# Fighting with a 200HP Powerflex 400...



## Cow (Jan 16, 2008)

A feedlot customer of ours has a 200HP turbine pump on a PF400. We did the original install probably 8-10 years ago. There are also 4 other various sized PF400's next to this 200HP VFD, all on the same service all within a few feet of each other.

Last year about this time, the 200HP VFD would throw random fault codes, overvoltage, motor overload, etc. I personally witnessed it throw a motor overload fault while the motor was running probably at least 5-10+ amps under the motor overload setting. Our local AB rep had no ideas. I replaced the drive. I can't remember if I bought a new one, or an AB reman. No more problems. Until now.

It's acting up again according to the customer, throwing F5 overvoltage and F64 drive overload faults. I show up on site and start the drive. I notice with a 30 sec ramp it pulls about 235-237 amps on this 235 amp rated drive for 30-60 seconds or so until the water line gets charged then the amps drop down to 215-225 or so. Motor is rated 225 amps, P33 "motor overload setting" is set to the same.

During this first start, the VFD trips out on overvoltage after about 2 minutes. None of the other PF400's that are running right next to it trip. I get out my Fluke 289, voltage is around 475v and pretty even across phases, so I clip it onto the DC bus. I adjust A179 to limit current at around 222 amps, I verify decel is still set to "coast to stop, cf" and start the drive again. No issues whatsoever, DC bus is around 670v when started and 635-640v when under full load. I notice motor speed is held back a couple Hz from commanded freq by current limiting, 58hz commanded to 56hz actual. This was Wednesday.

Customer sent me a text Friday showing an F64 drive overload fault again.

What am I missing? I'm surprised it's even possible to get a drive overload fault on a VFD that's rated 235 amps with a 222 amp current limit set.

If this was a smaller VFD and not $10k+, I'd swap it out again just to rule it out.

Thanks for the help.


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## Wirenuting (Sep 12, 2010)

Cow said:


> A feedlot customer of ours has a 200HP turbine pump on a PF400. We did the original install probably 8-10 years ago. There are also 4 other various sized PF400's next to this 200HP VFD, all on the same service all within a few feet of each other.
> 
> Last year about this time, the 200HP VFD would throw random fault codes, overvoltage, motor overload, etc. I personally witnessed it throw a motor overload fault while the motor was running probably at least 5-10+ amps under the motor overload setting. Our local AB rep had no ideas. I replaced the drive. I can't remember if I bought a new one, or an AB reman. No more problems. Until now.
> 
> ...


I think JRaef just posted a thread a couple weeks ago talking about this same type of issues.
My search results bring back nothing at all,, it seems to not be working.


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## gpop (May 14, 2018)

take a look at the pipe work on the pump. If it has a high head height its possible that the pump is being forced forward due to siphoning. 
Im not sure what you class as a turbine pump. That would be a positive displacement pump with blades that contact the housing. It seems odd that it should pull high amps on start which is something that would be expected on a centrifuge pump. 

You can choose on the drive how you would like it to react to high dc bus voltage and overload conditions. Give the drive more freedom to recover from these conditions. 

Also check that all 3 legs are about the same on amps by clamping all 3 at the same time. 


This is one time that drive software loaded on a laptop would really help so you can trace whats going on in real time.


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## varmit (Apr 19, 2009)

Did you check (meg) the motor and check for mechanical problems in the pump or motor? If the motor is not VFD rated, the bearings may be badly pitted causing binding.

If there are several VFDs on the same power source with no individual isolation using transformers or line reactors, one of the other VFDs can be the culprit. Check the line side hertz.

Yes it can be the VFD failing again- probably a control board. The pattern of VFD failures, that I see are 1-2 days when new or close to a year or they last a normal life span 7- 10 years and sometimes longer.


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## geoffpowell (Mar 12, 2017)

Never had this issue before but looked at a manual for the 400 and you could change A181 to max OL select (2) and possibly A182 to CLim (2). Love to hear how it turns out.


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## Cow (Jan 16, 2008)

Wirenuting said:


> I think JRaef just posted a thread a couple weeks ago talking about this same type of issues.
> My search results bring back nothing at all,, it seems to not be working.


I hope he responds, being the resident AB VFD guru.



gpop said:


> take a look at the pipe work on the pump. If it has a high head height its possible that the pump is being forced forward due to siphoning.
> Im not sure what you class as a turbine pump. That would be a positive displacement pump with blades that contact the housing. It seems odd that it should pull high amps on start which is something that would be expected on a centrifuge pump.


