The difference between intermediate relay and AC contactor

The intermediate relay is a kind of relay product that we usually use. It is widely used. In the place where the relay is used, the intermediate relay is used. It is mainly used in relay protection and automatic control systems to increase the number and capacity of contacts.

When using intermediate relays, we often encounter contactors, whose functions and uses are almost identical to those of intermediate relays. So what is the difference between them?

The structure and principle of the intermediate relay are basically the same as those of the AC contactor. The main difference with the contactor is that the main contact of the contactor can pass a large current, and the contact of the intermediate relay can only pass a small current. Therefore, it can only be used in control circuits. It generally has no main contacts because the overload capability is relatively small. So it uses all the auxiliary contacts, the number is more. The new national standard defines the intermediate relay as K, and the old national standard is KA.

The intermediate relay can be used as a protection or as an automatic device control to increase the number and capacity of contacts of the protected control circuit and to increase the control range and control capability. However, in the face of complicated and modern electrical products, how to properly select and use them correctly is a practical problem that controls the operation of the system and the management personnel pay close attention to and must be preferably solved. Due to the limitation of the work place of my unit, the particularity of the power system automation device during operation is enhanced. In order to make a reasonable choice and use correctly, it is necessary to fully analyze the corresponding actual use conditions and actual technical parameters of the control system, and appropriately propose the selection of intermediate relays to meet the technical performance requirements that must be achieved.