From the picture above, you can see that the relay is generally composed of an iron core, coil, armature, contact reed and so on. After connecting the power supply, it will produce electromagnetic effect, the electromagnetic force will attract the armature, let it contact the iron core, drive the armature of the normally closed contacts and normally open contacts suction, after the current is cut off, the electromagnetic suction is also gone, the armature will return to its original position, the circuit will be cut off.
The role of the relay is mainly amplified, with a very small current, you can control a very high power circuit, but also to expand the control range, in the signal reaches a certain value, according to the different forms of contact groups, at the same time, switching, disconnecting, connecting multiple circuits, to achieve the purpose of automatic switching.
In addition to the above functions, the role of the relay there are many, it can be composed with other electrical appliances together with the program control line to achieve automated operation, at the same time, it will be the signal synthesis, you can pass through the relay of the multiple control signals integrated, to achieve the intended control effect.
Principle of operation;
When the input quantity (e.g., voltage, current, temperature, etc.) reaches a specified value, the electrical appliances that make the output circuit to be controlled on or off. Can be divided into electrical quantity (such as current, voltage, frequency, power, etc.) relay and non-electrical quantity (such as temperature, pressure, speed, etc.) relay two categories. It has the advantages of fast action, stable work, long service life, small size and so on. Widely used in electric power protection, automation, motion, remote control, measurement and communication devices.
Relay is an electronic control device, it has a control system (also known as the input circuit) and the control system (also known as the output circuit), usually used in automatic control circuits, it is in fact a smaller current to control a larger current of an "automatic switch". Therefore, in the circuit plays a role in automatic regulation, safety protection, conversion circuit.