# Two drives blown up



## sparkiez (Aug 1, 2015)

If the main tripped, the problem is in the line side of the new VFD. Load side issues would likely be handled by the VFD. The VFD could have sat on the shelf for a long time. It also could have been defective from the manufacturer, could have been hooked up incorrectly, all kinds of things. Who knows? I would check the feeders for the line side, and meg to the disconnect. If nothing found meg to the motor. Then chalk it up to a bad VFD or one that has sat for a long time.


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## micromind (Aug 11, 2007)

If the replacement drive sat unpowered for more than a couple of years and the capacitors were not reformed, I could very easily see it blowing up at some point. 

I don't know about the first one though. Any possibility it was single-phased on the line side?

How many drives were running when each one blew up? Do they have line reactors? If no reactor, a very short power failure can blow a drive under the right circumstances.


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## gpop (May 14, 2018)

Its always interesting when they say it blew up. I think you have a plan of starting with the basics like checking and meging the motor unfortunately if it really did go boom the display and fault codes are lost. My only suggestion would be to disable the drive from resetting itself until you find the problem.


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## Helmut (May 7, 2014)

Motor is bad, or is going bad.


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## just the cowboy (Sep 4, 2013)

+1 for the sitting on shelf. Some manuals say do not let sit more than two years without power.


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## oliquir (Jan 13, 2011)

ive seen bad motor burned up abb vfds, motors had coolant leaking in them.


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## Cow (Jan 16, 2008)

Pictures tell the story. Motor megged fine.


Thanks for the replies and ideas everyone.


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## sparkiez (Aug 1, 2015)

Glad you found it. It is always a trip figuring this chit out.


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## JRaef (Mar 23, 2009)

I can't tell what that is. I see the burn marks on the first shot but I'm not sure what the other shots are showing. Was it the caps then? They usually pop immediately on energizing them though, not 6 hours later. I suppose its possible though that the report is purposely false, they popped immediately but the HVAC guy thought he had hooked it up wrong, so he claimed that it ran for 6 hours to make it look as though it was hooked up correctly, but died anyway. 

Had a pharma customer last year that blew a 10 year old 40HP PowerFlex 400, replaced it, then the new one blew immediately, they replaced it 3 more times with spares from their storage before calling me. Turns out that although when they bought them 10 years ago they were told about energizing the spare drives once per year for 2 hours, that info had been lost in layoffs. What shocked me though was them plowing through 4 sets of spares before thinking to call someone...


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## gpop (May 14, 2018)

JRaef said:


> I can't tell what that is. I see the burn marks on the first shot but I'm not sure what the other shots are showing. Was it the caps then? They usually pop immediately on energizing them though, not 6 hours later. I suppose its possible though that the report is purposely false, they popped immediately but the HVAC guy thought he had hooked it up wrong, so he claimed that it ran for 6 hours to make it look as though it was hooked up correctly, but died anyway.
> 
> Had a pharma customer last year that blew a 10 year old 40HP PowerFlex 400, replaced it, then the new one blew immediately, they replaced it 3 more times with spares from their storage before calling me. Turns out that although when they bought them 10 years ago they were told about energizing the spare drives once per year for 2 hours, that info had been lost in layoffs. What shocked me though was them plowing through 4 sets of spares before thinking to call someone...



I have to agree. If it did run for 6 hrs it probably would have faulted and put a warning on the screen. Of course someone could have just hit the reset and said goodbye to the drive.


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## just the cowboy (Sep 4, 2013)

*Ground fault*



JRaef said:


> I can't tell what that is. I see the burn marks on the first shot but I'm not sure what the other shots are showing. Was it the caps then? They usually pop immediately on energizing them though, not 6 hours later. I suppose its possible though that the report is purposely false, they popped immediately but the HVAC guy thought he had hooked it up wrong, so he claimed that it ran for 6 hours to make it look as though it was hooked up correctly, but died anyway.
> 
> Had a pharma customer last year that blew a 10 year old 40HP PowerFlex 400, replaced it, then the new one blew immediately, they replaced it 3 more times with spares from their storage before calling me. Turns out that although when they bought them 10 years ago they were told about energizing the spare drives once per year for 2 hours, that info had been lost in layoffs. What shocked me though was them plowing through 4 sets of spares before thinking to call someone...



