DC Distribution System

Question 1

Describe the mission time of class 1E batteries

Answer 1

Designed to maintain loads (maximum discharge) for 4 hours.

Question 2

What trips are available to DC breakers

Answer 2

Overcurrent ONLY

Question 3

List the major loads on 1D1

Answer 3

1. Auto Turbine Tester cabinet
2. Turbine Stress Evaluator
3. Seal Steam Controller
4. EHC Controller
5. Extended Turbine Protection Cabinet
6. Vibration Monitoring
7. Electrical Generator Protection Cabinet
8. Hydraulic Control Equipment Rack

‘Turbine & Generator protections, seal steam controls, EHC Controller’

Question 4

Describe the power supplies to, and major loads, on 1D2

Answer 4

DC Bus 1D2 is supplied by BC1D2 (fed from 1EB2-1) and BC1D4 (fed from 1EB4-1), or BC1D24 fed from 1B1-1.

Major loads include:
1. Electrical Trip controls for the Main Feed Pumps
2. Main Turbine DC L/O pump
3. Main Feed Pump DC L/O pump
4. Main Generator Emergency Seal Oil pump

Question 5

Describe the power supplies to, and major loads, on 1D3

Answer 5

DC Bus 1D3 is supplied by BC1D3-1 and BC1D3-2

Major loads include:
1. RCP control power
2. IV1C5
3. IV1C6