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Unread 15-03-2011, 10:04
philso philso is offline
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Re: Fixing Burnt Motors

When choosing a replacement inductor, one should take into account the series DC resistance, or DCR on many of the data sheets from the manufacturers.

I measured the DC resistance of an unburnt inductor at 0.2020 Ohms and 0.1991 Ohms with a second meter. I used two brand new (one still had the protective plastic on the display) Fluke 8845A 6 1/2 Digit bench DVM's connected in the 4-wire mode to cancel the resistance of the meter leads. These meters are accurate to 0.006 Ohm on the range used. For comparison, the resistance across the metal back plate of the motor measured 0.0050 Ohms.

The power connection tabs on the motor had been broken off by rough handling and the inductor showed no signs of turning brown in the middle.