Any one pls explain what are the causes of IGBT failure?It has happened in a brand new simovertVC drive, there was no fault on the load side.

 

Hi,
In the very early days of inverters, failure rates on iunstallation were high, IGBT quality nowadays is very good, having said that If the unit was correctly installed, then the clue was
it the fact that it was brand new, the bathtub
curve of reliability comes into play! Minute manufacturing faults, which could easily have passed commissioning tests can kill these devices stone dead in mS. It is usual for manufacturers to replace 'out of box failures' and of the very few I have had, the manufacturers always seem happy to do this.

 

With Simovert drives I have experienced when you do auto calibration of the drive the IGBT blows up. There was no problem in the load.
We found latter that it was because the motor resistance value is not manually keyed in to the motor manager and this was not documented.
The default motor resistance data in the motor manager was about ten times more to the to the actual motor resistance value. So as the drive tends to calibrate it pumps in more DC current ( I suppose) and destroyed the drive. A bad and costly lesson to us. The drive supplier refused to accept and damaged one drive also !
regards,
sekar