201.30 Off-site Electrical

Question 1

• LOT 201.30 Off-site Electrical*
• • *

DESCRIBE the theoretical operation of transformers.

Answer 1

Expanding, collapsing, and reversing field caused by AC current flow through primary windings induces EMF in the secondary windings.

Question 2

• LOT 201.30 Off-site Electrical*
• • *

Characteristics of Wye connected transformer.

Answer 2

Phase voltage is less than line voltage by a factor of √3 (1.73) and phase current equals line current.

E₁ = √3 E ɸ

I₁ = I ɸ

Question 3

• LOT 201.30 Off-site Electrical*
• • *

Characteristics of Delta connected transformers.

Answer 3

the line voltage equals the phase voltage and phase current is less than line current by a factor of √3 (1.73).

Question 4

• LOT 201.30 Off-site Electrical*
• • *

Where/why are potential transformers used?

Answer 4

on high voltage AC sources for indication and protection

(UV and OV relays)

Question 5

• LOT 201.30 Off-site Electrical*
• • *

Where/why are current transformers used?

Answer 5

measure current flow on high voltage circuits for indication and protection

Question 6

• LOT 201.30 Off-site Electrical*
• • *

Function of Off-site Electrical Distribution System

Answer 6

provides reliable distribution of power generated from both units and a reliable source for plant auxilary power systems

Question 7

• LOT 201.30 Off-site Electrical*
• • *

Mitsubishi Pneumatic Controlled Breakers (PCB)

(Function/Voltage)

Answer 7

Allow control of power distribution and protect grid stability by isolating transmission line faults. “Breaker and a half” scheme allows isloation of any line maintaining distribution from others

345 KV

Question 8

• LOT 201.30 Off-site Electrical*
• • *

Disconnects

Answer 8

Manual isolation of components to ensure safety of workers. NOT designed to break load.

Question 9

• LOT 201.30 Off-site Electrical*
• • *

Main Transformer

Answer 9

Step up generator output to yard voltage when generator is online, or step down yard voltage to supply UAT when generator is off-line.

345/25 KV

Question 10

• LOT 201.30 Off-site Electrical*
• • *

Standby Transformer

Answer 10

Supply the standby buses

345/13.8 KV

2 secondary windings

Question 11

• LOT 201.30 Off-site Electrical*
• • *

Unit Auxiliary Transformer

(UAT)

Answer 11

Supply the Aux Buses and designated Standby Buses (F, H)through cross tie with respective Aux Bus

25/13.8 KV

Question 12

• LOT 201.30 Off-site Electrical*
• • *

Emergency Transformer

Answer 12

Provides backup power to one ESF bus in each unit at a time only, via emergency outdoor bus 1(2)K and MODs

138/13.8 KV

Question 13

• LOT 201.30 Off-site Electrical*
• • *

Draw and Label Off-Site Electrical Distribution System

Answer 13

Question 14

• LOT 201.30 Off-site Electrical*
• • *

Who is responsible to coordinate switching orders involving offsite elctrical distribution?

Answer 14

Unit 1 Control Room

Question 15

• LOT 201.30 Off-site Electrical*
• • *

Who can accept and execute switching orders?

Answer 15

Designated Qualified Personnel

Question 16

• LOT 201.30 Off-site Electrical*
• • *

Which lines cannot be used to satisfy Tech Spec requirements for Off-Site Power?

Answer 16

Hillje 44, 64

Blessing 44, 138 KV