Difference between isolator and circuit breakers

Difference between isolator and circuit breakers

Main Difference is: Isolator is an off-load device while, circuit breaker is an on-load device. The isolator is a manually operated switch that disconnects the circuit from the mains and discharges the charges trapped in the circuit. Isolators have low resistance compared to circuit breakers.

Both circuit breakers and circuit breakers are designed like switches and for a high current. However, if you want to break a large current by opening the switch or contact, an arc can form that can damage the switch or contact. The arc can persist between the pole of the switch in the air and so the current continues to flow (with increased losses and of course damage).


Now the circuit breaker is designed to extinguish this arc when the circuit-breaker is operated in various ways, for example with SF6 gas, vacuum or oil. The isolator, on the other hand, is a simple mechanical switch that operates whenever there is no current in the circuit. It is actually intended for works such as maintenance and complete isolation of the component or circuit.

Assuming that line A and line B are to be disconnected, you must first open the circuit breaker, then you can open the circuit breaker, and then the circuit breaker can be used for maintenance. If you want to connect the cables, first close the two isolator and then the circuit breaker.

circuit breakers

List of Difference between Isolator and Circuit Breaker:

  • The isolator is used to isolate the circuit, but can not operate in the load state, whereas the circuit breaker can be operated in the load or idle states, which means that the isolator is an open circuit device while the circuit breaker is a load device.
  • The isolator can not break the faulty circuit if there is a fault while the circuit breaker is used as a protection device and break the circuit under faulty conditions.
  • The isolators are switches with manual action, can be operated manually (in the case of maintenance activities) or automatically (in case of isolation of errors) means Isolator is a manually operated switch, which separates the circuit from the electrical network and discharges the loads trapped in the circuit.
  • The circuit breakers operate automatically, are triggered by the electromechanical mechanism inside and are a safety feature for abnormal loads and voltages in the circuit.
  • C.B. is an electronic device made with the help of MOSFET or BJT. ISOLATOR is a mechanical device that acts as a switch.
  • In the isolator gearbox, three coils are supplied, mainly Open / Trip, Close & Interlock, while in the case of switches, only Open / Trip & Close coils are supplied.
  • The isolator cuts off a portion of a secondary station when a fault has occurred. The other devices work without interruption. The switch is a device known as the Automatic Switch (ACB) or Miniature Switch (MCB), which triggers the entire system if a malfunction occurs and thus the entire system is affected.
  • The isolators have a low resistance capacity compared to the circuit breaker.

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