Electrical Disconnector

An electrical disconnector, also called a disconnect switch or isolator switch, is a switching device with visible contacts used to ensure that a circuit is completely de-energized for service or maintenance, most often found in electrical distribution networks and high-voltage substations, where it isolates equipment such as circuit breakers, transformers and transmission lines. Unlike a circuit breaker, a disconnector has no mechanism for suppressing the electric arc that forms when current-carrying conductors are mechanically separated, so it is an off-load device with very low breaking capacity meant to be opened only after another device has already interrupted the current, and utility safety rules are built around never opening one while it still carries load. Disconnectors can be operated manually or by motor, are often fitted with lockout-tagout provisions so they cannot be closed inadvertently while people are working on the isolated circuit, and some designs add the further ability to earth the isolated section for extra safety; the international standard IEC 62271-102 defines a disconnector required functionality and features.