What Are The Differences Between AC Contactors And Relays?

AC contactors are used for long-distance connection or disconnection of large current loads. Due to the presence of arc extinguishing equipment, their main circuit breaker can connect or disconnect over 100 to several hundred amperes of current. They are generally used to control the start and stop of three-phase asynchronous motors.

Except for operating small loads (generally below 5A), intermediate relays are usually used in power circuits for data signal transmission, data signal protection, and data signal amplification. For example, the output current of a transistor output type PLC is generally only over 100 mAh. If it is immediately used to drive external loads, it may burn out the internal power circuit of the PLC
At this point, it is possible to first drive the intermediate relay, and then use the electric shock accident control of the intermediate relay to manipulate the AC contactor, which has the effect of increasing data signal protection.

The principle of AC contactors and intermediate relays is mostly the same. It is all based on the electrification of the electromagnetic coil, the opening or closing of the circuit breaker, to connect or disconnect the load.
What's different is that AC contactors are mainly used in the main power supply circuit to supply power to loads with high output power such as motors and heating tubes. Due to the power supply system being activated, when the current of the power supply system is disconnected, it will cause electric arcs. In order to avoid electrical short circuits, AC contactors are equipped with arc extinguishing devices.
Intermediate relays are mostly used in control circuits, such as in temperature controllers that output automotive relays. This means that the instrument panel drives the intermediate relay first, while the automotive relay drives large loads such as AC contactors or relays.

In terms of the total number of circuit breakers, the total number of circuit breakers for intermediate relays is therefore higher than the total number of circuit breakers for AC contactors. However, due to the different loads carried, the main circuit breaker for AC contactors is much larger than that of intermediate relays, making AC contactors much more expensive than intermediate relays.
In the natural environment of industrial production, the electromagnetic coils of AC contactors are mostly AC current, while intermediate relays are commonly AC voltage.