Analysis and optimization for electromagnetic susceptibility of solid state relay in the presence of incident wave

This paper presents a method for analyzing and optimizing electromagnetic susceptibility (EMS) of solid state relay (SSR) in the presence of incident wave. The model of SSR is built in Ansoft HFSS and analyzed by finite element method (FEM). The SSR is tested with electromagnetic interference (EMI) from different directions and the results show that the SSR is sensitive to the EMI whose electrical field is along the axis of the cables. The induced voltages of input port and tracks on the PCB are computed. And the results show that the voltage of the input port is the key factor to cause misoperation of SSR. So the voltage of input port is then taken as an optimization target. The structure of SSR including external cables and holes through which the cables enter the SSR is optimized so the EMS of the SSR is reduced.