What is the role of the intermediate relay

Update:04-11-2021
The intermediate relay is a relay. Its principle is the same as that of an AC contactor. It is composed of a fixed iron core, a moving iron core, a spring, a moving contact, a static contact, a coil, a terminal and a shell. When the coil is energized, the moving iron core acts to pull in under the action of electromagnetic force, driving the moving contact to move, so that the normally closed contact is separated and the normally open contact is closed; the coil is de-energized, and the moving iron core drives the moving contact under the action of the spring Reset.
In the industrial control circuit and the current household appliance control circuit, there are often intermediate relays. For different control circuits, the role of the intermediate relay is different. The common functions of the intermediate relay in the circuit are as follows.
1. Replace small contactors
The contact of the intermediate relay has a certain load capacity. When the load capacity is relatively small, it can be used to replace small contactors, such as the control of electric rolling gates and some small household appliances. The advantage of this is that it can not only achieve the purpose of control, but also save space and make the control part of the electrical appliance more delicate.
2. Increase the number of contacts
This is the most common use of intermediate relays. For example, when the contact of a contactor in a circuit control system needs to control multiple contactors or other components, an intermediate relay is added to the circuit.
3. Increase contact capacity
We know that although the contact capacity of the intermediate relay is not very large, it also has a certain load capacity, and the current required for its drive is very small, so the intermediate relay can be used to expand the contact capacity. For example, it is generally not possible to directly use the output of induction switches and triodes to control electrical components with a relatively large load. Instead, an intermediate relay is used in the control circuit to control other loads through the intermediate relay to achieve the purpose of expanding the control capacity.
4. Conversion contact type
In industrial control circuits, such a situation often occurs. The control requires the use of the normally closed contacts of the contactor to achieve the control purpose, but the normally closed contacts of the contactor itself have been used up and the control task cannot be completed. At this time, an intermediate relay can be connected in parallel with the original contactor coil, and the normally closed contact of the intermediate relay can be used to control the corresponding component, and the contact type can be changed to achieve the required control purpose.
5. Used as a switch
In some control circuits, the on and off of some electrical components often use intermediate relays, which are controlled by the opening and closing of their contacts, such as automatic degaussing circuits commonly seen in color TVs or displays. The role of the coil on and off.
6. Conversion voltage
7. Eliminate interference in the circuit
In industrial control or computer control circuits, although there are various interference suppression measures, the interference phenomenon still exists more or less.
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