Reliability, availability, and maintainability of high-power variable-speed drive systems

This is an overview of various aspects of reliability, availability and maintainability of large AC drives (medium voltage and >5 MW). The focus is on the definition and practical use of the relevant and most frequently used terms in this field, with the purpose to provide a base for common understanding between customers and suppliers. It is also mentioned how reliability evaluation procedures have been applied in a few cases. Reference is made to typical misinterpretations. The overview is limited to electric drives and does not include comparisons with other drive systems like gas and steam turbines.