345kv Flashcards
345kv (21 cards)
DRAW and label a block diagram of the 345 kV and 25 kV distribution systems, including all major system tie-in points, PCBs, and MODs +
STATE the two functions of the 345 kV distribution system
• Connect station grid when the Main Generator in operating • Connect grid to unit auxiliaries when the Main Generator is shutdown
DESCRIBE the functions of the SF6 insulated bus
We use it as an insulating agent to allow low profile “enclosed” SY
LIST the automatic actions that occur upon loss of SF6 pressure in the bus
• Normal Pressure 30-85 psig @ 68F • 26 psig LO SF6 Gas System Trouble • 22 psig LO-LO Gas System Trips • bus segment isolation
DESCRIBE the function of the 345 kV power circuit breaker (PCB)
• Designed to interrupt a circuit and still extinguish the arc. • Use HP Air for closing • Use spring force for opening
STATE the normal, alarm and action level pressure for PCB HP SF6 gas
• Normal: 265 psig • Alarm: 240 psig • Lockout: 230 psig
STATE the normal, alarm and action level pressure for PCB LP SF6 gas
• Norm: 45# • Low: 35# • Lockout: 30# • Compressor trip: 30#
STATE the normal, alarm and action level pressure for PCB air pressure
• Normal Pressure 250 psig • Low alarm @ 230 psig • PCB Lockout @ 225 psig NO TRIP • Why? • Prevents sluggish closing of breaker
LIST the precautions to be observed when operating a 345 kV breaker from the switchyard
Single pole operation bypasses all interlocks
LIST all the locations from which the following can be manipulated PCB
• MCB • ESCC • Relay Room • Local Electrically • Local Manually
LIST all the locations from which the following can be manipulated Disconnect
• MCB/ESCC • Relay Room • Locally
LIST all the locations from which the following can be manipulated Grounds
• MCB/ESCC • Relay Room • Locally
EXPLAIN the purpose of the disconnect and ground switches
• Deenergize bus isolation for maintenance. • Dissipate the static charge remaining on the newly deenergized bus & to prevent any future static build-up
STATE how to locally verify a disconnect or ground is open or closed
• 5-6” gap when observed through the window when open
STATE why a disconnect should not be observed from the window as it is being operated.
• Eye damage will result from the intense light given off by the arc.
DESCRIBE the basic sequence of steps involved in using the Kirk key system to remove a PCB from service and to place it back in service
• Functions to prevent local inadvertent / unauthorized energizing of 345 kV components in an improper sequence • Ensures proper sequence by: • Trapping the key(s) unless the equipment is in the required position / status. • Disallowing operation if the key is absent
STATE the location of the spare Kirk keys when not in use
• They are stored in a lock box in the relay room
STATE the color of the bypass Kirk key and EXPLAIN its function
• The bypass Kirk key is red and bypasses all safety interlocks
STATE the function of protective relaying
• Designed to clear faults in the 345 kV zones by tripping breakers to deenergize the transmission lines
OUTLINE the actions to be taken upon discovery of a tripped relay
• Report information to the Control Room • Using Form ODI-17A, Record: • Time Found • Time Reset • Relay Number • Relay Name • Relay condition i.e. tripped
STATE the normal and emergency source of (AC) power to SF6 compressors, heaters and 345KV DC breaker control
• Normal Auxiliary Power comes from US-26 and US-14 • LOP causes emergency power to kick in via ABTs via US-53 • On a LOP if A EDG fails to reenergize Bus 5, then no power would exist for 345 kV auxiliary power • Temporary cables can be run from LC-14 to the ABT output, to supply 480VAC power to serve 345 kV PCB auxiliaries, SY Battery Charger, & DC Breaker Controls • This is because LC-14 is powered from another offsite source, the Exeter/Hampton line.
