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LOIT > Non-Class Elec Dist. (NA, NB, NG, NH) COPY > Flashcards

Non-Class Elec Dist. (NA, NB, NG, NH) COPY Flashcards

1
Q

What is the electrical flow path from the Startup Yard to the WRF NB system for the Cooling Tower Make Up and Blowdown (TB) system?

Do these NB busses have cross tie capability?

A

NAN-S05/S06 -> NBN-X05/X06 -> NBN-S05/S06

Yes

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2
Q

On a 13.8 kV (NA) breaker, what does the red light mean?

A

Breaker closed

continuity through trip coil

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3
Q

On a 13.8 kV (NA) breaker, what does the Green light mean?

A

Breaker Open

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4
Q

On a 13.8 kV (NA) breaker, what does the bright green light mean?

A

Breaker tripped on fault

breaker racked to test

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5
Q

On a 13.8 kV (NA) breaker, what does the white light mean?

A

status of lockout relay

if light is ON, relay is reset and continuity through it

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6
Q

On a 13.8 kV (NA) breaker, what does the clear light mean?

A

closing springs are charged

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7
Q

What are the control room indications for a breaker?

A

Red light - breaker closed & continuity through trip coil
green light - breaker open
bright green light - breaker tripped on fault or racked to test

voltmeter on B01
ammeter on B01

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8
Q

What is the Startup Oscillograh for?

A

Multi-channel transient recorder (Digital Fault Recorder) that detects and automatically records power system abnormalities in analog and on-off event form.

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9
Q

When do the closing springs recharge for big breakers?

A

immediately after discharging to close the breaker

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10
Q

When do 480 VAC LC breaker closing springs recharge?

A

when the breaker reopens

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11
Q

What is the purpose of Anti-pumping protection?

A

to ensure that the breaker only attempts to close ONCE per control switch operation

prevents closure attempt with an uncharged spring

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12
Q

When would you have to locally manually operate big breakers?

A

loss of control power

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13
Q

Can we parallel power supplies locally electrically on non-class busses?

A

No

there are interlocks that prevent multiple supply breakers from closing at the same time when operating the breaker locally electrically

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14
Q

What is the purpose of the synch switch in the control room in relation to operating breakers?

A

enables closure of multiple supply breakers in parallel

energizes synch indications on B01

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15
Q

What is the purpose of the Line Breakers Control Transfer Switches regarding the 525kV SRP Switch Yard breakers?

A

Provides permissives to operate the SRP breakers from the Unit 1 control room

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16
Q

What are the two positions for the 525kV line breaker Control Transfer Switches?

A

PDO - SRP Control only

CON RM1 / PDO - allows Control Room control

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17
Q

What indications are available for voltage on the EAST and West Busses in the SRP Switchyard?

A

two digital meters on U1 B01

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18
Q

What alarm window indicates degraded or loss of voltage on the East/West busses in the SRP Switchyard?

A

EAST/WEST 525 KV SWYD LO/LO-LO VOLTS

(1B06B)

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19
Q

What is a “ring bus” regarding the SRP Switchyard?

A

the East/West Busses that are connected to each other in 8 locations

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20
Q

Regarding SRP Switchyard design, why is the ‘breaker and half scheme’ important?

A

transmission lines, startup transformers and main transformers connect between 525kV breakers. This ensures two paths that current can take in the switchyard.

prevents huge impact from a single fault (breaker failing open)

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21
Q

What voltage does the AE-ZYN-X05 transformer step down to from 525 kV?

A

12.47 kV

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22
Q

What is each Start-up transformer secondary winding designed to have the capability of doing?

A

Start and carry half the auxiliary loads of one unit while feeding one train of ESF loads of one of the two other units

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23
Q

How are the control and indication signals sent to/received from NAN-S05/S06?

A

Controls are hardwired and indications are multiplexed

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24
Q

What are the requirements for fastbus transfer on NAN-S01/S02 busses?

