Advanced Uncertainty Calculation Method for Converter-Fed Motor Loss Determining

There is only a single practical method to determine the losses of converted-fed electrical machines. The method is based on mechanical output and electrical input power measurements. When this method is used, the loss measurement uncertainty is a function of the efficiency. The electrical motor efficiency increases non-linearly with increasing rated power. Therefore, the higher the rated power of the motor is the more care should be laid in the analysis of the efficiency measurement results. Here, a workflow starting from measurement instruments' data sheet information to final measurement uncertainty result is presented for three converted-fed induction motors with different rated power of 15 kW, 37 kW and 75 kW. The results are applicable for all rotating field machines regardless of technology.