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General Category => General Discussion => Topic started by: Paul Whelan on October 23, 2014, 20:12:36 PM

Title: Question on Permanent magnet DC motor
Post by: Paul Whelan on October 23, 2014, 20:12:36 PM
I am checking a brushed, Permanent magnet DC motor with 8 commutator bars, and brushes contacting 180 degrees apart. I am checking for an amperage waveform with a digital storage scope and a low current probe. My question is, is the amperage higher when the brushes are contacting directly on the two commutator bars, or is it higher when the brushes are each bridging across commutator bars?
Title: Re: Question on Permanent magnet DC motor
Post by: kam on October 23, 2014, 21:44:21 PM
most likely (and i take a guess here) is that when the brushes touch 4 bars (2 each), then 2 different coils are connected in parallel lowering the overall resistance and therefore increasing the amps. Most likely this is what happens.