# Wrong rpm in vfd setup



## miller_elex (Jan 25, 2008)

maybe overvoltage. What was the fault code?


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## K2500 (Mar 21, 2009)

What's it pumping?


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## tommu56 (Nov 19, 2010)

Motor speed and poles would possibly cause it 

We had an issue at work with a Siemens drive at our wwtp.

I had to program the speed to slow down the motor as the current approached the max amps.
This happened because the head would get to low (EQ tank would fill to full and reduce head) to be pumped to the Aeration tank.

tom


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## MDShunk (Jan 7, 2007)

K2500 said:


> What's it pumping?


It's pumping milk. The product does not change, nor does the path that the product takes through the connected pipework. I'm about as certain as I can be that there's no issues on the wet end, since the max running amps never even approaches FLA of the pump.


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## MDShunk (Jan 7, 2007)

miller_elex said:


> maybe overvoltage. What was the fault code?


Wish I knew. Some brainiac cleared the fault log.


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## John Valdes (May 17, 2007)

Change the parameters back to the correct settings and see if the problem goes away. Motor data setup (nameplate info) is the most important part of the programming process. I am certain if the wrong poles and speed were to be entered, the drive would fault on something. Overload does not sound right. But there is no fault for wrong information being entered?

Since the drive does not know what the motor actually is, (it has to trust what is entered) an OL trip is believable as there is no trip function for incorrectly entered motor data.

Have you checked the fault log "history"? It may help you determine how and when this incorrect info was entered. Good luck.


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## MDShunk (Jan 7, 2007)

John Valdes said:


> Change the parameters back to the correct settings and see if the problem goes away.


That's really all I've done for them so far, but so far I have had no reports of it tripping out yet. Might have done the trick. I'm just puzzled how the drive might use the motor's RPM and number of poles in any of it's internal calculations. It confounds me. 



John Valdes said:


> Have you checked the fault log "history"? It may help you determine how and when this incorrect info was entered. Good luck.


That's pretty much the first thing I wanted to do, but it was empty. One of the guys on site told me he cleared it in a mistaken first attempt to clear the fault and restart the pump. To his credit, the A-B drives aren't the most intuitive things to reset a fault on. Course, he could have power cycled the whole works, but power cycling a 40hp drive can be sort of scary for an untrained person. That's not exactly a small starter.


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## lefleuron (May 22, 2010)

MD,

is the drive set up for straight V/H (I would think so), or is it running sensor less vector? If its set up for sensor less, the drive is getting way different current feedback numbers then its expecting because the parameters are all messed up. This could be the cause.

I would change the motor RPM, and the poles to the right numbers. Then I would set the "max motor speed" to 1750 (maybe that is all the faster the blades should run?).


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## MDShunk (Jan 7, 2007)

lefleuron said:


> MD,
> 
> is the drive set up for straight V/H (I would think so), or is it running sensor less vector? If its set up for sensor less, the drive is getting way different current feedback numbers then its expecting because the parameters are all messed up. This could be the cause.
> 
> I would change the motor RPM, and the poles to the right numbers. Then I would set the "max motor speed" to 1750 (maybe that is all the faster the blades should run?).


It's actually got the 20-comm-e card in the drive, and it's being controlled by a scada system over ethernet. It's basically running the motor speed according to a outlet flow meter. They ramp up the motor until a certain flow is achieved. I don't think that the 1750 was any sort of limit. It's a c-face pump, and the pump is rated at 3600 rpm (handy that the pump had a really nice dataplate also).


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## John Valdes (May 17, 2007)

MDShunk said:


> That's really all I've done for them so far, but so far I have had no reports of it tripping out yet. Might have done the trick. I'm just puzzled how the drive might use the motor's RPM and number of poles in any of it's internal calculations. It confounds me.


All the new drives employ complicated algorithms and can process lots of information very quickly as you already know.

In my personal experience, drives will fault for reasons we may never know. I call them nuisance trips. Like when a slight power surge trips a drive. It does not always trip on "over voltage". It could trip on OL but no overload ever existed.
I would call your AB guy on Monday and get his feedback even if it continues to run. I for one would like to hear what he has to say.

One other thing is it could have been an overload and you were not there to see it. They cleared the log, so you really have no idea of the true fault right?


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## MDShunk (Jan 7, 2007)

I think I will call A-B on Monday to get their take. My tech support subscription thing doesn't expire until august. 

Its crazy how complex farm automation has gotten in my short career so far.

Sent from my iPhone using the ElectricianTalk Forum app


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## Wirenuting (Sep 12, 2010)

When I installed a newer AB drive about a month ago we had a rep swing by for start up for warrantee. He disabled the mechanical o/l saying the new drives trip them. That step wasn't in the install or start up manuals. He told me the program will catch the over load but that we now had to provide our own 3 phase protection to the unit.


