Electrical Overview

Question 1

What is preferred source of power during outage?

Answer 1

Back feeding via 500 kv switchyard, so auto transfer is still available

Question 2

U-1 main gen output breakers

U-2 MG output breakers

230 output bkr

Answer 2

632, 532

642, 542

212

Question 3

Purpose of 230 kv switch yard?

Purpose of 500 kv switch yard?

Answer 3

230- power during S/u, S/d, provide immediate source of offsite power during unit trip

500- connect MG to grid, provide delayed access source of offsite power

Question 4

What allows us to backfeed from 500 kv switchyard and not motor the MG?

Answer 4

MOD (motor operated disconnect)

Question 5

Numbering scheme of transformers

Answer 5

1-1………. first number unit, second number voltage…=>. Aux xfr 1-1 , unit 1, step down from 25 kv -> 12 kv

Aux xfmr 2-2, unit 2, step down 25 kv -> 4 kv

Question 6

Describe vital and nv bus numbering

Answer 6

12 kv D,E nv

4 kv D,E nv

4 kv F, G, H vital (diesel backed)

Question 7

Difference between vital and nv 480 bus configuration

Answer 7

Vital- ever bus has dedicated 4 kv -> 480 v step down xfmr

NV- ten step down xfmr’s going to 17 480 v buses with cross tie bkrs for flexibility