VFD to power 200 volt motor?

[Ohio Mike]

So I recently acquired a machine with a 5HP 200 volt 60 Hz 3 phase motor, yes name plate 200 volt. Motor is a Rockwell OEM'ed from Baldor. It was previously run on a 208 three phase service. I have 240 single phase and 240 three phase via a 10HP rotary phase converter but don't feel real comfortable pushing the motor to 240 volts. So I got to wondering which if any of the reasonably priced VFD units can take 240 input and trim the output voltage back to the 200-208 volt range? I started looking and got frustrated, the manuals all seem to be written by EE's with English as a second language.

 

[kerrywil]

The hitachi VFD is good. $230 there is a diagram on the net on how to wire it.

The switch caused me problems.

If your in n. Calif I
Can help

 

[sch]

Here is a writeup that explains how VFD work and may answer your question: Variable Frequency Drive (VFD) Warehouse
How the machine uses the motor might help to know, as many machines rarely if ever demand full output from the motor, but some do
run at a very large fraction of motor rating constantly. Generally speaking 200V motor and "240V" drive are not necessarily a mismatch.
Have you checked your actual supply voltage under load?

See also recent discussion as to this very ?: http://www.practicalmachinist.com/v...rs-vfd/208v-220v-230v-240v-what-gives-295862/

 

[mike_kilroy]

Virtually ALL vfds will let u set 200v@60hz.

 

[mike_kilroy]

Absolutely NO problem running it on ur 240v source.

 

[Ohio Mike]

I'm not completely VFD illiterate, I have two of them. I know based on how the VFD works its possible it can regulate the voltage I just wasn't sure the user interface would allow you to control it. I didn't include what the machine was because I really don't think it matters, but its a table saw if you really care. When I started looking most of the cut sheets mention something like "Input 1ph 200-240VAC - Output 3ph 200-240VAC" with a note that the output is proportional to the input voltage. Since posting I noticed something else. It would appear most of the VFDs designed for single phase input stop at 3HP. The 5HP and up units I was finding are designed for 3ph input. At least one of those included phase lost detection which would indicate it likely would not work on single phase input.

 

[mike_kilroy]

It would appear most of the VFDs designed for single phase input stop at 3HP. The 5HP and up units I was finding are designed for 3ph input. At least one of those included phase lost detection which would indicate it likely would not work on single phase input.

Yep and nope....

yep all but a few stop at 3hp for 1ph input w/o derate.

nope, most 3ph WILL work w/1ph input - just check the specs.

as a hitachi distributor, i guarantee you all hitachi 3ph models will run on 1ph input.

I would recommend

WJ200-055LF Inverter, 200 volt, 3 phase, 7.5 CT (10 VT) HP, 25.0 CT (30.0 VT) Amps

rule of thumb is to double the 3ph hp size for 1ph input.

 

[Ohio Mike]

Looks like that would work but at $600-700 it isn't going to happen. For that kind of money I'd probably replace the motor. I don't need the machine right now so its probably going to sit for bit.