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thread237-100416 Just wanted to we

thread237-100416 Just wanted to we

thread237-100416 Just wanted to we

thread237-100416: 60Hz AC motor at 120Hz?
Just wanted to weigh in on using a VFD as a power supply where PD measurement will be performed. I worked for Hipotronics for many years and am very familiar with performing PD on transformers at 180Hz. If you are using a VFD to power the DUT, there are some issues to consider:
1. The VFD will radiate high frequency components which could be seen by the PD system as PD in the transformer typical PD frequency range is 30 to 300 kHz.
2. The VFD without a lot of filtering will cause "noise" in the DUT output which also can bee seen as PD. Typical filtering for a VFD would consist of inductor/capacitor stages in each phase (series L and parallel C to ground 20db/decade).
This is why typically a motor generator set is used. However it has been done using VFD's and filtering. I just wanted thread originator to be aware.

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