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NLO Systems 2023 > PB/PG/PH/PK/PN- Class Electrical > Flashcards

PB/PG/PH/PK/PN- Class Electrical Flashcards

1
Q

What are the colors associated with each train, A, B, C, D?

A

A-red
B-green
C-yellow
D-blue

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2
Q

What are the system designators for the class 4.16kV, 480V load centers, 480V MCCs, 125VDC and the 120VAC systems?

A 
PB-4.16kV
PG-480VAC load centers
PH-480v MCCs
PK-125VDC
PN-120VAC
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3
Q

What happens to the class 4160V busses when a Loss of Off-site power occurs?

A

the emergency diesels would start and auto load to the class busses

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4
Q

what is the purpose and design of the class 4.16kV power (PB) system?

A

purpose:
provides 4160V power to one of two redundant and independent safety related load groups, or equipment that is required to safely shut down the unit

design:
has normal (off-site power) and alternate (emergency diesels) power source

detects degraded voltage and loss of voltage on normal power source and will send a LOP to ESF actuation system

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5
Q

Can one safety train of equipment safely shut down the unit, or are both required?

A

only one train is required

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6
Q

Where does PBA-S03 and PBB-S04 get power from?

A

NAN-S03/04 through the ESF(NBN-X03/04) transformers.

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7
Q

What purpose do the FLEX portable diesel generators serve?

A

In a Beyond Design Basis event, they can be tied to supply PBA-S03 or PBB-S04, downstream of the ESF transformers

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8
Q

How does the NA system interface with the PB system?

A

provides all power to the PB system via the preferred, alternate or normal shutdown configuration, including SBOGs

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9
Q

How does the NB system interface with the PB system?

A

PB receives power from the NB ESF transformers

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10
Q

How does the DG system interface with the PB system?

A

PB receives power from the Class emergency diesels during a LOOP

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11
Q

How does the PG system interface with the PB system?

A

PB supplies power to the PG load centers

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12
Q

How does the PH system interface with the PB system?

A

PB receives 120VAC from the PHD-panels for switchgear heaters

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13
Q

why do switchgear require space heaters?

A

to maintain temperature above the dew point

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14
Q

How does the PK system interface with the PB system?

A

PK provides control power to the PB switchgear

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15
Q

How does the BOP(ESFAS/SA) system interface with the PB system?

A

PB sends signals for each load group of bus under-voltage to the SA system and receives load shedding and load sequencing signals from the SA system

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16
Q

How does the SP system interface with the PB system?

A

PB supplies power to the Essential spray pond pump motors

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17
Q

How does the SI system interface with the PB system?

A

supplies power to the Safety injection pump motors (HPSI/LPSI)

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18
Q

How does the EC system interface with the PB system?

A

PB supplies power to the essential chillers

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19
Q

How does the WC system interface with the PB system?

A

PB supplies power to the A normal chiller

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20
Q

How does the EW system interface with the PB system?

A

PB provides power to the essential cooling water pump motors

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21
Q

How does the AF system interface with the PB system?

A

PB provides power to the B and N auxiliary feedwater pump motors

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22
Q

How does the HJ system interface with the PB system?

A

HJ provides normal and emergency cooling to the class switchgear rooms

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23
Q

what is the purpose, operation and location of the ESF transformers?

A

purpose/operation:
step down 13.8kV to 4160V and provide that power from the preferred off-site source or from the SBOGs

oil/ air and forced air cooling

cooling is powered from 480VAC

can fault isolate

location:
outdoors, south side of the turbine building

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24
Q

what is the purpose, operation and location of the PB switchgear?

A 
purpose/operation:
distribute power to class safety related loads, start and trip loads as required and protect bus from damage due to faults and overloads

can be operated remotely from control room, remote shutdown panel (B train only) or locally

location:
separate class switchgear room, 100' control building
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25
Q

In PB breaker cabinets, what are the fuse names and what do they supply power to?

A

UC-closing circuits and green light
UT-tripping circuits and red light
UE-control room connections to the tripping and closing circuits
UL- for racking motor

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26
Q

What D-panels do PBA-S03 and PBB-S04 receive control power from?

A

PKA-D21 (S03)

PKB-D22 (S04)

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27
Q

What breaker inside the breaker cubicle provides control power to the fuses?

A

RRA

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28
Q

For seismic concerns, when PB breakers are racked out, what must be done?

