text: <s>[INST] Powerflex 40 smoking, but working... Hi.We have an application with about 20 VFD's (PF40 and 400) up and running OK for 3 years.One day the operator noticed that smoke (a lot) where coming out from one of the PF40's, he tripped the EM stop to cut power to the drive. The drive was stopped (motor NOT running) at the time of the smoke.Maintanence people changed the motor (it turned out that the motor also was broken) they did NOT change the drive.After this everything worked fine.What is most likely to burn when the drive is stopped? (Varistors?)Can the faulty motor (short circuit) on the output of the drive make the drive burn without tripping the overload etc? (When motor not running)The circuit breaker on incoming lines to the drive never tripped. And finaly; Yes, the drive is changed now (even thoug its working fine). Best regardsMartin [/INST] We had a problem some years ago on the PF4/40's where our vendor was putting too much conformal coating on the precharge resistor. The drive would smoke for awhile until the coating burned off. Not sure if this is the same problem, but it sounds like it. \\n </s>