RE: Wire-wound resistors as dummy test load

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Original poster: "Mccauley, Daniel H by way of Terry Fritz <twftesla-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>


Well, now you know the reason wirewound resistors aren't used in pulse-type
applications etc... because they 
are so inductive.

Your inductance values seem normal for what you have.

Dan




I found 4 200-Ohm, 200-Watt wire wound resistors all the same brand, that I
thought I would string together as an 800 Ohm, 800 Watt, test load for my TC
power supply, while checking things such as PFC cap size, etc.  However,
when I
checked them with my meters, I got these readings:

1) 205 Ohms 339 uHy 
2) 206 Ohms 221 uHy 
3) 210 Ohms 225 uHy 
4) 208 Ohms 508 uHy 

Physically, they all seem to be the same size, shape, and construction, but
the
variation in inductance seems unreasonable. Has anyone looked into the
inductance of wire-wound resistors before? If so, is this reasonable? I know
that at 60 Hz, this only amounts to about 0.1 to 0.2 Ohms inductive
reactance,
but it seems strange.
TIA,
Matt D.