IEEE Std 1566, standard for performance of adjustable speed AC drives rated 375 kW and larger, was written by users, consultants and manufacturers to provide a common performance standard for large adjustable speed AC drives. The standard is a stand alone document which lists the performance requirements of all aspects of an adjustable speed drive system. It includes data sheets for the purchaser and the user plus some tutorial information. It is expected that the use of the standard will lead to less confusion and work in selection of drives, plus eventually a more durable drive system