Last picture. Motor bug was not taped right.


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## Cow (Jan 16, 2008)

JRaef said:


> I can't tell what that is. I see the burn marks on the first shot but I'm not sure what the other shots are showing. Was it the caps then?


I'm not sure. Since I wasn't the one to replace the drive, I didn't tear into it. The customer called the HVAC company to come replace the drive again after I made the repairs.

All I could see is what you see in that first photo. Something blew and shot all that soot out from behind the circuit board behind the incoming line voltage terminals.



JRaef said:


> They usually pop immediately on energizing them though, not 6 hours later. I suppose its possible though that the report is purposely false, they popped immediately but the HVAC guy thought he had hooked it up wrong, so he claimed that it ran for 6 hours to make it look as though it was hooked up correctly, but died anyway.


It did run for 6 hours. The customer told me that, and I have no reason at all to doubt him.

The customer did tell me after the HVAC tech replaced the drive, they could only run the motor up to 85-90% percent speed. They didn't know why at the time.

After I found the burned up motor connections, the customer of course wanted to know why the drive hadn't just shown a ground fault, etc?

I didn't have a good answer for that, other than telling him I have seen a few drives blown up from a ground fault. It's not common, but it's also not uncommon in my experience.

Unfortunately, they went through two drives to learn that, since it appears the HVAC tech didn't do any troubleshooting when he replaced the drive.


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## just the cowboy (Sep 4, 2013)

*Was it delta feed*



Cow said:


> All I could see is what you see in that first photo. Something blew and shot all that soot out from behind the circuit board behind the incoming line voltage terminals.
> 
> 
> QUOTE]
> ...


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## gpop (May 14, 2018)

Cow said:


> I'm not sure. Since I wasn't the one to replace the drive, I didn't tear into it. The customer called the HVAC company to come replace the drive again after I made the repairs.
> 
> All I could see is what you see in that first photo. Something blew and shot all that soot out from behind the circuit board behind the incoming line voltage terminals.
> 
> ...


On that drive 3023 would disable line fault and 30?? can disable ground fault warnings. Unfortunately on a blown drive its hard to tell what someone has done in the program.


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## Cow (Jan 16, 2008)

just the cowboy said:


> Is it a high leg or ungrounded delta feed? Look like MOV blew.



No, just regular 480/277v wye.




gpop said:


> On that drive 3023 would disable line fault and 30?? can disable ground fault warnings. Unfortunately on a blown drive its hard to tell what someone has done in the program.



Tough to know, the HVAC company have been the ones to do the programming since installation.


Since it has a removeable HIM, I'd wager they're copying parameter sets from it every time.


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## paulengr (Oct 8, 2017)

Cow said:


> No, just regular 480/277v wye.
> 
> 
> 
> ...




Check resistance between neutral (wye) and ground. Wouldn’t be the first time nobody hooked up X0 or something got damaged or corroded. MOVs are consumables. They are used up every time voltage exceeds their design limit. When they are used up they can fail open or shorted. Listed external surge arresters are fuse protected for that reason. Distribution class ones just blow their guts out.


Sent from my iPhone using Tapatalk


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## oliquir (Jan 13, 2011)

most drive will blow when it run at full power and a sudden spark to ground happen. Gnd fault will appear when a partial short to ground in the motor or a full short before the drive start. Also some drive needs ultra fast fuse protection so the fuses blow before the output igbt blow like they do on this case.


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## oliquir (Jan 13, 2011)

paulengr said:


> Check resistance between neutral (wye) and ground. Wouldn’t be the first time nobody hooked up X0 or something got damaged or corroded. MOVs are consumables. They are used up every time voltage exceeds their design limit. When they are used up they can fail open or shorted. Listed external surge arresters are fuse protected for that reason. Distribution class ones just blow their guts out.
> 
> 
> Sent from my iPhone using Tapatalk


the MOVs are not blown, they will explode or become black on overvoltage, those ones in the picture are in perfect shape,soot come from the big igbt module.


