How to Use the AC Contactor?

Low voltage control high voltage is very common in electrical work. The purpose has two, one is to ensure that people can effectively control the use of equipment in the safe voltage range, the other is to be compatible with the low-voltage control system (such as PLC, SCM equipment). ATO.com will use examples to tell you how to control contactor with relay (safety voltage 24VDC control danger voltage 220VAC).

The main components need to be used are: circuit breaker, AC contactor, micro relay, VFD.

The contactor of CJX2 series AC Contactor we are going to use is type 4NO, type 3NO and type 2NO+2NC. The main contact point has different performance in 220V~660V. The control coil voltage is 110VAC, 220VAC, 24VAC and 24VDC, and the 220VAC is used this time.

The control principle is: use 24VDC relay to connect 220VAC contactor coil, make the armature of contactor pull, the main contact close to connect the main circuit. (KA is relay, KM is contactor)

It can be seen from the schematic diagram that the control circuit is in an isolated state from the main circuit, the control circuit is 24VDC safe voltage, and the main circuit is controlled by the normally open contact of KA. Therefore, we can control the whole circuit by setting a switch SB in the control circuit.
The following is the physical picture after the wiring is completed. This type of electric cabinet is very common. The right side is the control circuit part, and the left side is the main circuit part.

After power-on, press the control circuit switch SB, it can be clearly found that the contactor is pulled in, the main circuit is also connected, and the VFD is powered on.

The above is a classic example of low voltage controlling high voltage (safe voltage controlling dangerous voltage), detailed steps can also be viewed on our YouTube channel: