ABB Sami - Star frequency converter

Is there anyone using ABB samistar frequency converter, I need help regarding GTO failures.
Its a scalar drive of 1250 kw capacity having multiple inverter conifiguration( Master - Slave).

I have had experience for a number of years with Sami drives up to 800kw which from memory are similar to the larger drives. i notice your question was posted a long time ago and may well have been resolved then. If not i offer the following comments relating to GTO failures. It is most important to torque the replacement GTO's as per the information provided by ABB. Failure to do this will result in sporadic failure of the GTO's. Use of calibrated torque meters is the way to avoid this. If you have done this and have further details of your problems still requiring a solution please e-mail me your question.