A

the breaker must be racked back up 1-2” off the ground or restrained

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29
Q

Describe the automatic features of the class 4160v power system.

A

under voltage relays prevent system running on low voltage and will fault the bus

8 of the 9 under-voltage relays input into the BOP ESFAS and initiate 2/4 logic and perform:

start respective diesel generator

load shed bus

close diesel generator breaker

load sequence diesel generator

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30
Q

What is a LOP?

A

Loss of Power

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31
Q

What is a LOOP?

A

Loos of Off-site Power

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32
Q

How many under-voltage relays are on each PB bus and what are they dedicated for?

A

9 total
5 for degraded voltage
4 for under voltage detection

the 5 degraded voltage relay will provide annunciation 10 seconds after voltage drops below 90%

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33
Q

When do the degraded voltage relays actuate?

A

30 seconds after voltage drops below 90% of rated capacity

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34
Q

When do the voltage detection relays actuate?

A

immediately after voltage drops to 75%

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35
Q

On PB busses, what trips the normal and alternate breakers?

A

if electrical load shed is generated

the opposite supply breaker is closed from B01
ESF transformer faults

if the 86 lockout operates

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36
Q

How will a loss of the PB system impact the plant?

A

power must be restored within two hours due to class battery system capacity

failure of one safety train will require the redundant train to meet safety functions

may enter abnormal operating procedure or emergency operating procedure to restore power

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37
Q

with a diesel generator running, how long do you have to get a spray pond pump running before the diesel shuts down?

A

2.6 minutes

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38
Q

What circumstance would require cross tying PB Busses?

A

when one shutdown cooling loop is not available and the opposite train diesel generator is not available

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39
Q

What does the Degraded Electrical Power Abnormal Operating Procedure provide guidance for?

A

LOP to any 480V or higher bus that does NOT cause a LOOP or blackout

PB bus cross tying

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40
Q

What do the Emergency Operating Procedures provide guidance for?

A

they address the availability of the 4160V busses to ensure ONE class bus is available to support a safety equipment train.

determining a blackout if no PB busses are available

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41
Q

What PB system equipment is related to tech specs while operating?

A

PBA-S03 and PBB-S04 must be energized to their proper voltages to be OPERABLE

tie breakers between redundant safety systems must be open

8 hours to become operable if either train becomes inoperable

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42
Q

What PB system equipment is related to tech specs while shutdown?

A

All systems necessary to support OPERABILITY of required systems, equipment and components

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43
Q

What is the purpose of the PG/PH system?

A

step down power from 4160v to 480v and send that power to safety related equipment as well as essential non class equipment.

equipment is design basis

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44
Q

How many load centers and MCCs are on each safety train?

A

Three load centers
Four class MCCs
Two SIAS load shed MCCs

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45
Q

What is a SIAS Load shed MCC?

A

A non-class MCC supplying power to essential non class loads that will be tripped in the case of a SIAS

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46
Q

Where do PG load centers get control power from?

A

125VDC (PK)

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47
Q

Where do PH MCC breakers get control power from?

A

They provide their own control power

48
Q

How do the PG/PH systems interface with ESFAS?

A

receives control signals from ESFAS

49
Q

How does PG/PH interface with CVCS?

A

PG- provides power to the charging pumps

PH- provides power to VCT outlet valve and RWT gravity feed line suction valve to charging pumps

50
Q

How does PG/PH interface with HVAC equipment?

A

provides power to containment normal ACU fans, CEDM normal ACU fans, and control room essential AHU fans

51
Q

How does the PG/PH system interface with pressurizer pressure control system?

A

provides power to two banks of class back up heaters.

52
Q

How does the PG/PH system interface with the Diesel Generators?

A

provides power to DG fuel oil pumps, air compressors, vent fans and lube oil pumps

53
Q

How does the PG/PH system interface with Fuel pool cooling system?

A

provides power to the fuel pool cooling pump motors

54
Q

What two PG load centers have forced air cooling fans?

A

PGA-L31 and PGB-L32

fans turn on at 190*C

rated at 1000kVA
(others rated at 750kVA natural air cooled)

55
Q

What is the purpose, operation and location of the load center transformers?

