Disconnecting Switch

Disconnecting Switch

A disconnecting switch (or disconnector) is a switching device that, when in the open position, has a specified insulation distance between its contacts and a clear disconnection mark; when in the closed position, it can carry current under normal circuit conditions and current under abnormal conditions (such as short circuits) for a specified time.

A disconnecting switch (commonly known as a “knife switch”) generally refers to a high-voltage disconnecting switch, that is, a disconnecting switch with a rated voltage of 1kV and above. It is often simply called a disconnecting switch and is the most widely used electrical appliance in high-voltage switchgear. Its working principle and structure are relatively simple, but due to its large usage and high reliability requirements, it has a significant impact on the design, construction, and safe operation of substations and power plants. The main characteristic of a disconnecting switch is that it has no arc-extinguishing capability and can only open and close circuits when there is no load current. Disconnecting switches are used at various voltage levels to change circuit connections or isolate lines or equipment from the power supply. It has no interrupting current capability; the line must be disconnected by other equipment before operation. It generally has an interlocking device to prevent accidental operation when the switch is under load, and sometimes a pin is needed to prevent the switch from opening under the magnetic force of a large fault.