A bistable relay, also known as a latching relay, is a type of electromagnetic switch that retains its position even after the control signal is removed. Unlike traditional relays, which require continuous power to maintain their state, bistable relays can hold their state—either open or closed—without needing a constant current. This feature makes them particularly useful in energy-efficient applications where minimizing power consumption is essential.

Principles of Operation The core principle behind a bistable relay lies in its ability to “latch” or “lock” into one of two positions (normally open or normally closed) once actuated, using minimal or no power to maintain that position. The relay consists of two stable states: a “set” state and a “reset” state. In a bistable relay, these two states are achieved through the use of permanent magnets, electromagnetic coils, or a combination of both. When a pulse is applied to the relay, it activates an internal mechanism that shifts the relay into one state. Once the relay has shifted, the internal mechanism “latches” into place, meaning the relay will stay in that position without requiring additional power. To change the state, another pulse is sent, which causes the relay to shift to the opposite position. This on-demand switching makes the bistable relay an efficient solution for applications requiring intermittent switching.