This part of IEC 60034 specifies test methods and an interpolation procedure for determining losses and efficiencies of converter-fed motors. The motor is then part of a variable frequency power drive system (PDS) as defined in IEC 61800-9-2. Applying the approach of the comparable converter, the motor efficiency determined by use of this document is applicable for comparison of different low voltage motor designs only. The comparable converter approach is not applicable to medium voltage motors. The document also specifies procedures to determine motor losses at any load point (torque, speed) within the constant flux range (constant torque range, base speed range), the field weakening range and the overload range based on determination of losses at seven standardized load points. This procedure is applicable to any variable speed AC motor (induction and synchronous) rated according to IEC 60034-1 for operation on a variable frequency and variable voltage power supply.