Modelling of the Electrical Fast-Transient Test

Tests against Electrical Fast Transient/Burst (EFT) represent a serious threat for modem high speed electronics: beside the conducted injection of high amplitude pulse, a strong radiated field is produced during this test. The prediction of the effects of this test, during the equipment early design stage, requires the equivalent circuit of the generator: the output waveform into a resistive 50 Ω load is not sufficient to recover the complete circuit, including inductive component and parasitic elements. These are essential to predict the disturbance produced in arbitrary loads, as the equipment under test can be viewed. The paper describes how to characterize the EFT generator by means of the measurement of the output voltage and current produced in presence of known loads; moreover, a procedure to calculate the current on the equipment power cord is showed, based on the use of a circuit simulator (PSPICE). Finally, the disturbance produced on different loads and the radiated field during the test are calculated and experimentally validated.