345kv

Question 1

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 +

Answer 1

Question 2

STATE the two functions of the 345 kV distribution system

Answer 2

• Connect station grid when the Main Generator in operating • Connect grid to unit auxiliaries when the Main Generator is shutdown

Question 3

DESCRIBE the functions of the SF6 insulated bus

Answer 3

We use it as an insulating agent to allow low profile “enclosed” SY

Question 4

LIST the automatic actions that occur upon loss of SF6 pressure in the bus

Answer 4

• Normal Pressure 30-85 psig @ 68F • 26 psig LO SF6 Gas System Trouble • 22 psig LO-LO Gas System Trips • bus segment isolation

Question 5

DESCRIBE the function of the 345 kV power circuit breaker (PCB)

Answer 5

• Designed to interrupt a circuit and still extinguish the arc. • Use HP Air for closing • Use spring force for opening

Question 6

STATE the normal, alarm and action level pressure for PCB HP SF6 gas

Answer 6

• Normal: 265 psig • Alarm: 240 psig • Lockout: 230 psig

Question 7

STATE the normal, alarm and action level pressure for PCB LP SF6 gas

Answer 7

• Norm: 45# • Low: 35# • Lockout: 30# • Compressor trip: 30#

Question 8

STATE the normal, alarm and action level pressure for PCB air pressure

Answer 8

• Normal Pressure 250 psig • Low alarm @ 230 psig • PCB Lockout @ 225 psig NO TRIP • Why? • Prevents sluggish closing of breaker

Question 9

LIST the precautions to be observed when operating a 345 kV breaker from the switchyard

Answer 9

Single pole operation bypasses all interlocks

Question 10

LIST all the locations from which the following can be manipulated PCB

Answer 10

• MCB • ESCC • Relay Room • Local Electrically • Local Manually

Question 11

LIST all the locations from which the following can be manipulated Disconnect

Answer 11

• MCB/ESCC • Relay Room • Locally

Question 12

LIST all the locations from which the following can be manipulated Grounds

Answer 12

• MCB/ESCC • Relay Room • Locally

Question 13

EXPLAIN the purpose of the disconnect and ground switches

Answer 13

• Deenergize bus isolation for maintenance. • Dissipate the static charge remaining on the newly deenergized bus & to prevent any future static build-up

Question 14

STATE how to locally verify a disconnect or ground is open or closed

Answer 14

• 5-6” gap when observed through the window when open

Question 15

STATE why a disconnect should not be observed from the window as it is being operated.

Answer 15

• Eye damage will result from the intense light given off by the arc.

Question 16

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

Answer 16

• 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

Question 17

STATE the location of the spare Kirk keys when not in use

Answer 17

• They are stored in a lock box in the relay room

Question 18

STATE the color of the bypass Kirk key and EXPLAIN its function

Answer 18

• The bypass Kirk key is red and bypasses all safety interlocks

Question 19

STATE the function of protective relaying

Answer 19

• Designed to clear faults in the 345 kV zones by tripping breakers to deenergize the transmission lines

Question 20

OUTLINE the actions to be taken upon discovery of a tripped relay

Answer 20

• Report information to the Control Room • Using Form ODI-17A, Record: • Time Found • Time Reset • Relay Number • Relay Name • Relay condition i.e. tripped

Question 21

STATE the normal and emergency source of (AC) power to SF6 compressors, heaters and 345KV DC breaker control

Answer 21

• 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.