[TheForge] Electric motor speed control

[James Binnion]

Most induction motors can't be easily speed controlled. In theory if 
you control both the frequency and voltage to the motor you can 
control the speed but many motors will not cool properly at low 
speeds because the internal fan is not moving enough air and you will 
fry the winding insulation  If it is a Permanent Split Capacitor 
(PSC) or Shaded-Pole type they can be controlled by just changing the 
voltage and you can buy controllers for it. These are the fan / light 
dimmer type variable controls that you get at the hardware store. If 
you buy one of theses make sure it can handle the load, most of the 
consumer type dimmers can't handle enough current to run a 1/4 hp 
motor. If it is not a PSC or Shaded pole type you will burn it up if 
you try to control the speed with the dimmer type control.
-- 
Jim Binnion

James Binnion Metal Arts
Phone (360) 756-6550
Toll Free (877) 408 7287
Fax (360) 756-2160
http://www.mokume-gane.com
jbin at mokume-gane.com
Member of the Better Business Bureau