It's a vertical turbine (well) pump. I'm sure the pump is down a few hundred feet. 



gpop said:


> You can choose on the drive how you would like it to react to high dc bus voltage and overload conditions. Give the drive more freedom to recover from these conditions.


I'm not aware of any more parameters to adjust. I would like to get to the root problem of why it's throwing faults in the first place.



gpop said:


> Also check that all 3 legs are about the same on amps by clamping all 3 at the same time.


I can do that.



gpop said:


> This is one time that drive software loaded on a laptop would really help so you can trace whats going on in real time.


That would be nice...



varmit said:


> Did you check (meg) the motor and check for mechanical problems in the pump or motor? If the motor is not VFD rated, the bearings may be badly pitted causing binding.


At 1000vdc, it tested at 2.1+Megohms. 

As far as any potential mechanical problems, that would have to be handled by a pump company. I'd have a hard time telling the customer to pull a pump several hundred feet down just to check it $$$$, but it may come to that. 



varmit said:


> If there are several VFDs on the same power source with no individual isolation using transformers or line reactors, one of the other VFDs can be the culprit. Check the line side hertz.


I can do that.



varmit said:


> Yes it can be the VFD failing again- probably a control board. The pattern of VFD failures, that I see are 1-2 days when new or close to a year or they last a normal life span 7- 10 years and sometimes longer.


With how the last one went out, throwing random codes, and this one doing similar, experience tells me I should be looking at the VFD being the problem before I look elsewhere....

I'd feel better if it was less of a guessing game and more of a definitive answer. It doesn't help the customer is 1 hour away either so I can't just run over there and try something. That said, I'm going to try and make a run up there tomorrow though and check some of the suggestions you guys have mentioned.

Thanks to everyone. Any other ideas, throw them out here!


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## gpop (May 14, 2018)

geoffpowell said:


> Never had this issue before but looked at a manual for the 400 and you could change A181 to max OL select (2) and possibly A182 to CLim (2). Love to hear how it turns out.


As well as what geoff said

another one to look at is A179 which by default is max amp output before current limiting comes into affect. Default is current limit x 1.1 so thats higher than the drive limit if im reading that correctly. 

AB always suggest that the drive be one size bigger than the motor so a 200 hp really should by there standards be a 250hp drive. 

A standard motor overload would show up as a F7 the f64 is showing a drive overload. Ive never used a drive thats the size of a motor so hopefully jref will butt in as this is his bread and butter.


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## John Valdes (May 17, 2007)

Man this could be anything.

8 years under water maybe the clue. Does it have a wet sensor in it?
But I do agree its unusual as water intrusion would give a definite fault the same over and over again.
*Have you ran the drive with the motor disconnected?* If the drive operates without the motor, you can pull it up with no concerns on your part.
Good luck and please tell us how this turns out.


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## MDShunk (Jan 7, 2007)

If a drive is giving a fault code, I tend to believe it. Very very rarely have I experienced a drive fault that didn't turn out to be "real".


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## paulengr (Oct 8, 2017)

First off for a motor under 1000 V the correct Megger voltage is 500 V and should be applied for 1 minute and temperature corrected. Then the limit is a minimum of 5 megaohms. That old 1 megaohms per kV stuff is strictly for nonpolymeric (pre 1970) motors. At 2.1 megaohms I’d tested correctly it failed. IEEE 43 is the standard for motor insulation resistance testing.

Second what you are describing sounds typical for bad/changed filtering. Check the drive input and output with an oscilloscope looking for spikes or ringing especially reflected waves. It’s not common but I’ve had multiple drives from different manufacturers do what you are describing and it turned into an input or output problem. 

The current stuff is usually because the drive instantlabeously reacts to what the sensors indicate which you can’t visibly see even with the reported values.

I’d suspect intermittent arcing in the motor based on the current overloads that you “can’t” see but the voltage overloads are more common with spikes on the input or output. Check AC ripple on the DC bus too.

The “one size larger” wouldn’t matter with an 8+ year install. It happens with all drives. With variable torque loads (centrifugal pumps and fans) torque increases with load while constant torque loads like hoisting and conveyors don’t change torque much. At low speeds drives have problems so manufacturers recommend larger drives for constant torque applications. Also loads that need high starting torque such as with a sliding load that requires high torque to get it started moving then it goes down to normal. Static friction can be up to 300% of dynamic friction so this is for a “heavy duty” application. This is all part of drive sizing.


Sent from my iPhone using Tapatalk


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## Bird dog (Oct 27, 2015)

Cow said:


> I hope he responds, being the resident AB VFD guru.


PM @JRaef


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## John Valdes (May 17, 2007)

MDShunk said:


> If a drive is giving a fault code, I tend to believe it. Very very rarely have I experienced a drive fault that didn't turn out to be "real".



