A bistable relay, also known as a latching relay or bi-stable relay, is a type of electromagnetic relay designed to switch between two stable states without the need for continuous power. Unlike conventional relays, which require a constant current to maintain a given state, bistable relays only use energy when changing states. This fundamental characteristic makes them an essential component in many energy-saving and low-power applications.

How Does a Bistable Relay Work? A bistable relay operates based on the principle of magnetic forces and can be switched between two positions (ON or OFF) using minimal energy. The relay is built with two electromagnets or a permanent magnet to hold the contact in either of the two stable states. When an electrical pulse is applied to one of the coils, the relay shifts to one state (e.g., “ON”), and when a pulse is applied to the second coil, the relay switches back to the other state (e.g., “OFF”). What differentiates bistable relays from traditional relays is their ability to maintain the state without needing continuous current. After being switched to a particular position, they will remain in that position until a new pulse is sent to change the state. This unique feature allows bistable relays to be ideal for applications where power conservation is important.