Locking refers to "self-locking", which automatically locks its state after the relay is energized and keeps the loop connected. Even if the control current is turned off at this time, its state will not be changed. That is to say, when the power is turned on and the control current is turned off, it will continue to be in the on state unless the unlock button is pressed.

Latching type relay: It can be divided into 1-coil latching type and 2-coil latching type.

(1) 1-coil latching relay: the coil is energized and the contact is activated; the coil is de-energized, and the contact remains in the previous state. Only when a reverse voltage is applied to the coil, the contact is reset.

(2) 2-coil lock type relay: when the setting coil is energized, the contact will act; when the coil is de-energized, the contact will remain in the previous state. Only when the reset coil is energized will the contact be reset.

The role of the relay

(1) Expand the control range: For example, when the control signal of a multi-contact relay reaches a certain value, multiple circuits can be switched, disconnected, and connected at the same time according to different forms of contact groups.

(2) Amplification: For example, sensitive relays, intermediate relays, etc., with a very small control quantity, can control a high-power circuit.

(3) Integrated signal: For example, when multiple control signals are input to a multi-winding relay in a prescribed form, they will be relatively integrated to achieve a predetermined control effect.

(4) Automatic, remote control, and monitoring: For example, the relay on the automatic device and other electrical appliances can form a program control circuit to realize automatic operation.