This part of IEC 61800 applies to general purpose adjustable speed a.c. drive systems which include power conversion, control equipment, and also an a.c. motor or motors. Excluded are traction and electrical vehicle drives. It applies to systems connected to line voltages up to 1 kV a.c., 50 Hz or 60 Hz, and load side frequency up to 600 Hz. EMC aspects are covered in IEC 61800-3. This part of IEC 61800 gives the characteristics of the converters and their relationship with the complete a.c. drive system. It also states their performance requirements with respect to ratings, normal operating conditions, overload conditions, surge withstand capabilities, stability, protection, a.c. line earthing, and testing. Furthermore, it deals with application guidelines, such as control strategies, diagnostics, and topologies. This part of IEC 61800 is intended to define a complete a.c. PDS in terms of its performance and not in terms of individual subsystem functional units.