PWM drive overvoltage trips in electrochemical plants

Case study application paper for a recurring problem the authors have recently experienced in electrochemical plants using low voltage PWM ASD´s. Low voltage ASD´s are tripping on 1.3 per unit voltage switching transients lasting 1-3 cycles. The ubiquitous ASD has been so successful that it is now used on critical plant processes that cannot tolerate outages. Most power system components are built to operate with a significant level of transient voltage resilience. This does not appear be the case for some of the low voltage ASD´s in use today. This paper examines this issue and provides a specifying methodology for new ASD´s, field proven cost effective corrective measures for installed ASD´s, and a case study.