# VFD burned



## eric7379 (Jan 5, 2010)

Were there any witnesses to your screw-up? Can you quietly throw it away and order another one? Can you put it back in the box and pretend you don't know what happened to it? Can you blame it on someone else?


In all seriousness, if this happened to me and the drive wasn't terribly expensive, I would just buy a new one and chalk it up as a lesson learned.

I would also look into an industrial electronics repair shop that might be able to fix it. We have several that we use. Can't speak for Peru, though.

When you say "something blew up" that usually isn't a good thing. The repair cost might be so expensive that you might be better off buying a new one.


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## oliquir (Jan 13, 2011)

when you reconnect it to 220v does the vfd was ok even if it has make varistor blow. Once varistor is exploded vfd should still work if only the varistor was damaged. Sometimes there is fuses inside the vfd to prevent damage to boards


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## chuzkin (Oct 2, 2013)

Dear Eric.

Price is 8000.00 dollars plus taxes, so I do not think it is a cheap product.

Dear oliquir. I think you are right, but i am a little afraid. I prefer to change any damaged component before applying power again. What do you think?

Best regards.


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## HARRY304E (Sep 15, 2010)

chuzkin said:


> Dear Eric.
> 
> Price is 8000.00 dollars plus taxes, so I do not think it is a cheap product.
> 
> ...


Well that stinks,

If you can replace the parts then do it,just make sure everything is rated for the voltage you're using .

Good luck and welcome to the forum:thumbsup:


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## HARRY304E (Sep 15, 2010)

chuzkin said:


> Dear friends.
> 
> Today I made a terrible mistake. I connected a SIEMENS MICROMASTER 440 220VAC input to 440VAC. After some seconds, smoke appears and I cut the circuit braker. Then, I change power supply to 220VAC (correct) and when turn on the braker, something blew up inside the VFD.
> I checked inside and it seems it was just 1 of the 3 input (line) varistor S20 K275. All the other boards look fine. I will change varistor. Capacitors look fine (how can I test them?), and rectifier diodes are ok.
> ...


Also check this out , you may be able to get some help...

http://cache.automation.siemens.com/dnl/jMxNzQzNQAA_14346893_HB/440_OPI_en_1202.pdf





.


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## John Valdes (May 17, 2007)

So, its a big drive. Now , you need a repair shop. Where are you located.
BTW. What the drive HP?

Most likely you took out the input section only as you never were able to start it. You may be able to replace the bridge yourself?


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## HARRY304E (Sep 15, 2010)

John Valdes said:


> So, its a big drive. Now , you need a repair shop. Where are you located.
> BTW. What the drive HP?
> 
> Most likely you took out the input section only as you never were able to start it. You may be able to replace the bridge yourself?


He is in Peru.


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## McClary’s Electrical (Feb 21, 2009)

Paging Jreaf.......


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## HARRY304E (Sep 15, 2010)

mcclary's electrical said:


> Paging Jreaf.......


He is the top Dog with this stuff..:thumbsup:


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## just the cowboy (Sep 4, 2013)

Yes you made a mistake and glad no one was hurt. But mistakes happen we all make smoke at least once, When i was teaching a basic electric coarse to a companies mechanic’s I told them it was going to happen someday. When it does you will say ah sh-- first then, then look around to see if anyone saw it, then fix it, no problem. So happens I was tracing wires at the same plant and a ground wire fell out of the panduit onto the 480V main lugs, booom half plant shut down, it was a bread plant and bread was in ovens. They came over asked if I was ok, then asked if I said oh Sh-- and looked around, yes I did. We restored power and sped up ovens so bread was ok. But remember sometimes "1 ah sh-- will cancel out 100 at-a-boys you may of had" 

Oh by the way did you say ah sh-- and look around
:whistling2:


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## eric7379 (Jan 5, 2010)

just the cowboy said:


> *But remember sometimes "1 ah sh-- will cancel out 100 at-a-boys you may of had"*
> 
> Oh by the way did you say ah sh-- and look around
> :whistling2:


Ain't that the truth!!

Seems like nobody remembers you by how good you are or were. They just remember you by your screw-ups!


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## eric7379 (Jan 5, 2010)

chuzkin said:


> Dear Eric.
> 
> Price is 8000.00 dollars plus taxes, so I do not think it is a cheap product.
> 
> ...


Ok, so that is obviously beyond the realm of just simply ordering another one. 

My best suggestion would be to contact your local Siemens rep or supplier. They might be able to help with finding a repair company or a service company that might be able to come directly to your site and do a thorough diagnosis of your drive.


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## Jlarson (Jun 28, 2009)

Micro drives aren't worth fixing.


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## JRaef (Mar 23, 2009)

Jlarson said:


> Micro drives aren't worth fixing.


