Instrument Power 120VAC (PN) Flashcards
What’re the 4 subsystems dedicated to provide power to ?
-Reactor Protection System(RPS)monitors reactor and plant conditions
-Engineered Safety Features Actuation System (LOCA, steam line break,feedwater line break)
What is normal flow path for PN system ?
Power comes from PK battery system, goes through inverter 125DC->120VAC,then static switch,& manual bypass switch, PN bus
What is alternate power for PN system ?
Class 480VAC MCC,through voltage regulating transformer 480->120, Static Transfer Switch, Manual Bypass Switch in inverter cabinet
What is primary power source for PN system ?
Receives power from PK battery system
What is housed inside the inverter cabinet ?
Inverter, static switch, and manual bypass switch
What is the pre charge push button for on inverter ?
Pre charges the DC input filtering capacitor, so the capacitor isn’t damaged closing the DC breaker ;energize alarm panel
Protective relays on PN system ?
DC under voltage (INPUT)
DC over voltage (INPUT)
AC under voltage (OUTPUT)
AC over voltage(OUTPUT)
AC instan.(OUTPUT)
Breaker indications on inverter?
Open(green light)
Closed(Red Light)
Pre Charge(orange light) must be lit before closing input breaker
What is Third of a kind swing lineup switch used for ?
Allows an alternate flow path to the respective train, and allows for maintnence to be done on the normal inverter cabinet
If the alternate supply power through voltage regulators were in use, what will open the contacts for it? what will close it 5 seconds later ?
It will open on a load shed signal during a LOP condition. Contacts will be sequenced on by a BOP ESFAS after 5 seconds DG output breaker closes
When will static transfer switch change to alternate power ?
Low DC input voltage
Low AC output voltage
High AC output current
What light indication is inverter to load ?
Green light
What light indication is bypass source to load ?
Orange light
What is used on the PN system to protect system from a fault?
A fuse disconnect after switch, the fuses are fast acting and current limiting to protect system
What do the PN system D-panels supply power to?
Each distribution panel supplies one channel RPS & ESFAS, they’re physically separated; If one fails the other three can safely monitor and shutdown reactor
What is the indication light for a ground fault on a distribution panel ?
It’s annunciated in control room, has a red light locally,and must be reset cleared and reset locally
How does PH interface with PN?
PH supplies alternate power to PN system
How does PK interface with PN system ?
PK supplies normal power to PN system
How does HJ interface with PN ?
HJ supplies ventilation to ESF DC equipment room that has the PN system in
How does PN interface with RPS ?
PN provides power to RPS to monitor reactor and nuclear steam support system
What does RPS do?
They initiate protective action shutdown the reactor if monitored parameters are out of range
How does PN interface with ESFAS ?
PN provides power to ESFAS to monitor plant parameters
How does PN interface with CEDMCS ?
PN supplies power to CEDMCS Auxiliary relay cabinets, which contain:
-Reed Switch Position transmitters to indicate CEA position
-Plant Protection System to initiate shutdown
How does PN system interface with SQ system ?
PN provides power to safety related Radiation Monitors
What happens if normal ventilation is lost to the ESF DC equipment room ?
Both trains essential ventilation will start up
What’re the two ways you can lose essential ventilation ?
The blower goes out or you lose essential chilled water
What is a temporary solution to the loss of the blower?
Installing a temporary blower and expandable ducting into DC equipment room
How many PN channels need to be lost for plant to trip ?
Need 2 channels for a plant trip ; One lost channel WONT trip plant
What’re tech spec for PN system in mode 5&6 ?
Must have ONE train of inverter, TWO channels with one inverter per channel, is required to be operable for LCO requirements
How does a Swing Lineup Switch work ?
Manual Break-Before-Make to change the position of all 3 connections to 1 of 3 positions, this is done to always allow the input & output to be on the same train/channel.
What’re the 3 connections for Swing Lineup Switch ?
-DC input from normal power supply(PK)
-AC input from alternate supply(MCC) that goes through voltage regulating transformer
-AC output is directed to to the Channel specific Manual Bypass Switch
How fast do you need to close the DC input breaker to inverter ?
You need to close it within a minute of charging the filtering capacitor, due to the capacitor having a bleeder resistor discharging to circuit.
