Effect of Dust Contamination on Electrical Contact Failure

Dust contamination is a major cause of current disruption in electric contacts. It is fast becoming the greatest influence on their reliability. However, due to its complexity, the effect of dust is difficult to simulate in the laboratory; and effective ways to reduce the failure caused by the fine dust particles on contacts still present a difficult and unsolved research problem. Based on the inspection of failed electric contacts, and also on the study of the characteristics of dust particles, this paper describes the composition of the materials in dust, and also the mechanical, electrical, and chemical characteristics of the particles. The conditions required for the dust to cause contact failure are discussed: in particular the effect of micro motion at the contact interface; the selective deposition of dust particles; the adhesion between particles; the chemical and electrostatic attachment of particles to the contact surface; and the creation of high resistance due to particle accumulation.