It is mainly composed of iron core coils, armature (moving iron core), tension spring, moving contacts, stationary contacts, and some terminals. Static contacts include normally closed contacts and normally open contacts. Under normal circumstances, the moving contact is closed to a normally closed contact. The relay base assembly only needs to apply relative voltage to both ends of the line, and the relative current will flow through the coil, generating electromagnetic effects. The armature will absorb the restoring force of the tension spring against the tension spring core under the effect of electromagnetic force suction bow, and then drive the motion. Separate the contacts from the normally closed contacts and connect them to the normally open contacts. When the coil is powered off, the electromagnetic attraction also disappears, and the armature returns to its original position under the reactive force of the tension spring, causing the movable contact and normally closed contact to return to closure and separate from the normally open contact.

It can be seen that the relay coil base combination can be easily controlled by the touch group to open or close the controlled circuit through the power on and power-off of the electromagnetic relay. Because there is no electrical connection between the working current passing through the coil and the contacts, the control circuit is separated from the controlled circuit by resistance.

Regarding each contact of the electromagnetic relay: when the coil is not energized, the contact in the open state is the "normally open contact", while the contact in the conducting state is the "normally closed contact".

The working principle of PCB relay can be further explained through the experimental circuit shown in the figure below: when the switch SA is disconnected, no current flows through the coil of the electromagnetic relay, and no magnetic field is generated in the coil. The electromagnetic relay is in the "open" state, usually opening the contact and closing the normally closed contact. The bulb H1 does not light up and H2 opens. When switch SA is closed, current flows through the coil of the electromagnetic relay, which generates a magnetic field. The internal armature is attracted, causing the electromagnetic relay to be in the "electromagnetic relay" suction gauge "state,

The normally open contact is closed, and the normally closed contact is opened. As a result, bulb H1 lights up and H2 closes. It can be seen that electromagnetic relay is a device that uses electromagnetic principles to control the opening and closing of touch switches. It generally uses circuits to control another circuit, which is also the origin of the term 'relay'.

Article source: Electromagnetic relay manufacturer www.jxzhongxuan.com