A

Bus XFR switch in AUTO.
Generator trip or MT trip (Zero VARs signal)
Early ‘b’ contact on S01 normal supply breaker must be closed
Synch check relay satisfied
NO bus lockouts
Voltage available on NAN-S03/04

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25
Q

When do the cooling fans start on the normal service transformer?

A

When “hot spot” temperature reaches 70C, if in AUTO

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26
Q

Where can we reset lockouts on non-class breakers (NA, NB, NG, NH)?

A

Locally ONLY

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27
Q

Where do MCC’s get control power from?

A

The magnetic starters get control power from downstream of circuit breaker

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28
Q

what features are lost when a Non-Class breaker loses control power?

A

remote breaker operation

electrical protection trips

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29
Q

How do you manually charge closing springs on high voltage breakers?

A

5/8” ratchet attached to the end of a charging motor

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30
Q

What two 86 lockout relays are featured on 480 VAC LC breakers?

A

Bell alarm

Ground fault (50G)

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31
Q

what is the bell alarm on the 480 VAC LC breakers?

A

White reset button provides local indication of:

overcurrent trip
breaker rack out interlock

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32
Q

Why are start up transformers physically and electrically separated from each other?

A

minimize the possibility of a single failure affecting more than one transformer

33
Q

What are the isolation boundaries for the startup transformers?

A

two 525kV breakers
13.8 kV breakers on switchgear
motor operated disconnects (MOD)

34
Q

What are the startup transformer stages of cooling?

A

<70C - Natural circ of oil, no fans
70C - first stage of cooling fans, forced circ of oil
>70C - second stage of cooling fans added to first stage, forced circ of oil

35
Q

How does the Open Phase Detection system work for Startup Transformers?

A

trip function disabled

CR alarm when open phase is detected

36
Q

Where are all the NAN-S05/S06 supply breakers controlled from?

Where are the load breakers controlled from?

A

Unit 1 can control ALL of the supply breakers, U2 and U3 can only control their respective supply breakers

load breakers are controlled from their respective units

37
Q

What protective relays are available for the Startup transformers?

A

Differential Current
Neutral Ground Fault
Overcurrent
Sudden Pressure
Open Phase Detection

38
Q

When will the supply breakers to WRF open automatically?

A

SIAS or CSAS

and

switchyard reaches low voltage setpoint

39
Q

Which bus supplies power to the SRP Switchyard for smaller loads?

A

NAN-S05

40
Q

Where does NAN-S05/S06 receive control power from?

How is it aligned?

A

NKN-M45/M46 through NKN-U45/U46

transfer switches

41
Q

Where do NAN-S03/S04 get control power from?

A

NKN-D41/D42

42
Q

Where do NAN-S01/S02 get control power from?

A

NKN-D41/D42

43
Q

What happens in the plant if the Main Generator fails to trip on reverse power?

A

Zero VARs signal is generated to promptly initiate a fast bus transfer

this prevents the Rx from tripping on low DNBR on the loss of RCPs

44
Q

Requirements for NAN-S01/S02 manual transfer

A

Synch switch ON
if NAN-S01/S02 energized, synch check satisfied
NO bus lockouts
voltage available on NAN-S03 and NAN-S04

45
Q

NAN-S01/S02 normal supply breaker trips?

A

Generator trip
bus overcurrent
during manual bus transfer, when alt supply breaker handswitch returns to normal after closing

46
Q

What is a coast down trip?

A

Generator trip concurrent with LOOP (loss of voltage on NAN-S03/S04)
NAN-S01/S02 remain aligned to UAT
all breakers except RCPs open on NA busses
RCPs maintain flow through the core as they coastdown for 20 seconds or until <80% voltage (whichever comes first)

47
Q

What electrical protection does the NAN-S01/S02 busses have?

A

overcurrent
undervoltage & negative phase alarm in CR
undervoltage relay for motor breakers and LC breakers
undervoltage relay for coastdown trip

48
Q

Big picture, how do we remove an NAN-S01/S02 bus from service

A

not an outage for other bus
verify app. for loads lost
remove loads from bus
Unit in MODE 5, 6, or defueled
secure CW pumps
secure RCPs
transfer NB bus to other NB bus
make sure both supply breakers are open

49
Q

What kind of cooling do the Normal Service Transformers have?

