# VFD Problem



## Great white hunter (Jan 5, 2014)

I have a lathe with a 2hp 3 phase motor on it. I switched from a static phase converter to a VFD. The VFD is rated for 3 hp. I am having torque problems. With the static phase converter you could not stop the chuck for anything. With the VFD I can stop the chuck with my bear hands at 1000 rpm. I can stop the chuck alot easier at lower rpm. Its not easy buy I can stop the chuck. I know nothing about vfd's. My friend has 3 of them on 3 different machines for 3 years so I bought the same one on ebay for $140.00. Its a Huanyang Inverter. I set all the parameters. One problem I am having is the name plate on my motor does not tell you the HZ. So I looked at alot of other 2 hp 3 phase motors and they are all about 60 HZ so thats what I set it at. Any help at all would be greatly appercaited The motor I have is a Rockwell 2 hp model 96-320, frame66, 1725 rpm, 6/3-7/3 amps. Its driving me nuts. I don't want to go back to the static converter. Thanks


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## Great white hunter (Jan 5, 2014)

One other thing. I have 220 single phase going in.


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## Stanshire (Jan 5, 2014)

Jason
not sure if this will cast any light on your question but...
Assuming that in the USA, the base frequency of AC power is 60hz. A VFD, set to 60hz will result in 100% of the motor's rated horsepower and torque. When the VFD is used to reduce the frequency, the horsepower is reduced proportionately but the torque remains at 100%.
When the VFD is "overrun", and the frequency is greater than 60hz, the torque is reduced, but the horsepower stays at 100%.


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## Pacer (Jan 5, 2014)

You might double check the hz to be on 60 - my Huangyang came set on 400hz even with the literature saying it was defaulted at 60hz, and this was a common problem with several posters that I read about on other sites.

FWIW my Huangyang was also a 3hp installed on a Sheldon lathe with a 2hp motor and other than having a couple glitches getting the parameters dialed in, it made a good install and performed well.


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## John Hasler (Jan 5, 2014)

jason nosse said:


> I have a lathe with a 2hp 3 phase motor on it. I switched from a static phase converter to a VFD. The VFD is rated for 3 hp. I am having torque problems. With the static phase converter you could not stop the chuck for anything. With the VFD I can stop the chuck with my bear hands at 1000 rpm. I can stop the chuck alot easier at lower rpm. Its not easy buy I can stop the chuck. I know nothing about vfd's. My friend has 3 of them on 3 different machines for 3 years so I bought the same one on ebay for $140.00. Its a Huanyang Inverter. I set all the parameters. One problem I am having is the name plate on my motor does not tell you the HZ. So I looked at alot of other 2 hp 3 phase motors and they are all about 60 HZ so thats what I set it at. Any help at all would be greatly appercaited The motor I have is a Rockwell 2 hp model 96-320, frame66, 1725 rpm, 6/3-7/3 amps. Its driving me nuts. I don't want to go back to the static converter. Thanks



Make sure your VFD is configured to put out 220V 60Hz and that your motor is configured for 220.  Check the phase voltages.


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## x-man (Jan 5, 2014)

Have you rewired from star to Delta? Just a thought.


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## Pcbye (Jan 5, 2014)

Does your VFD have a parameter for the number of poles ?  It should.

A 3600 RPM motor is a 2-pole.  1800 (1725) would be a 4-pole and so forth.

Yes, you should set it for 220/240 or what your actual line voltage is and 60Hz.

The 400 Hz you refered to may actually be the modulation frequency and not the output freq.  If possible, do a factory reset on it to set all the default parameters as they are "usually" pretty close to "typical" for your setup with only a little fine tuning needed.

I use Hitachi Inverters exclusively and they have a nice piece of software that makes setup and debugging easy, even from the front display.  If you can measure the current going to the motor, that will give you a good indication of what is going on.  If you are running it at 1000 RPM or some number and you can stop it with your hand, it better not be pulling a lot of current or something is very wrong.

