Suggestions on 1PH motor connected to VFD with 3PH output

[curtie12]

I have connected a 1PH 240V 1.1kw motor to a VFD which has 1PH 240V input and 3PH 240V output. I disconnected the cap and can run the motor but it is drawing excessive current and is not getting up to full speed? Any ideas on how to rectify this would be appreciated.

 

[itsmoked]

Yes. Replace the motor with a correct three phase unit. Find one on ebay.

What you are attempting will never run correctly. You're violating a fist-full of physical requirements and should soon be needing a new VFD.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[CustomHVAC]

Anacon Systems makes speed control products for single phase motors. Check out their web site for more information. I used one on a project about 10 years ago. I never had any complaints, but wasn't able to evaluate its operation for more than about an hour during the operational test before it left the factory.

 

[sanugw]

Not only is the application of the VFD wrong , the reason it is not running at full speed is that the current requirement at lower voltages i more and the VFD is not designed to run the same.
Is there a reason why you are running a Single Phase Motor ?

If it is cost then replacing the VFD will cost you more int he long run !!

Electrical Design Solutions -

http://www.javelin-tech.com/main/products/electrical_design.htm

Great articles, whitepapers and more. Connect with Javelin! -

http://solution.javelin-tech.com/connect

 

[waross]

Your issue is difficult because most of us here have a lot of experience doing it right but not that much experience doing it wrong.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

Speak for your self Bill, I am an EXPERT at wrong.

But I learn...

 

[LionelHutz]

You can not run a 1-phase motor on a 3-phase VFD.

If the 1-phase motor has starting caps then it is not suitable for a VFD speed control application, even if you get a different VFD.

It is possible to control certain types of 1-phase motors on a 3-phase VFD by connecting 3 or a multiple of 3 motors to the VFD.

 

[ozmosis]

Here is a useful article from a VFD manufacturer who builds a 1ph output drive. They advise which motors can be used:

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

 

[triphase]

As a general rule, VFD's are optimized for 3phase motors. That being said within a few constraints a VFD can be used on a single phase motor as well provided a few things are true:
#1 motor should be a perminant split capacitor type
#2 motor should NOT have a start capacitor or start winding or centrifugal switch
#3 motor should NOT be used in an application where it must have high starting torque or start under load (ie air compressor or power tools)

Really one of the only times you can use a vfd with an induction motor is in a fan/blower type application.

You really should use a single phase vfd in this type of application when possible. A single phase vfd will often remove the capacitor that is built into the motor and generator the main and phase (shifted) waveforms and allow speed control and reversing. The other alternative is to use one that generates the main waveform only and use the capacitor in the motor. The other gotcha with single phase vfd is that the efficiency and torque is no where near flat compared to a 3ph motor. torque and efficency will suffer greatly at low and higher speeds, usually more of a problem as motor frame size increases. Like I said best used in a fan/blower application where this will not be an issue. hope this helps

 

[curtie12]

Thanks guys, I have with your wealth of knowledge decided to give it up and not bother with the 1PH motor. It was only an experiment which i was trying on an old pool pump motor but obviously does not work.

Thanks again