Class 125 VDC (PK) Flashcards
Is PK grounded or ungrounded?
PK is ungrounded
Ground detector installed
Alarms in the control room and has a white light locally.
What mechanical interlock exists on the PK battery chargers?
Prevents having a swing charger tied to both busses.
For example AC swing charger will never power both PKA and PKC
What are the conditions of the PKC and PKD battery chargers concerning large loads such as SDC DC powered suction valves?
- PKC and PKD battery chargers do not have enough capacity to solely carry large loads
- Battery must be connected to the bus when Operating SIC-UV-653 or SID-UV-654 (SDC DC Powered Suction Valves)
Note: It doesn’t say the charger has to be connected to the bus
What happens on a loss of PK bus with regards to the RTSG breakers?
ADV’s?
Losing a PK bus causes it’s associated RTSG breaker to open
* For a Rx Trip to occur you would need a loss of two PK buses and if it were only two the combination could not be PKA and PKC or PKB or PKD due to CEDMCS power distribution
* 1 PK bus causes 2 ADV’s not to work.
What is the normal operating voltage of the PK buses?
- Normally operates at ~ 135 VDC.
How long can the class batteries supply loads?
Supply required loads for 2 hours (loss of charger) at a minimum temperature of 60°F in the battery room
What is the DC Equipment Rooms ventilation supplied from normally and after a SIAS?
- DC Equipment Rooms normally cooled by ESF Switchgear Room Normal AHU (WC).
- Control Building Normal AHU normally takes suction on each DC equipment room.
- SIAS or LOP: DC Equipment Room Essential AHUs (EC) cool DC Equipment and Battery rooms.
What is the normal power supply for A 125 VDC battery charger?
PHA
How does a loss of PKA-M41 affect the following:
Letdown
ADV’s
Rx trip switchgear
ESFAS 2-4 leg trip
loss of letdown will occur
2 ADV’s are INOP
RTSG A will open
(all ESFAS 2-4 leg trips will NOT occur)
