Re: Why Pos Ground

Posted by John T on August 11, 2005 at 12:38:26 from (66.244.90.73):

In Reply to: Re: Why Pos Ground posted by JT on August 11, 2005 at 07:43:37:

JT, youre right and I agree. As I said, small permanent magnet motors DO RUN BASS ACKWARDS if polarity is reversed. HOWEVER, DC Motors like most all tractor starter motors which have electromagnetic field windings (i.e. NOT permanent magnet fields) WILL RUN THE SAME DIRECTION EVEN IF REVERSED.

The reason is to reverse the motor you have to change the N/S polarity orientation BETWEEN the Armature and Field (reverse current flow direction in either) which a simple polarity swap in an electromagnetic field motor doesnt accomplish. The reason reversing polarity in a permanent magnet motor makes em run backwards is cuz youre changing the magnetic polarity in the armature by reversing current flow direction while the permanent magnetic field stays the same.

Clear as mud ???

John T retired electrical engineer

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• Re: Why Pos Ground JT 16:41:45 08/11/05 (0)

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