Electrical Distribution

Question 1

What is the at power lineup?

Answer 1

Main transformer supply grid

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

SG supplying C, D & E bus.

Question 2

What is Fast Transfer?

Answer 2

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

Question 3

What are the safety related Load Control Centers?

Answer 3

11, 12, 19 and 20

Question 4

Which LCCs can be crosstied?

Answer 4

11 & 12, 13 & 14, 77 & 78

Question 5

What is the continuous current rating for 52-1307?

Answer 5

225 amps. Trips at 285.

Question 6

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

Answer 6

2400 primary - 480 secondary.

Question 7

What are safety related MCCs?

Answer 7

1/2, 7/8, 21-26

Question 8

What are power supplies for main transformer cooling fans?

Answer 8

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

Question 9

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

Answer 9

Draw

Question 10

What is Y-01?

Answer 10

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

Question 11

How does ABT Y50 work?

Answer 11

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.

Question 12

What makes up a DC system?

Answer 12

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

Question 13

How are DC buses split?

Answer 13

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

Question 14

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

Answer 14

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

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

Question 15

What is D-10R associated with?

Answer 15

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.

Question 16

What is D-20R associated with?

Answer 16

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.

Question 17

How long are the batteries designed to last?

Answer 17

4 hours, at least.

Question 18

Discuss the design requirements of the Preferred AC system.

Answer 18

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%.

Question 19

What is the bypass regulator?

Answer 19

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.

Question 20

What is the float and equalize rate of the chargers?

Answer 20

Float - 130, equalize 138

Question 21

What powers Chargers 1 & 4?

Answer 21

MCC-1

Question 22

What powers Chargers 2 & 3

Answer 22

MCC-2

Question 23

What does Charger 1 supply?

Answer 23

D-10R

Question 24

What does Charger 3 supply?

Answer 24

D-10L

Question 25

What does Charger 2 supply?

Answer 25

D-20R

Question 26

What does Charger 4 supply?

Answer 26

D-20L

Question 27

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

Answer 27

+/- 3 milliamps

Question 28

What are D-206/207?

Answer 28

DC power supply to CFMS Inverter Y-210 and Y-220

Normal Output Voltage 130 – 135 VDC

Question 29

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

Answer 29

Supply control power to LCC-90 and LCC 91.

Question 30

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

Answer 30

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

Question 31

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

Answer 31

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

Question 32

What is the Inverter to load (push button)?

Answer 32

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

Question 33

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

Answer 33

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

Question 34

What is the Normal/Bypass Source (switch)?

Answer 34

Used to bypass the inverter and static switch

Question 35

Define a stored energy breaker.

Answer 35

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.

Question 36

Define a solenid breaker.

Answer 36

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.