Loss Of AC Power Flashcards
Where is Degraded Bus voltage sensed?
On the A and D T buses.
What is the AC systems response to a Main turbine or Generator trip?
The Generator Lock out relays (HEAs) simultaneously trip feed from the UATs and close in feed from the RATs.
What is under voltage protection?
When 2 of 3 the under voltage relays sense a loss of voltage to the safety related 4kv busses (T busses), 80% for 2 seconds. It divorces the T bus from the RCP bus and the master relays automatically start the associated EDG, when the EDG reaches rated speed and voltage, loads sequence on.
What happens on a loss of EP (69kv)?
Under voltage is sensed on the 69kv EP bus for 150secs.
An open signal is sent to MDS.
After the MDS opens, a start signal is sent to the SDGs.
The first SDG to reach speed and voltage closes its breaker on the the dead bus.
The remaining SDG auto synchronizes to the bus and closes its output breaker.
Then the tie breaker is closed to the EP bus.
What action is an AEO to do in response to a Reactor Trip?
Reports to the control room to be briefed.
What is the time we have to cross tie charging?
Within 40 minutes from the announcement that the control room is being evacuated due to a fire.
What is the time requirement for locally closing QCM-350 and why?
15 min so you don’t steam bind the charging pumps.
