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Phillip weaver16/01/2020 19:32:23
4 forum posts

Hi All If I purchased a VFD to run a 5 horse motor will it still run a smaller motor like a suds pump Phillip

Steviegtr16/01/2020 19:37:53
481 forum posts
126 photos

The one I have has a parameter that you set within telling it the full load current of the motor being used so it could be anything up to the rating of the inverter. That is an Omron. Not sure about any others though.

Mike Poole16/01/2020 19:44:41
2331 forum posts
53 photos

I think an inverter to run a suds pump is a bit of overkill, they are usually pretty small motors and run happily with just a capacitor to generate a third phase. Most inverters do not complain about a motor being too small but check that the parameters for the motor can be set to something suitable if possible.


SillyOldDuffer16/01/2020 20:28:55
5138 forum posts
1074 photos

Do you mean will a 5HP VFD run the main motor on a big machine and its suds pump at the same time? The answer is maybe, but most smaller/inexpensive VFDs are emphatically one motor only devices not clever enough to cope with two totally different motors. Posher units are designed to do it. Have to read the manual or ask the supplier to find out what a particular VFD supports.


not done it yet16/01/2020 20:53:24
3946 forum posts
15 photos

It definitely would if it was hideously over-sized. How over-sized is a matter between you and your supplier. I doubt anyone is going provide a definitive ‘yes’ to your question without knowing the finer details - and then likely not, as they would not want to be responsible for duff advice, should it fail.

I’m quite certain that two suitably sized inverters would be cheaper than buying one with sufficient excess capability to reliably cope with both. There are up-sides to running two - the motor trip on the small motor could be used, the variable speed for both machines would be available separately and the small motor could be left running while the large one is off.

Some run whole workshops on one VFD, so it can be done. Just how expensive - and they would not have the soft start possibility either.

Edited By not done it yet on 16/01/2020 20:54:15

Stuart Bridger16/01/2020 21:28:07
387 forum posts
23 photos

For a suds pump, you can get away with a motor run capacitor across the 3rd phase. No need for a VFD.

Phillip weaver17/01/2020 14:30:37
4 forum posts

Hi thank you all for the replies and it does help me understand many thanks Phillip

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