This part of 61377 applies to the combinations of motor(s), inverter and their control system, and its object is to specify: - the performance characteristics of electric drives consisting of an inverter, alternating current motors, and the related control system; - methods of verifying these performance characteristics by tests. Two categories of combined systems can be considered: a) alternating current motors fed from an inverter without any control between the mechanical output (torque, speed) and the inverter itself (mostly auxiliary motors, for example cooling fan motors). The motor works exactly as if it were fed from a busbar (at variable frequency and voltage or not); b) alternating current motor(s) (paralleled or not) with a control between the mechanical output and the inverter. The first category of systems is tested according to IEC 60349-2 and IEC 61287-1. This standard applies to the second category, mainly traction drives. IEC 60349-2 applies to convertor-fed alternating current motors, IEC 61287-1 to power electronic convertors, IEC 60571 to electronic equipments, and this standard applies to the combination of motor(s), inverter, and their control system. As a consequence, IEC 60349-2 describes the tests to demonstrate the compliance of the motor to its specification, IEC 61287-1 does the same for the inverter. It is self-evident that some of the tests mentioned in this standard generally may replace the corresponding ones described in the abovementioned standards. An agreement should be reached between the parties to avoid the duplication of tests. A complete combined test is heavy, and often requires high power, which is not always available in a workshop. An agreement between user and manufacturer may be reached to allow testing either in the workshop or on the vehicle. Testing may be split off partially in a workshop and partially on track. At the time of drafting this standard, only the following combinations of motors and inverters were used for traction applications, but it may also apply to other combinations which may be used in the future: - asynchronous motors fed by voltage stiff (voltage source) inverter; - asynchronous motors fed by current stiff (current source) inverter; - synchronous motors fed by current stiff (current source) inverter. The input of these inverters can be a d.c. supply line, a rectifier, a chopper, an input convertor, a diesel generator with integrated rectifiers, etc.