Operation and Maintenance of AC Contactors

    Regular or regular inspection of ac contactor operation and necessary maintenance are important measures to ensure its reliable operation and prolong its life. When inspecting and repairing, the power supply should be disconnected first, and the following steps should be taken.

    1. Appearance inspection to remove dust, cotton cloth can be dipped with a small amount of gasoline to wipe off oil stains, and then dry with cloth; tighten all the screw of pressing wires to prevent loosening and falling off, causing joint heat.

    2. Contact system inspection

    1) Check whether the static and dynamic contacts are aligned, whether the three phases are closed at the same time, and adjust the contact spring to make the three phases consistent.

    2) Measure the value of insulation resistance between phases. With 500V shaker, the phase resistance should not be less than 10 megaohms.

    3) New parts should be replaced when the contact wear thickness exceeds 1 mm, or when the contact is severely burned or the welding is broken off. Slight burning or contact hair or blackening do not affect the use, can not be treated. If contact is affected, small file can be used to polish flat.

    4) After repairing or replacing the contacts, attention should be paid to the distance between the contacts and the overrun. Overtravel of contacts will affect the final pressure of contacts.

    5) Check whether the auxiliary contacts are flexible, whether the static contacts are loose or falling off, contact distance and distance should meet the requirements, and the resistance of contacts can be measured by multimeter. When it is found that the contacts are not good and difficult to repair, new contacts should be replaced.

    3. Maintenance of arc extinguishing hood

    1) Remove the arc extinguishing cover and use the brush to remove the falling objects or metal particles in the cover. If it is found that the arc extinguishing cover is damaged, it should be replaced in time.

    2) For the shield, attention should be paid to whether the shield is complete or deformed due to burning, serious loosening and position change. If it is not easy to repair, it should be replaced.

    4. Maintenance of Electromagnetic Coils

    1) The attraction coil of AC contactor should work reliably when the power supply voltage is 85%-105% of the rated coil voltage.

    2) Check whether the electromagnetic coil is overheated or not. The coil overheating is reflected in the aging and discoloration of the outer layer. The coil overheating is usually caused by the inter-turn short circuit. At this time, the resistance of the coil can be measured and compared with the same kind of coil. If it cannot be repaired, it should be replaced.

    3) Whether the lead and wiping parts are open-welded or will be disconnected.

    4) Whether the coil skeleton is cracked, worn or immobilized abnormally. If found, it should be fixed or replaced as soon as possible.

    5. Maintenance of Iron Core

    1) Wipe the end surface with cotton yarn and gasoline to remove grease or dust.

    2) Check whether the buffers are complete and the positions are correct.

    3) whether the rivet is broken or not, resulting in loose end face of iron core;

    4) Whether or not the short-circuit ring has fallen off or broken, special attention should be paid to cracks. If there is breakage or serious noise, the short circuit ring or iron core should be replaced.

    5) Check whether the electromagnet is well absorbed and whether there is any dislocation.