Non Class 120V Instrument AC

Question 1

In Unit 2, the normal power source to NNN-D16 has been lost. State the new power source you would expect to be powering NNN-D16.

Answer 1

NHN-M20 (U1 & U2 only)

Question 2

(ANNUNCIATOR)
120VAC
PNL D11/
D12/D15/D16
TRBL

Answer 2

Alarm warns the operator of one of the following conditions on the distribution panl:
Ground (NNN-D11 and D12 ONLY)
UV (100 VAC)
Bkr overload trip (main feed or load bkrs)

Question 3

The single phase regulators that supply power to NNN-D15 and D16 are GROUNDED or UNGROUNDED?

Answer 3

GROUNDED

Question 4

In Unit 3, what is the emergency (alternate) power source to NNN-D16?

Answer 4

PHB-M38

Question 5

What type of “Transfer Switch” is used on NNN-D11 & D12 and at what under voltage condition is it expected to shift from the Normal to Emergency power source?

Answer 5

Static Transfer Switch

Automatic transfer to emergency source is accomplished when the normal source drops below 90 volts.

Question 6

What is the location of NNN-D15?

Answer 6

Turbine Building 100’

Question 7

What is the main difference between the “Static” and “Auto/Manual” Transfer switches?

Answer 7

“Static” Transfer switches operate much faster than the “Auto/Manual” Transfer switches used in NNN-D15 and D16, requiring only 4 cycles to transfer vice 30 to 90 cycles required by the “Auto/Manual” Transfer switches.

Question 8

Where is NNN-D16 located?

Answer 8

Aux Building 120’

Question 9

Control power to the ground fault detection ckt for panels NNN-D11 and NNN-D12 is supplied from ______.

Answer 9

NKN-D42 (Non-Class IE 125VDC)

Question 10

The purpose of the NNN system is to provide four sources of 120 VAC, single phase, 60 Hz regulated and filtered power supplies for the following:

Answer 10

Non-essential Rx auxiliary control instrumentation (ungrounded).
BOP loads (grounded)
Provide by auto transfer, an alternate regulated pwr supply when the normal supply is lost

Question 11

The ‘Static’ & ‘Auto/Manual’ Transfer switches are both _______ seeking; and the type of transfer to and from the normal/emergency power sources is ______ before ______.

Answer 11

power

break, make

Question 12

List all the NNN panels and their locations.

Answer 12

NNN-D11, Control Building 120’
NNN-D12, Control Building 120’
NNN-D15, Turbine Building 100’
NNN-D16, Aux Building 120’

Question 13

If a ground fault was detected on NKN-D11 or D12, what local and Control Room indications would you expect?

Answer 13

The ungrounded D11/D12 buses have ground fault detection relays which illuminate a “red” indicating light locally on the respective panel and annunciates a trouble alarm in the Control Room.

Question 14

Palo Verde has lost all offsite power.
Unit 3 had a Loss of Coolant Accident that resulted in an actuation of both trains of SIAS. All equipment operated as designed.
What is the status of NNN-D15 and NNN-D16 in Unit 3?
NNN-D15 is ___(1)___ and NNN-D16 is ___(2)___.
A. (1) energized; (2) energized
B. (1) energized; (2) de-energized
C. (1) de-energized; (2) energized
D. (1) de-energized; (2) de-energized

Answer 14

C

Question 15

Where is NNN-D11 & D12 located?

Answer 15

Control Building 120’