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## varmit (Apr 19, 2009)

A possible cause: If there is a loose or damaged load side connection or if a motor winding has an intermittent break after it gets warm, this could cycle the load off-on. This would be a VFD killer. Yes, I have seen both scenarios before.


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## Cow (Jan 16, 2008)

I ran into the customer again today for a different service call. I asked how the drive was doing, I hadn't heard anything. No news=good news.


He said it's been running fine since the other day. Supposedly, the HVAC tech had called ABB tech support and told them what I had found and fixed, tech support didn't think a blown apart motor connection would cause the drive to fail, that it had to be something on the line side.


The customer told me he went ahead and bypassed the line reactor before they replaced the drive the second time, because he didn't want to take any chances that may be the culprit.


I reminded the customer I megged the incoming VFD wiring back through the line reactor to the breaker the other day and it tested fine. I had also checked incoming voltage at the drive as well.


In any case, it's running, just without a line reactor now. If the customer is happy, I'm happy.


I think they may be debating on whether to remove all the other reactors too, at this point. I know they've been in for YEARS, and mentioned they are slowly dying off and probably all need to be replaced at this point. So they don't nickel and dime him to death as they die one at a time shutting down his process every time.


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## gpop (May 14, 2018)

They have a small built in line reactor on line and load so i wouldn't stress about removing a extra external one. 

Unless you send the drive out for repair or field strip it to see where the arc started you just have to except its blown and it most probably had something to do with the burnt out wiring in the pecker head. Had you have been onsite when the first drive blew i don't think we would be having this discussion. 

Now its time to sell the manager on a motor pm program.


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## paulengr (Oct 8, 2017)

Next replacement use a DC bus reactor instead. Same effect as line and load reactor but 1/4 The size, weight, and cost.

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## JRaef (Mar 23, 2009)

Line reactor causing the problem... LOL!


if they remove all of them, their drive failures will INCREASE! So get the PM contract now, you are going to make a MINT!


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## SpaceMonkey (Sep 19, 2018)

JRaef said:


> Line reactor causing the problem... LOL!
> 
> 
> if they remove all of them, their drive failures will INCREASE! So get the PM contract now, you are going to make a MINT!


JRaef (aka Drive Master) do you always recommend line reactors? I've read up on some of the instances where it is necessary, but am curious if its a good idea to always have one.


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## JRaef (Mar 23, 2009)

SpaceMonkey said:


> JRaef (aka Drive Master) do you always recommend line reactors? I've read up on some of the instances where it is necessary, but am curious if its a good idea to always have one.


Cheap insurance. It's not really about "harmonics" as most people seem to think. There are numerous instances that can cause severe voltage transients to come down the line from the utility and those transients can cause the VFD rectifier to allow destructive current flows. A reactor slows down the rise time of those transients to where that doesn't happen. But if your source transformer is closer to the VFD size, the transformer itself will do that for you.

But the best "rule of thumb" I use is that if the VFD has a DC bus choke, then you need a line reactor if your source kVA is more than 20 times the VFD kVA. If it is a cheaper drive with no DC bus choke, then you need a line reactor if the source is 10 times the drive kVA. Most Asian drives do not have DC bus chokes, most European drives and American drives do (although be careful, because smaller cheaper drives from them are likely Asian).

So for example if you have a cheap 5HP 230V VFD rated for 16A (3.6kVA) with no DC bus choke and the utility service transformer for the site is a 25kVA transformer, you probably don't need a line reactor because 3.6 x 10 = 36kVA. But if the utility transformer is 50kVA, you should use one. Then if you used a more expensive drive that DOES have a DC bus choke, you don't need the reactor again, because 20 x 3.6 = 72kVA. But if the transformer is 500kVA, you absolutely need one.

Also, you can use one larger line reactor ahead of multiple VFDs, which is a good strategy for when you have a bunch of small ones in one area. Just size the reactor for the collective FLA of the motors.


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