PB/PG/PH/PK/PN- Class Electrical Flashcards
What are the colors associated with each channel, A, B, C, D?
A-red
B-green
C-yellow
D-blue
What are the system designators for the class 4.16kV, 480V load centers, 480V MCCs, 125VDC and the 120VAC systems?
PB-4.16kV PG-480V AC Load Centers PH-480V AC MCCs PK-125V DC PN-120V AC
What happens to the class 4160V busses when a Loss of Off-site power occurs?
the emergency diesels would start and auto load to the class busses
what is the purpose and design of the class 4.16kV power (PB) system?
purpose:
provides 4160V power to one of two redundant and independent safety related load groups, or equipment that is required to safely shut down the unit
design: has normal (off-site power) and alternate (emergency diesels) power source
detects degraded voltage and loss of voltage on normal power source and will send a LOP to ESF actuation system
Can one safety train of equipment safely shut down the unit, or are both required?
only one train is required
Where does PBA-S03 and PBB-S04 get power from?
NAN-S03/04 through the ESF(NBN-X03/04) transformers.
FLEX portable diesel generators purpose?
-Beyond Design Basis event,
-Can be tied to supply PBA-S03 or PBB-S04, downstream of the ESF transformers
How does the NA system interface with the PB system?
provides all power to the PB system via the preferred, alternate or normal shutdown configuration, including SBOGs
How does the NB system interface with the PB system?
PB receives power from the NB ESF transformers
How does the DG system interface with the PB system?
PB receives power from the Class emergency diesels during a LOOP
How does the PG system interface with the PB system?
PB supplies power to the PG load centers
How does the PH system interface with the PB system?
PB receives 120VAC from the PHD-panels for switchgear heaters
why do switchgear require space heaters?
to maintain temperature above the dew point
How does the PK system interface with the PB system?
PK provides control power to the PB switchgear
How does the BOP(ESFAS/SA) system interface with the PB system?
PB sends signals for each load group of bus under-voltage to the SA system and receives load shedding and load sequencing signals from the SA system
How does the SP system interface with the PB system?
PB supplies power to the Essential spray pond pump motors
How does the SI system interface with the PB system?
supplies power to the Safety injection pump motors (HPSI/LPSI)
How does the EC system interface with the PB system?
PB supplies power to the essential chillers
How does the WC system interface with the PB system?
PB supplies power to the A normal chiller
How does the EW system interface with the PB system?
PB provides power to the essential cooling water pump motors
How does the AF system interface with the PB system?
PB provides power to the B and N auxiliary feedwater pump motors
How does the HJ system interface with the PB system?
HJ provides normal and emergency cooling to the class switchgear rooms
what is the purpose, operation and location of the ESF transformers?
purpose/operation:
step down 13.8kV to 4160V and provide that power from the preferred off-site source or from the SBOGs
oil/ air and forced air cooling
cooling is powered from 480VAC
can fault isolate
location:
outdoors, south side of the turbine building
what is the purpose, operation and location of the PB switchgear?
purpose/operation: distribute power to class safety related loads, start and trip loads as required and protect bus from damage due to faults and overloads
can be operated remotely from control room, remote shutdown panel (B train only) or locally
location: separate class switchgear room, 100' control building
In PB breaker cabinets, what are the fuse names and what do they supply power to?
UC-closing circuits and green light
UT-tripping circuits and red light
UE-control room connections to the tripping and closing circuits
UL- for racking motor
What D-panels do PBA-S03 and PBB-S04 receive control power from?
PKA-D21 (S03)
PKB-D22 (S04)
What breaker inside the breaker cubicle provides control power to the fuses?
RRC
For seismic concerns, when PB breakers are racked out, what must be done?
the breaker must be racked back up 1-2” off the ground or restrained
Describe the automatic features of the class 4160v power system.
under voltage relays prevent system running on low voltage and will fault the bus
8 of the 9 under-voltage relays input into the BOP ESFAS and initiate 2/4 logic and perform:
start respective diesel generator
load shed bus
close diesel generator breaker
load sequence diesel generator
What is a LOP?
Loss of Power
What is a LOOP?
Loos of Off-site Power
How many under-voltage relays are on each PB bus and what are they dedicated for?
9 total
5 for degraded voltage
4 for under voltage detection
the 5th degraded voltage relay will provide annunciation 10 seconds after voltage drops below 90%
When do the degraded voltage relays actuate?
30 seconds after voltage drops below 90% of rated capacity
When do the under voltage detection relays actuate?
immediately after voltage drops to 75%
On PB busses, what trips the normal and alternate breakers?
if electrical load shed is generated
the opposite supply breaker is closed from B01
ESF transformer faults
if the 86 lockout operates
(PB page 22)
How will a loss of the PB system impact the plant?
power must be restored within two hours due to class battery system capacity
failure of one safety train will require the redundant train to meet safety functions
may enter abnormal operating procedure or emergency operating procedure to restore power
with a diesel generator running, how long do you have to get a spray pond pump running before the diesel shuts down?
2.6 minutes
What circumstance would require cross tying PB Busses?
when one shutdown cooling loop is not available and the opposite train diesel generator is not available
What does the Degraded Electrical Power Abnormal Operating Procedure provide guidance for?
LOP to any 480V or higher bus that does NOT cause a LOOP or blackout
PB bus cross tying
What do the Emergency Operating Procedures provide guidance for?
they address the availability of the 4160V busses to ensure ONE class bus is available to support a safety equipment train.
determining a blackout if no PB busses are available
What PB system equipment is related to tech specs while operating?
PBA-S03 and PBB-S04 must be energized to their proper voltages to be OPERABLE
tie breakers between redundant safety systems must be open
8 hours to become operable if either train becomes inoperable
What PB system equipment is related to tech specs while shutdown?
All systems necessary to support OPERABILITY of required systems, equipment and components
What is the purpose of the PG/PH system?
step down power from 4160v to 480v and send that power to safety related equipment as well as essential non class equipment.
equipment is design basis
How many load centers and MCCs are on each safety train?
Three load centers
Four class MCCs
Two SIAS load shed MCCs
What is a SIAS Load shed MCC?
A non-class MCC supplying power to essential non class loads that will be tripped in the case of a SIAS
Where do PG load centers get control power from?
125VDC (PK)