A

Forced Air/Oil

(air is blown across the cooling fins filled with oil)

50
Q

On the Normal service transformers, what is the purpose of the Auto-Throwover switch?

A

auto transfers control cabinet power supply to the alternate on a loss of the normal supply

must be manually reset

51
Q

What powers the Normal Service Transformer control cabinets?

A

NH

52
Q

What protection does the normal service transformer have?

A

sudden pressure fault relay
differential current
phase and ground over current

53
Q

what does the synch switch do for NBN-S01/S02 busses?

A

closes the tie breaker

opens to associated normal supply breaker when the control switch is returned to normal

54
Q

what are the requirements for NB auto bus transfer?

A

B01 Bus Transfer Switch in AUTO
Normal Service Transformer NBN-X01 FAULT
NBN-S01 Normal Supply breaker OPEN (early “b” contact)
Voltage sensed on NBN-S02
Synch Check relay satisfied
No lockout on either bus

55
Q

manual NB bus transfer requirements

what happens if you take the handswitch to the wrong position?

A

synch switch aligned
NBN-X01/X02 NOT locked out
no lockout on either NB bus

the wrong breaker will trip (dont overshoot, either)

56
Q

Where do NBN-S01/S02 get control power from?

A

NKN-D41/D42

individual control power breakers (RRC) inside the breaker cubicle

57
Q

Purpose of the kirk key interlock?

A

prevent opening the mechanical disconnect under load

58
Q

What indications are available for LCs in the control room?

A

breaker position
voltage

59
Q

Where are LC main feeder breakers normally operated from?

A

B01

can be locally also

60
Q

Where are MCC breakers operated from?

A

locally ONLY

61
Q

where do MCC breakers get control power from?

A

itself, downstream of the breaker

62
Q

What could bring in this alarm window?

A

generator lockout
fault on the UAT

63
Q

What could bring in this alarm window?

A

startup transformer lockout

64
Q

What could bring in this alarm window?

A

525kV breaker(s) tripped

65
Q

What could bring in this alarm window?

A

undervoltage/negative sequence on the bus. UNIT 1 ONLY

66
Q

What could bring in this alarm window?

A

525kV startup transformer supply breaker tripped

67
Q

What could bring in this alarm window?

A

loss of control power to the SU Transformer protection circuits

Unit 1 ONLY alarm

68
Q

What could bring in this alarm window?

A

undervoltage
negative sequence
loss of control power
cooling fan failure

69
Q

What could bring in this alarm window?

A

issue with digital fault recorder
UNIT 1 ONLY

70
Q

What could bring in this alarm window?

A

when 13.8 kV breakers are paralleled

71
Q

What could bring in this alarm window?

A

supply breaker lockout
undervoltage
negative sequence
loss of control power
undervoltage load shed
cooling fan trouble

72
Q

What could bring in this alarm window?

A

4.16 kV breakers in parallel

73
Q

What could bring in this alarm window?

A

trip or problem with transformer

must be investigated by AO if not a trip

74
Q

What could bring in this alarm window?

A

transformer high temp
bus undervoltage
main feeder breaker lockout

each LC has its own window

75
Q

What could bring in this alarm window?

A

potential Tech Spec issue concerning off-site power capability

76
Q

What could bring in this alarm window?

A

low switchyard bus voltage
excessive load on the metering circuitry (sync switch on)
loss of power to WRF trip permissive relays (NKN-D4303)
loss of power to voltage metering (NNN-D1116)

77
Q

What could bring in this alarm window?

A

issue with transformer

AO must investigate

UNIT 1 ONLY

78
Q

Describe the response of the Non-Class Distribution system to a failure of power

NA -
NB -

A

complicates operation of the plant

loss of RCPs - Rx trip
loss of CDPs and EDPs - FWP trip on low suction psi and have to feed S/Gs with AF

LOIT (32 decks)

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