Also, unless your motor is "Inverter Duty" Rated, ie. It has Class-F Insulation and Conductive Grease, you should not load it too hard at slower speeds -- heat -- and you may want to somehow ground the motor shaft.  VFD's produce a lot of Reverse EMF and will over time toast your motor bearings.

Peter


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## Great white hunter (Jan 5, 2014)

I did everything everyone said and still doing the same thing. Maybe I should buy an American vfd?

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Pacer said:


> You might double check the hz to be on 60 - my Huangyang came set on 400hz even with the literature saying it was defaulted at 60hz, and this was a common problem with several posters that I read about on other sites.
> 
> FWIW my Huangyang was also a 3hp installed on a Sheldon lathe with a 2hp motor and other than having a couple glitches getting the parameters dialed in, it made a good install and performed well.



Mine was also set on 400hz, that was the first thing I set to 60hz


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## John Hasler (Jan 5, 2014)

jason nosse said:


> I did everything everyone said and still doing the same thing. Maybe I should buy an American vfd?
> Mine was also set on 400hz, that was the first thing I set to 60hz



What did you get when you measured the phase voltages?  You set the output frequency to 60Hz, not the carrier frequency, right?  And you have it configured for single-phase input, three-phase output?


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## 777mechanic (Jan 5, 2014)

was your static inverter set for 230v 3ph or 440v 3ph , also tell us what output amps you set the vfd . also what is full load amperage on motor .


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## John Hasler (Jan 5, 2014)

Pcbye said:


> ...and you may want to somehow ground the motor shaft.  VFD's produce a lot of Reverse EMF and will over time toast your motor bearings.
> 
> Peter



Good point, but the important thing to do is to connect it to the motor frame (which should be grounded for safety but might not be).


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## Great white hunter (Jan 5, 2014)

I figured it out The parameters were set correctly but I was running at 1000 rpm at only 30HZ I ramped it up to 60hz and it works great.

- - - Updated - - -

I figured out my problem with the VFD but now I have a new problem. I  noticed when I had my arm resting on the machine I could feel current  going into my arm. What do I have to ground to fix that. Thank you  Jason.


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## Pmedic828 (Jan 6, 2014)

Ground the motor to earth ground or the ground terminal on a 110V receptacle.  If the panel is close, ground to the panel.


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## Pcbye (Jan 6, 2014)

I figured out my problem with the VFD but now I have a new problem. I  noticed when I had my arm resting on the machine I could feel current  going into my arm. What do I have to ground to fix that. Thank you  Jason.[/QUOTE]

That is the back EMF issue with VFD's I noted in my last post.  It is not electrically induced it is magnetically induced from the rotor to the motors case.  Inverter Duty motors have the shaft grounded one way or another -- electrically conductive grease or a brush of some sort.

You absolutely have to have the VFD Input grounded by running L1-L2-Gnd from your power panel -- and it needs to be a real "Earthed" ground in your panel.  The whole machine -- Lathe, Mill, etc, must be bonded to this same ground.  Then the VFD to the motor must have a ground by running L1-L2-L3-G.  This may or may not solve the issue.  I suspect maybe not.  Been down the road before.  When running, you can take a volt meter and measure a significant voltage from the motor shaft or case to ground.  Generally not lethal, but very annoying.  I have eventually replaced all my motors with Inverter Duty Motors and don't have the problem.

You can verify that you have a ground by measuring the voltage from any hot leg to ground.  You should get 120 Volts or so.  If not you do not have a good ground.

You can reduce the effect by lowering the carrier frequency, but the added effect is heat and only helps a bit.  If it is still an issue after you have verified everything is well grounded then maybe figure out a way to make a brush to your motor shaft with some stranded copper wire just rubbing on the shaft / pulley, etc, and attached to the common VFD frame ground.  That will make it go away.

The same phenomenon occurs with the High Frequency Arc Starters on Plasma and AC TIG, where you need to ground half the metal items in your shop or you can get a nice tingle just touching something metal and something that has does have a ground.

Peter


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