AC contactor is an electrical component that many electricians are familiar with. Electrical engineers need to be very clear about the principle, function and use of AC contactor, but it is not so simple for some technicians who have just started to learn electrical technology. It may be very difficult for them.

Today we will focus on the AC contactor, fully unlock the AC contactor, to do a basic knowledge literacy:

1、 There are three properties of AC contactor

1. AC contactor coil. Coils are usually marked with A1 and A2, which can be simply divided into AC contactor and DC contactor. We often use AC contactor, among which 220 / 380V is the most commonly used

2. Main contact of AC contactor. L1-L2-L3 is connected with three-phase power incoming line, t1-t2-t3 is connected with power outlet, which can be used to connect load line. The main contacts of AC contactor are normally open contacts, which are mainly connected in the main circuit to control the start and stop of motor and other equipment!

3. Auxiliary contact of AC contactor. The auxiliary contact can be divided into no and NC.

3-1 normally open point No. in general, normally open point no is mainly used for contactor self-locking control and transmission of operation signal. For example, the normally open point no of AC contactor is connected with a red indicator light, which can be used as the running indicator of motor. When AC contactor is powered on, normally open point no is closed and indicator light is connected to transmit operation signal of motor or circuit.

3-2, NC of AC contactor. Normally closed point NC of AC contactor is mainly used for circuit interlock and signal transmission.

For example: the positive and reverse control circuit of motor is to use the interlock function of NC contactor.

For example, a green indicator is connected to the NC of the AC contactor, which can be used as the stop indication of the circuit or motor. When the AC contactor is powered on, the NC of the normally closed point is disconnected, the stop indicator is off, and the corresponding operation indicator is on, and the circuit is running.

2、 After knowing the three external properties of AC contactor, we can take a simple look at the interior of AC contactor

1、 The main parts of AC contactor are coil, iron core, return spring, contact system and armature.

1. Briefly understand the armature of AC contactor. The armature is connected with the contact system. When the armature moves up and down, the contact will change accordingly, for example, the normally open point no is closed, the normally closed point NC is disconnected, and so on!

2. Other important parts: iron core, coil and return spring! Let's have a brief understanding:

Let's use the most understandable language to explain the working principle of AC contactor:

Before the AC contactor is electrified: the coil is not electrified, the iron core has no electromagnetic attraction, the armature will not move, and the spring force remains normal. At this time, the normally open point no is off, and the normally closed point NC is on, which is normal.

After the AC contactor is powered on: when the coil is powered on, the iron core generates electromagnetic attraction, which can overcome the elasticity of the return spring and pull the armature to move downward. At this time, the contact system will change: no at the normally open point is closed, and NC at the normally closed point is open. This is the most basic contactor control. The contact indirectly controls the circuit by the on-off change of the contact!

After the AC contactor loses power or is cut off, the coil is not electrified, and the iron core has no electromagnetic attraction. At this time, the spring force of the return spring drives the armature to reset, and the armature pops up. At this time, the armature drives the contact system of the AC contactor to move and return to the original state: the normally open point no is disconnected, and the normally closed point NC is closed and connected.