201.32 Non-Class 480

Question 1

• 201.32 Non-Class 480*
• • *

Functions of 480V Non-Class 1E Electrical Dist. System

Answer 1

Provides reliable AC power to balance of plant 480V loads

Question 2

• 201.32 Non-Class 480*
• • *

Functions of a Load Center (LC).

Answer 2

Electrical distribution supply points for motors >= 100 HP, static loads >= 100 KW, and Motor Control Centers (MCC)

Question 3

• 201.32 Non-Class 480*
• • *

What is a double-ended Load Center?

Answer 3

Two separate transformers ,supply two separate buses, which can be connected with a cross-tie breaker. Each end normally supplied from separate Aux buses.

Question 4

• 201.32 Non-Class 480*
• • *

Interlock for Double-ended LCs

Answer 4

To prevent inadvertent paralleling of buses that could be powered from different offsite AC sources, only two of the three breakers (2 feeder, 1 X-tie) can be closed at a time.

Question 5

• 201.32 Non-Class 480*
• • *

What is a single ended load center?

Answer 5

One transformer feeds the LC.

(1N, 1P, 1R, 1S, 1T, 12L, and 1W)

Question 6

• 201.32 Non-Class 480*
• • *

Function of Motor Control Center

Answer 6

Power distribution point for motors of less than 100 HP and static loads 100 KW or less.

Exception is IA Compressor 14(24). 200 HP powered from 1(2)G5. Has soft start to limit current.

Magnetic trip elements and thermal overloads

Question 7

• 201.32 Non-Class 480*
• • *

Which Non-Class MCCs are fed from Class-1E MCCs?

Answer 7

1A5, 1B5, 1C5.

NOT safety-related, but supply safety-related support systems.They are shed during emergencies by the sequencer.

Question 8

• 201.32 Non-Class 480*
• • *

Function of 208/120 VAC Distribution Panels (DPs)

Answer 8

Located at MCC’s as well as throughout the plant Typical Loads: Space heaters, AFW sample pump, Cold Chem Lab toilet exhaust fan

Question 9

• 201.32 Non-Class 480*
• • *

Selective Tripping

Answer 9

Isolate branch circuit breaker closest to fault first.

Load supply breaker should trip first protecting MCC. If it fails to trip, then MCC feeder breaker would be next to trip

Question 10

• 201.32 Non-Class 480*
• • *

How are 480 V LC transformers cooled?

Answer 10

Forced air from fans. Inside transformers are dry, outside are oil filled.

Local amber light when fan is running

Question 11

• 201.32 Non-Class 480*
• • *

What are the MCCs that are diesel backed and where are they located?

Answer 11

1G5 - SE TGB 29’ (actually 31’)

12K3 - south yard, next to LTG Diesel Bldg

1G8 - EAB penthouse 83’

Question 12

• 201.32 Non-Class 480*
• • *

Which LC is diesel backed and where is it located?

Answer 12

LC 1W - EAB penthouse 83’

Question 13

• 201.32 Non-Class 480*
• • *

Normal and Emergency power for MCC 1G5

Answer 13

LC 1U

BOP Diesel

Question 14

• 201.32 Non-Class 480*
• • *

Normal and Emergency power for MCC 1G8

Answer 14

LC 1W

TSC Diesel

Question 15

• 201.32 Non-Class 480*
• • *

Normal and Emergency power for 12K3

Answer 15

LC 12L

LTG Diesel

Question 16

• 201.32 Non-Class 480*
• • *

BOP Diesel Generator Electrical Ratings

Answer 16

700 KW

480 V

Question 17

• 201.32 Non-Class 480*
• • *

LTG Diesel Generator Electrical Ratings

Answer 17

700 KW

480 V

Question 18

• 201.32 Non-Class 480*
• • *

TSC Diesel Generator Electrical Ratings

Answer 18

1200 KW

4160 V

Question 19

• 201.32 Non-Class 480*
• • *

Automatic start for BOP diesel

Answer 19

UV on MCC 1G5, will start and load w/in 15 secs (unless feeder tripped on over current to prevent energizing a faulted bus)

Question 20

• 201.32 Non-Class 480*
• • *

Automatic start for LTG Diesel

Answer 20

UV on MCC 12K3, will start and load w/in 15 secs (unless feeder tripped on over current to prevent energizing a faulted bus)

Question 21

• 201.32 Non-Class 480*
• • *

Automatic start on TSC Diesel

Answer 21

UV on LC 1W , will start and load w/in 15 secs (unless feeder tripped on over current to prevent energizing a faulted bus)

Question 22

• 201.32 Non-Class 480*
• • *

Source of control power for LCs

Answer 22

125 VDC control power

Question 23

• 201.32 Non-Class 480*
• • *

Source of control power for MCCs

Answer 23

Small transfomer downstream of each load breaker inside cubicle provides 125 VAC control power

Question 24

• 201.32 Non-Class 480*
• • *

Causes for “480V LC Trouble”

Answer 24

CP010

Bus Ground Fault (except 12H)

Bus Undervoltage

Feeder breaker status (breaker alignment abnormal)

Transformer high temperature