Difference Between isolator and circuit breaker

As we know that both isolators and circuit breakers switch to isolate a section of the power system but one point is that the isolator is an offload device while in the circuit breaker in on load device. Let us have a deep insight into what is an isolator and circuit breaker and key difference between them in this article. 

Definition of isolator:

An isolator is just like a switch, only can be operated under offload condition. It mostly used in industry-level applications. It can not protect the circuit under fault conditions. 

Definition of circuit breaker:

A circuit breaker is basically a protecting switch, it can be operated both manually as well as auto, actually. It follows the instruction of protecting devices under various fault conditions such as over current, short circuit, etc.

Difference between isolator and circuit breaker : 

  • The isolator is switch operated manually while the circuit breaker is operated automatically.
  • The isolator is an electronics device made by using MOSFET or BJT while the circuit breaker is a mechanical device that acts as a switch.
  • Isolator has a low withstand capacity as compared to that of the circuit breaker.
  • The isolator is an offload device while the circuit breaker is an on load device.
  • The isolator is meant only for interrupting the power during maintenance or repair while in circuit breaker are meant for protection of a circuit or equipment from short circuit and overload faults while they are in operations.
  • The breaking capacity of isolators is very less compared to the circuit breaker.
  • In isolator protection relay does not require while in circuit breaker protection relay control the breaker.
  • Isolator has a less cost while in circuit breaker has a high cost.
  • In isolator atmospheric air is used as arc quenching medium while in circuit breaker different kinds of a medium are used in typically atmospheric.
  • Isolator has high safety while in circuit breakers need well-trained technicians.
  • Arc quenching medium is used for isolator while in circuit breaker SF6  and vacuum atmospheric air were used.
  • Physical contact status can be seen. since they are necessary during the maintenance process while in the circuit breaker we cannot see the physical condition.
  • Isolator cuts out a portion of a substation when some fault occurred. Some other devices operate without any interruption, but in the circuit breaker know as an automatic circuit breaker which trips the entire system if any fault occurs and thus the whole system is affected.