Systems Exam 1 - Switchyard Flashcards
What is the minimum operating voltage for the 345 kV switchyard?
340 kV
What is the minimum operating voltage for the 138 kV switchyard?
135 kV
What are corona rings?
Corona is an electrical discharge caused by ionization of the atmosphere surrounding high voltage conductors causing heat buildup.
What is distance relaying?
→an electrical protection scheme where protective devices (relays) which are geographically separated can communicate with each other to detect and isolate faults at the appropriate locations to minimize effect on the grid
How does distance relaying work?
→relays communicate with each other via high frequency carrier signal on the grid conductors; signal is detected at each location and used to send trip signals to the appropriate locations when a fault is detected
How do reclosers work?
reclose on time delay only; do not detect if fault has cleared or not
What is the purpose of the manual disconnects in the Switchyards?
personnel and electrical safety for maintenance or fault isolation
(require a key to unlock)
Capacitor Bank Breaker 8435 closes when….
Capacitor Bank Breaker 8435 opens when….
→closes when grid voltage drops below 136.5 kV for 2 seconds
→opens when grid voltage increases to 143 kV for 2 seconds
(capacitor bank expected to raise 138 kV grid voltage by 1 kV when in service)
What are the common trips for 345 kV breakers?
→pole disagreement
→low SF6 gas pressure
→bus lockout
→transmission line fault (only for breakers tied directly to transmission lines)
What are the unit differences for the switchyard?
Unit 1 Safeguards Buses:
→normal power is 345 kV
→alternate power is 138 kV
Unit 2 Safeguards Buses:
→normal power is 138 kV
→alternate power is 345 kV
What are the main generator breaker trips?
→common trips
→main generator lockout
→turbine trip
What are the trips for:
Breaker 7020 (Carmichael Bend to 138 kV West Bus)
AND
Breaker 7050 (Stephenville to 138 kV East Bus)
→line fault
→bus fault
What are the trips for breakers 7030 and 7040?
(138 kV east and west bus to XST1/1A)
→bus fault
→transformer fault
What are the trips/switches for:
Breaker 7022 (Transformer #1 - 138 kV West Bus to 25 kV Loop)
AND
Breaker 7052 (Transformer #2 - 138 kV East Bus to 25 kV Loop)
→86 on associated transformer
→associated transformer sudden pressure
→bus differential
→bus overcurrent
XST1/XST1A High Speed Ground Switch
→auto closes on fault of XSTA or XST1A
→must be manually reset
What auto-opens 138 kV MOAS (8085/8095)?
8085: XST1 supply
8095: XST1A supply
→86-1 or 86-2 on associated transformer
→associated transformer no-load relay energized
What conditions must be present for manually closing 138 kV MOAS (8085/8095)?
8085: XST1 supply
8095: XST1A supply
→86 lockout relays must be reset
→ground switch GXST1 must be open
→associated transformer no-load relay energized (transformer is unloaded)
What auto-opens 345 kV MOAS (8012/8032/8052)?
8012: XST2 supply
8032: XST2A supply
8052: 1ST supply
→86-1 or 86-2 on associated transformer
→supply breakers open (7970/7980)
→associated transformer no-load relay energized
→once applicable MOAS is open, then breakers 7970/7980 will reclose to restore power to the other transformer
What conditions must be present for manually closing 345 kV MOAS (8012/8032/8052)?
8012: XST2 supply
8032: XST2A supply
8052: 1ST supply
→86 lockout relays must be reset
→associated transformer no-load relay energized (transformer is unloaded)
→8032 (XST2A supply) has no interlocks; local operation only
Why do we control generator output breakers?
“Control” means any apparatus or mechanism that, if manipulated, directly affects the reactivity or power level of the reactor.
Generator output can directly affect reactor power.
Who controls Switchyard access?
shift man
(need a key from control room or security to enter)
Tech Spec 3.8.1 AC Sources - Operating
→Modes 1-4
→two offsite sources must be available
→two DGs must be available
→automatic load sequencers for Train A and Train B
Two offsite sources can be satisfied by:
→”Stephen Parker” - 138 kV Stephenville with 345 kV Parker #1 OR Parker #2
→”Number 2 Bends” - 138 kV Carmichael Bend with any 345 kV line except for Mitchell Bend
(138 kV Stephenville line crosses all 345 kV lines other than Parker 1 and 2)
Which Switchyard lines connect to only one bus, and which bus do they connect to?
→Parker 1 - 345 kV East Bus
→Stephenville - 138 kV East Bus
→Carmichael Bend - 138 kV West Bus
Tech Spec 3.8.2 AC Sources - Shutdown
→Modes 5 & 6
→one offsite source must be available
→one DG must be available
What happens if we don’t satisfy Tech Spec 3.8.1 (AC Sources - Operating, Modes 1-4)?
1 Hour or Less Actions
→LCO 3.8.1.A One required offsite source inoperable: SR 3.8.1.1 (same as OPT-215) with completion time of one hour AND once per 8 hours thereafter
→LCO 3.8.1.B One required DG inoperable: SR 3.8.1.1 (same as OPT-215) with completion time of one hour AND once per 8 hours thereafter
→LCO 3.8.1.C Two required offsite circuits inoperable: restore one required offsite circuit to operable within 24 hours
→LCO3.8.1.H Three or more required AC sources inoperable: enter TS LCO 3.0.3 immediately
What happens if we don’t satisfy Tech Spec 3.8.2 (AC Sources - Shutdown, Modes 5-6) with regard to offsite sources?
1 Hour or Less Actions
LCO 3.8.2.A - One required offsite source inoperable
NOTE: Enter applicable Conditions and Required Actions of LCO 3.8.10, with the required train de-energized as a result of Condition A.
→A.1: Declare affected required feature(s) with no offsite power available inoperable immediately OR
→A.2.1: Suspend CORE ALTERATIONS immediately AND
→A.2.2: Suspend movement of irradiated fuel assemblies immediately AND
→A.2.3: Suspend operations involving positive reactivity additions that could result in loss of required SDM or boron concentration immediately AND
→A.2.4: Initiate action to restore required offsite power circuit to OPERABLE status immediately
What happens if we don’t satisfy Tech Spec 3.8.2 (AC Sources - Shutdown, Modes 5-6) with regard to diesel generators?
LCO 3.8.2.B One required DG inoperable
→B.1: Suspend CORE ALTERATIONS immediately AND
→B.2: Suspend movement of irradiated fuel assemblies immediately AND
→B.3: Suspend operations involving positive reactivity additions that could result in loss of required SDM or boron concentration immediately AND
→B.4: Initiate action to restore required DG to OPERABLE status immediately
