How to Judge The Model of AC Contactor?

Figure 1: Judging the model of AC Contactor.

Contactor is the most basic and common electrical component in relay control system. It is mainly used to connect and disconnect lines, or frequently control the operation of motors and other equipment. It is an intermediate control element. Its advantage is that it can connect or disconnect lines frequently by controlling large current or large voltage with small current or small voltage. In addition to the motor, the control objects of the contactor also include electric loads, such as electric heater, electric welding machine, lighting equipment and so on.

1. Method

So when we do electrical engineering or automation projects, how to correctly select AC contactors is very important. If we want to choose AC contactor correctly, we must first understand the model and performance parameters of the contactor. Now I will take the AC contactor as an example to introduce the model and performance parameters of the contactor.

For example, the AC contactor CJX2H-1811 shown in the figure below. Where C represents the contactor, J represents AC, X2H represents the product series code, 18 represents the rated working current of the main contact, 11 represents that it has a group of normally open contacts and a group of closed contacts. And if the last two digits are 10, it means a group of normally open contacts and no normally closed contacts. It's useful to identify it in this way. Normally open contact is NO and normally closed contact is NC, which is generally marked on it. As shown in the figure, terminals 13 and 14 are normally open contacts, and terminals 21 and 22 are normally closed contacts. If you don't understand the meaning of NO / NC, you can also distinguish whether it is normally closed or normally closed by recording the tail number of the number. Generally, the tail numbers of the number 3 and 4 means normally open contacts, and the tail numbers of 1 and 2 means normally closed contacts.

Figure 2: Contactor CJX2H-1811.

For the following high current AC contactor, the model is CJX2H-120. Since it is a high current, 120 represents that the rated working current of the main contact is 120A. From the front, there is no auxiliary contact. The model is also different from that mentioned above. Does it have no auxiliary contact? Of course no, the fact is that the AC contactor can expand the auxiliary contacts on both sides of it.

Figure 3: The contacts of Contactor CJX2H-1811.

The figure below shows the auxiliary contact of the contactor. The model of the auxiliary contact is FC6s-11, in which 11 also indicates that it has a group of normally open contact and a group of normally closed contacts. In the figure, terminals 153 and 154 are normally open contacts, terminals 161 and 162 are normally closed contacts. Contacts with tail numbers 3 or 4 are normally open contacts, and contacts with tail number 1 and 2 are normally closed contacts. Of course, if auxiliary contacts are extended on both sides, there will be two groups of normally open and two groups of normally closed contacts.

Figure 4: The auxiliary contacts of Contactor CJX2H-1811.

2. Matter

In addition, we can also see some performance parameters from the product focusing on the control voltage of the coil and the rated current of the auxiliary contact. Please pay special attention to the level of the control voltage when you use it.

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