4pin relay is generally composed of iron core, coil, armature, contact reed, etc. As long as a certain voltage is applied to both ends of the coil, a certain current will flow in the coil, which will produce electromagnetic effects. Under the action of electromagnetic force, the armature will overcome the pull force of the return spring and attract to the core, thereby driving the armature. The moving contact and the static contact are sucked together. When the coil is de-energized, the electromagnetic attraction will also disappear, and the armature will return to its original position under the reaction force of the spring, releasing the moving contact and the original static contact.

The 4pin relay pulls in and releases in this way, so as to achieve the purpose of conducting and cutting off in the circuit. The "normally open and normally closed" contacts of the relay can be distinguished as follows: the static contact that is in the off state when the coil of the 4pin relay relay is not energized is called "normally open contact"; the static contact that is in the on state The points are called "normally closed contacts". A 4pin relay relay generally has two circuits, a low-voltage control circuit and a high-voltage working circuit. Two pins of 4pin relay85.86 are small current and small magnetic attraction, and the other two pins are connected to high current line.

The pin number arrangement of the 4pin relay is generally a pair of normally open and normally closed contacts with three pins in the shape of a product on one side. The middle is the common point. The multimeter measures that it is connected to one of the other two pins as a normally closed contact, and the non-connected one is a normally open contact; the other two pins are coil pins, and there is a resistance value during measurement.