Latching Relay is a relay that is set (ON) or reset (OFF) by the input of a pulse voltage. Even after the input voltage is interrupted, this relay maintains its set or reset condition until it receives the next inverting input. It is also called a keep relay.

There are two types of mechanisms for maintaining the set and reset conditions:

a magnetic holding type and a mechanical holding type.

There are also two types of coils for applying the set and reset pulse voltages:

a single-winding type and a double-winding type.

Basic Operation:

Item	Basic circuit	Operation pattern	Outline
Classification
Double- winding Latching Relays			In these Relays, the input pulse of the set coil causes the operating condition to be maintained magnetically or mechanically, whereas the input pulse to the reset coil side puts the Relay into the reset condition.
Single- winding Latching Relays			In these Relays, the set input pulse causes the operating condition to be maintained magnetically, whereas the reset input pulse (input with inverse polarity of set input) puts the Relay into the reset condition.