Isolators are electrical switches used to completely de-energize circuits for service or maintenance of machinery. They are commonly found in electrical distribution systems and industrial applications where power must be removed for equipment adjustment or repair. High-voltage isolation switches in substations allow circuit breakers, transformers, and transmission lines to be isolated for maintenance, and function as a second master switch that can independently disable a circuit even if the primary switch is turned on.

1. Isolators
In electrical engineering, a disconnector or isolator switch or disconnect switch
is used to make sure that an electrical circuit can be completely de-energised
for service or maintenance. Such switches are often found in electrical
distribution and industrial applications where machinery must have its source
of driving power removed for adjustment or repair.High-voltage isolation
switches are used in electrical substations to allow isolation of apparatus such
as circuit breakers and transformers, and transmission lines, for maintenance.
Often the isolation switch is not intended for normal control of the circuit and
is used only for isolation; in such a case, it functions as a second, usually
physically distant master switch (wired in series with the primary one) that can
independently disable the circuit even if the master switch used in everyday
operation is turned on.