Once in a plant, every day around 2:00 pm several machines would just stop. Differing faults with not much to go on. Some had no faults at all.
OEM installed drives in each and every one of them.

We fiddled with this issue for a month or so until we asked the POCO to come in and assist.
They set up monitoring on one machine we knew quit most every day.
Once we got the report and meeting with the POCO rep, we found out what the problem was.
The power correction caps on the POCO side had not been working for years. Once they fixed the problem is when the drive issues showed up.
Turns out switching of the POCO caps where tripping the drives. Nuisance trips corrected by every single drive in the plant outfitted with line reactors.
That solved it.


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## gpop (May 14, 2018)

MDShunk said:


> If a drive is giving a fault code, I tend to believe it. Very very rarely have I experienced a drive fault that didn't turn out to be "real".


I have seen it go total random on a AB 1336 but it was so unstable it would not run at all. We sent it back in for repair and they said that the fault buffer was over filled and that it just had to be factory reset to clear the memory. Years later we had another one do it so i looked super smart just resetting and reprogramming the drive. 

The powerflex is a way more of a complicated beast and this one is throwing errors that seem to point to a motor/drive problem rather than random errors. If you know the program a reset to factory defaults couldn't hurt it i just dont think it will fix it either. 
Of course over the years someone could have fat fingered some settings in the drive so a reset would at least get you to a clean slate to start with.


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## gpop (May 14, 2018)

John Valdes said:


> Once in a plant, every day around 2:00 pm several machines would just stop. Differing faults with not much to go on. Some had no faults at all.
> OEM installed drives in each and every one of them.
> 
> We fiddled with this issue for a month or so until we asked the POCO to come in and assist.
> ...


Ours was the same way. All the faults were high dc buss voltage. It was even worse when they use to bring on the generators during peek load.


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## frenchelectrican (Mar 15, 2007)

Cow .,

I know few guys did posted few good info for you to check it out and I been wondering as myself and John mention is POCO supply.,

If the supply is very clean or kinda bouncing around ( switching capaitors will be a most common curpit ) 

Is this VSD is in the control cabient ? or it stand alone ? because I am not too sure but if get too warm it can cause some issue with it. 

did that unit came with bypass contractor in case you are running full 60 HZ supply ?


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## gnuuser (Jan 13, 2013)

varmit said:


> Did you check (meg) the motor and check for mechanical problems in the pump or motor? If the motor is not VFD rated, the bearings may be badly pitted causing binding.
> 
> If there are several VFDs on the same power source with no individual isolation using transformers or line reactors, one of the other VFDs can be the culprit. Check the line side hertz.
> 
> Yes it can be the VFD failing again- probably a control board. The pattern of VFD failures, that I see are 1-2 days when new or close to a year or they last a normal life span 7- 10 years and sometimes longer.


also check the seals on the bearings, contamination of the bearing lube can cause all kinds of weird crap to happen 
changing a vfd may solve the problem for a short time but vfd's like any electronic device can be damaged by excessive heat over a period of time
our monthly pm included blowing the dust out of the vfd cooling fan and fins.


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## John Valdes (May 17, 2007)

gnuuser said:


> also check the seals on the bearings, contamination of the bearing lube can cause all kinds of weird crap to happen
> changing a vfd may solve the problem for a short time but vfd's like any electronic device can be damaged by excessive heat over a period of time
> our monthly pm included blowing the dust out of the vfd cooling fan and fins.



Got a call once and the plant said the drive (Baldor 15H) would not do anything.
Said the display was very dim and nothing worked on the keypad or the remote operation.
When I arrived I noticed how dusty the cabinet was.
So I got down on the floor (of course I laid down cardboard first) to look up at the cooling fans. All three were not running and were covered with dust.

So I unplugged each one to remove and clean.
As soon as the fans were disconnected I closed the main switch and bingo. We had life. Display lit up and drive ran.

I had the guy remove all three fans, clean them and run them on the bench. Drive worked just fine after that.
I ordered 3 new fans for him and all was well.


Moral of the story.
Drive manufacturers should not use onboard control power to run cooling fans.
Had those fans had their own power supply, the drive would have faulted on Over Temp. That would have told them what the issue was right away.
Lucky for them I was their sales guy so they got this service call for free.


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## gnuuser (Jan 13, 2013)

John Valdes said:


> Got a call once and the plant said the drive (Baldor 15H) would not do anything.
> Said the display was very dim and nothing worked on the keypad or the remote operation.
> When I arrived I noticed how dusty the cabinet was.
> So I got down on the floor (of course I laid down cardboard first) to look up at the cooling fans. All three were not running and were covered with dust.
> ...


