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Two Motors On One VFD?

steve45

Stainless
Joined
Jan 16, 2012
Location
Midland, Texas
I recently picked up a Samson surface grinder that has two motors on it. One operates the grinding wheel, the other runs a built in dust collector. Both are 220 volt-3 phase. I had planned to use a single VFD to operate both or these, as I really only need the conversion to 3 phase and don't need the other features of the VFD.

Before I hook it up and try it, does anyone see any problem in doing this?

Thanks!
 

atomarc

Diamond
Joined
Mar 16, 2009
Location
Eureka, CA
If both motors combined are within the current/HP range of the drive, it can be done. One motor is protected by the O/L program parameters of the drive while the second motor is wired through a stand-alone O/L relay with NC contacts wired into the logic buss of the drive to achieve a STOP in the event of a motor overload on that motor.

This is a lot of monkey motion to go as small drives are quite inexpensive these days and equipping the machine with two drives wouldn't kill the piggy bank..but it will work.

Having said that, I will mention that I ran 5 motors of different sizes, all powered from a single 480v, 3 phase VFD for over 20 years with no problems.



Stuart
 

JST

Diamond
Joined
Jun 16, 2001
Location
St Louis
A number of folks run a shop from one oversized VFD as a converter. It works, if the VFD has the capacity current-wise to run the normal load plus start the biggest motor.

A Phase-Perfect is really an enhanced and oversized VFD that provides only the third wire. It has a few refinements, bit the same basic technology in terms of output circuitry.
 








 
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