Non-Class 120 VAC (NN)

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

What is the status of NNN-D15/D16 in Units 2 and 3 after a LOOP? LOOP and SIAS (after one minute)?

Answer 4

Unit 2&3 LOOP both panels energized (from SIAS load shed)
Unit 2 LOOP&SIAS NNN-D15/D16 de-energized
Unit 3 LOOP&SIAS NNN-D15 de-energized, NNN-D16 is energized

Question 5

What is the normal source of supply power to NNN-D11?

Answer 5

non-vital MCC via a voltage regulating transformer