At $8000, I hope to shout that isn't a MICRO drive! If so, he needs to find a better supplier!

chuzkin,
I seriously doubt that one of the MOVs burning out is the only problem, but sometimes you can get lucky!

More likely because you exceeded the voltage rating of the diodes, they all conducted simultaneously. That then could mean a dead short on the rectifier section, which might account for the magic smoke coming out. If you were lucky, hopefully that was just the pre-charge resistor burning open and preventing the capacitors from swelling. At the very least, you will likely need to replace the entire diode bridge front end, and most likely the pre-charge circuit. Even though the diodes may test OK (although I don't know what you tested for and with), they are likely severely stressed and ready to fail now anyway. I would not trust them. If you know what you look for on the caps you can inspect them for signs of swelling, which indicates they are burned out too.

My experience on things like this is that you end up rebuilding the drive one section at a time, only to find the next failure point, so you end up at 5X the cost of just replacing it in the first place.

If you have the Siemens drive manual, somewhere near the back should be a troubleshooting guide with a description of how to test the diodes, capacitors and transistors. If not, you can get that info in any A-B VFD manual, it's all the same.

Oh and on the MM440, I believe that the control power supply for the electronics is pulled off of the DC bus as well, so that means the DC-DC converter may have been toasted too. They are really finicky.


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## Jlarson (Jun 28, 2009)

IDK, I'm not up on my Siemens drives (really bugs a friend that reps Siemens, keeps giving us catalog CD's :laughing Didn't think there was a lot of a 240 v offering for the 440 drives.


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## ScooterMcGavin (Jan 24, 2011)

Here. This should take care of your problem...


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## JRaef (Mar 23, 2009)

I take it back on the Siemens manual providing test information. Apparently they don't think very highly of their customer's abilities... No mention of troubleshooting at all, other than reading the display information.

Here's a halfway decent simplistic guide to doing basic VFD component checks with a multimeter.

http://www.newark.com/pdfs/techarticles/agilent/TroubleshootingVFD.pdf


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## oliquir (Jan 13, 2011)

JRaef said:


> At $8000, I hope to shout that isn't a MICRO drive! If so, he needs to find a better supplier!
> 
> chuzkin,
> I seriously doubt that one of the MOVs burning out is the only problem, but sometimes you can get lucky!
> ...


almost all 3ph bridge rectifiers are 1200V and more. it is probably the same bridge in a 600v vfd. so yes maybe it just burn the precharge resistor. i have repaired several vfd, on a moderate overvoltage they are not so bad, on a lightning surge that not the same game


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## JRaef (Mar 23, 2009)

oliquir said:


> almost all 3ph bridge rectifiers are 1200V and more. it is probably the same bridge in a 600v vfd. so yes maybe it just burn the precharge resistor. i have repaired several vfd, on a moderate overvoltage they are not so bad, on a lightning surge that not the same game


You're right on the bridge components, i should have thought that through a little more. It's not true on the transistors though, there is a big difference in cost on 300V class and 500V class transistors so a 230V drive will have lower rated transistors than a 480V drive. Then if the drive is small enough to use an IPM instead of discrete diodes and IIGBTs, the bridge components (and traces, conductors in the IPM, etc. etc.) will only match the lower voltage requirements. That's where that thought came from, but I should have remembered that this was obviously going to be big enough to not be using an IPM, so the discrete bridge diodes would be the same regardless of voltage. 

Good catch. Increases his chances of surviving this with just a costly repair instead of total replacement.


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## chuzkin (Oct 2, 2013)

Dear friends!

Only one of the 3 mov's in input stage was burned.
I replace it and now everything is working ok.

thanks for suggestions.


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## triden (Jun 13, 2012)

Good jog chuzkin!

Varistors are designed to fail shorted when their clamping voltage is exceeded. This is so that they can shunt the high voltage away from the sensitive components that can't handle it. The MOV part of the circuit will be very "beefy" in order to shunt that voltage and accompanying current from the rest of the PCB. I would say in most cases, the MOV's will do their job and replacing them is most often the solution. Although there are always exceptions with transients with high slew rates (lightning, etc), but no component manufacture has yet to put a guarantee on lightning.

When I used to be in the PCB design industry, I used to always put a fuse before the MOV so that it kills the power to the circuit in a transient condition. I can assure you that Siemens designed the PCB with a similar approach that was able to blow the specified breaker feeding the drive when the MOV shorted.

Again, good troubleshooting skills, and I'm glad you fixed it!


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## Safari (Jul 9, 2013)

John Valdes said:


> So, its a big drive. Now , you need a repair shop. Where are you located.
> BTW. What the drive HP?
> 
> Most likely you took out the input section only as you never were able to start it. You may be able to replace the bridge yourself?


welcome back john valdes hope am not so late in saying so

Sent from my HUAWEI Y210-0100 using Tapatalk 2


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