Improvement in Low Frequency Emission Test Method by Live Impedance Measurement

The MIL-STD-461 CE101 test is one of the essential low frequency emission tests in the range of 30 Hz – 10 kHz for military and aerospace equipment, however, its application remains challenging. The primary concern is the effect of the power source or grid impedance on test results because the LISNs are not functional in such a low frequency range. Therefore, the emission levels depend on the source impedance and, consequently, the reproducibility of test results is generally poor. In this paper, we thoroughly analyse this problem and propose a solution based on the live impedance measurement of the CE101 test circuit. For the live impedance measurement, we used the CS101 military low frequency immunity test system along with the addition of FFT and current measurement capabilities.