Switchs/switching

Question 1

What is the timing after a fault for a mid point RCS?

Answer 1

1. Circuit relays, CB opens
2. CB recloses after 15 seconds
3. Circuit relays again (tests no good)
4. The midpoint automated RCS will open automatically in 30-35 seconds if the loss-of-AC voltage time-delay relay doesn’t reset
5. CB recloses for test after 55 seconds. If circuit locks out the switching center shall verify midpoint RCS is open and will remotely close in the tie switch through radio command picking up the back half of the circuit.

DOM SW-11 page 7

Question 2

Can you use a load break elbow to energize a capacitor?

Answer 2

No. Do not use LBE’s to energize or de energize a capacitor bank.

DOH CC-5

Question 3

At what temperature difference between cable and load break elbow can the load break elbow not be used?

Answer 3

Load break elbow can not be used if there is a 10 degree difference between cable and load break elbow.

Elbow must also be scheduled to be changed out.

DOM CC-5

Question 4

What’s the formula to find full load amps on a capacitor bank?

What’s the rule of thumb? For 12kv.

Answer 4

KVAR times 1000 divided by voltage times 1.73

Rule of thumb take a 0 off the KVAR number and divide remaining number by 2

Example for 12kv
 KVAR 600
Remove a 0 
60
Divide by 2 
30 full load amps

Question 5

If you are not behind CLF, above how many amps of fault duty are you not allowed to close energized load break elbows?

Answer 5

5,700 amps of fault duty

DOM CC-5 page 11

Question 6

Can you de-energizes a transformer with bayonet fuses?

If so, can it have any load on it?

Answer 6

Yes. As long as each bayonet fuse does not exceed100 amps.

DOM TR-2 attachment 3

Question 7

What’s the maximum amps you can break with a break safe tool?

Answer 7

300 amps

Question 8

What are the 5 switches that can break capacitive voltage?

Answer 8

1. Load buster
2. Fiddler switch
3. Kyle switch
4. CB
5. Vacuum switch

Question 9

How many amps of circulating current can a KPF Switch break? 12kv 16kv? 33kv?

Answer 9

12 & 16kv
12’ arm no whiskers: 150amps
No whiskers: 100amps
Whiskers: 350amps

33kv
12’ arm no whiskers: 0 amps
No whiskers: 0 amps
Whiskers: 80 amps

Portal overhead switches.

Question 10

Where is ferroresonance not a consideration?

Answer 10

• on 6.9 single phase radials
• any radial switched with a gang operated switch.
• 4kv wye primary systems switch with the primary neutral grounded.

DOM TR-8 pg 8

Question 11

What are the 4 R’s when switching on 4kv?

Answer 11

Make Recloser solid
Take Reads
Block Regulators and turn off controls
Make ground Relay solid

Question 12

What would happen if you didn’t block the ground relay and closed the bypass switch on a RAR? I’m

Answer 12

If current goes through a RAR and doesn’t return on the RAR then the RAR will open on ground. So when then bypass switch is closed not all the current will flow back through the RAR, some will flow throw them bypass switch.

Question 13

After replacing the fuses inside a load brake fuse cabinet what is the sequence for energizing the cabinet?

Answer 13

After replacing fuses, the fuse cabinet shall be energized with the line side load break elbow first then the load side load break elbow will be used to pick up the load.

**DOM PD -4 4.1.h

Question 14

What precautions must be taken prior to energizing any new piece of cable or equipment?

Answer 14

• No piece of cable or switching device shall be energized until it has been positively identified by tags or other approved means
• No piece of equipment shall be energized until all terminals cables and positions have been safe ended or otherwise protected in a way that would prevent short-circuit, ground or personal contact
• APM RULE 303

Question 15

What describes a RAJ switch?

Answer 15

1st position solid to the bus
2nd position and 4th position can be open, closed, or tie
3rd position is solidly connected to the tie position.

** 3rd step book underground switches pg 14

Question 16

What are the four reasons we bypass an RAR?

Answer 16

1. Change the status of the circuit
2. Working on the high side of the RAR.
3. Switching ( going in parallel with another circuit )
4. RAR inoperable

Question 17

What is the rule of thumb to figure out full load amps on a cap bank for 4kv 12kv and 16kv

Answer 17

4 kv-Kvar divided by 7

12 kv- kvar divides by 20

16 kv - kvar divides by 30

Question 18

How many amps can a load break elbow break?

Answer 18

200 amps

DOM CC-5