# Rotation meters



## case548 (Jul 23, 2019)

I am testing for rotation on the output side of a 20 hp Altivar VFD. My meter reads BOTH CW and CCW. Does this on both drives in the pump station

Reads CW on the input side

Any ideas??


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## Peewee0413 (Oct 18, 2012)

case548 said:


> I am testing for rotation on the output side of a 20 hp Altivar VFD. My meter reads BOTH CW and CCW. Does this on both drives in the pump station
> 
> 
> 
> ...


Bump test it.

Sent from my SM-G965U using Tapatalk


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## Tonedeaf (Nov 26, 2012)

its on a VFD you can rotate slow to see if its the right direction

set speed to 10 RPM and bump


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## HertzHound (Jan 22, 2019)

It might help to know what meter you are using. My Knopp K3 can’t spin in two directions at once. But for all I know it might not be a good tester for VFDs.


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## gpop (May 14, 2018)

Tonedeaf said:


> its on a VFD you can rotate slow to see if its the right direction
> 
> set speed to 10 RPM and bump


That's how we test them. If you turn up the hertz you can use a old school spinning disk tester but some drive will spit a hissy fit as they struggle to sense the load. 

On something that has to be right we pull the motor and test it un-coupled. If you are allowing the drive to tune itself it will generally ask if the rotation is correct.


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## bill39 (Sep 4, 2009)

Will a rotation meter even work properly on the output of a VFD?

I know swapping two leads on a VFD connected motor will not reverse its rotation. You have to go into the VFD’s settings to change rotation.


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## gpop (May 14, 2018)

bill39 said:


> Will a rotation meter even work properly on the output of a VFD?
> 
> I know swapping two leads on a VFD connected motor will not reverse its rotation. You have to go into the VFD’s settings to change rotation.


Thats not true. 

Swapping 2 input leads will not but swapping 2 motor leads will.


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## John Valdes (May 17, 2007)

bill39 said:


> Will a rotation meter even work properly on the output of a VFD?
> I know swapping two leads on a VFD connected motor will not reverse its rotation. You have to go into the VFD’s settings to change rotation.


It will reverse the rotation, but if you autotuned it before the swap, on some VFD's you will need to autotune again.

I have never used a rotation instrument with a VFD and frankly do not think it will work. Agree.



gpop said:


> Thats not true.
> Swapping 2 input leads will not but swapping 2 motor leads will.


Correct.


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## Peewee0413 (Oct 18, 2012)

bill39 said:


> Will a rotation meter even work properly on the output of a VFD?
> 
> I know swapping two leads on a VFD connected motor will not reverse its rotation. You have to go into the VFD’s settings to change rotation.


Is that your final answer? Lol...who knows if you know that I know your wrong. Knowing isn't really knowing sometimes... should be I think or I believe. Any evidence? Have you swapped two legs on a drive and rotation stayed the same? If you have then the rest of us dont know what we thought we knew.


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## micromind (Aug 11, 2007)

If the meter is an electronic one (with lights, not a rotating disc), then most likely it cannot handle the distorted waveform that a VFD makes. 

A mechanical one would likely work ok but I've never tried one. 

As far as I know, every VFD will produce CW rotation when it is in 'run forward'. 'Run reverse' will produce CCW. The rotation of the incoming lines has no effect on the output rotation. 

If the motor runs the wrong way, in my opinion, it's best to swap 2 leads at the load side of the VFD or at the motor rather than program the VFD to run reverse. The reason being that if the VFD needs to be re-programmed, there's a chance that the programmer will set it to 'factory default'. This will provide a known base from which you can program but it'll also set the direction to forward, which means the motor will now run backward......


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## gpop (May 14, 2018)

micromind said:


> If the meter is an electronic one (with lights, not a rotating disc), then most likely it cannot handle the distorted waveform that a VFD makes.
> 
> A mechanical one would likely work ok but I've never tried one.
> 
> ...


I agree and it also stops the display showing the minus sign meaning its running ccw.

The old dial type do work and the only reason i know is we use to bet with the mechanics on right or wrong rotation. Looser paid for coffee so i learnt to cheat. 

Non contact and digital can not deal with dc pulses so they do not work. (at least the cheap ones don't)


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## frenchelectrican (Mar 15, 2007)

If you really want to check the rotation of the output of VSD .,, just get a old school mechanical rotation tester.,, 

I have a old one that do work on 25 HZ source and if you set for 10 maybe 12 HZ it will pick it up and the tester I have is old simpson type. 

One is for 25 to 60 HZ and second unit is calberated for 400 HZ ( rarely I use this beside aircraft AC system that is the only time I have to use that ) 

Normaly most VSD's are clockwise by default so it will be ABC but few case CBA I have ran into but not too often unless the reverse command is enabled.


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## frenchelectrican (Mar 15, 2007)

gpop said:


> Non contact and digital can not deal with dc pulses so they do not work. (at least the cheap ones don't)


No they dont especially if from square wave or modified sine wave either one will basically drive those electronic rotation tester nuts


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## oliquir (Jan 13, 2011)

but why check the rotation on a vfd, it is always the same A-B-C if run if forward


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## bill39 (Sep 4, 2009)

Peewee0413 said:


> Is that your final answer? Lol...who knows if you know that I know your wrong. Knowing isn't really knowing sometimes... should be I think or I believe. Any evidence? Have you swapped two legs on a drive and rotation stayed the same? If you have then the rest of us dont know what we thought we knew.
> 
> 
> Sent from my SM-G965U using Tapatalk


Peewee & John Valdez,
Yes, I have swapped 2 VFD output leads to a motor and the motor did NOT change direction. I had to go into the VFD parameters and change the rotation there. 

Sorry if I did not make that clear in my 1st response.