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## CJE (Oct 10, 2010)

We have an AB drive at work that runs a 250 hp centrifugal pump that goes in fits of this. It will run fine for months at a time sometimes and then trip twice or 3 times in a day, then work fine again. AB has worked on it and blamed the old motor we had. The old pump was tired and has been replaced with a pump with an inverter rated motor, parameters reset for the new motor- still occasionally trips, usually on overvolt. We've tried putting a logger on it for periods of time with no success in finding a problem. We need to get one we can leave on it until the next time it has a fit. It's been a head scratcher, but I think we will eventually find it's malfunction.


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## tommu56 (Nov 19, 2010)

CJE said:


> We have an AB drive at work that runs a 250 hp centrifugal pump that goes in fits of this. It will run fine for months at a time sometimes and then trip twice or 3 times in a day, then work fine again. AB has worked on it and blamed the old motor we had. The old pump was tired and has been replaced with a pump with an inverter rated motor, parameters reset for the new motor- still occasionally trips, usually on overvolt. We've tried putting a logger on it for periods of time with no success in finding a problem. We need to get one we can leave on it until the next time it has a fit. It's been a head scratcher, but I think we will eventually find it's malfunction.


Is there an other pump in series with it?

It might be wind milling or being driven from the flow.

We had trouble with 2 40 hp fans and fincore drives in one really long duct duct one ended up pushing the other windmilling it tripping on over voltage.

In another one we retrofitted ac drives were dc's were and if the press (printing) crews didn't get the mechanical adjustments correct machine will drive the roller and trip drive.


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## CJE (Oct 10, 2010)

tommu56 said:


> Is there an other pump in series with it?
> 
> It might be wind milling or being driven from the flow.
> 
> ...


Good idea, but no other pump in series. 3 pumps total, seperate clearwells. Only one pump runs at a time, unless there is a fire or something. Common main they all pump into upstream, but there's a check valve on the discharge of each pump too and they hold properly, so no backflow through the pump into the clearwell from the main. I'm not 100% convinced that it isn't piping related though.


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## JRaef (Mar 23, 2009)

MDShunk said:


> That's really all I've done for them so far, but so far I have had no reports of it tripping out yet. Might have done the trick. I'm just puzzled how the drive might use the motor's RPM and number of poles in any of it's internal calculations. It confounds me.


*Possibly:* (but I'm not a PowerFlex expert by any stretch):

The VFD is tracking more than just the thermal overload, it is also tracking motor performance. One of the beauties of Sensorless Vector Control is that it is capable of looking at motor performance as a feedback control loop into the mP, rather than just telling the motor what to do and hoping for the best as a Scalar (V/Hz) drive used to do. It accomplishes this tracking by looking at the current signals going to the drive, and the effects that the motor rotor bars have on them as they pass through the magnetic fields. Even if you are not using the SVC mode, and in many pump applications you may not want to, the VFD may still using this capability of tracking the performance for protection reasons. 

So how this might relate to your issue: If the VFD is ASSUMING the motor is 1725RPM, and the rotor bars are passing through the magnetic fields at TWICE that rate, it may have been accumulating that data and interpreting it as an overhauling load and adding it into the Motor OL algorithm (still assuming it was tripped on OL).


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## miller_elex (Jan 25, 2008)

MDShunk said:


> he could have power cycled the whole works, but power cycling a 40hp drive can be sort of scary for an untrained person. That's not exactly a small starter.





Wirenuting said:


> He disabled the mechanical o/l saying the new drives trip them. That step wasn't in the install or start up manuals. He told me the program will catch the over load but that we now had to provide our own 3 phase protection to the unit.


:001_huh: Is this a retrofit? Did you take the old motor starter out of the MCC bucket? Did you take the old safety interlock ladder and move it onto the start/stop interlock on the new drive? Or is it still on the old motor starter in the bucket? The only O/L's I've seen installed downstream of a drive is when there is one drive on multiple motors. 

Could it be a 'skip frequency' issue? Some motors resonate at a particular frequency or it's harmonic, hence the skip frequency setting.


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## miller_elex (Jan 25, 2008)

JRaef said:


> So how this might relate to your issue: If the VFD is ASSUMING the motor is 1725RPM, and the rotor bars are passing through the magnetic fields at TWICE that rate, it may have been accumulating that data and interpreting it as an overhauling load and adding it into the Motor OL algorithm (still assuming it was tripped on OL).


Wow, that's some good sh1t. :blink:


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## Jlarson (Jun 28, 2009)

I'd say that could be the problem. I've seen it in other brands of drives before. I'd correct the settings and see what happens.


