Acceleration and Suppression Factors for Contact Failure due to Silicone Contamination

Silicone vapor contamination is very serious problem to be solved for degradation of electrical contacts. It was clarified by the author that adsorbed silicone vapor molecules decompose to SiO₂ under elevated temperature. For make-break contacts, heat sources of decomposition of the molecules are molten metallic bridges and arc discharges. In this paper, in order to clarify acceleration and suppression factors for electrical contact life in the silicone vapor environment, the silicone contaminated atmospheric environmental including humidity, nitrogen (N₂), ozone (O₃), and amine were examined respectively under low electrical conditions of metallic bridge and micro arc regions. The N₂ environment with the silicone showed no effect on the improvement for the life of contact. However, humid, O₃, amine environment with the silicone showed suppression effect for the silicone contamination. In these environments, switching operation of the contacts was prolonged for the contact failure due to high level contact resistance. These results were compared with normal air environment contained the silicone vapor. The concentration of the silicone vapor was the key factor to determine the resistance failure and this concentration changes differently under different testing environments.