AC Distribution

Question 1

Describe which Transformers use an Inert Cover Gas system and which use a COPS Tank system

Answer 1

Inert Cover Gas - 1UT, 2UT, XST1, XST1A, XST2

COPS Tank - 1ST, 2ST, 1MT1/2, 2MT1/2, XST2A

Question 2

Describe the Fire Protection available to transformers

Answer 2

Deluge is available to 1UT, 2UT, 1MT1/2, 2MT1/2, XST1, XST1A, and XST2

Deluge is NOT available to 1ST, 2ST, and XST2A

Question 3

What type of cooling is available to the Main Transformers and what are the actions following its loss?

Answer 3

The Main Transformers only have FOA (Forced Oil, Forced Air) cooling

Following cooling loss due to equipment failure OR Generator Lockout (due to sudden pressure relay actuation), rapidly reduce turbine load to less than 50% within 30 minutes. The turbine should be tripped if oil temperature reaches 100 degrees-Celsius OR winding temperature reaches 130 degrees-Celsius.

Question 4

What is the concern associated with starting an RCP while back-feeding the UT?

Answer 4

During back-feed operations the UT should not be used to power RCPs for extended periods due to increased amps in this alignment.

Question 5

Describe the automatic actions following the actuation of a LOR (lockout relay) on 1ST

Answer 5

1. 1A1-2, 1A2-2, 1A3-2, 1A4-2, and XA1-1 breakers will trip. This could result in a Rx Trip if <20% power and RCPs are being supplied by 1ST
2. Incoming feeder breakers 7970 and 7980 will trip and then reclose when MOAS 8052 opens
3. All 1ST transformer cooling will stop, MOAS opens and is prevented from re-closing
4. XST2 will temporarily lose power due the loss of 1ST resulting in a slow transfer on the Unit 1 1E busses and a BOS actuation

Question 6

Describe the automatic actions following the actuation of a LOR (lockout relay) on 2ST

Answer 6

1. 2A1-2, 2A2-2, 2A3-2, 2A4-2, XA1-2 breakers will trip. This could result in a Rx Trip if <20% power and RCPS are being supplied by 2ST
2. Incoming feeder breakers 8075 and 8080 will trip.
3. All 2ST cooling will stop.

Question 7

Describe the automatic actions following the actuation of a LOR (lockout relay) on XST1

Answer 7

1. High Speed ground switch 8083 will close
2. MOAS 8085 Opens
3. 1EA1-2, 1EA2-2. 2EA1-1, 2EA2-1 breakers open, slow transfer 1E busses and BO sequencer fires
4. 138kV switchyard breakers 7030 and 7040 open
5. The transformer deluge valve will be armed

Question 8

Describe the automatic actions following the actuation of a LOR (lockout relay) on XST2

Answer 8

1. MOAS 8012 Opens (XST2)
2. MOAS 8032 Opens (XST2A)
3. 1EA1-1, 1EA2-1, 2EA1-2, 2EA2-2
4. Incoming switchyard breakers 7970 and 7980 open, then reclose when MOAS 8012 and 8032 open.
5. The transformer deluge valve will be armed