microswitch

A microswitch is a small electric switch that uses a snap-action mechanism to switch contacts rapidly and reliably when the actuator is operated. It is designed for high durability and precise actuation with low actuation force, making it suitable for position sensing and safety interlocks in a wide range of equipment.

Most microswitches consist of a metal or plastic housing, an internal bistable mechanism, and external actuators such as a small button, a lever, or a roller. The internal mechanism employs a spring and a set of contacts that flip between normally open and normally closed states when the actuator is pressed, producing a fast transition with minimal contact arcing.

Electrical characteristics vary: common configurations are SPST, SPDT, and DPDT, with ratings from around 0.5 to 20 amperes at 125 or 250 volts AC, and lower voltages or DC ratings for signaling purposes. Mechanical life often ranges from hundreds of thousands to several million actuation cycles, depending on load and quality.

There are numerous variants, including subminiature types, lever-actuated, roller-actuated, side-actuated, and waterproof versions. They are widely used in appliances, control panels, safety switches on doors, limit switches in machinery, automotive sensors, and medical equipment.

Manufacturers commonly test microswitches to standards such as UL, CSA, and CE markings. Operating characteristics include actuation force, differential travel, make/break actions, and electrical life, which help select devices for specific applications.