Non-Class 1E Distribution Flashcards
What is different about U1 and its 13.8 kV Switchyard breakers during a degraded Switchyard voltage condition?
The WRF supply breakers load shed if a degraded grid condition is present along with a Safety Injection Actuation Signal (SIAS) signal in Unit 1. This arrangement is designed to aid in preventing a “double sequence” event. In the WRF, two 13.8 kV to 4.16 kV transformers supply power to NBN-S05 and S06.
Describe the controls and indications of NAN-S05 and NAN-S06
Indications are multi-plexed, controls are hardwired.
List the conditions for Fast Bus Transfer of NAN-S01/2
FBT in Auto
Main Generator Trip
Bus being transferred to has voltage
Early ‘b’ contact closed
Sync check satisfied
No Bus Lockout
List the conditions for Fast Bus Transfer of NBN-S01/2
FBT in Auto
Normal Service Transformer Trip
Bus being transferred to has voltage
Early ‘b’ contact closed
Sync check satisfied
No Bus Lockout
Which non class but essential panels are load shed on SIAS(NOT on LOP)?
NHN-M19, M-20, M-71, M-72 these panels are tripped on SIAS signal but are not shed on LOP.
What are the meaning of the following breaker indication lights?
Red:
Green:
Bright Green:
White:
Clear:
Red: Breaker is CLOSED and continuity exists through the breaker trip coil
Green: Breaker is OPEN and racked in
Bright Green: Breaker TRIPPED on fault or in TEST position
White: 86 Lockout is reset and has continuity
Clear: Breaker closing springs are charged
What are the operating characteristics of the controls associated with
NAN-S05 and NAN-S06?
Controls are HARDWIRED
Indications are MULTIPLEXED
This means breaker control may still be available while breaker positions are not indicating. Or Vice Versa
What conditions will result in a WRF load shed?
Why?
Degraded voltage as measured on (NAN-S05/S06 in UNIT 1)
While simultaneously receiving a SIAS signal
WRF breakers will open de-energizing WRF to prevent double sequencing
What are the requirements for a fast bus transfer on NAN-S01 and NAN-S02 from the UAT to NAN-S03 and NAN-S04?
BUS XFR SWITCH must be in AUTO
Generator Trip must have occurred
Early “B” contact energized
Synch Check is SAT
NO BUS LOCKOUT
Voltage is available on NAN-S03/S04
When would a coastdown trip occur?
What happens regarding NAN-S01 and NAN-S02?
Coast down trip occurs:
When the generator trips (On Reverse Power) concurrent with a loss of off-site power (Loss of Off-site power as sensed by NAN-S03 **and/or **S04 voltage).
Reactor Trip is also required
When this happens there is nowhere for NAN-S01/S02 to receive power
NAN-S01/S02 stay aligned to the UAT and sheds all breakers except RCP breakers
Keeps RCPs running maintaining flow through the core
What are the conditions that would result in a fast transfer of NBN-S01 and NBN-S02 to the other train?
What loss would prevent this fast transfer from occurring?
Normal Service Transformer fault
Normal Supply Breaker Open
Voltage sensed on opposite bus
Synch Check SAT
NO Lockout on either bus
Loss of NKN-D41/D42 result in failure of fast bus transfer
Do the Non class load centers operate with KKI’s?
Why or why not?
Yes.
Prevents damaging the disconnect if it was operated under load.
What is the capacity of one secondary winding on a Startup Transformer?
1 half of the non-class loads from one unit, 2 trains of ESF loads (1 train of class loads from the same unit, and 1 train of class loads from a different unit)
What is control power for NAN-S05?
Normal: NKN-M45
Alternate: NKN -M46
What will happen on a loss of control power to NBN-S01?
Upstream transformer (NAN-S01N) will lockout to clear the fault
