How electromagnetic relays work

The working principle of electromagnetic relaysElectromagnetic relays are generally composed of iron cores, coils, armatures, contact reeds, etc. As long as a certain voltage is added to both ends of the first circle, a certain current will flow through the coil, resulting in an electromagnetic effect, and the armature will overcome the tensile force of the return spring under the action of electromagnetic force attraction to attract the core, thereby driving the dynamic contact of the armature to engage with the static contact (normally open contact). When the coil is de-energized, the electromagnetic suction force disappears, and the armature returns to its original position under the reaction force of the spring, so that the moving contact engages with the original static contact (normally closed contact).

In this way, it is engaged and released, so as to achieve the purpose of conduction and cutting in the circuit. For the "normally open, normally closed" contacts of relays, they can be distinguished as follows: the static contacts that are in the open state when the relay coil is not energized are called "normally open contacts"; Static contacts that are turned on are called "normally closed contacts".

The role of the relay: The relay has an interactive relationship between the control system (also known as the input loop) and the controlled system (also known as the output loop). Usually used in the control circuit of automation, it is actually a kind of "automatic switch" that uses a small current to control the operation of a large current. Therefore, it plays the role of automatic adjustment, safety protection, and conversion circuit in the circuit.

Technical parameters of the relay 1, rated working voltage.

It refers to the voltage required by the coil when the relay is working normally. Depending on the model of the relay, it can be either AC voltage or DC voltage.

2. Suction current.

It refers to the minimum current that the relay can produce a pick-up action. In normal use, the given current must be slightly greater than the pick-up current in order for the relay to work stably. For the working voltage added to the coil, generally do not exceed the times of the rated working voltage, otherwise a large current will be generated and the coil will be burned.

3. DC resistance.

It refers to the DC resistance of the coil in the relay, which can be measured by a universal meter.

4. Release the current.

It refers to the maximum current that the relay produces a release action. When the current in the relay engagement state decreases to a certain level, the relay returns to the unenergized release state. The current is much smaller than the pick-up current.

5. Contact switching voltage and current.

Refers to the voltage and current that the relay is allowed to load. It determines the size of the voltage and current that the relay can control, and it cannot exceed this value when used, otherwise it is easy to damage the contacts of the relay. -

Principles and application circuits of electromagnetic relays.