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Catawba Nuclear Station > 250VDC Auxiliary Power System(EPJ) > Flashcards

250VDC Auxiliary Power System(EPJ) Flashcards

1
Q

What is the purpose of the 250VDC Auxiliary Power System?

A

The 250VDC Auxiliary Power System provides an uninterruptible power supply to non-safety related high inrush 250VDC loads that generally serve as backups to
AC-powered loads(such as the emergency turbine bearing oil pump motor and backup lighting).

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2
Q

What are the major system components of the 250VDC Auxiliary Power System?

A
  1. One Battery for each unit(1DPB and 2DPB)
  2. One Battery Charger for each unit(1DPC and 2DPC)
  3. One Spare Battery Charger for both units(SDPC)
  4. A Distribution Center for each unit(1DPD and 2DPD)
  5. Deadlight Panelboards, 4 for each unit
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3
Q

What are the designations for each Battery and Battery Charger?

A
  1. Batteries:
    A. 1DPB
    B. 2DPB
  2. Battery Chargers
    A. 1DPC
    B. 2DPC
    C. SDPC(Spare Charger)
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4
Q

What are the designations for each Distribution Center?

A
  1. 1DPD

2. 2DPD

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5
Q

What is the purpose of the Unit Battery Chargers?

A
  1. Serve as the normal supply to the distribution center.

2. The Battery Charger can recharge it’s battery in 8 hours OR carry the largest load for testing purposes.

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6
Q

Where are the Unit Battery Chargers powered from?

A

The Unit Battery Chargers are powered from Blackout Load Centers 1LXH and 2LXH.

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7
Q

What is the maximum load demand that will ever be placed on a Unit Battery Charger?

A
  1. Both Unit’s 250VDC Distribution Center loads.

2. A “floating charge” on the respective battery.

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8
Q

What is the purpose of the Standby Battery Charger?

A

The Standby Battery Charge is used:

  1. When one of the Unit Battery Chargers is out of service.
  2. To perform equalize charges on the batteries.
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9
Q

What is the power supply to the Standby Battery Charger?

A

1SLXC

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10
Q

How is the time controlled for an “equalize” charge that is being applied to a Unit Battery?

A

The Standby Battery Charger has a Float/Equalize timer that is set during equalize charges. When the timer times out the charger automatically goes from “equalize” to “float”.

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11
Q

How are the Standby Battery Charger Output Breakers interlocked?

A

The Standby Battery Charger output breakers are interlocked such that only one breaker at a time can be closed.

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12
Q

What is the purpose of the Unit Batteries?

A
  1. The Unit Batteries provide emergency power to the 250VDC Distribution Centers.
  2. Provide an alternated 125VDC source of power to the following systems which are normally supplied from 125VDC CDA:
    A. (ETB) 4160V Blackout Train A Control Power
    B. (ETC) 600V Blackout Train A Control Power
    C. CAPT Control Power
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13
Q

What are the Unit Batteries rated for?

A

The Unit Batteries are designed to carry the loads of one unit for 3 hours.

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14
Q

When the Unit Batteries are providing alternate power to 125VDC systems how is the 250VDC & the 125VDC system affected??

A
  1. The 125VDC will not swap back to the CDA Bus until all three normal breakers are closed and the reset button in Blackout Switchgear is depressed.
  2. Until the 250VDC system is restored, Deadlight Panels and Emergency Oil Pumps will be powered from the Unit Batteries.
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15
Q

When are batteries susceptible to cell reversal and what is it?

A

When multi-cell batteries under a heavily loaded condition for a long period of time “cell reversal” may occur. Cell reversal is the changing of the poles charges. The cell will actually become a load on the battery and caused the battery voltage to decrease rapidly.

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16
Q

When does Cell Reversal typically happen and can it be reversed?

A

Cell Reversal occurs at approximately 80-85% of normal battery voltage. Once a cell has undergone cell reversal, it cannot be recovered.

17
Q

What is the affect on equipment of having a low battery voltage?

A

Operation with a low battery voltage can damage loads being supplied by the battery and damage battery cells.

18
Q

What is the most accurate indication of a battery’s condition while under load?

A

The most accurate indication is that taken at each individual battery cell.

19
Q

When do we remove a battery from service based on voltage?

A

Whenever battery voltage drops to 210VDC the battery is removed from service.

20
Q

How many 250 VDC Distribution Panels are there per unit, and what are their designators?

A
  1. There is one Distribution Panel per unit.

2. 1DPD and 2DPD

21
Q

When are the 250VDC Distribution Panels cross-tied?

A
  1. Tie breakers are provided on each for each distribution panel to allow tying the units together.
  2. The tie breakers are normally open and are closed whenever a battery is taken out of service.
22
Q

What are the loads on the 250VDC Distribution Panels?

A
  1. Turbine Emergency Bearing Oil Pumps
  2. Generator Emergency Seal Oil Pumps
  3. CFPT A and B Emergency Oil Pumps
  4. Bus DPD ground and undervoltage detectors.
  5. Deadlight Panels
23
Q

How are grounds indicated locally on the Distribution Panels?

A
  1. If a ground is detected a Control Room alarm and an Operator Aid Computer alarm is generated.
  2. White lamps that are dimly lit under normal conditions will show brightly for which leg has the ground.
  3. There is a Ground Voltmeter locally to indicated the magnitude of the ground in volts.
24
Q

What is the precaution and limitation associated with DC Tie Breakers?

A

DC Tie Breakers will normally remain open. The are closed ONLY during equalizing charges to batteries of other out of normal situations which require the ties to be closed.

25
Q

What is the precaution and limitation associated with Battery Room Ventilation?

A

250VDC Auxiliary Power shall not be operated for long periods of time without the Battery Room Ventilation in service.

26
Q

What is the precaution and limitation pertaining to the order of breaker closure for a battery charger?

A
  1. When placing a battery charger in service, the AC input breaker SHALL be closed first to protect the output breakers from heavy surge currents.
  2. Keeping all battery chargers energized with AC input improves reliability.

Catawba Nuclear Station (72 decks)

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