Non-Class 120 VAC Instrument Power (NN)

Question 1

What are the normal/alternate power supplies for NNN-D11?

Answer 1

Normal - NHN-M13
Alt - PHA- M31

Question 2

What are the normal/alternate power supplies for NNN-D12?

Answer 2

Normal - NHN-M10
Alternate - PHB-M32

Question 3

Are NNN-D11 and 12 grounded or ungrounded?

Answer 3

ungrounded with ground detection system

Question 4

What are the normal/alternate power supplies for NNN-D15?

Answer 4

Normal - NHN-M06
Alternate - NHN-M19 (SIAS LS)

Question 5

What are the normal/alternate power supplies for NNN-D16?

Answer 5

Normal - NHN-M10
Alternate - NHN-M20 (U1/U2) (SIAS LS) or Unit 3- PHB-M38

Question 6

Are NNN-D15 and D16 grounded or ungrounded?

Answer 6

grounded

Question 7

Which NNN panels do you lose on a SIAS?

How do we get them back?

Answer 7

NNN-D15 and D16

reset at LC (MCC feed breaker) after DG loads the bus

Question 8

What is the purpose of NN system?

Answer 8

Supply 120VAC power to:

Non-essential reactor auxiliary control instrumentation (D11/D12)

Balance of plant loads (D15/D16)

Provide by automatic transfer, an alternate regulated power supply when the normal power supply is lost

Question 9

When does the NNN static transfer switch automatically switch to the emergency power source?

When does the alarm come in?

Answer 9

<90 volts (power seeking switch)

<100 volts

Question 10

Will the NN static transfer switch automatically transfer back to the normal power source if it is on the alternate source and loses power?

Answer 10

yes

Question 11

What could bring in this alarm?

Answer 11

This alarm window (1C11B) warns the operator of one of the following
conditions on the distribution panel:
* Ground
* Undervoltage (100 VAC)
* Breaker overload trip (main feed or load breakers)

Automatic Actions:
If the transfer switch is selected for auto, NNN-D11 will transfer to the
backup power supply on an undervoltage condition on the normal supply.

Question 12

What could bring in this alarm?

Answer 12

This alarm window (1C12B) warns the operator of one of the following
conditions on the distribution panel:
* Ground
* Undervoltage (100 VAC)
* Breaker overload trip (main feed or load breakers)

Automatic Actions:
If the transfer switch is selected for auto, NNN-D12 will transfer to the
backup power supply on an undervoltage condition on the normal
supply.

Question 13

What could bring in this alarm?

Answer 13

This alarm window (1C11C) warns the operator of one of the following
conditions on the distribution panel:
* Undervoltage (100 VAC)
* Breaker overload trip (main feed or load breakers)

Automatic Actions:
If the transfer switch is selected for auto, NNN-D15 will transfer to the
backup power supply on an undervoltage condition on the normal
supply.

Question 14

What could bring in this alarm?

Answer 14

This alarm window (1C12C) warns the operator of one of the following
conditions on the distribution panel:
* Undervoltage (100 VAC)
* Breaker overload trip (main feed or load breakers)

Automatic Actions:
If the transfer switch is selected for auto, NNN-D16 will transfer to the
backup power supply on an undervoltage condition on the normal
supply.