How to solve the problem of unreliable contact of the contacts of the contactor

Unreliable contact of the contacts of the contactor will increase the contact resistance between the dynamic and static contacts, resulting in excessive temperature of the contact surface, making the surface contact into point contact, and even non-conduction.
1. The reasons for this failure are:
(1) There are oil stains, hairs and foreign objects on the contacts.
(2) After long-term use, the surface of the contact is oxidized.
(3) Arc ablation causes defects, burrs or forms metal shavings particles, etc.
(4) There is jamming in the moving part.
Second, the troubleshooting methods are:
(1) For oil stains, lint or foreign objects on the contacts, you can wipe them with cotton cloth dipped in alcohol or gasoline.
(2) If it is a silver or silver-based alloy contact, when an oxide layer is formed on the contact surface or a slight burn and blackening are formed under the action of an arc, it generally does not affect the work. It can be scrubbed with alcohol and gasoline or carbon tetrachloride solution. Even if the surface of the contact is burned uneven, you can only use a fine file to remove splashes or burrs around it. Do not file too much, so as not to affect the life of the contact.
For copper contacts, if the degree of burn is relatively light, you only need to use a fine file to repair the unevenness, but it is not allowed to use fine emery cloth to polish, so as not to keep the quartz sand between the contacts, and can not maintain good contact; If the burn is serious and the contact surface is lowered, the contact must be replaced with a new one.
(3)If there is jamming in the moving part, it can be disassembled for maintenance.