Non Class Control Power (NK) Flashcards
What is ground detection?
Hard ground: <2k ohms
Soft ground:>2kohms; <35k ohms
What’re the NKN-U46 & NKN-U45 for ?
Gives power to NAN-S05& NAN-S06
How many battery chargers & batteries are there for the NK system ?
E subsystem:TWO battery chargers & battery;125VDC MCC w/ control panel
F subsystem:One batter charger &battery;125VDC MCC w/ control panel
G subsystem: Battery charger & battery ; 125VDC distribution panel
Why are the 125VDC systems(NK) ungrounded ?
So one ground fault doesn’t trip the whole system, need multiple faults for it to trip
Where are the battery chargers powered from and what do the chargers do ?
Non class 480VAC MCC(NH) & convert 480VAC-> 135VDC
What does NKN-U45 & U46 give control power to ?
Gives control power to NAN-S05 & S06
What does Float Position mean for a battery charger ?
Supplies 135VDC to NKN-M45&M46 bus to supply DC loads and maintain the batteries charged
What does “equalize” operation mean for battery charger ?
Supplies 139.8 VDC to all DC loads and to recharge batteries (after batteries have been discharged)
What’re the indication that the battery charger is in service ?
Pilot lamp lights up when 480VAC is going through AC breaker; local DC ammeter and DC voltmeter
How do we prevent condensation and possible damage to battery chargers ?
Internal space heaters controlled by thermostats
What’re the features of the battery storage assemblies ?
.60 cells of lead calcium type
.sealed and assembled in heat resistant
.shock absorbing
.plastic containers with explosion resistant vent plugs
Why must there be constant ventilation to the battery room ?
To prevent explosive environment from hydrogen build up in battery room
What happen on a bus under voltage ?
Under voltage relay lights up a white indicator and send alarm to CR
What’re the indications for a ground detection ?
Soft ground : white light at control center will be on;(>2kohm &<35kohm)
Hard ground: white light at control center and in CR (<2kohm)
How does NK interface with NA?
Provides control power for switchgear and startup transformer indications & control
How does NK interface with NB ?
Provides control power to Switchgear & NSF transformer
How does NK system interface with NG system ?
Provides control power to load centers
How does NK system interface with NH system ?
480VAC MCC gives power to battery chargers
How does NK system interface with NN system ?
NK provides control power for ground detector relay circuits on distribution panels
How does NK system interface with NQ system ?
NK system provides power to NQ system through inverter for plant computer
How does NK system interface with PB system ?
Provides control power for class switchgear isolation relay section and normal chiller
What is the battery discharge voltage ?
125DC
How does ungrounded operation work for NK system ?
Need simultaneous faults in both the positive and negative bus
What is the mechanical interlock for on the two output breakers of the Swing Battery Charger(EF) ?
It’s to prevent closing of both breakers at the same time
How should battery chargers be swapped ?
Parallel the new battery charger with the in service battery charger, then remove the in service charger
What do panels NKN-D41,42,43 provide power to ?
Controls, instrumentation, and annunciation for all non-class equipment
How does NK system interface with MA system ?
Provides power to normal tripping circuit & the back up tripping circuit
What does NKN-D19 provide power to ?
Control and annunciation power for cooling tower Load Centers and MCC& annunciation power for control panels
