Distribution switching

Question 1

What are three things we should ALWAYS consider when we prepare for distribution switching?

Answer 1

System Protection, Load, and Voltage

Question 2

For voltage consideration, what equipment are you focusing on?

Answer 2

Capacitors and Regulators

Question 3

On the distribution system, are capacitors normally controlled manually or automatically?

Answer 3

Capacitors are normally controlled Automatically on the distribution system.

Question 4

Since Capacitors are controlled automatically, what must TSO do before taking them out of service?

Answer 4

Capacitor controls need to be put to SOLID before taking out of service.

Question 5

What are regulators used for on the distribution system?

Answer 5

Regulators are used to control voltage automatically on distribution lines and on some buses.

Question 6

When dealing with a regulator, what must be done prior to switching?

Answer 6

Regulator should always be BLOCKED prior to switching.

Question 7

Why do you want to block regulators prior to switching?

Answer 7

To ensure there is no uncontrolled voltage changes.

Question 8

When dealing with regulators, as you are preparing to switch what questions should you be asking yourself?

Answer 8

Are you dealing with a field parallel or a station parallel.

Question 9

How do you identify if you are dealing with a station parallel or field parallel?

Answer 9

Parallel before feedpoint is a station parallel.

Parallel beyond feedpoint, is a field parallel.

Question 10

For a station parallel, how do you address the regulator?

Answer 10

Block regulator on Neutral and off control.

Question 11

For a field parallel, how do you address the regulator?

Answer 11

Block regulator on step and off control.

Question 12

What is circulating current?

Answer 12

When busses or lines at different voltages are paralleled, circulating current (vars) will flow from the higher voltage to the lower voltage which may cause loading on a circuit reach an unacceptable level.

Question 13

What SOB sets the limit for circulating current?

Answer 13

SOB 305

Question 14

What the circulating current limit set by SOB 305 for a station parallel?

Answer 14

50 Amps

Question 15

What is the circulating current limit set by SOB 305 for a field parallel?

Answer 15

75 amps

Question 16

At a conventional station, clearing a low side bank CB. What must you do to the bus tie CB and bank CB?

Answer 16

Bus Tie, you must make overload and ground relay solid

Bank you must make bank differential solid. Closing transfer bus disconnects will create a alternate path and CTs will not see in coming load and trip.

Question 17

For distribution, what are the steps to clearing CAPS?

Answer 17

Put Capacitor controls to Manual
Open Capacitor CB
Wait five minutes
Check Capacitor CB open
Open bus Disconnects
Check Capacitor Dead
Close Shorting Disconnects
Close Ground Disconnects

Question 18

When you put bank on Bus tie, do you make Bus Tie recloser solid? If no, why?

Answer 18

No, because all protection and testing is handled by Bank HS overload.

Question 19

Put low side Bank CB on the Bus tie at a SAS station, how do address protection on the bus tie?

Answer 19

Put Bus Tie Relay settings to Bank position and off primary