# Is this motor suitable for a VFD?



## Ropata (Sep 4, 2017)

Hi guys,

Is this motor capable of being run off a VFD?


I seem to remember 2 speed motors being a bit troublesome.


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## markba633csi (Sep 4, 2017)

I think the 400 volt requirement will be the difficulty, although I have heard of people using step-up 3 phase transformers on the output
of a 230 volt VFD but it tends to be an expensive solution unless you get the transformer cheap or free.
Check the cost of rewinding the motor to a lower voltage vs replacing the motor with a lower voltage one.
Mark
ps if your motor is a "star" winding you can power it from a 230 volt 3 phase source (or VFD) directly but if it is a "delta" type winding you would need a step-up also.


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## Ropata (Sep 4, 2017)

markba633csi said:


> I think the 400 volt requirement will be the difficulty, although I have heard of people using step-up 3 phase transformers on the output
> of a 230 volt VFD but it tends to be an expensive solution unless you get the transformer cheap or free.
> Check the cost of rewinding the motor to a lower voltage vs replacing the motor with a lower voltage one.
> Mark


I have my eye on a VFD with 240v input to 400v output such as the 1hp gs2 model from automation direct. 

Sent from my SM-N920P using Tapatalk


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## markba633csi (Sep 4, 2017)

That sounds like a good solution, I wasn't sure if something like that was available
Mark
ps I checked their website and couldn't find a model like that- can you post the model #?
M


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## Ropata (Sep 5, 2017)

markba633csi said:


> That sounds like a good solution, I wasn't sure if something like that was available
> Mark
> ps I checked their website and couldn't find a model like that- can you post the model #?
> M


Pretty sure this will do the trick. Only thing I'm not sure of is the 2 speed motor and how it would work.


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## mksj (Sep 5, 2017)

The GS2 VFD will not step up the voltage from 230 to 400V, there are only a few VFDs that I am aware of that are capable of this and they are available through a UK vendor (link below). The usual setup is using a step-up transformer and a 400V series VFD (some can handle a range of output voltages, so something like the WJ200-007HF is rated for 380-480V). The problem you will run into is the VFD is only rated for 3 phase input in this voltage range, so if run off of single phase you would need to run it off of a WJ200-015HF (usually a 3 phase input VFD needs to be ~1.7X if run off of single phase). Otherwise you can go from a RPC to a step-up transformer to your 3 phase input  VFD with no derating. 
http://www.drivesdirect.co.uk/how_to_choose.htm

I have not had much success with 2 speed motors and VFDs, they seemed not to perform as well in particular on the lower pole (high speed) setting. I have also setup switch gear and VFD programming to be able to switch the VFD settings and motor connections between both speeds, but it is complicated. I would use the higher pole setting and over-speed the motor to 120Hz. Also, I believe this is a constant Hp motor, so they may behave differently, but I just dealt with one used on a mill and we went with the low speed (higher pole) setting and adjusted the output Hz to over-speed the motor. You can try one or the other and see which works best with your VFD.


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## killswitch505 (Sep 5, 2017)

Yep that's a go with the gs2 I've used them on a lot different applications they're a great drive. I would really consider a new drive rated motor and GS2. Side note none drive rated motors have a had time keeping cool at lower frequencies. I'm not sure what your budget is but it's only money and you can't take it with you when you're gone.


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