1)Expand the control range: for example, multi-contact relay control signal reaches a certain value, you can according to the different forms of the contact group, at the same time switching, open and close the multi-channel circuit.
2) amplification: for example, sensitive relays, intermediate relays, etc., with a very small amount of control, you can control a very high power circuit.
3) synthesize signals: for example, when multiple control signals are fed into a multi-winding relay in a specified form, they are compared and synthesized to achieve a predetermined control effect.
4) Automatic, remote control, monitoring: for example, the relay on the automatic device together with other electrical appliances, can be formed into a program control line, so as to achieve automated operation.