Medium-voltage adjustable-speed drives-users' and manufacturers' experiences

Energy management and the efficient use of electricity are being promoted by most electric utilities in Canada and the USA. In some cases, cash incentives are being offered toward conducting feasibility studies and project implementation when the energy paybacks are attractive. This paper presents the results of a comprehensive study completed in July 1995 for a large Canadian electric utility, covering users' and manufacturers' experiences with medium-voltage adjustable-speed drives (ASDs) for induction motors. Thirty out of forty users, primarily from the petrochemical industry in the USA and Canada, participated in completing a detailed questionnaire and reported on 66 medium-voltage drives ranging from 800 to 10000 hp. Information was gathered on the performance and reliability of the total drive system, including the motor, drive, driven equipment, isolation transformer, line filters and selection criteria. Also, four manufacturers of medium-voltage drives provided pertinent information on their ASD system, technology, features, customer requirements and future trends. This paper presents the analysis of the data gathered from both the users and the manufacturers. Based on the study findings, suggestions and recommendations are made to ASD manufacturers, users and utilities.