This standard specifies test methods and an interpolation procedure for determining losses and efficiencies of converter-fed motors within the scope of IEC 60034-1. 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 standard is applicable for comparison of different motor designs only. The standard also specifies procedures to determine motor losses at any load point (torque, speed) within the base speed range (constant torque range, constant flux 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.