I read some good threads on that but can't search them up right now
Stacy had some really good comments as usual
from what I remember...
AC controller (VFD) on an AC motor
DC controller on a DC motor
DC works well and existed before VFD's were common, but the motors are VERY expensive.
If you can find cheap - used motors in 180 VDC then go for it
KB sells DC controllers also
AC with VFD's are common and work well.
VFD is a Variable Frequency Drive
It works by changing the frequency of the AC current
Rob frink sells the KBAC-27D
rated up to 2 HP selectable by installing a resistor pack
It is NEMA 4 - meaning it is a sealed unit and doesn't have the hazards the Nathan mentions above.
Sure you can buy cheaper NEMA 1 ...but some members here have smoked them
NEMA 4 makes so much sense to me.
when using a VFD you NEED a
3 phase motor to match it.
meaning if you are already running an "normal" single phase 110-220v motor
you do need a different motor
be sure the motor is TEFC totally enclosed fan cooled.
check duty cycle ratings - continuous
There are special VFD rated motors with heavier windings to prevent overheating, but at a higher price and not necessary.
In Mississauga you can get VFD's and motors within the city off the shelf...no need to order from the USA
Canada
Mississauga, Ontario
Mechanical Sales Company
Phone: 905-828-1222
Fax: 905-828-1225
E-mail:
gordj@mesaco.com
You can pick white, grey,
http://www.kbelectronics.com/catalog_nema_4x_ac.htm
There are excellent data sheets and manual pdf downloads on this site
Accessories
Reversal switch-It's just a switch, no magic..no need to pay $60 for it.
(SPDT 3 position centre off ?????????)
Resistor - needs to be matched to the HP of the motor and is specific to the controller
(max 1.5 HP from 110 input: or 2 HP from 220v input)
According to Rob Frink, you can run a 1.5 HP AC motor on VFD using a standard 15 amp 110V household outlet.
If you are into research-this link was in another google books thread
http://rapidshare.com/files/182251594/Industrial_motor_control.pdf
.
). You can mount the unit away from the grinder and control it via wired remotes, and you'll want to power it off and blow the dust out occasionally. However, eventually (if not sooner) you may have to replace it because of a short. I bought a TECO FM50 drive that was not dust proof and built a clean box for it to keep dust out with wired remotes to my grinder station. I hung the clean box on the wall to the side of the grinder. No problems so far with mine and no dust getting to the unit. 