A

Purpose/operation:
step down 4160v to 480v to supply larger 480v loads and to MCCs for smaller 480v loads

Location:
in the load centers on the 100’ control building

56
Q

Which breaker on a 480VAC load center is always the feeder breaker distributing power to the loads?

A

B2 breaker

57
Q

What three positions are there for a load center breaker to be in?

A

operating, test, withdrawn
or
connect, test, disconnect

58
Q

What three types of circuit breakers are found on a 480VAC load center?

A

main feeder breaker, motor feed breaker, MCC feed breakers

59
Q

What position are the main and auxiliary contacts in while a load center breaker is in the test position?

A

main contacts disconnected, aux contacts connected

60
Q

What is the main difference between the three types of circuit breakers found on a load center?

A

amperage rating and protection schemes

61
Q

On PG load centers, where can the main feeder breaker 86 lock out relays be reset?

A

locally and control room

62
Q

What does the white bell alarm button indicate on load centers?

A

it means the breaker was tripped on overcurrent specifically and must be pushed in to be reset prior to closing the breaker again

63
Q

What three positions do MCC breakers have?

A

on, off, tripped

64
Q

Class MCCs are normally operated locally. When continuity of operation is essential, and required for hot shutdown, where else can class MCCs be operated from?

A

Remote shutdown panel

65
Q

In MCC breakers, what do the magnetic starters do?

A

turning the load ON and OFF.

the starter is de-energized in an overload condition

66
Q

What is the purpose and operation of the Train B disconnect switches?

A

They are in place to, in the case of a control room fire, separate the control room from the B train equipment electrically.

There is a REMOTE/LOCAL and LOCAL switch locally.

67
Q

Describe the automatic feature associated with the PG/PH system.

A

In the case of a SIAS, the four essential, non class, SIAS load shed MCCs will trip.

trip can be over ridden locally

68
Q

What impacts would the plant feel if there was a loss of the PG/PH system?

A

low level impacts, possibly lose a charging pump or back up pressurizer heaters.

69
Q

What impact would the PG system feel if it lost control power?

A

breakers need local manipulation

70
Q

What impact would the PH system feel if PG was lost?

A

MCC breakers would trip open

71
Q

Describe the FLEX modifications that were made to the Class 480V Electrical System in order to support the PVNGS Extended Loss of All Site AC Guidelines.

A

two FLEX generators will be connected to the PG system via FLEX connection junction boxes on the south wall of the control building with conduit to the A train LC’s, L31, L33, L35

72
Q

In regards to requiring the use of flex equipment in an emergency situation, why is the primary strategy to recover the A train LC’s? What is the alternate strategy?

A

these LC’s will allow the plant to repower vital battery chargers to allow infinite coping time.

Alternate strategy is to re-energize the B train LC’s via 480VAC connections via FLEX junction boxes on the east control building wall.

73
Q

What must be done prior to Starting the Flex diesel generators to prevent overloading them?

A

opening all LC and MCC breakers

74
Q

How long do you have for FLEX 480VAC diesel generators to be deployed and operational?

A

T+34 hours

75
Q

Where do FLEX 480VAC Diesel generators get fuel from?

A

gravity-fed hose connected to one of two safety related diesel fuel day tanks in the diesel building.

76
Q

What is the purpose of the PK system?

A

consists of four subsystems that provide 125VDC to four independent class loads, essential AC power inverters and ESF equipment.

provides two hours of 125VDC power

77
Q

What are the two PK load groups and what channels are they representing?

A

A-A/C

B-B/D

78
Q

How does the PK system interface with the HJ system?

A

HJ provides cooling and exhaust to the battery rooms to remove H2 build up

79
Q

How does the PK system interface with the PH system?

A

PH sends 480VAC to the battery chargers

80
Q

How does the PK system interface with the PB system?

A

control power

81
Q

If switchgear breakers lose control power, would they trip on a fault?

A

No

82
Q

How does the PK system interface with the PG system?

A

control power

83
Q

How does the PK system interface with the PE system?

A

Control power and field flashing

84
Q

What would happen to the Emergency Diesel generators if PK was lost?

A

Diesels would trip but output breaker would remain closed

85
Q

How does the PK system interface with the AF system?

A

PK supplies power to MOVs and controls for the steam driven A aux. feed pump

86
Q

How does the PK system interface with the Si system?

A

PK supplies power to shutdown cooling suction isolation valves -653 and -654

87
Q

How does the PK system interface with the PN system?

