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Unread October 4th, 2011, 08:14 AM   #1
chud
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igbt desaturation

Im tearing my hair out regarding this issue. We have a motor with an ATV61 on it. The drive keeps tripping out on IGBT desaturation. We have meggered the cable and motor and everything comes up clean. We have even changed the motor and still get this fault.
The ATV61 does have an IGBT diagnostics which checks the status op each IGBT. The test says all the IGBT's are ok with or without the motor connected.
Just hoping here someone has had the same problem somewhere.
Thanks for any advice
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Unread October 4th, 2011, 08:49 AM   #2
L D[AR2,P#0.0]
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New start-up or has this problem developed on an exiisting installation ?

What are the fault conditions: e.g. drive runs for 1 sec/min/hour/day (delete as applicable) and then faults?
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Unread October 4th, 2011, 09:01 AM   #3
chud
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Existing installation.
It tripped a couple of times in the past on this fault but then clears and then runs for weeks. But now it cant even do an autotune anymore without tripping on this fault. We are bypassing the motor choke now just to see if it makes a difference. As soon as the motor accelerates it trips out. +- 1s into startup
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Unread October 4th, 2011, 10:19 AM   #4
jrwb4gbm
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Just guessing here maybe something will help. Here are a few guesses.
Might be heat related. Do you have an extra fan you can temporarily add to blow on the the IGBT's? The IGBT's might be breaking down under starting load conditions. Try a small motor connected to it for a test. Maybe try long acceleration and long deceleration setting.
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Unread October 4th, 2011, 11:32 AM   #5
Johnster
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I saw something similar on some C-H SV9000 drives. To get it going you de-power everything, and short the drive leads together (discharges some capacitors inside the drive...or maybe the ghosts of Cutler and Hammer are encouraged by this move...not sure then reconnect, power-up and go.

Only fix was outright replacing the drive- that worked every time We are always commissioning so it was an easy warranty claim (the salesdude came out and looked at our install and loads, and did the paperwork to get us a new drive)

(we also bought an arseload of those drives (400+ per year) so the salesdude/CH was probably going to cut us more slack than other customers...)

-John
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Unread October 5th, 2011, 07:40 AM   #6
chud
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Quote:
Originally Posted by jrwb4gbm View Post
Just guessing here maybe something will help. Here are a few guesses.
Might be heat related. Do you have an extra fan you can temporarily add to blow on the the IGBT's? The IGBT's might be breaking down under starting load conditions. Try a small motor connected to it for a test. Maybe try long acceleration and long deceleration setting.
Thanks for the reply guys. We got the schneider techs to come have a look. I dont think it can be heat though. The drive has been standing the whole night and day and when we tried again this morning same thing. Even when we just to an auto-tune.
Will let you know what happened
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Unread September 16th, 2019, 03:21 AM   #7
kaareem
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Hi
I got this problem, please help me what's I have to do if igbt desaturation happens without any issues with motor and igbt test
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Unread September 17th, 2019, 06:02 AM   #8
John.S
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Hi,

In our GE innovation series drives this message means that the measured voltage over the IGBT that is turned on stays at a to high level.
There can be a problem with the gate drivers, but mostly it is a problem with internal connections, or dirt in the drive.

gr. John.
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Unread September 17th, 2019, 01:52 PM   #9
jraef
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IGBT saturation is a way in which some mfrs detect a short circuit on the output in order to protect the IGBT and the DC bus. It is measuring the voltage on the collector-emmitter as a way to use the IGBT itself as the current measurement device in order to cut down on the number of components in the drive. One down side to that method is that it is susceptible to noise issues causing false trips. So additional (less expensive and smaller) components are added to filter out that noise, usually comprising an RC snubber circuit. If one of the components in the RC snubber is failing, it will give you false trips. If the tripping seems random and inconsistent, my guess is that's what is happening.


That said, these are not typically discrete components that can be replaced, they are buried in the IPM (Intelligent Power Module) of the VFD, so you would have to replace the IPM, and in most cases that is not economically feasible to do in the field.

Last edited by jraef; September 17th, 2019 at 01:55 PM.
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Unread September 18th, 2019, 05:12 AM   #10
kaareem
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Quote:
Originally Posted by John.S View Post
Hi,

In our GE innovation series drives this message means that the measured voltage over the IGBT that is turned on stays at a to high level.
There can be a problem with the gate drivers, but mostly it is a problem with internal connections, or dirt in the drive.

gr. John.
thank you very much
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Unread September 18th, 2019, 05:12 AM   #11
kaareem
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thank you very much sir
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Unread September 25th, 2019, 09:49 AM   #12
kaareem
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Quote:
Originally Posted by John.S View Post
Hi,

In our GE innovation series drives this message means that the measured voltage over the IGBT that is turned on stays at a to high level.
There can be a problem with the gate drivers, but mostly it is a problem with internal connections, or dirt in the drive.

gr. John.
HI everyone
I have removed motor connections from VFD and tested its showing now igbt short circuit in fault history and I done test procedure I found 6 igbt are open, what it's means and why it's happened
Firstly I would like to inform that with morot connection it's alarm was igbt desaturation and now when I started without motor it's alarm changed I want to know why it's happened, is this possible that without motor igbt will be short circuited ?????
Please let me know
Thanks everyone for replying me
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