Mechanical and Electrical Characteristics of the Electromagnetic Relay under Vibration and Shock Environment

Abstract

The electromagnetic relay, which has mechanical structure and break/make contacts, is affected by vibration and shock environment greatly. Contact wear and failure will be result from serious mechanical conditions. The samples used in this study were relays consisting two spring sets connected with armature component. Simulation results for a variety of vibration levels, frequencies, and shock levels are presented. Thereafter main factors and threshold conditions which influencing contact reliability were determined by the modal analysis and the harmonic response analysis and transient response analysis. The vibration and shock characteristics of movable parts within relay were also obtained by using high speed camera PhantomV7.3�ƒ 10000fps�≈ , thus the mechanism of contact failure is revealed clearly. In addition, the characteristics of contact resistance were investigated when relay working in the mechanical environment. The results are valuable in modeling characteristics degradation and contact failure evaluation caused by mechanical environment for electromagnetic relay. structure. Zhai (3) studied the natural frequency and vibration reaction force of reed by using the analytical method and the finite element program ANSYS/LS-DYNA individually. In his research, the limit vibration acceleration of spring system, referring to the maximum of vibration acceleration which can keep the spring contact reliable, is presented. The results are valuable in determining the thresholds of vibration condition for electromagnetic relay. The other relative research on testing and analyzing performance for relay that working in the mechanical vibration environment were so few, except Flowers (4-7) investigated the electrical connector fretting behavior induced by vibration. We have ever designed the vibration characteristics testing and analyzing system specialized for electromagnetic relay (8). In this paper, simulation model of some commercial electromagnetic relay was built by using FEA software MSC.Patran/Nastran, subsequently modal analysis and harmonic analysis and transient analysis induced by vibration and shock were completed. Experiment results agreed with simulation results well, so the threshold conditions that keep the spring contact reliable was determined. At last the effect of vibration and shock condition on contact resistance of relay is also investigated.