A latching relay is an electric switch that keeps its position without power using the polarization of perpetual magnets. It contains an electromagnet and a perpetual magnet in interaction, serving for the control of removable contacts. Unlike regular relays, which reset with a spring in case power is cut off, latching relays use perpetual magnets to hold their position even when power is off. This characteristic makes magnetic holding relays very useful in applications where the state of the circuit needs to be maintained, such as holding a door lock open or closed after a power failure.

The principle of operation of a magnetically held relay is relatively simple: when a coil is energized, the resulting magnetic field combines with the magnetic field of a permanent magnet to push a contact closed or open. Once the contact reaches the set position, the permanent magnet will keep the position of the contact unchanged even if the coil is de-energized. To change the state of the contacts, they need to be energized again and the opposite magnetic field applied.

Advantages of these relays include low power consumption, high reliability, and long life. Since they do not require a constant current to maintain the state, they excel in energy conservation. In addition, since there is less switching action of the contacts, wear and tear is reduced accordingly, thus extending the life of the relay.

They are applied in industrial automation, home appliances, and security systems. For example, in fire protection, they keep essential doors open in emergencies even if power is lost. Their capability to hold position without power makes them crucial in electronic engineering, offering reliable switching for many applications.
In conclusion, magnetic retention relays play an important role in the field of electronic engineering with their unique retention capability, providing stable and reliable switching solutions for a variety of applications.