In industrial control or computer control circuits, although there are various interference suppression measures, the interference phenomenon still exists more or less. Relay is usually used in automatic control circuit. It is actually an "automatic switch", which uses smaller current to control larger current. Therefore, it plays the role of automatic regulation, safety protection, switching circuit and so on. There are many types of relays. The finder intermediate relay is shown below.
actuallyFinder intermediate relayIt is a relay. Its principle is the same as that of AC contactor. It is composed of fixed iron core, moving iron core, spring, moving contact, static contact, coil, wiring terminal and shell. When the coil is energized, the moving iron core moves and attracts under the action of electromagnetic force, and the moving contact moves to separate the normally closed contact and close the normally open contact; When the coil is powered off, the moving iron core will bring the moving contact to reset under the action of the spring.
In the control circuit of industrial control circuit, there are often finder intermediate relays. For different control circuits, the functions of intermediate relays are different, and their common functions in the circuit are as follows.
The contact of finder intermediate relay has a certain load capacity. When the load capacity is relatively small, it can be used instead of small contactors, such as the control of electric rolling gate and some small household appliances. The advantage of this is that it can not only achieve the purpose of control, but also save space, but also make the control part of electrical appliances more delicate.
For example, in the circuit control system, when the contact of a contactor needs to control multiple contactors or other components, an intermediate relay is added to the circuit.
We know that although the contact capacity of the intermediate relay is not very large, it also has a certain load capacity, and its driving current is very small, so the finder intermediate relay can be used to expand the contact capacity. For example, the output of induction switch and triode cannot be directly used to control electrical components with large load. Instead, the intermediate relay is used in the control circuit to control other loads through the intermediate relay, so as to expand the control capacity.
In the industrial control circuit, such a situation often occurs, which requires the normally closed contact of the contactor to achieve the control purpose, but the normally closed contact of the contactor itself has been used up, and the control task cannot be completed. At this time, a finder intermediate relay can be connected in parallel on the coil of the original contactor, and the normally closed contact of the intermediate relay can be used to control the corresponding components, change the contact type, and achieve the required control purpose.
In some control circuits, the on-off of some electrical components is often controlled by the finder intermediate relay to open and close its contacts. For example, in the common automatic degaussing circuit in color TV or display, the triode controls the on-off of the intermediate relay, so as to control the on-off effect of the degaussing coil.