NN: Non-Class 120 VAC

Question 1

Which NN buses are grounded and which are ungrounded?

Answer 1

NNN-D11 and NNN-D12 are ungrounded

NNN-D15 and NNN-D16 are grounded

Question 2

What are the normal and backup power supplies for NNN-D11 and NNN-D12?

Answer 2

Normal: Non-Class MCC through a Voltage Regulator
Backup: Class MCC

Question 3

What are the normal and backup power supplies for NNN-D15 and NNN-D16?

Answer 3

Normal: Non-Class MCC through a Voltage Regulator
Backup: SIAS Load Shed Panel
- Except D16 for Unit 3 which is a Class MCC

Question 4

Are the ABTs Power Seeking or Normal Seeking?

Answer 4

Power Seeking

Question 5

What will be the status of the NN buses if a SIAS + LOP were to occur?

Answer 5

NNN-D11 - Transferred to Class MCC Backup
NNN-D12 - Transferred to Class MCC Backup
NNN-D15 - de-energized
NNN-D16 - U1 and U2 - de-energized
NNN-D16 - U3 - Transferred to Class MCC Backup

Question 6

Which NN buses have ground detectors?

Answer 6

NNN-D11 and NNN-D12

Question 7

What indications are there for a ground on an NN bus?

Answer 7

• A local red light

- A Control Room Alarm

Question 8

What would bring in the Common Control Room trouble alarm for NN?

Answer 8

• A Ground on NNN-D11/12

- Loss of backup power on SIAS