# Altivar 71 - IGBT SHORT CIRCUIT FAULT



## Sheel (Aug 26, 2019)

Hi.
I have a Schneider Altivar 71 drive that is giving an error of "IGBT short circuit". I have replaced the IGBT Power Card with a new card. After reconnecting the drive and powering it up, it is still giving the same error.
Any help or advice on how to resolve this would be highly appreciated.
Thanks.


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## Peewee0413 (Oct 18, 2012)

https://www.schneider-electric.com/en/faqs/FA315241/

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## Flyingsod (Jul 11, 2013)

Well seeing that the fault was an Igbt fault you prolly shoulda changed the igbt’s. And don’t go cheap and replace just the one. If something happened to it something happened to the others. Customers always seem to think I’m lying to them and insist I just replace the shorted one. Seems like about 70% of the time I’m back within 3 months to replace the others that have failed. 


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## just the cowboy (Sep 4, 2013)

Flyingsod said:


> And don’t go cheap and replace just the one. If something happened to it something happened to the others. Customers always seem to think I’m lying to them and insist I just replace the shorted one. Seems like about 70% of the time I’m back within 3 months to replace the others that have failed.
> 
> 
> Sent from my iPhone using Tapatalk


Yes! Back in the old days we on drives we replaced all SCR's and even on Tube drives we changed both Thyratron tubes due to stress.

Cowboy


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## JRaef (Mar 23, 2009)

What is the size of the drive? If it's under 50HP, most likely the drive uses what's called an "IPM" (Integrated or Intelligent Power Module) that has all 7 IGBTs, all 6 Diodes and the firing circuits for them mounted into one epoxy molded unit. What that means is that you cannot change just one IGBT any more, in fact you likely cannot even replace the IPM as a unit because they are wave soldered into the control board then glued to the heat sink. That would explain why the FAQ says you must replace the entire drive.


This is what the IPM looks like:









What you probably replaced was the CONTROL BOARD for the IGBTs, not the IGBTs themselves.


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## JRaef (Mar 23, 2009)

Here is what the IPMs look like inside with the potting goop removed: (again, these are NOT repairable, this is just for illustration)


Control layer, where all of the firing circuitry resides. The VFD will have a firing board that uses TTL (Transistor-Transistor Logic) level 5VDC signals to tell the IPM which device to fire and when, then these circuits amplify those signals to the transistors themselves:









Transistor and diode layer, the diodes are on top, the transistors are on the bottom. These look small because of the tiny little wires going to each device, but this photo is of a 300A rated IPM:


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## paulengr (Oct 8, 2017)

Set it to V/Hz mode if it isn't already. Disconnect motor. If it fires up and runs you found your problem. Sometimes overcurrent faults confuse the drive software as to whether it's an IGBT or not. If this test fails, replace the drive or if it's big enough to be modular the IGBHe themselves. There are a tiny few applications where the 71 is still needed but for most use the 630 or 930 depending on application.


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## psgama (Oct 26, 2015)

Check the drive over with your multimeter.

There are some input fuses on the larger drives as well under the cover.


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## BrodVictor (Apr 30, 2021)

Hi....your error likely lays outside the force card at that point.

I have no clue about the gadget or some other parts within it. Possibly we could be more assistance in the event that you showed more pictures of how it functions and how it associated outside the force card.

printed circuit boards


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## SWDweller (Dec 9, 2020)

what is a force card?


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## paulengr (Oct 8, 2017)

psgama said:


> Check the drive over with your multimeter.
> 
> There are some input fuses on the larger drives as well under the cover.


What is that screwy picture and notation saying?

You can do a diode test on LV drives but it only detects failed back diodes and shorted IGBTs and SCRs. Is that what this is showing?

A shorted thyristor failure is just that. Unless your drive is modularized like a bricks drive you can’t repair. The bricks drives are repairable. The way you can tell is if the DC bus is not accessible...you don’t see 2 or 3 terminals between the RST and UVW connections. Either way 888-SQU-ARED can walk you through this over the phone.


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