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Systems > DC power distribution > Flashcards

DC power distribution Flashcards

1
Q

What are float and equalize values?

A

float 130VDC

Equalize 135VDC

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2
Q

Battery charger output limited to…..

A

output current is limited to 125% of full load. full load =400 amps

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3
Q

125VDC battery charger trouble alarm causes

A
  1. charger output volts<120VDC
  2. Charger output volts>140VDC
  3. Charger near 0 amps
  4. Loss of AC input to charger
  5. Blown fuses inside charger
  6. Charger DC O/P breaker open due to high current
  7. Loose or faulty charger failure alarm card inside cabinet
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4
Q

Battery charger AC input breaker trips on high DC output voltage value of…..

A

> 138VDC

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5
Q

Safety design basis of 125VDC system

A

Provide two physically and electrically independent, redundant systems:

  1. Meets single failure criteria
  2. Loss of either bus will not prevent safe shutdown during simultaneous design basis LOCA with a LOOP
  3. Safety Category 1
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6
Q

UV alarm, If alarm comes in but control board V indication ….

A

..;Normal bus voltage=loss of non esf bus

…No bus voltage= loss of both esf and non esf bus

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7
Q

Bus crosstie limitations

A

Verify <100VDC grounds on both busses
Voltages within 20VDC
Once crossties, <400 amps on running charger

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8
Q

Ground Levels I, II, and III

A

> =75 <100VDC—–Level I—–Implement BOPDC15, notify EMS to initiate ground testing on C priority
=100 <=115VDC—Level II—-Implement BOPDC15, notify EMS to initiate ground testing on a B2 priority
115VDC————–Level III—-Implement BOPDC15, notify EMS to initiate ground testing on a B1 priority. Notify unit planning supervisor, system engineer and repair grounds 24 days

*100VDC ground actuates an alarm on _PM01J

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9
Q

How does Loss of bus 111 or 112 affect IA to containment and PZR porvs?

A

Isolates IA to containment (IA66 or 65 closes) but PORVs have accumulators so opposite train of failure will still function.

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10
Q

125VDC ESF is fed to RTB and RT bypass breakers to….

A

…..energize shunt trip when RX trip is called for.

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11
Q

111 Batt charger supplied from….

A

….USS 131X

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12
Q

CB-1 trips on ….

A

High DC output voltage >138VDC

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13
Q

CB-2 (DC output) trips on….

A

Overcurrent

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14
Q

If AF-2 is opened…

A

….the bus is deenergized because it isolates both the battery charger and the battery from the bus.

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15
Q

3 sources of DC power

A

Battery charger (normal)
Battery (Emergency Backup)
X-tie to opposite unit (Backup power supply)

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16
Q

Loss of 111 or 112, What is lost or affected?

A
  1. Feed reg valves fail as is
  2. Instrument air isolates to containment
  3. PZR PORVs 455/456 fail closed (accumulators might keep them operating)???????
  4. DG 1A/B (respectively) fail to start
  5. Lose letdown 1CV8152/8160 respectively fail closed
17
Q

Loss of bus 113, what is affected?

A
  1. MF 1a/1c and startup feed pump recircs fail open

2. Lose 1C TDMFWP trip capability from control room

18
Q

Loss of bus 114, what is affected?

A
  1. Loss of letdown, 1CV459/460 and all three LD orifices fail closed.
  2. Lose DC to trip 1B TWMFWP
  3. Main feed pump 1B recirc fails open
  4. Can not start 1A MFP from MCR
  5. Lose 1B TDMFWP trip capability from MCR
19
Q

Purpose of 125 VDC system(supplies power to which systems).

A

Supply 125VDC for each of 2 ESF divisions:

  1. Rx trip switchgear
  2. MCB ESF section
  3. ESF switchgear control systems
  4. Other safety related systems requiring DC power
20
Q

Indications of loss of DC

A

ESF: 125VDC low alarm and MCB meter reading 0 Volts

Non-ESF: 125VDC low alarm and MCB meter reading normal Volts

21
Q

LCO 3.8.4

A

3.8 ELECTRICAL POWER SYSTEMS
3.8.4 DC Sources-Operating
LCO 3.8.4 Division 11(21) and Division 12(22) DC electrical power
subsystems shall be OPERABLE and not crosstied to the
opposite unit.
APPLICABILITY: MODES 1, 2, 3, and 4.

