating. The D/G is required to be emergency stopped locally.

61
Q 
(ANNUNCIATOR)
ESF SERV
XFMR X03(4)
PROT TRIP/
TRBL
A

Alarm indicates either a trip or a problem with the transformer.

NOTE: An AO must be dispatched to investigate the local annunciator panel.

62
Q 
(ANNUNCIATOR)
4.16KV
IE TR A(B)
SWGR S03(4)
TRBL
A

Alarm is generated by the following bus problems:
UV (3675 V)
Negative sequence
Control power failure
Closing spring not charged
A sustained (10s) degraded voltage (3745V) condition

63
Q 
(ANNUNCIATOR) - Green alarm window
4.16KV
PWR
SOURCES
PARALLELED
A

4.16 kV bkrs in parallel

NOTE: This is an expected alarm when transferring power supplies to a bus

64
Q

Which “Class” train is designated to meet the 10CFR50 Appendix ‘R’ requirements? What is installed in order to meet this requirement?

A

Train “B”
A disconnect switch is installed to disable the CR operation which could, as a result of a fire, interfere with local control.

65
Q 
(ANNUNCIATOR)
480 VOLT
IE TR A(B)
LC L##
SPLY BKR
TRBL
A

Alarm is generated by:
A high temp condition in the x-former
Bus UV -or-
Control power failure

Note: LCs L31, L32, L34, L35, L36 each have their own alarm

66
Q 
(ANNUNCIATOR) - Yellow alarm window
480 VOLT
IE TR A
LC L31(35)
SPLY BKR
LKO TRIP
A

Alarm is generated by a lockout of the Main Feed Bkr

67
Q 
(ANNUNCIATOR)
MCC
FEEDER BKR
LKO
TRIP
A

Common alarm for all class MCCs that are fed from PGA-L33

Note: The MCC (PHA-M33, PHA-M37 and NHN-M71) can be determined by looking for a ‘green’ light on one of the MCCs on B01.

68
Q 
(SESS Component Alarm)
480V IE
LC ##
SPLY/FDR
BKR

When is the WHITE section (SEIS) lit?
When is the BLUE section (SEAS) lit?

A 
WHITE section: 
Supply/Feeder Bkr Inoperable
Bkr tripped on Overload
Control Power fuses blown
Supply/Feeder Bkr closing springs fail to charge

BLUE section:
Lit when the bkr is OPEN when it’s actuated position is CLOSED.
Possible reasons for the bkr in the OPEN position are:
Overload trip
Loss of 125 VDC control power or fuses
Bkr racked out

.JS ZZ LOIT Questions Ken Walter (75 decks)

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