New Verification Methods for Low-Frequency Susceptibility Testing

The MIL-STD-461 CS101 test is one of the essential low-frequency conducted susceptibility tests for military and aerospace equipment. The CS101 test firstly requires a calibration process performed using a 0.5 Omega resistor to verify functionality of the test equipment and to establish a maximum drive power. The test stage follows the calibration using the verified test equipment. Observation is required during the CS101 calibration and test stages to detect the sinusoidal quality of the injected signal into the EUT. The standard supports the use of a frequency domain measurement receiver which limits verification of the sinusoidal waveform characteristics. This issue arises for AC-powered devices even if an oscilloscope is used instead of the frequency domain measurement receiver. As a solution, in this research, we evaluated using quick 2nd and 3rd harmonic measurements of each test frequency during the calibration and test stages. If the 2nd d and 3rd harmonic levels are high for the test frequency of interest, this will reveal distortion of the injected CS101 test signal. In addition to the injected signal quality verification, we also evaluated an effective just-before-test verification for CS101 testing to detect issues with the test setup and employed AC power frequency filter solutions and to examine the influence of power frequency feedback to the amplifier before a test.