EMC Symposium: MIL-STD-461F demos

Today at the EMC Symposium, Steve Ferguson of Washington Labs gave a demonstration on test setups for MIL-STD-461F Method CS116 for conducted susceptibility on cables and power leads. It uses damped sinusoidal transients at frequencies from 10 kHz to 100 MHz. He discussed the test setup and its calibration where he used an HV Technologies pulse generator to inject current into cables.

“There’s no such thing as a shielded power cable,” he noted, “because when you get to the AC mains, there’s no shielding.” In the demo, he injected a damped 100-kHz sine wave with a peak voltage of 260 mV into 50 Ω, which is too much voltage to comply with the test.

Ferguson used an oscilloscope to show the audience the damped waveforms. He also used the oscilloscope with a currnet probe to measure the injected current. He explained that for low-impedance circuits you have to gradually increas the current to find the level that creates susceptibility problems.

To learn more about how MIL-STD-461F differs from previous versions of the standard, see “Military standard gets a revision,” where you can download Ferguson’s paper that covers the standard paragraph-by-paragraph.