Contactor is a more common electrical component, which is ubiquitous to welders. AC contactor grasp for every beginner welder is particularly important, after the circuit diagram is not to understand, analysis of circuit diagram and the use of circuit diagram is very important. It's basically a top priority.

AC contactor sometimes wrong operation, or in bad environment application, will also reduce the service life of the contactor, resulting in common faults, it is easy to lead to common faults machine equipment and safety accidents. Normally open and normally closed connection of AC contactor is also particularly important. Today's network is compiled for everyone to share normally open and normally closed connection of AC contactor.

Structure of AC contactor, normally open and normally closed connection

1. 3 and 5 connected to three-phase power supply (part of main power supply circuit)

2. 4, 6 connected to three-phase motor

A1 and A2 are the coils of the contactor, which are received in the control circuit. According to the operation of the coils (A1 and A2) of the contactor, a part of the motor in the power supply circuit is controlled (small control large control).

13. 14 indicates the auxiliary contact of the contactor, no indicates that it is normally open, that is, 13 and 14 are disconnected when the power supply is not connected, and 13 and 14 are closed when the power supply is connected. Put a part of the control circuit with the source lock (in series on the start button), to achieve the purpose of continuous operation.

Normally open and normally closed connection method of AC contactor

After the AC contactor coil is connected to the power supply, it pulls in the internal rod, and the other end of the rod is the normally open (closed) contact. When the lever is pulled in, the other end of the lever will tilt up, causing the original contact to break now and the original contact to close now.

It is often said that the originally connected contact is normally closed (when the coil is not connected to the power supply, it is closed); the originally broken contact is normally open (when the coil is not connected to the power supply, it is broken).

In this way, it is not difficult to understand the open contact - when the wiring coil is not connected to the power supply, the normally closed contact can break at the normally open contact according to the amount of current (it can be understood as the power switch); when the contactor coil is connected to the power supply, the normally closed contact breaks and the normally open contact closes, which is the working characteristic of the contactor.

The functions of these four contacts are different. No must be connected in the control circuit, while L1, L2 and L3 are connected in the main control circuit.