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## MDShunk (Jan 7, 2007)

Jlarson said:


> I'd say that could be the problem. I've seen it in other brands of drives before. I'd correct the settings and see what happens.


Yeah, that's pretty much what I did. Without knowing how the hocus-pocus machine processes all the information available to it, probably the best thing a guy can do is make sure it's accurate. Time will tell.


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## Wirenuting (Sep 12, 2010)

miller_elex said:


> :001_huh: Is this a retrofit? Did you take the old motor starter out of the MCC bucket? Did you take the old safety interlock ladder and move it onto the start/stop interlock on the new drive? Or is it still on the old motor starter in the bucket? The only O/L's I've seen installed downstream of a drive is when there is one drive on multiple motors.
> 
> Could it be a 'skip frequency' issue? Some motors resonate at a particular frequency or it's harmonic, hence the skip frequency setting.


No this was a replacement. It was a complete unit, breaker, drive & o/l all in one unit mounted on the wall for one 10 HP motor @ 480 for just an air handler. Nothing special except the factory rep disabled the o/l block so that it wouldn't see loss of phase. 
I'll try to swing by that Bld and grab some data off it.


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## John Valdes (May 17, 2007)

Wirenuting said:


> When I installed a newer AB drive about a month ago we had a rep swing by for start up for warrantee. He disabled the mechanical o/l saying the new drives trip them. That step wasn't in the install or start up manuals. He told me the program will catch the over load but that we now had to provide our own 3 phase protection to the unit.


You do. The breaker or fused disco is the input protection. The drive protects itself and the motor. The OL relay if opened during VFD operation, might fault the control. Never switch anything on the drive output. 



CJE said:


> We have an AB drive at work that runs a 250 hp centrifugal pump that goes in fits of this. It will run fine for months at a time sometimes and then trip twice or 3 times in a day, then work fine again. AB has worked on it and blamed the old motor we had. The old pump was tired and has been replaced with a pump with an inverter rated motor, parameters reset for the new motor- still occasionally trips, usually on overvolt. We've tried putting a logger on it for periods of time with no success in finding a problem. We need to get one we can leave on it until the next time it has a fit. It's been a head scratcher, but I think we will eventually find it's malfunction.


I bet the addition of a line reactor stops the tripping. Does it happen around the same time everyday? Nuisance trip.



miller_elex said:


> Wow, that's some good sh1t. :blink:


Yep, He's pretty good. :thumbsup:


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## Wirenuting (Sep 12, 2010)

John Valdes said:


> You do. The breaker or fused disco is the input protection. The drive protects itself and the motor. The OL relay if opened during VFD operation, might fault the control. Never switch anything on the drive output.
> 
> I bet the addition of a line reactor stops the tripping. Does it happen around the same time everyday? Nuisance trip.
> 
> Yep, He's pretty good. :thumbsup:


I understand that part. An I was mistaken about disabling the o/l. He disabled the phase loss and current unbalance function on the o/l relay. It's a cutler hammer o/l,, I'm not sure of the drive as I haven't had a chance to swing back there yet. 
Here is a rotten snap of the cut sheet,,
Pub # 49602 overload relay quick set up guide.


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## controllogix (Jan 26, 2008)

*hi*

Check parameter 
40Motor Type41Motor NP Volts42Motor NP FLA43Motor NP Hertz44Motor NP RPM45Motor NP Power46Mtr NP Pwr Units47Motor OL Hertz48Motor OL Factor

140
Accel Time 1Secs141Accel Time 2Secs142Decel Time 1Secs143Decel Time 2Secs


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## John Valdes (May 17, 2007)

controllogix said:


> Check parameter
> 40Motor Type41Motor NP Volts42Motor NP FLA43Motor NP Hertz44Motor NP RPM45Motor NP Power46Mtr NP Pwr Units47Motor OL Hertz48Motor OL Factor
> 
> 140
> Accel Time 1Secs141Accel Time 2Secs142Decel Time 1Secs143Decel Time 2Secs


Huh? What?


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## Rockyd (Apr 22, 2007)

Bookmarked. More experience analyzing this than mine, be over on the corner, following the thread...:thumbsup:


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## lefleuron (May 22, 2010)

> Check parameter
> 40Motor Type41Motor NP Volts42Motor NP FLA43Motor NP Hertz44Motor NP RPM45Motor NP Power46Mtr NP Pwr Units47Motor OL Hertz48Motor OL Factor
> 
> 140
> Accel Time 1Secs141Accel Time 2Secs142Decel Time 1Secs143Decel Time 2Secs


 OK John, I get it.

Parameter # 40 = motor type
Parameter # 41 = motor name plate voltage

Etc. etc.... I just have no idea what any of this means as we have hashed this over already?:001_huh:


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