22
Q

LCO 3.8.4 action times one battery charger out

A 
A. One battery charger
inoperable.
A.1 Crosstie
opposite-unit bus
with associated
OPERABLE battery
charger to the
affected division.
AND
A.2 Restore battery
terminal voltage to
greater than or equal
to the minimum
established float
voltage.
AND
A.3 Verify battery float
current < 3 amps.
AND
A.4 Restore battery
charger to OPERABLE
status.
2 hours
2 hours
Once per 12
hours
7 days
OR
In accordance
with the Risk
Informed
Completion Time program
23
Q

LCO 3.8.4 action times, loss of one dc elec system for any reason not listed in conditions A, B, C

A 
D. One DC electrical
power subsystem
inoperable for reasons
other than Condition
A, B, or C.
D.1 Restore DC electrical
power subsystem to
OPERABLE status.
2 hours
OR
In accordance
with the Risk
Informed
Completion time program
24
Q

LCO 3.8.5 Shutdown distribution systems

A

3.8 ELECTRICAL POWER SYSTEMS
3.8.5 DC Sources-Shutdown
LCO 3.8.5 One DC electrical power subsystem shall be OPERABLE.
—————————-NOTE—————————-
The required DC electrical power subsystem may be crosstied
to the opposite unit, when the opposite unit is in MODE 1,
2, 3, or 4 with an inoperable battery charger.
————————————————————
APPLICABILITY: MODES 5 and 6,
During movement of irradiated fuel assemblies.
ACTIONS
————————————-NOTE————————————-
LCO 3.0.3 is not applicable.
————————————————————–

25
Q

LCO 3.8.5 DC power source becomes unavailable

A 
A. One required DC
electrical power
subsystem inoperable
for reasons other than
Condition B.
A.1 Declare affected
required feature(s)
inoperable.
OR
Immediately
(continued)
DC Sources-Shutdown
3.8.5
BYRON — UNITS 1 & 2 3.8.5 — 2 Amendment 198
ACTIONS
CONDITION REQUIRED ACTION COMPLETION TIME
A. (continued) A.2.1 Suspend CORE
ALTERATIONS.
AND
A.2.2 Suspend movement of
irradiated fuel
assemblies.
AND
A.2.3 Initiate action to
suspend operations
involving positive
reactivity additions.
AND
A.2.4 Initiate action to
restore required DC
electrical power
subsystem to OPERABLE
status.
AND
A.2.5 Declare affected Low
Temperature
Overpressure
Protection feature(s)
inoperable.
Immediately
26
Q

LCO 3.8.6 Battery parameters

A

3.8 ELECTRICAL POWER SYSTEMS
3.8.6 Battery Parameters
LCO 3.8.6 Battery parameters for Division 11(21) and Division 12(22)
batteries shall be within limits.
APPLICABILITY: When associated DC electrical power subsystems are required
to be OPERABLE.
ACTIONS
————————————-NOTE————————————
Separate Condition entry is allowed for each battery.
————————————————————

27
Q

What float V and float current values are specified in LCO 3.8.6?

A

<=2.07V, 2 hour action time, restore in 24 hours
>3.0 Amps, 2 hour action time, restore in 12 hours
Also concerned with proper electrolyte level and pilot cell electrolyte temperature

28
Q

Main and reserve breaker scheme description

A
  1. Ensures control power available if the main feeder breaker or cable should fail.
  2. Available for control power to:
    - Main gen relaying and metering
    - MCB turbine panel
    - ESF and Non-ESF (480VAC, 4160VAC, and 6900VAC)

Front and rear panel supplies

29
Q

3.8.9 distribution systems

A

Requires 111 and 112, 2 hours if a dc system not operable (looks at the DC bus)

30
Q

250VDC loads

A 
Main turbine oil emergency oil pump
Air side seal oil back up pump
Turbine drive FW pump emergency oil pumps
Main condenser vacuum breaker
Computer inverter
31
Q

Duration of power requirements for 250VDC loads

A 
ASSO backup pump 2 hours
MTO Emergency bearing oil pump 1/2 hour
TDFW B and C FW Emergency oil pump 1/2 hour
Computer inverter 1/2 hour
Vacuum breaker valve Momentary only
32
Q

Modes of operation (float equalize) for 250vdc

A

Float 260 VDC

Equalize 270 VDC

33
Q

Power supplies to 250VDC busses 123 and 223

A

134Z and 234Z (Non ESF loads)

34
Q

To crosstie 250VDC busses……

A

…..<140VDC grounds on both busses, and voltages within 30VDC

35
Q

5.5.17 Battery monitoring and maintenance program

A

5.5.17 Battery Monitoring and Maintenance Program
This program provides for restoration and maintenance, based on the
recommendations of IEEE Standard 450, “IEEE Recommended Practice for
Maintenance, Testing, and Replacement of Vented Lead – Acid
Batteries For Stationary Applications,” or of the battery
manufacturer of the following:
A. Actions to restore battery cells with float voltage
< 2.13 V, and
B. Actions to equalize and test battery cells that had been
discovered with electrolyte level below the minimum
established design limit

36
Q

Battery room temperature limit

A

<= 60F any connected cell electrolyte temperature

108F

37
Q

Loss of control power on ABT

A

ABT will not function

38
Q

Amp hour rating of batteries

A

2320 Amp hours

Systems (80 decks)

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