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## case548 (Jul 23, 2019)

case548 said:


> I am testing for rotation on the output side of a 20 hp Altivar VFD. My meter reads BOTH CW and CCW. Does this on both drives in the pump station
> 
> Reads CW on the input side
> 
> Any ideas??


Thanks all. It is a new electronic meter. EXTECH 480400

The dilemma was complicated by the old VFD running exactly 45 seconds and clicking off with no error codes. Turn control off and on and it would run another 45sec. Found that the submersible pump it was running had shorted to ground. I guess it burnt something in the VFD


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## glen1971 (Oct 10, 2012)

bill39 said:


> Peewee & John Valdez,
> Yes, I have swapped 2 VFD output leads to a motor and the motor did NOT change direction. I had to go into the VFD parameters and change the rotation there.
> 
> Sorry if I did not make that clear in my 1st response.


Weird. I've never had to change a parameter to change rotation after swapping 2 leads.. Every one I've done I just swap 2 leads and move on.. Typically I do them at the motor, and it's usually the red and blue that I swap. Just a habit..


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## John Valdes (May 17, 2007)

bill39 said:


> Peewee & John Valdez,
> Yes, I have swapped 2 VFD output leads to a motor and the motor did NOT change direction. I had to go into the VFD parameters and change the rotation there.
> 
> Sorry if I did not make that clear in my 1st response.


Bill. I guess all VFD's are not created equal. I have swapped two load wires to change direction on every VFD I have worked with.
But my experiences were long ago. Not today.
So I'm all ears.


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## bill39 (Sep 4, 2009)

John Valdes said:


> Bill. I guess all VFD's are not created equal. I havže swapped two load wires to change direction on every VFD I have worked with.
> But my experiences were long ago. Not today.
> So I'm all ears.


All I can do is report from my experience. These were Rockwell Powerflex drives and happened 10-12 years ago. Ever since then I just changed the rotation parameter rather than swap two leads. Next time I’ll try it your way. Thanks fro the feedback.


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## gpop (May 14, 2018)

bill39 said:


> All I can do is report from my experience. These were Rockwell Powerflex drives and happened 10-12 years ago. Ever since then I just changed the rotation parameter rather than swap two leads. Next time I’ll try it your way. Thanks fro the feedback.


Ive seen it happen and have been called out because the motor shop, 2 engineer and 3 e&i's couldn't believe it either. Every time they swapped 2 leads it went the same direction. 

Only took a few minutes to work out that they had changed the motor from a 400 to 500 hp and didn't realize that when the drive was reprogrammed it still had to do it auto sense run. (remote start from the field so they couldn't see the drive)

I asked them to start the motor and the motor twitched then started to run backwards really slowly. They started to scream to turn it off but i told them to leave it running. About 20 seconds later the motor stopped then went into full ramp up running forwards.


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## JRaef (Mar 23, 2009)

The phenomenon you guys are reporting was a known glitch in PowerFlex drives years ago when customers enabled the "Flying Start" feature and had a motor with a high amount of residual magnetism, and/or the load was something like a fan that MIGHT be moving even every so slightly when the drive got a Run command. The Flying Restart got enough of a signal from the motor (because of the residual magnetism) to where it believed it was being told to do a Flying Start, and override the commanded rotation direction because the motor was already turning, and the design decision in the operating code was made to not have the drive try to plug reverse a spinning motor. It was "curable" by just turning off the Flying Start feature, but eventually A-B just fixed the code, then put a warning in the manual that if you have that turned on and the motor is spinning the opposite direction, the drive may damage the machinery (which is what everyone else tells you if they have that feature).


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## psgama (Oct 26, 2015)

Or your motor has a rotary speed encoder terminated to the VFD that is telling the drive it is spinning the wrong direction, the drive then corrects the rotation to the "actual" forward based on the encoder, so swapping motor leads has no effect.


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## MechanicalDVR (Dec 29, 2007)

bill39 said:


> All I can do is report from my experience. These were Rockwell Powerflex drives and happened 10-12 years ago. Ever since then I just changed the rotation parameter rather than swap two leads. Next time I’ll try it your way. Thanks fro the feedback.


It's so much easier to push a few buttons than open things up and swap wires around.


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## MechanicalDVR (Dec 29, 2007)

John Valdes said:


> It will reverse the rotation, but if you autotuned it before the swap, on some VFD's you will need to autotune again.
> 
> I have never used a rotation instrument with a VFD and frankly do not think it will work. Agree.
> 
> ...



On new installs it's always start off at low rpm and check then change the setting for rotation if incorrect.


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## Cow (Jan 16, 2008)

micromind said:


> If the motor runs the wrong way, in my opinion, it's best to swap 2 leads at the load side of the VFD or at the motor rather than program the VFD to run reverse. The reason being that if the VFD needs to be re-programmed, there's a chance that the programmer will set it to 'factory default'. This will provide a known base from which you can program but it'll also set the direction to forward, which means the motor will now run backward......



This has been the standard practice in our shop for years, for the reasons you mentioned.


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## MechanicalDVR (Dec 29, 2007)

bill39 said:


> All I can do is report from my experience. These were Rockwell Powerflex drives and happened 10-12 years ago. Ever since then I just changed the rotation parameter rather than swap two leads. Next time I’ll try it your way. Thanks fro the feedback.


It's so much easier to push a few buttons than open things up and swap wires around.


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## MechanicalDVR (Dec 29, 2007)

John Valdes said:


> It will reverse the rotation, but if you autotuned it before the swap, on some VFD's you will need to autotune again.
> 
> I have never used a rotation instrument with a VFD and frankly do not think it will work. Agree.
> 
> ...


There really isn't a good reason to use a rotation meter on a drive that can switch rotation so readily.

On new installs it's always start off at low rpm and check direction then change the setting for rotation if incorrect.


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