Electrical Isolator

Electrical Isolator

Switching low and high voltage power we use many electrical switching devices like A.B.S. But the main principle for those equipments is same to isolate any electrical components from the system. We called this type of switch is isolator. Electrical Isolator is a mechanical switching device that uses to disconnect any electrical component from system when system is online or offline.

Electrical Isolator
Electrical Isolator

Isolator does not have any system to avoided arching during disconnection. Because In electrical substation isolator is use to disconnect a power transformer when it is in no load condition or a small amount of load is present. It is dungarees to operate isolator in full load condition.

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Difference Between Isolator and Circuit Breaker:

Isolator is off load device and circuit breaker is a on load device. But both are having same disconnection principle to isolate any pats of circuit form the system. Isolator cannot operate in on load condition where is there is any trouble in system then circuit breaker can trip automatically. Now you may think why we use isolator when we cannot operate it on load condition?

Answer is very simple. When a circuit breaker tripped in on load, no load or fault situation, then we cannot see the circuit breaker actually tripped or not. Because disconnection happened inside the circuit breaker. For this reason we use a manual mechanical isolating system that we can confirm that load is removed from the system.

Different Types of Isolator:

Depending of system requirements isolator can be separated by these three types,

  1. Double Break Isolator.
  2. Single Break Isolator.
  3. Pantograph Type Isolator.

According to the location of power system isolator can be divided as follows,

  1. Bus Side Isolator: This type of Isolator stay connected with the main bus.
  2. Line Side Isolator: This type of Isolator stay connected with feeder in line side.
  3. Transfer Bus Side Isolator: This Type of Isolator stay connected with the main bus of a transformer.

Related: General Question About Circuit Breaker

Operation Procedures for an Isolator:

There are two type of operation for operating an isolator,

Opening Operation:

  1. At first open the main circuit breaker.
  2. Then open or separated load from system by opening isolator.
  3. Close the earth switch. Earth switch can be come with an interlock system with isolator. That’s means when isolator is open only that time earth switch can be closed.

Closing Operation:

  1. Disconnect earth switch.
  2. Close the isolator.
  3. Close the circuit breaker.


Related: Electrical Busbar Classification, Management With Calculation

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