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

Abstract

During their operating life, electromechanical relays (EMRs) are subjected to external mechanical vibrations that can induce undesirable vibratory responses in the movable part of the relay and thus produce an unwanted temporary break in electric connections. This paper presents a simplified multiphysics model dedicated to the prediction of the maximum vibration levels that these relays can undergo before a loss of contact occurs. Our methodology considers the magnetic aspects as well as the mechanical aspects. The dynamic behaviour of the movable part is modelled as a cantilever beam subjected at its extremity to an elastic force. The dynamic parameters were updated from the identification of the first natural modes of the movable part of the relay. The magnetic force acting on the movable part was computed using a one-dimensional approach with an equivalent magnetic circuit and was corroborated thanks to experimental measurements and two-dimensional Finite Element simulations. The interaction between the electromagnetic and mechanical phenomena was taken into account using a parameterization coupled approach. Our methodology has been applied to the study of the PED PXC-1203 relay. The numerical predictions were validated using experimental data measured in the frequency range [2–8 kHz]. A parametric analysis of our model was performed and shows the influence of some factors, like the air gap and the rated voltage, that affect the performance of the relay under external mechanical vibrations.