120VAC

Question 1

List what 120 Vital AC powers

Answer 1

7300 Process instruments
Excore NIs
SSPS
Safety Related Rad monitors
RSS Panels Instruments

Question 2

Discuss how a UPS provides power when 480V is available

Answer 2

480VAC gets stepped down to 130VAC and rectified to 139VDC

139VDC gets inverted to 120VAC

Question 3

Discuss how a UPS provides power when 480VAC is unavailable

Answer 3

Rectifier output drops below battery bus voltage of 131.5VDC and battery supplies DC volts to Inverter section of UPS

Question 4

State function of Blocking Diode in UPS

Answer 4

Blocking Diode prevents DC current flow from the Rectifier assembly into the DC bus preventing the UPS from supply the DC bus loads, charging the battery and possibly overloading the Rectifier

Question 5

State the function of the precharge pushbutton

Answer 5

Prevents excessive current surge to inverter capacitors

Question 6

Discuss how vital power panels can not be operated in parallel with normal and maintenance supplies

Answer 6

Mechanical interlocks prevent this from occuring via a metalplate

Question 7

Discuss function of static transfer switch associated with UPS 1E/F

Answer 7

Normal power seeking ABT that transfers to alternate when power is unreliable.

Question 8

Discuss UPS 2A shunt trip located in battery bus 11C

Answer 8

This trip protects Vital battery 1C
when voltage drops to 132VDC a 13.5 min timer starts
if power is not restored then UPS 2A supply breakers at 11C opens
T.S. 3.8.3.3 limit is 15min

Question 9

Discuss UPS 2B UV trip

Answer 9

When UPS 2B DC link voltage drops to battery supply voltage a 15 min timer is started.
If power is not restored then then UPS opens 2CB at the UPS

Question 10

Discuss T.S. 3.8.3.2

Answer 10

For modes 5 and 6 if LCO is not met then:
Immediately suspend all Core Alterations, positive reactivity changes, or movement of irradiated fuel, initiate corrective action to energize the required electrical buses and panels in the specified manner as soon as possible, and within 8 hrs, depressurize and vent the RCS through at least a 1.58 square inch vent.