Plant Operating Standard

ED-52 Electrical Distribution

A. Normal Operation, Reactor at Power

• 1. Two TG's operating in parallel:
  • a) Maximum load on either TG - 1500KW.
  • b) Bus voltage steady state - 450V.
  • c) Frequency - 60 cps.
  • d) Phase rotation sequence - A-B-C (Black-White-Red)
• 2. Bus Tie Breaker closed.
• 3. Both ADG's set for Auto start.

  [ADG is Auxiliary Diesel Generator.]

• 4. EDG set for AUTO start.

  [EDG is Emergency Diesel Generator.]

• 6. All main and Emergency Switchboard circuit breakers which feed reactor associated loads, closed.
• 7. Instrumentation Battery back bus energized with one DC/AC MG set operating or both sets in parallel, battery fully charged and floating on the DC bus and one AC/DC-MG set running.

  [MG is motor-generator]

  • Instrument bus voltage 117 +- 1V
    Instrument bus frequency 60 +- 0.2 cps
• 8. No grounds on reactor power circuits.
• 9. Emergency lighting system operable.
• 10. Breaker 52 in Position A with key interlock release in "OFF" position.

A. Normal Operation, Reactor Startup

ALL ED System conditions the same as for Reactor at power except:

• 1. Both ADG's operating until sufficient power can be supplied by TG's.

Minimum Condition for Reactor Operation

• 1. One TG set operating with at least one ADG available or both ADG's operating in TG's are unavailable.
• 2. Sustained source of power to all reactor load power panels and all group controls, i.e., loss for no longer than the time required for ABT or MBT operation.

  [ABT is Auxiliary Bus Tie, and MBT is Main Bus Tie.]

• 3. Load on any one generator not to exceed continuously its 125% load rating.
• 4. Instrumentation battery capable of supplying operating load for one hour.
• 5. Instrumentation bus energized by one DC/AC MG set.
• 6. Emergency Diesel Generator set for Auto-Start.