After a spectrum analyzer or EMI receiver, an electrostatic discharge (ESD) simulator is often one of the other most expensive items required for a compliance test lab or contained in a precompliance tool kit. If you have to purchase one, you might as well get as much mileage out of it as you can, right?
ESD Simulator Usage
You may have thought that ESD simulators could only be used for performing ESD testing in accordance with published ESD test compliance standards such as IEC 61000-4-2. It turns out there is another application for ESD simulators besides performing compliance tests strictly in accordance with the rules. Here’s a list of a few of the things ESD simulators can do:
- Test products in accordance with published standards (full compliance testing).
- Aid in troubleshooting ESD compliance test failures at the bench (precompliance testing).
- Aid in troubleshooting electrical fast transient/burst (EFT) test failures at the bench (precompliance testing).
EFT Precompliance Testing
This last item is one that you might not have thought about before. EFT pulses, as described in IEC 61000-4-4, are very similar to the pulses produced by ESD generators. If you don’t possess an expensive EFT generator, but you do own an ESD simulator, and your product is failing the EFT compliance test, you can try to induce EFT failures by using the ESD simulator to generate transients onto the cables of the EUT. One way to accomplish this is to take a “source” cable grounded at one end and tie it to a “victim” EUT cable for a length of at least 1 m. Apply ESD pulses of 10 to 20 pulses per second to the non-grounded (open-end) of the source cable, and then look for failures of the EUT. EFT test failures are replicated more precisely when the ESD simulator is set to double the desired EFT test voltage (i.e. a 4 kV EFT pulse is more closely replicated when the ESD simulator set to 8 kV). Next time you experience this situation, give this quick and dirty experiment a try.
If you don’t own a real ESD simulator, there are several books that describe less-expensive and simple alternatives that can be easily constructed. These include fabricating an ESD simulator from a butane fire starter utilizing its piezoelectric element or placing a few coins inside a plastic bag and shaking around the EUT to produce intense EM fields. In fact, the above-mentioned simulation of EFT failures using a real ESD simulator might be replicated more easily and less-costly by setting up what is referred to as the chattering-relay test. Consult the references for details on how to fabricate these alternative ESD test methods.
References and Further Reading
- Ott, Electromagnetic Compatibility Engineering, Wiley, 2009.
- André & Wyatt, EMI Troubleshooting Cookbook for Product Designers, Scitech Publishing, 2014.
- Wyatt, Create Your Own EMC Troubleshooting Kit (Volume 1) – Essential Tools for EMI Troubleshooting, Wyatt Technical Services, LLC, 2020.
- Electromagnetic compatibility (EMC) – Part 4-2: Testing and measurement techniques – Electrostatic discharge immunity test (IEC 61000-4-2:2008).
- Electromagnetic Compatibility (EMC) – Part 4-4: Testing and Measurement Techniques – Electrical Fast Transient/Burst Immunity Test (IEC 61000-4-4:2012).