:vs_laugh:i have run independent power to the cooling fans before as a quick fix until the replacement drives came in!
( large power pack and multiple connectors)

salvaged blowers from certain dell computers also work real well

the boss kept the setup after replacing the drives for emergencies


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## JRaef (Mar 23, 2009)

Cow said:


> ..
> 
> Customer sent me a text Friday showing an F64 drive overload fault again.
> 
> ...


Current Limit is a software calculated function based on measurements also done in software, so it takes time to take effect, maybe only a few seconds, but time is time. How a VFD limits current is to override the commanded speed and lower it in an attempt to lower the load on the motor. How fast it can do this is then also determined by your Decel rate settings. So the response time to a Current Limit even can end up being very long. The Drive Overload function on the other hand is a hardware based trip function, it is an 'interrupt" into the drive's mP from dedicated hardware that is protecting the power components of the drive itself. It acts MUCH faster than the calculated software functions like Current Limit or even overload. For the Drive Overload functtion, the protection is hard coded as:


> Drive rating of 110% for 1 minute or
> 
> 150% for 3 seconds has been exceeded.



From your description, I suspect that you have some sort of mechanical issue taking place in your pump or the motor. The previous OV trip issues might indicate a siphoning issue as previously mentioned, but my suspicion is that you have a bad bearing and it occasionally seizes momentarily, then frees up again and when it does, that causes either a current surge too fast for the Current Limit to act (triggering the Drive OL trip), or by essentially suddenly "braking" the impeller, it causes a suction effect that then becomes a siphon and pulls the rotor AFTER the Current Limit attempts to reduce the speed, causing the motor to regenerate (causing the OV trip). it's basically a race to see which one happens first.


By changing the Stop mode to "Coast", you likely eliminated the OV trips because now the drive is no longer trying to Decelerate the pump, it just lets the speed fall. So now the only trip you are getting is the Drive OL version, which is more rare, at least for now. The thing about these kinds of issues however is that the frequency will increase as the bearings get worse and worse.


Side note though, you mention this is a submersible turbine pump. Any chance it is sucking sand?


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## gpop (May 14, 2018)

gnuuser said:


> :vs_laugh:i have run independent power to the cooling fans before as a quick fix until the replacement drives came in!
> ( large power pack and multiple connectors)
> 
> salvaged blowers from certain dell computers also work real well
> ...


I have a 120v computer type fan i think it came from a softstart. We normally tie wrap it to the drive if we dont have the correct spare fan in stock. Part of our pm is to check the drive fans as they seem to have a shorter life expectancy than the drives.


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## Cow (Jan 16, 2008)

frenchelectrican said:


> Is this VSD is in the control cabient ? or it stand alone ? because I am not too sure but if get too warm it can cause some issue with it.


It's in Rockwell 3R drive enclosure with bypass contactors.



frenchelectrican said:


> did that unit came with bypass contractor in case you are running full 60 HZ supply ?


Yes.



JRaef said:


> Current Limit is a software calculated function based on measurements also done in software, so it takes time to take effect, maybe only a few seconds, but time is time. How a VFD limits current is to override the commanded speed and lower it in an attempt to lower the load on the motor. How fast it can do this is then also determined by your Decel rate settings. So the response time to a Current Limit even can end up being very long. The Drive Overload function on the other hand is a hardware based trip function, it is an 'interrupt" into the drive's mP from dedicated hardware that is protecting the power components of the drive itself. It acts MUCH faster than the calculated software functions like Current Limit or even overload. For the Drive Overload functtion, the protection is hard coded as:From your description, I suspect that you have some sort of mechanical issue taking place in your pump or the motor. The previous OV trip issues might indicate a siphoning issue as previously mentioned, but my suspicion is that you have a bad bearing and it occasionally seizes momentarily, then frees up again and when it does, that causes either a current surge too fast for the Current Limit to act (triggering the Drive OL trip), or by essentially suddenly "braking" the impeller, it causes a suction effect that then becomes a siphon and pulls the rotor AFTER the Current Limit attempts to reduce the speed, causing the motor to regenerate (causing the OV trip). it's basically a race to see which one happens first.


I spent the better part of an hour and 15 minutes with AB tech support and got transfered up through one technical support person and two levels of engineers. The last "senior engineer" that I talked too, mentioned something similar. A bearing or similar might be momentarily locking up faster than the current limit function can catch it. If there are enough "instances" of it locking up and spiking the current in a short enough time period, it could throw an F64 drive O/L fault. He mentioned an oscilloscope would help narrow this down, just like someone else mentioned above. He even pointed me towards a technote for a similar issue to help get me started with a scope.



