Electrical Isolators :
Q. What is the function of isolator in a power system?
Q. State the sequence of operation of isolator, circuit breakor and earthing switches :
While closing the circuit
While opening the circuit
Q. What is the function of isolator in a power system?
Q. State the sequence of operation of isolator, circuit breakor and earthing switches :
While closing the circuit
While opening the circuit
- Isolator (disconnecting switch) operates under no load condition. It does not have any specified breaking capacity or current making capacity. Isolator is not even used for breaking load currents.
- Isolators are used in addition with circuit breakers. and are provided on each side of every circuit breaker to provide isolation and enable maintenance.
- Isolators used in power system are of 3-pole type. 3-poles are identical one.
- Each pole consists of two or three insulators posts mounted on a fabricated support.
- The conducting parts are supported on the insulator posts. The conducting parts consist of conducting copper or aluminium rod, fixed and moving contacts.
- During the opening operation the conducting roas swings apart and isolation is obtained.
- The simultaneous operation of 3-poles is obtained by mechanical interlocking of the three poles. Further all the three poles, there is a common operating mechanism.
Sequence of operation while opening/closing a circuit.
While opening :
> Open the circuit breaker.
> Open isolator.
> Close earthing switch.
While closing :
> Open earthing switch.
> Close isolator
> Close circuit breaker