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 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.

Modelling of the Dynamic Behaviour of Electromechanical Relays for the Analysis of Sensitivity to Shocks and Vibrations

“…Indeed, the value identified for the contact stiffness is coherent with the one estimated using Hertz's contact theory (Fig. 9) and the Young's modulus of the magnetic keeper is comparable to the ones usually met for this kind of relays [15,16]. The sensitivity of the first two natural frequencies in relation to the contact stiffness and Young's modulus is shown in Figs.…”

“…However, Ren et al [15,16] have shown that the contact stiffness can be estimated using Hertz's contact theory (Fig. 8).…”

“…in which the constant K depends only on the geometrical and material data of the two bodies in contact [15]. For small variations around a given configuration (F 0 , δ 0 ), equation (9) can be linearized by introducing the equivalent stiffness defined by Figure 9 shows the evolution of the linear contact stiffness k in relation to the normal contact force F and the contact radius R of the movable part when the contact surface of the static part is flat.…”

“…The criterion of contact opening is that the force exerted by the spring becomes larger than the minimum force F min that has to be applied to the end of the movable part to switch off the contact [12,15]:…”

“…Zhai et al [11,12], Ren et al [13][14][15][16] have established analytical and numerical models that allow to analyse the performances of relays under a mechanical vibratory environment. Their approach is advantageous because it can easily be applied to a great variety of relays.…”