Isolators are generally used on both side of the circuit breaker, this measure is taken just to ensure extra safety and protection because in power system incoming and outgoing lines can have multiple sources of power and disconnecting one side is sometimes not enough.
According to the power system location, the isolator can be classified into three types namely bus side, line side, and transfer bus side isolator.
The isolator is a switch which isolates the part of the circuit system when it is required. Electrical isolators are the separate part of the system that is created for the safe maintenance. Isolators are generally used at the end of the breaker to repair or to replace.