Re: [ATM] DC Motor for grinding machine question

["Don Clement" <don_clement@charter.net>]

An alternative to DC motor to control speed is to use a VFD (variable
frequency drive) and three phase motor. VFD drives are in common use now in
machine tools like lathes and mills. A three phase motor with a VFD drive
does not need a three phase power source and is as smooth as a DC motor but
without the trouble prone brushes and commutator.  VFD drives can be found
here: http://www.electricmotorsale.com/variable-frequency-drives.html

 Used three phase motors in the 1-5hp range are in common use and easily
found. Since a three phase motor has no brushes, commutator, or slip rings,
or starting circuit to break or wear out, a used motor that works is a good
bet to find.



Don Clement

Running Springs, California
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