Is It Possible to Use 3 Phase VFD for Single Phase Application?

Depends on the motor (type), load and also on the 3 phase drive. A sophisticated VFD, if not foreseen for single phase will probably keep you busy with alarms of different nature. Unless it has been designed for it, you will have to fool it big time.

When using 1 of the 3 phases there are 2 not connected and all the load has to be provided by that one phase. If you try with 2 different phases on the separate coils, your rotation field will be 120 degrees different in phase (no condenser needed). But again, your VFD may object.

Keep us posted.

I may be wrong, but I think you need to re-think this operation. If your trying to save money by slowing the compressor motor down it's not going to happen. Wattage is wattage., if the motor uses it or the VFD uses it,you still pay by Kw used. If you tyring to run the compressor at a heavy load by increasing the RPM. Then buy a bigger compressor and size the rest of the system to it. If you still want to run a VFD, then pruchase a single phase unit sized for the application at hand.

Goodluck!

Multiple problems with this:

Unlike 3 phase motors, there are many different types of single phase motors, most of which CANNOT be used with any type of VFD. only two types can, PSC (Permenent Spit Capacitor) and Shaded Pole types. Shaded Pole are never used on any heavy loaded machine like a compressor, PSC rarely and you will not be able to distinguish easily from the outside. So attempting it may damage the motor and the VFD.

Next is that most 3 phase VFDs will detect that no current is flowing in one leg and turn off. If you find one that doesn't, you must DOUBLE the size of the VFD with respect to the motor because of the single phase input. There are a few VFDs available specifically for single phase motors, but the same motor restrictions apply, and there is the following issue in your case.

Next is that AC compressors typically use the refrigerant to cool the motor, and are designed expecting to run full speed. If you slow them down, they don't cool. Add to that the fact that a VFD makes a motor run hotter, and you cook the motor quickly.

Bottom line, it's not viable.

Is the OP trying to lash together a variable capacity refrigeration system as found in newer "invertor" type systems?

I think it will probably work. A little rough for me, but hey, give it a try.

Let us know how you get on.

In a word, No!

3 phase Variable Frequency Drives are designed to operate to give a 3 phase output powering a Star or Delta motor. A single phase motor has phase and neutral, this will throw the snubber boards and IGBT's into confusion and you'll have alarms galore! Then there is the motor... I doubt very much if it will handle/work with a VFD

Why do you want to slow down or speed up the compressor motor? If its an air compressor I don't see the need, if it's a refrigeration compressor it won't work any better by using a VFD.

If you think you might save power by using a VFD, then the rating of the single phase motor would not be that much as it is a small single phase motor, I'm guessing not more that 10HP.

In a nut shell the time and effort taken, the cost in material, the damage you WILL do to the equipment will not give you the results you are hoping for, costing you more in the long term.

However..... However.. if this is an experiment... and the compressor motor is expendable, then go for it, and keep us all updated on your success or dare I say, failure..

Brich, you are 100 persent correct. I did a little more checking and in your words "NO" it won't work no matter how hard they want it to.

Fixitoresle

Thanks

It is a good question from the newbie, I am still wondering if someone told him, not members of CR4, it would work. At least he checked.

If it is a project, then go for it. I remember when a trainee, we tried to control linear motors to expel hot rolled steel from the mill table if it cobbled.... after 6 months we did it, the only thing was the hot steel left the mill table at a speed approaching a Exocet missile leaving its launching pad!

But we had fun doing it!!

You've convinced me that trying to use the OP's VFD to run a single phase motor is most probably going to be a futile effort.

This may answer your question. Why do you want to slow down or speed up the compressor motor? If its an air compressor I don't see the need, if it's a refrigeration compressor it won't work any better by using a VFD.

thanks for the reply, but I really wanted the OP to answer the question, now all he has to do is follow your post and tell me what i already know!

But, with all that said from wikipedia, I still see no need to use a VFD....

There are two manufacturers of single phase VFD's that I know of for at least lower hp motors .25hp up to 1.5hp. Anacon Systems makes the Optidrive E2 series that will run single phase motors.

http://www.anaconsystems.com/text/opti_e2.html

Automation Direct makes a GS1 & GS2 Drives That will run a single phase motor. The spec sheet they supply does not say so but if you contact their tech support department they will tell you that it will.

http://www.automationdirect.com/adc/shopping/catalog/drives

We have used both of the above to run single phase pumps and have had good luck with them. The problem as pointed out by another on the board is the motors must be Permanent split capacitor or Shaded Pole to work with the VFD's. Both of these drives are also capable of taking 120VAC input and converting it to run a 3 phase motor.

The Anacon is actually made by Invertek out of the UK.

http://www.invertek.co.uk/product_optidrive_e21.aspx

Also sold in the US by Bardac.

http://www.bardac.com/pages/products/ac_optidrive-e2.html

Thank you for raising an interesting question. VFD manufacturers should take this into scope....may be they have had.

See if there exists a motor gearbox for your single phase motor so that you may still control speed via the gearbox.