Calculation of the EMP response of transmission lines with nonlinear loads

The analysis of transmission line under non-uniform incident field and with nonlinear loads is discussed in this paper. A test system is established according to IEC 61000-4-24, which consists of fast pulse generator and SPD (Surge Protection Device) test fixture. By using this system, the nonlinear Volt-Ampere characteristics of SPD can be measured and the nonlinear model of SPD is established. The response voltage of SPD to EMP with different rising time is also measured and discussed. A time-domain transmission line model is then employed to calculate the terminal response of transmission lines under nonlinear loads. Calculation results show the estimated response voltage is in good accordance with the measured one. This kind of method provides a systemic approach for evaluating the EMP protection ability of electronic and electrical systems.