RQ-C-4833 (250 VDC Distribution)

Question 1

What impact does loss of DC control power have on the EDG

Answer 1

• EDG will not start. If running, only trips available are mechanical overspeed and the MFV

Question 2

What impact does loss of DC control power have on 4 kV breakers

Answer 2

• Cannot be operated from the control room and no automatic functions available

Question 3

What is the normal power supply for the Train A 250 VDC distribution

Answer 3

• 600 VAC ESS system via battery charger rectifier

Question 4

What would a plant battery charger float current of greater than 2 amps mean when the battery has been isolated from any active charger for some time before restoration

Answer 4

• Battery has discharged and the charger is restoring it to full voltage

Question 5

What loads must be manually shed from the BOP battery following a loss of all AC

Answer 5

• DCS inverters and the Main and MFP emergency oil pumps (2 hours)

Question 6

Why are loads manually shed from the BOP battery following a loss of all AC

Answer 6

• To maintain BOP battery capacity for 8 hours to maintain the Emergency Generator Seal Oil Pump (retains H2 in Generator)

Question 7

Can the BOP battery chargers be manually restored following a load shed

Answer 7

• No. Buses that are load shed are not recovered. BOP battery supplies the loads

Question 8

What N train battery load must be load shed following a loss of all AC

Answer 8

• AMSAC inverter