MAIN ELECTRICAL DISTRIBUTION Flashcards
What are the minimum conditions for criticality?
2 EDGs with 25K gallons, 1 6900V bus, 2 230kV lines, 1 230kV bus, and batteries with 2 chargers.
What is the minimum grid voltage before auxiliary transformers are declared INOPERABLE?
223kV.
What is the LCO for 1 auxiliary transformer INOP?
30-day LCO with EDG running.
What is the LCO for 1 EDG INOP?
7-day LCO with redundant EDG operable and tested within 24 hours.
What is the LCO for 2 EDGs INOP or 1 EDG and 1 auxiliary transformer INOP?
12 hours to Hot Shutdown (HSD).
What action is required if only 1 230kV line is available or there is a load rejection?
Start and run a diesel generator continuously.
What happens if grid voltage drops below 223kV?
Both auxiliary transformers are declared INOPERABLE, and you enter 3.0.1.
What is the function of the Rapid Pressure Relief Device (MPT)?
It uses 2 of 2 logic to trip the main generator breaker and exciter breaker.
What is the precaution for aligning 4kV ES buses to a single transformer?
Do NOT align them due to the risk of separation from the grid during ES block loading.
What is the limitation for the 1N high side breaker change?
Limited to <70 Amps as measured on the high side; otherwise, the 1J cross-tie breaker will trip on overload.
What happens to RCP motor currents on lowering grid voltage?
RCP motor currents rise towards the trip setpoint, and the compensatory action is to raise MVAR output.
Where are DCA and DCB located?
On the West Wall of the Substation Building
What is the procedure for opening the 1Y 480V disconnect switch under load?
It must be opened procedurally by first opening the 480V feeder to minimize arc damage.
What is the function of the Bell Alarm Switch?
It indicates overcurrent and requires the manual trip button to reset
What action is required if 1091 and 1092 are OOS with a fault on the 4 Bus?
The reactor must be in Hot Shutdown (HSD), and criticality cannot be achieved until a second 230kV line is available
