Disconnect Switch (Isolator)

A manually- or motor-operated switching device that provides visible air-gap electrical isolation of a section of the power system for maintenance, but which can only be operated with negligible current — it cannot interrupt load current or fault current. Disconnect switches are always opened and closed with the associated circuit breaker first placed in the open position to ensure no current flows. Visible open contacts are required by safety procedures before crews are allowed on de-energized equipment. They come in vertical break, horizontal break (double-end), pantograph, and rotary designs.

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