JRaef said:


> By changing the Stop mode to "Coast", you likely eliminated the OV trips because now the drive is no longer trying to Decelerate the pump, it just lets the speed fall. So now the only trip you are getting is the Drive OL version, which is more rare, at least for now. The thing about these kinds of issues however is that the frequency will increase as the bearings get worse and worse.


The drive has always been set to a "coast to stop, cf", I just verified it was still set when I showed up the first time.



JRaef said:


> Side note though, you mention this is a submersible turbine pump. Any chance it is sucking sand?


I have no idea.

At this point, I going to give the customer some options. 

1. Tweak a few parameters AB tech support said to try. No guarantees.

Adjust slip to 0Hz.
Turn boost down to 30 V.T or less.
Turn drive overload parameter to "disabled". He said a "HW Overcurrent" fault would still protect the drive, if it got serious enough.

2. Have the customer call the pump company in to pull the pump and check the mechanical side of it. Send the motor to the motor shop.

3. Rent an oscilloscope and let it run for a while. Never done this before...

4. Run it on the bypass starter setup for a while to flush the problem out. This might not end well though.

5. Some combination of the above 4 options.

I have more phone calls to make in the morning. I didn't visit the site today, I was waiting on the local AB drive specialist to return my call today before I head up there. I also wanted to ask him if he had a scope before I go online to rent one somewhere.

We'll see.


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## frenchelectrican (Mar 15, 2007)

Cow ., 

I want to say thank you for answering my question .,

I am leaning 50 to 50 between the VSD and the turbine pump.

Try to run the turbine in very slow speed mode so you can able watch the rotation if you can see it and if kinda jerky or not running smooth then you got bearing issue on pump side.

the one I have is Mitushibi variable speed controller it kinda simauir to your style. 

I set it on 1 % slip but ramp up I kinda shorten up some so it can build up pressure little quicker for water bearing.

But yes you can run the scope to see excatally what is going on with the motor and also with supply source to make sure it is clean.

and try to run it in bypass mode to read the current drawage to make sure it reading the same level as what you are pulling thru the vsd. 

The well I did work on few months back it came with 4 main bearings and yes it is about 120 meters deep.


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## keegank (Nov 1, 2018)

New to the forum. Used this to do a little troubleshooting and wanted to add what was ultimately our issue to add to the list.

Our problem is in a conveyor environment. We had master motor ahead in the line that was faulting out momentairly causing us to loose the other motors in the chain. This motor was our only drive motor and it caused an overcurrent when it went ON/OFF real quick. I guess the lesson in this is check your run connection to make sure you aren't loosing it momentairly. Test the drive up in Hand and if it turns off without coming back on, it's probably in your run signal somewhere.


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## Cow (Jan 16, 2008)

I haven't been back since I last posted. 



The customer was adamant the motor/pump were fine, but it still kept randomly faulting every couple, few days or so. The last time I talked to them, I mentioned leaving the cabinet doors open during the hot weather we were having at the time, since it seems like heat makes these act funny. They said they would try it.


I haven't heard from them since, looks like it's been about 3 months ago now.


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## John Valdes (May 17, 2007)

KeeGank
Welcome to Electrician Talk.
Please take a few minutes and fill out your profile.


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## JRaef (Mar 23, 2009)

Cow,
the PF400 has a separate Drive over temperature fault, I would have expected that yo have shown up if that was the case.


In re-reading this thread now, another issue recently came up, worth sharing if for no other reason than edumacation.


A similar situation turned out to be moisture in the conduit. There were burn-through holes in the conductors that were not detectable with the 500V megger they were using. I told them to use a 1000V megger and lo and behold, they found phase-to-phase shorts in the conductors. Then after having the cabinet open for a few hours as we waited for a management type to come down and accept this (because it was going to be expensive to pull new conductors), suddenly the shorts seems to go away! The boss leaves, satisfied that he doesn't have to spend money. The next day, the faults are back! They opened it up and meggered again, the shorts had returned. The issue was, condensation from the pump room was getting into the conduit and allowing the shorts to jump phase-to phase. But when the NEMA 12 enclosure door door was open for 2 hours waiting for the boss man, it evaporated through the open conduits into the electrical room and the megger held again (we could feel the air coming through the conduits). The next day, new condensation, the shorts returned, failed the megger. This time they closed the door again while waiting for the boss, he showed up, they showed him the failed megger test and got approval to pull the conductors. The old ones were THHN by the way, I had them replace it with XHHW, which is what I now recommend to everyone for the output conductors (when in steel conduit. Use VFD cable in any other situation).


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