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 an isolator. An electrical Isolator is a mechanical switching device that is used to disconnect any electrical component from the system when the system is online or offline.
The isolator does not have any system to avoid arching during disconnection. In an electrical substation, an 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 have the same disconnection principle to isolate any parts of the circuit from the system. The isolator cannot operate in load conditions where if there is any trouble in the system then the circuit breaker can trip automatically. Now you may think why do we use an isolator when we cannot operate it on load conditions?
The answer is very simple. When a circuit breaker tripped in on the load, no-load, or fault situation, then we cannot see whether the circuit breaker actually tripped or not. Because disconnection happened inside the circuit breaker. For this reason, we use a manual mechanical isolating system so that we can confirm that the load is removed from the system.
Different Types of Isolators:
Depending on system requirements isolators can be separated into these three types,
- Double Break Isolator.
- Single Break Isolator.
- Pantograph Type Isolator.
According to the location of the power system, the isolator can be divided as follows,
- Bus Side Isolator: This type of Isolator stays connected to the main bus.
- Line Side Isolator: This type of Isolator stays connected to the feeder on the line side.
- Transfer Bus Side Isolator: This Type of Isolator stays connected to the main bus of a transformer.
Operation Procedures for an Isolator:
There are two types of operation for operating an isolator,
- At first, open the main circuit breaker.
- Then open or separate the load from the system by the opening isolator.
- Close the earth switch. Earth switch can come with an interlock system with an isolator. That means when the isolator is open only that time the earth switch can be closed.
- Disconnect the earth switch.
- Close the isolator.
- Close the circuit breaker.
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