Switchyard Flashcards
(14 cards)
List the power lines capable of feeding the 345 kV switchyards and associated buses.
Parker 1
Parker 2
Timberview
Wolf Hollow
Mitchell Bend
Johnson
List the power lines capable of feeding the 138 kV switchyards and associated buses.
Stephenville
Carmichael Bend
7020, 7030, 7040, and 7050 are examples of these kinds of breakers. Describe their design function.
7020 & 7050 are the West and East bus 138 kV feeder breakers, respectively, and 7030 and 7040 are the West and East 138 kV bus-tie breakers.
These are examples of SF6 (Sulfur-Hexafluoride) gas breakers. SF6 functions as an arc-quenching gas.
List the trips associated with 7020 and 7050 (138 kV bus feeder breakers)
Breakers 7020 and 7050 will trip on Line Fault and Bus Fault.
List the trips associated with 7030 and 7040 (138 kV bus-tie breakers)
Breakers 7030 and 7040 will trip on Bus Fault or Transformer (XFMR) Fault.
List the Transformers supplied by the 138 kV switchyard
XST1, XST1A
List the Transformers supplied by the 345 kV switchyard and describe their layout.
The 345 kV switchyard supplies 2ST from an independent line. XST2, XST2A, and 1ST are supplied by the 345 kV switchyard via a common line.
Describe the design and function of the capacitor banks and breaker 8435 in relation to 138 kV switchyard.
The Capacitor banks function to “boost” 138 kV switchyard voltage by approximately 1 kV above nominal value when placed in service via the closure of breaker 8435 onto the East bus. The capacitor banks are placed in service when 138 kV switchyard voltage drops below 136.5 kV for 2 SECONDS (when breaker control is in AUTOMATIC). When voltage rises to 143 kV for 2 SECONDS, breaker 8435 will automatically open.
Describe the AUTOMATIC TRIPS and Conditions required to close MOAS 8085 & MOAS 8095 and the loads which these feed
MOAS 8085 feeds XST1
MOAS 8095 feeds XST1A
AUTO OPEN if ALL THREE are met:
1. 86-1 or 86-2 on XST1 or XST1A respectively
2. 138 kV switchyard transfer trip signal (transmission line fault present)
3. No Load Relay energized (prevents opening breaker under load)
TO CLOSE if ALL THREE are met:
1. 86-1 and 86-2 relays reset
2. Ground Switch open
3. No Load Relay energized
Describe the function and AUTOMATIC TRIPS of 8000, 8010, 8020, and 8030 (Main Generator output breakers).
Breakers 8000 and 8010 supply power to the 345 kV switchyard via the Unit 1 Main Transformers. Breakers 8020 and 8030 supply power from the Unit 2 Main Transformers.
AUTO OPEN:
1. Turbine Trip
2. Generator Trip
3. Pole Disagreement
4. Bus Lockout (86-1 or 86-2)
5. Low Gas Pressure (Less than or equal to 71 PSIG)
List the loads fed through MOAS 8012, 8032, and 8052, and describe the AUTOMATIC TRIPS associated with them.
MOAS 8012 feeds XST2
MOAS 8032 feeds XST2A
MOAS 8052 feeds 1ST
AUTO OPEN if ALL THREE are met:
1. Transformer fault (86-1/86-2)
2. 7970/7980 (feeder breakers) open
3. No load relay energized
TO CLOSE (XST2 and 1ST ONLY):
1. Supplied transformer unloaded
2. 86-1/86-2 relay reset
Describe the TS requirements associated with available off-site sources of AC power while OPERATING.
TS 3.8.1 is applicable in Modes 1-4 and requires:
1. Two qualified circuits between the offsite transmission network and the onsite Class 1E AC distribution system
2. Two EDGs capable of supplying the onsite Class 1E AC distribution system
3. Automatic load sequencers for Train A and Train B
Required Actions (RO) (3.8.1):
1. One Offsite Source inoperable - Perform SR 3.8.1 within 1 hour and ONCE per 8 hours after.
2. One EDG inoperable - Perform SR 3.8.1 within 1 hour and ONCE per 8 hours after.
3. Three or more offsite sources inoperable - Enter LCO 3.03 immediately.
4. One Blackout Sequencer inoperable - Train-related EDG inoperable immediately
Describe the TS requirements associated with available off-site sources of AC power while SHUTDOWN
TS 3.8.2 is applicable in Modes 5-6
1. One qualified circuit between the offsite transmission network and the onsite Class 1E AC distribution system available.
1. One EDG capable of supplying one train of the onsite Class 1E AC distribution system is available
Required Actions (RO) (3.8.2):
1. One Offsite Source inoperable - Declare affected required features with no offsite power available inoperable immediately OR Suspend core alterations, movement of irradiated fuel, operations involving positive reactivity additions that could affect required SDM and boron concentration AND initiate actions to restore compliance immediately.
2. One EDG inoperable - Suspend core alterations, movement of irradiated fuel, operations involving positive reactivity additions that could affect required SDM and boron concentration AND initiate actions to restore compliance immediately.
SR 3.8.1 describes pairs of offsite power sources that may be used to supply the 345 kV and 138 kV switchyard and thus meet the ‘Two AC sources available’ requirement. Why are there restrictions on which two lines may be paired?
The 138 kV Stephenville line enters the switchyard and passes under all incoming 345 kV transmission lines with the exception of Parker #1 and Parker #2. Therefore, to avoid an incoming 345 kV transmission line fault resulting in subsequent loss of the incoming 138 kV line, Stephenville may ONLY be paired with Parker #1 or Parker #2. Carmichael Bend (138 kV) may be paired with any of the 345 kV lines with the exception of Mitchell Bend.
(Reference OPT-215 Attachment 10.1 pg. 2 for more information)
