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.