Switching low and high voltage power we use many electrical switching devices like A.B.S. But the main principle for that equipment is the same to isolate any electrical components from the system. We called this type of switch is an isolator. Electrical Isolator is a mechanical switching device that uses to disconnect any electrical component from the system when the system is online or offline.
Isolator does not have any system to avoided arching during disconnection. Because In electrical substation isolator is used 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 isolators in full load conditions.
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Difference Between Isolator and Circuit Breaker:
The isolator is an offload device and the circuit breaker is an on load device. But both are having the same disconnection principle to isolate any parts of the circuit form the system. The isolator cannot operate in on load condition where is there is any trouble in the system then circuit breaker can trip automatically. Now you may think why we use isolator when we cannot operate it on load condition?
The answer is very simple. When a circuit breaker tripped in on the 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 on system requirements isolator can be separated by these three types,
- Double Break Isolator.
- Single Break Isolator.
- Pantograph Type Isolator.
According to the location of power system isolator can be divided as follows,
- Bus Side Isolator: This type of Isolator stay connected with the main bus.
- Line Side Isolator: This type of Isolator stay connected with the feeder in line side.
- 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 types of operation for operating an isolator,
Opening Operation:
- At first, open the main circuit breaker.
- Then open or separated load from the system by the opening isolator.
- Close the earth switch. Earth switch can come with an interlock system with isolator. That’s means when isolator is open only that time earth switch can be closed.
Closing Operation:
- Disconnect earth switch.
- Close the isolator.
- Close the circuit breaker.
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