text: <s>[INST] Powerflex 755 - Input Module Explosion Summary: Issues involving the performance of the new Powerflex 755- productsGood Morning, I came here to find more information or suggestions regarding the last issue that we had in our plant. We have five Powerflex 75HP drives running pulp pumps. The electrical room has HVAC and optimal temperature and humidity conditions. Last week we had a sudden failure in one of the powerflex 700 drives, it had been in service for more than four years, and we haven't had any events during its normal operation. We began doing an extensive inspection and we found a hotspot in one of the modules, and one of the IGBTs were damaged. So far it was an isolated event but during last week we have two additional explosions of two new powerflex 755 drives. The whole rectifier module was damaged, and we guess it has something to do with the pre-charge circuit. We have lost three drives and we want to make sure that our installation is reliable. The typical installation scheme for our plant includes the input circuit breaker an output contactor and reactance. We did an extensive inspection of the ground scheme with no issues. We only found no PE-B jumper installed on the drives but we don´t think this has something related to the input module failure. What do you suggest?. How do you improve the MTTF of our drives (typical 3- 5 years ). ? Did anyone had a similar experience?. What did you install to reduce the probability of a sudden failure?. Does the new family powerflex 755 demand more from the installation in comparison with the powerflex 700 drives. Thank you for your comments or suggestions, Best Regards, Daniel Riascos. [/INST] If your supply is solidly grounded, then both the PE-A and PE-B jumpers should be installed. If it is not solidly grounded, then both jumpers should be removed. Rockwell has NEVER been able to adequately explain why they ship drives in an indeterminate state with one jumper installed and one removed. It's both IN, or both OUT, according to Rockwell's own literature. It just doesn't make sense. The jumper configuration could play a role in your failures. The output contactor is a different problem. Is there any chance the contactor opened while the drive was still running? If the contactor opens before the drive is disabled, you could blow up the drive. You must make sure the drive run command is removed before opening the output contactor. You would do better to move the contactor to the input side of the drive, or better yet use safe-torque-off option card and eliminate the output contactor entirely. \\n </s>