Development of Coupling and Decoupling Network for Surge Immunity Test

In order to simulate the effects of lightning and switching transients on power lines, coupling and decoupling network (CDN) is necessary for performing surge tests on electrical and electronic equipment. This paper presents a particular analysis of the circuit of CDN and design details according to the requirement of the standard IEC 61000-4-5. The CDN circuits are simulated by electromagnetic transients program (EMTP) to judge the suitability of the selected component values and performance of the designed CDN. Simulation results also show that increasing of decoupling capacitance or inductance can reduce the residual surge voltage on the power line inputs of the CDN. Based on the voltage drop control and residual surge voltage limiting, smaller decoupling inductance and relatively larger decoupling capacitance should be chosen if EUT has a higher rated current. The CDN developed according to the simulation results satisfy the design specifications well.