Distribution switching Flashcards
What are three things we should ALWAYS consider when we prepare for distribution switching?
System Protection, Load, and Voltage
For voltage consideration, what equipment are you focusing on?
Capacitors and Regulators
On the distribution system, are capacitors normally controlled manually or automatically?
Capacitors are normally controlled Automatically on the distribution system.
Since Capacitors are controlled automatically, what must TSO do before taking them out of service?
Capacitor controls need to be put to SOLID before taking out of service.
What are regulators used for on the distribution system?
Regulators are used to control voltage automatically on distribution lines and on some buses.
When dealing with a regulator, what must be done prior to switching?
Regulator should always be BLOCKED prior to switching.
Why do you want to block regulators prior to switching?
To ensure there is no uncontrolled voltage changes.
When dealing with regulators, as you are preparing to switch what questions should you be asking yourself?
Are you dealing with a field parallel or a station parallel.
How do you identify if you are dealing with a station parallel or field parallel?
Parallel before feedpoint is a station parallel.
Parallel beyond feedpoint, is a field parallel.
For a station parallel, how do you address the regulator?
Block regulator on Neutral and off control.
For a field parallel, how do you address the regulator?
Block regulator on step and off control.
What is circulating current?
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.
What SOB sets the limit for circulating current?
SOB 305
What the circulating current limit set by SOB 305 for a station parallel?
50 Amps
What is the circulating current limit set by SOB 305 for a field parallel?
75 amps
At a conventional station, clearing a low side bank CB. What must you do to the bus tie CB and bank CB?
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.
For distribution, what are the steps to clearing CAPS?
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
When you put bank on Bus tie, do you make Bus Tie recloser solid? If no, why?
No, because all protection and testing is handled by Bank HS overload.
Put low side Bank CB on the Bus tie at a SAS station, how do address protection on the bus tie?
Put Bus Tie Relay settings to Bank position and off primary
