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VFD Programming question on 2"x72"


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I recently built my first 2"x72" belt grinder and it runs GREAT!!! Everything tracks dead on straight. It's super strong, super stable and generally bad a$$! HOWEVER- I've got what I believe is a problem with a programming parameter on the VFD. Let me note the tech specs then I'll describe the problem and see if anyone has any input from there. Thanks.

1hp, 3 phase SEW-EURODRIVE motor TEFC

60Hz, Volts: 230YY/460Y Amps: 3.70/1.85

Duty: continuous RPM: CT 300-1800/10-60Hz.   Ins Class: F

 

Other pertinent data:

I'm running a SOYAN SVD-E phase converter that seems like a pretty decent piece. Everything seems to run well. I don't have the specific technical details in front of me now however I believe it is rated at 3.0kW and it does run my machine.

I've got a 4" drive wheel, a bunch of new various types of belts. Nothing else pertinent I can come up with.

 

I'm at work so I don't know what I currently have my parameters set at however I've tried many.

 

Here is my issue. It seems to run with adequate speed but ZERO torque. If I TOUCH a piece of steel (even just mild round bar) to the belt it will grind the metal ever so slowly but will not even throw sparks. If I put basically as little as one finger pressure against the bar on the belt it will be enough to stop the belt from running. If I remove said pressure it returns to running well. I don't have an RPM counter on it but it seems to my perception to be running at about that max of 1800rpms but like I said, it seems to run with NO torque. It is ALMOST impossible to get it to spark. I get that it isn't a 3450rpm motor and I follow that it is only a 4" drive wheel. But am I wrong in assuming that I should be able to do some kind of reasonable grinding with it? If I were to attempt shaping or any kind of stock removal on even the thinnest of a billet I'd be there for DAYS.

 

I did recently acquire a 3hp, 1ph, 220v 3450 motor and a 7" drive wheel as well as most of the other necessary components to craft another even more serious beast....B) But I've put a lot of work into my other grinder design, development, fine tuning, parts, labor etc and I would like to get acceptable performance out of it.

 

Any thoughts?

 

Thanks again,

Chris from Michigan

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First question is whether the motor is wired correctly? Over here, most small 3-phase motors are wound to be run at 230V in Delta or 400V in star (wye).

 

Connecting a motor over here to 230V in Wye gives a similar problem to yours, easily sorted by reconnecting in Delta. I am in the UK and strongly advise you to avail yourself of local knowledge.

 

I'm not sure whether the high Voltage being double the low Voltage on your nameplate means there are 2 sets of windings, to be wired in parallel for 230V or series for 460V. Check your wiring diagram.

 

Are the PBxx settings correct for your motor?

 

 

 

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  • 4 weeks later...
On ‎2‎/‎4‎/‎2020 at 2:13 PM, timgunn said:

First question is whether the motor is wired correctly? Over here, most small 3-phase motors are wound to be run at 230V in Delta or 400V in star (wye).

 

Connecting a motor over here to 230V in Wye gives a similar problem to yours, easily sorted by reconnecting in Delta. I am in the UK and strongly advise you to avail yourself of local knowledge.

 

I'm not sure whether the high Voltage being double the low Voltage on your nameplate means there are 2 sets of windings, to be wired in parallel for 230V or series for 460V. Check your wiring diagram.

 

Are the PBxx settings correct for your motor?

 

 

 

Hey thanks for the idea Tim! I hadn't thought of the wiring there being an issue. I THOUGHT it was right but now that you mention the idea, it is like leaving the house and second guessing whether or not you turned the lights off and locked the door. You KNOW you did, then you THINK you did, then you WONDER if you did...:lol::lol::lol: As far as my VFD, I have tried multiple settings ad nauseum. I have now read the manual OVER and OVER again to the point that I know it by heart. Literally. I've sent emails to the manufacturer. Nobody has yet suggested that the motor could be the issue. It is a VERY high quality motor that I got brand new in the box from someone who didn't know what they had. So given that I am as confident in my VFD settings as I can possibly be, checking the motor is the next course of action. Thanks a ton!!!

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I suspect Tim was on the right track.  It my not be a Wye/Delta mismatch, but I would bet your motor came default setup for the high voltage windings. 

 

Generally speaking, when a motor is setup for dual voltage like that, there are a number of winding leads inside the connection box.  Wired one way the coils are all in series for high voltage, and wired the other way they are all in parallel for low voltage. (There will be a chart on the lid of the connection box explaining how to make the connections)

 

The speed of your motor is dictated solely by the frequency of the voltage.  The torque is a function of how much current is flowing through the windings.  If you try to run a high voltage motor on too low of a voltage, it should make speed.  However the current would be too low, and therefore it won't produce the expected torque.

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I get very confused with electrical things, but in the UK our standard, full fat mains 3 phase is 400 volts (ish). 3 phase generated by a VFD, with single phase input,  is 200 (ish*) volts. You have to swap the bars in the motor terminal box, from either horizontal to vertical, or the other way around, which switches it from star to delta, or the other way around. 

 

Either way, im usually so frustrated I swap the bars and dont care if the smoke escapes. It generally works. 

 

If you had not guessed, I have no electrical knowledge :D - listen to Tim - he does !

 

@timgunn are you going to Owens in May ? Im going to build a new forge for my rolling mill, so we can talk technical burner stuff whilst drunk if your there !!! :) 

 

* for the record 'ish' is not electrical terminology, I just dont worry overly about +/- a few volts !

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