Electrical Distribution Flashcards by Larry King

What is the at power lineup?

Main transformer supply grid

SP 1-1 & 1-3 supplying A/B and F/G buses

SG supplying C, D & E bus.

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What is Fast Transfer?

On a plant trip there is no time to manually transfer power from Station Power to Startup Power. Fast Transfer prevents a sustained loss of power to Bus 1A, 1B, 1F, 1G

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What are the safety related Load Control Centers?

11, 12, 19 and 20

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Which LCCs can be crosstied?

11 & 12, 13 & 14, 77 & 78

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What is the continuous current rating for 52-1307?

225 amps. Trips at 285.

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What are the primary and secondary voltages of LCC 11/12, 13/14, 77/78?

2400 primary - 480 secondary.

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What are safety related MCCs?

1/2, 7/8, 21-26

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What are power supplies for main transformer cooling fans?

MCC 4 is normal, 5 is alternate. Auto-swapping.

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Draw and label 4160/2400 system including main, start-up, and station power transformers, ABFGCDE busses, MOD 389, Switchyard connections

Draw

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What is Y-01?

120 VAC distribution system supplied by MCC 1 & 2. Not considered uninterruptable.

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How does ABT Y50 work?

On loss of MCC-1 will switch to MCC-2 for Y-01 supply. Once MCC-1 is restored, a 5 minute time delay will take place before switching back.

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What makes up a DC system?

Battery, DC bus, Distribution panels, and Two battery chargers and instrumentation

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How are DC buses split?

Each DC bus is split into 2 more buses. D-10L/R and D-20L/R.

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What are D-10L and D-20L associated with?

D-10L is supplied by Charger 3 and supplies Inverter 3.

D-20L is supplied by Charger 4 and supplies Inverter 4.

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What is D-10R associated with?

Directly Connected Charger

D-10R is supplied by Charger 1 and supplies Inverter 1.

D-11-A, D-11-1 and D-11-2 are tied to D-10R.

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What is D-20R associated with?

Directly Connected Charger

D-20R is supplied by Charger 2 and supplies Inverter 2.

D-21-A, D-21-1 and D-21-2 are tied to D-20R.

How long are the batteries designed to last?

4 hours, at least.

Discuss the design requirements of the Preferred AC system.

Designed as a Class 1E to supply uninterruptible AC power to the Preferred AC buses at a sufficient power level to support both normal and emergency bus loads independent of disturbances in the offsite AC system.The voltage provided should remain regulated at 118 volts ±3%, 60 Hz ±1/2%, noise of output sine wave is ≤ 5% with no single harmonic ≥ 3%.

What is the bypass regulator?

Alternate feed to the Preferred AC Buses from Instrument AC Bus Y-01. This power supply is available to supply one Preferred AC Bus at a time.

What is the float and equalize rate of the chargers?

Float - 130, equalize 138

What powers Chargers 1 & 4?

MCC-1

What powers Chargers 2 & 3

MCC-2

What does Charger 1 supply?

D-10R

What does Charger 3 supply?

D-10L

What does Charger 2 supply?

D-20R

What does Charger 4 supply?

D-20L

When does the ground alarm come in for the DC bus?

+/- 3 milliamps

What are D-206/207?

DC power supply to CFMS Inverter Y-210 and Y-220 Normal Output Voltage 130 – 135 VDC

What is the purpose of the Feedwater Purity Battery Charger D-212?

Supply control power to LCC-90 and LCC 91.

When is Feedwater Purity Batterch Charger D-212 in service?

When output voltage is greater than 125 VDC and Breaker 72-31 in Panel D-211 is closed.

What does the In-Sync light on the inverters (1-4) mean?

The inverters compare their frequency to Instrument AC Bus EY-01 (Y-01) frequency. They will adjust their frequency based on that comparison.

What is the Inverter to load (push button)?

Used to change the position of the static switch to the inverter output

What is the Bypass source to load (push button)?

Used to change the position of the static switch to the Bypass Source position

What is the Normal/Bypass Source (switch)?

Used to bypass the inverter and static switch

Define a stored energy breaker.

Two sets of springs (closing and opening). A motor charges the closing springs (energizes when breaker closes if control power is available). There are separate springs to open the breaker. Once the springs are charged the breaker can sit for an indefinite time. Even if control power is lost the breaker can still be closed one time (manually), and tripped manually since the opening springs are charged as the breaker closes. The closing springs can also be manually charged if necessary (advantage for equipment needed for safe shutdown during blackout condition). 1) Close with lanyard if springs are charged or pushbutton on non vacuum breakers 2) Trip with push rod/bar assembly 3) Springs can be charged with hand crank.

Define a solenid breaker.

a. Normally used as load breakers b. Trip with push rod/bar assembly inside cubicle c. Uses a huge electrical solenoid to close the breaker. There is no way to close the breaker without control power. Closing charges the opening springs.