A

PK is the power supply to four inverters to 120VAC class instrumentation

88
Q

How does the PK system interface with the SG system?

A

SG uses DC power to provide a permissive signal to the ADV’s to allow remote operation

89
Q

PK provides power to many containment isolation valves. What is the fail state of majority of containment isolation valves?

A

closed.

90
Q

What is the purpose, operation and location of the class battery chargers?

A

purpose:
step down and invert the 480VAC supply to 135VDC with the capacity to supply all demands and charge batteries from minimum charge within 12 hours

operation:
float and equalize modes with a 24hr equalizing timer

has transfer switches for isolating load shedding, sequence permissive relays and other equipment in the CR

The A battery can be isolated from the control room

location:
100’ control building

91
Q

How long will the class batteries supply power in the case of a LOOP?

A

2 hours

92
Q

What two shutdown cooling isolation valves does the PK system supply from the PKC-M43 and PKD-M44 busses?

A

SIC-UV-653 and SID-UV-654

93
Q

What prevents condensation build up in the 125VDC control centers?

A

120VAC space heaters

94
Q

What safety channels are equipped with transfer switches on the battery breakers and why?

A

A,B, and D have them to take local control and indication in the event of a control room fire.

95
Q

How would a loss of the PK system affect the plant?

A

PN will transfer to alternate power

the A aux. feed pump turbine will trip

ADV’s will fail closed

containment isolation valves will fail closed

the respective Reactor Trip Switchgear (RTSG) breaker will trip open

96
Q

If only one PK bus is lost, can the unit stay at 100% power?

A

Yes.

97
Q

If a PK bus is lost, will the swing charger automatically transfer?

A

No, the AO will perform this in the field.

98
Q

What is the purpose of the PN system?

A

provide 120VAC through preferred or back up sources of power to four independent channels of class vital instrumentation

control power to the reactor protection system (RPS) and ESFAS

99
Q

Between the Channel load groups in the PN system, A/C and B/D, which load group has to be switched to its back up power source manually?

A

A/C (unit 1 only)

A/C and B/D in units 2 and 3 will all transfer automatically

100
Q

How does the PN system interface with HJ?

A

HJ provides cooling air and ventilation to the equipment rooms

101
Q

How does the PN system interface with PH?

A

PH supplies 480VAC to back up power source for PN

102
Q

How does the PN system interface with PK?

A

PK provides power to PN bus and ground fault indication circuit

103
Q

How does the PN system interface with EC

A

powers EC flow transmitter

104
Q

How does the PN system interface with RPS/ESFAS?

A

RPS supplies 120 VAC power to class instrumentation, control, protection and indication circuits

105
Q

What is the purpose, operation and location of the inverters in the PN system?

A

purpose/operation:
to invert 125VDC to 120VAC

location:
100’ control building

106
Q

There is an input and an output breaker on the inverter. What do they do?

A

input provides DC to the inverter and output supplies power to the “forward transfer” switch that automatically switches to back up power source (except unit one A/C group)

107
Q

On the PN inverters, why is the pre charge button important?

A

it must be pressed prior to closing the input DC breaker on the inverter

108
Q

Why is the Unit 1 PN system A/C inverter manual transfer switch break-before-make?

A

to prevent paralleling AC sources out of phase

109
Q

In which units does the PN inverters have a manual bypass switch for bypassing the static transfer switch?

A

Units 2 and 3

110
Q

In the PN system, where do the voltage regulators receive power from?

A

PH

111
Q

How many class 120VAC D-panels are there in each unit? Are they grounded?

A

four

they are ungrounded

112
Q

What do the PN D-panels supply power to?

A

they each supply one channel in the RPS and ESFAS control systems

113
Q

How are ground faults indicated on the PN D-panels?

A

red light will be on

114
Q

What is the impact on the Plant when the PN system is lost?

A

losing one channel of PN will not cause a trip, but the instrumentation for that channel will be lost.

if two channels are lost, the plant will trip.

115
Q

What is the tech spec for the PN inverters?

A

to stay operable, one inverter can be taken out of service and bypassed to the voltage regulator as long as all other inverters are in service

116
Q

Why would one PN inverter need to be bypassed to the voltage regulator?

A

to accomplish an equalizing charge on the respective battery within 24hours

NLO Systems 2023 (67 decks)

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