Relays are electromechanical devices that control the voltage of switches. Latching relays send volts to a coil that runs the relay. Unlike other relays, a latching relay does not need unbroken voltage. Taking away the voltage does not place the relay back in its first position. It takes another force action to force it back, such as another operation or a mechanical reset. Other types of relays will return to their original position once the current is removed. The fact that the switch stays in position after a pulse moves means that the need for electricity is reduced, making it a great method for saving energy.
There is a small metal strip on a latching relay that is used to rotate between the two terminals. The switch is either connected to a magnet or it is magnetized. Two small wire coils called solenoids are on the sides of the magnet. There is an input for the switch along with two outputs at the terminals. The switch is used to turn on the single circuit or turn it off. This is called a single coil latching relay. A current is passed through in a single direction to latch, and it is released by swapping the current in the opposite direction. A latching relay can also control the power between the two separate circuits. This is known as double coil latching because it uses both coils. The current in one coil latches the switch, and the circuit in another coil moves it back again.
The latching relay is controlled by the two wire coils that are attached to it. A magnetic field is created when the electric current is sent into the coils. The magnetic field is turned off when the coils also turn off. The magnetic strip is balanced between the two wire coils, which means that it is affected by the magnetic field that they generate. Electricity moves through the coils when it is generated by the circuit, and the switch is moved from one side to another. Another magnetic pulse is needed to move the switch back to its original position.