Bringing New Life to High-Capacity Systems: Modernization of Legacy Adjustable-Speed Drives

This article discusses a method of modernizing existing adjustable-speed drives (ASDs). It provides the philosophy and the decision-making tools needed for performing a drive upgrade of installed old drives, from a drive manufacturer's perspective. In addition, a blueprint is provided for end users on evaluating the various retrofit/replacement options available. The end-user benefits and a comprehensive site survey are presented, reinforcing the concept of a drive modernization. The modernizations, whether on a dc paper mill drive or a large pipeline compressor drive, have given new life to the ASD while saving the operator thousands, perhaps millions, of dollars in capital expenditures to maintain or replace it. We conclude that manufacturers and operators have a new option to explore that eliminates the concern of the ASD being expensive to maintain or even obsolete after 15-20 years of operation.