The nature of the works of the Isolator and Circuit Breaker is the same, both are used to isolate the circuit from the connected supply. The operating characteristics of both the equipment are different and based on the requirement they are used in a different locations in electrical switchgear.
What is Isolator?
The isolator is electrical equipment that is used to isolate the circuit from the main supply in off-load conditions. The design of the isolator is very simple and the operating time of the isolator is high compared to the circuit breaker. The isolator is used in electrical switch gear for maintenance work of other equipment and transmission lines.
What is Circuit Breaker?
A circuit Breaker is electrical equipment that is used to isolate the circuit from the main supply in on-load conditions. High-speed operating mechanism is used in the circuit breaker for fast isolating of the circuit. Arc generates in the circuit breaker during on load operation of the circuit breaker depending on the circuit load.
A circuit breaker is designed in a way that it can be easily quenched and operate as fast as possible. A circuit breaker is required to switch off the elements during load conditions and protects the circuit by isolating the main supply during fault conditions.
Key differences between Isolator and Circuit Breaker
- The isolator operates under off-load conditions to isolate the circuit and the Circuit Breaker operates under load conditions to isolate the circuit.
- The operating time of the isolator is slow, the operating time of the isolator is around 14 seconds in 400KV Switchgear, and the operating time of the circuit breaker is very high as compared to the isolator. The operating time of the Circuit breaker is around 25 ms in 400KV Switchgear.
- Isolator used in switchgear for maintenance work of other equipment and transmission lines. Circuit breaker used in switchgear for switch off the element under load condition and protect the system due to any fault.
- Air medium used to operate the isolator and including air medium, SF6 gas, and oil medium are also commonly used in higher voltage circuit breakers for operation.
- The mechanism of the isolator is very simple and it is a low-cost device compared to a Circuit breaker. The mechanism of the circuit breaker is very complex due to fast operation and the cost of the breaker is very high as compared to the isolator.
- A grading capacitor and pre-insertion resistor (PIR) are not required for the isolator. A grading capacitor and pre-insertion resistor (PIR) are required for the operation of the high voltage circuit breaker.