What is the need of providing isolator on the supply sides of the circuit breaker?

Answer: the main function of providing isolators on the supply side of circuit breaker is to ensure isolation of the circuit breaker from the live part for the purpose of maintenance.

In simple, If there is a need of maintenance in circuit breaker, first we have to disconnect it from live part and this is done with the help of isolator.

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In Line feeder it must be Isolated for both sides for the purpose of maintenance of the circuit breaker and power line also but in transformer we may find transformer with only bb isolators because when transformer is offline & earthed well there are no need for Q9 for maintenance but if exit it better for safety.

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