Does anyone know how to test for harmonic distortion without purchasing and expensive testing instrument. I priced one for around $4000 ouch... need an alternate method. one of the schools that we work in is blowing power supplies in their computers and their engineer thinks it might be caused by harmonics. I would like to test over time, like a chart recorder would be used.
I believe that if you are only looking for "qualitative" testing (i.e. whether or not harmonics exist) and not "quantitative" testing (an actual value of distortion), and you already own an average sensing and a True RMS amp meter, you can determine if harmonics are present. http://support.fluke.com/find-sales/download/asset/1260362_k_w.pdf
Other than that I have rented sophisticated logging analyzers several times and they are not that expensive overall. http://www.us-instrument.com/
Look at the "Dranetz" products
[This message has been edited by Redsy (edited 03-12-2005).]
#49670 - 03/12/0507:23 PMRe: Cheap way to test harmonics?
Measure current with standard amp-clamp. Measure again with "true RMS" amp=clamp. More than 15% difference is enough to start worrying about. And- remember- there are no harmonics on single phase systems.
#49673 - 03/13/0510:47 PMRe: Cheap way to test harmonics?
He wasn't talking about overloading the neutral, they said the harmonics were damaging the PC supplies. You can have nasty harmonics on a single phase system but I still don't think it will hurt a switcher supply. I won't get into whether a situation where current lags voltage by 8ms could exist.