Kinetic model of contact resistance increment of electromagnetic relay in storage

Electromagnetic relay's contact resistance overstepped standard is the main failure model in storage. The growth of surface insulating film is influenced by the anion diffusion in contacts. And the growth of surface insulating film is the main reason of contact resistance increment. The ingression mechanism of pure metal contacts surface corrosion film is analyzed. A model, based on diffusion mechanism is derived for contact resistance increasing in a contact material of electromagnetic relays as a function of contact stress, voltage drop across the contacts area and temperature. A kinetic model for evaluating the contact resistance increasing in contact spots of normal close contacts is described. The results show that there is good agreement tendency between the experimental data as reported by different authors in the literature. Finally, the results of calculation and experiment are compared and the validity of the kinetic model presented is verified. And, these studies provide the new ideas and reference for prediction of contacts storage life.