Class Electrical Flashcards
What is the difference between the unit’s class inverters?
Unit 1’s PN Distro panel needs to be manually transferred to the emergency source on a loss of power. While Unit’s 2 and 3 are static switches and power seeking. They will automatically switch to their alternate source.
Why is there an extra handswitch on some PBB equipment?
Remote/Local switches that disconnect the control room from safety equipment during a control room fire.
What are the SIAS load shed panels?
M19, M20, M71, M72
What do you check on PBA-S03 and PBB-S04
Lights (expected), Faults on overvoltage relays, protected equipment scheme, latches all facing up
How many class LC’s can you have racked out before there are seismic concerns?
8 on one load center may be racked out. Either in the test position or disconnected position.
Difference’s between LC’s and MCC’s?
-Load HP rating.
> 50 HP LC
Where do we find blue lights and white lights?
Blue lights- Cooling tower fan tripped on high vibes
White lights- SIAS load shed panel when SIAS signal overridden
What do we need to do to class breakers for seismic concerns?
The breaker needs to be raised two inches off of the ground or secured with approved seismic restraints.
Where are the directions for over-riding a SIAS load shed breaker?
On the associated LC. Push the trip button, after this is done a white “override light” will illuminate indicating the SIAS signal has been overridden.
What are the fuses inside of a breaker?
UL- Lifting
UC- Closing
UA/UE- CR control circuit
UT- Tripping
How do you trip an 86 relay? Why?
Open the breaker cubicle door, flip the 125 VDC breaker to off, removed the 86 relay cover. With gloves on push the 86 release tab. Put the cover back on, close the 125 VDC breaker and close the breaker cubicle.
What is the “other” inverter for the in the class DC equipment room?
For the SDC suction isolation valves. DC is converted to AC for use inside of containment. Prevents sparking.
Explain the unit differences in power (13.8 kV)
Unit one supplies power to the technical support center, WRF, and loads in the Startup yard.
Between the units 13.8 kV breakers, is one of the units different when racking it out?
When racking out unit 3’s breaker, you must pull the breaker out of the cubicle slightly to get the springs to discharge. Then we will push the breaker back into the cubicle
Explain the relays for degraded and under voltage conditions.
- 4 are for under-voltage are set to actuate when voltage drops below 75% rated.
- 4 relays are for degaded voltage are set to actuate when voltage drops below 90% rated and remains for 30 seconds
