Stray load losses in induction machines a review of experimental measuring methods and a critical performance evaluation

Abstract

As stray load losses are the most unknown element of the balance of power in induction machines a number of theories how to calculate and to measure these losses exist. The following intends to describe, compare and criticise a number of different measuring methods performed with the same machine. By discussion of the theoretical background of additional losses the deficiencies of the different methods can be seen. The comparison of the results delivers surprising equalities of methods in the loss values but also very disturbing false measurements which might support the engineering community in sticking to the convenient percentage value given in the standards. However to meet the stringent requirements of high efficiency motors a thorough investigation on measurement of stray load losses is still necessary.