Contact instability will make the contact resistance between the static and dynamic contacts increased, make the surface temperature to be too high, make the surface contact becoming the point contact, and even occur the non-conducting phenomenon. The cause of this failure:
1. Oily, floral and foreign objects are on the contact head.
2. Long-term use, contact surface oxidation.
3. Arc ablation cause the defects, burrs or the formation of metal particles, etc.
4. The part movement part has the card resistance phenomenon.
The processing methods are:
1. For oily, floral or foreign objects on the contact head, you can use cotton cloth dipped in alcohol or gasoline to scrub.
2. If it is silver or silver base alloy contact, in the arc action, the formation of oxide layer in the contact surface maybe will form a slight burn and turn black, generally won’t affect the work, can be scrubbed by alcohol and gasoline or carbon tetrachloride solution.
Even if the contact surface is burned uneven, you can only use a fine file to clear around the bead or burr, do not file and repair too much, so as not to affect the contact life.
3. The movement part has the card resistance phenomenon, may overhaul it.