1. Selection:
(1) The rated current of the main circuit contact shall be greater than or equal to the rated current of the controlled device. The motor contactor of the control motor shall also take into account the starting current of the motor. In order to prevent the frequent operation of the motor contactor main contact ablation, frequent action of the motor contactor rated current can be reduced use.
(2) The electromagnetic coil voltage of electrical ac contactor is 36V, 110V, 220V, 380V and so on. The electromagnetic coil is allowed to use within the range of 80% ~ 105% of the rated voltage.
2. Operation and maintenance:
(1) Check items in operation:
1) Whether the load current is within the electrical ac contactor rating;
2) The splitter signal of the electrical ac contactor indicates whether the circuit status is consistent;
3) Whether the normal operation of the sound, whether due to poor contact with the discharge sound;
4) Whether the electromagnetic coil overheating, electromagnet short-circuit whether the abnormal.
5) Whether the release of arcing and damage;
6) Auxiliary contact with or without burning situation;
7) Whether the transmission part of the damage;
8) Around the operating environment with or without adverse factors, such as vibration is too large, poor ventilation, dust and so on.
(2) Maintenance:
In the electrical equipment for maintenance work, should be carried out on the contactor maintenance work.
1) External maintenance:
a. Cleaning external dust;
b. Check whether the fasteners are loose, especially the conductor connection part, to prevent loose contact and heat;
2) Contact system maintenance:
a. Check the dynamic and static contact position is correct, three-phase is closed at the same time, if the problem should be adjusted contact spring;
b. Check the degree of contact wear, wear depth of not more than 1mm, the contact has burned, open welding off when the need to be replaced; a slight burning, the general does not affect the use. Clean the contacts do not allow the use of sandpaper, should use plastic file;
c. Measuring interphase insulation resistance, the resistance of not less than 10MΩ;
d. Check the auxiliary contact action is flexible, contact travel should meet the specified value, check whether the loose contact off, find the problem, should be promptly repaired or replaced.
3) core part of the maintenance:
a. Cleaning dust, especially moving parts and iron suction contact between the surface;
b. Check the core of the tightening of the situation, loose core will cause the operation to increase the noise;
c. Core short circuit ring off or broken to be timely repair.
4) Electromagnetic coil maintenance:
a. Measuring coil insulation resistance;
b. Coil insulation with or without discoloration, aging phenomenon, the coil surface temperature should not exceed 65 ℃;
c. Check the coil lead connection, if open welding, burning should be timely repair.
5) Part of the arc cover maintenance:
a. Check the arc cover is damaged;
b. Whether or not the position of arc extinguishing cover is loosened or changed;
c. Clear the metal particles and debris in the gap of the arc hood.