Inverter-rated motors: what they are and how to identify them

An increasing number of industry specifications, especially those for specific projects written by engineering companies, call for inverter-rated motors. Despite this being a common request, Australian standards do not provide an official definition for the term inverter-rated electric motor.

By and large, users are left to decide on their own, the motor requirements suited for use with inverters. On the other hand, suppliers are free to interpret the term inverter-rated in whichever breadth and depth they wish.

This white paper reviews the significant effects an inverter has on an induction motor; it summarises the international guidelines for the inverter-driven motor applications, mainly those contained in the latest International Electrotechnical Commission (IEC) technical specifications.

This white paper also includes a study investigating current leading inverter brands and discusses how the results influence these standard guidelines. It proposes additional technical considerations for a given electric motor to be used safely and reliably with modern IGBT-based inverters.