1. Detection method of AC contactor
The AC contactor is located at the upper level of the thermal protection relay to connect or disconnect the power supply line of the appliance. The main contact of the contactor is connected to the electrical equipment, and the coil is connected to the control switch. If the contactor is damaged, the resistance value of the contact and the coil shall be detected. The diagram shows a typical motor control wiring diagram
Before detection, the terminals of the contactor are identified according to the identification on the contactor housing. According to the identification, terminals 1 and 2 are terminals of phase line L1, terminals 3 and 4 are terminals of phase line 12, terminals 5 and 6 are terminals of phase line L3, terminals 13 and 14 are auxiliary contacts, and A1 and A2 are coil terminals for pin identification.
In order to make the maintenance result accurate, the AC contactor can be removed from the control line, and then after the grouping of the wiring terminal can be judged according to the identification, and the multimeter can be adjusted to the “100″ resistance time to detect the resistance value of the contactor coil. Put the red and black watch pens on the wiring terminal connected to the coil, and under the normal circumstances, the measured resistance value is 1,400 Ω. If the resistance is infinite or the resistance is 0, the contactor is damaged. The figure shows the resistance value of the detection coil
According to the identification of the contactor, both the main contacts and the auxiliary contacts of the contactor are often open contacts. The red and black watch pens are placed on the wiring terminal of any contact point, and the measured resistance value is infinite. The figure shows the resistance value of the detected contacts.
When the lower bar is pressed by hand, the contact will close, the red and black table pens will not move, and the measured resistance becomes 0. Figure shows the resistance value of the contact by pressing the lower bar.
Post time: Jun-09-2023
