Validity of conventional and modern methods of no-load loss calculation in asynchronous machines - statistic approach

Abstract

A database of 460 asynchronous machines was established in order to investigate factors affecting the no-load iron losses of large cage induction motors and the validity of conventional and modern calculation methods for no-load iron losses. The database consists of design factors (such as dimensions, materials etc.), results of various no-load loss calculation methods and data from type tests. The factors affecting the iron losses are investigated statistically by using regression analysis. Based on the results of the regression analysis, a method for calculating the iron losses of open-slot cage induction motors is presented. The no-load losses are calculated with a conventional, finite element and the new statistical method, and the results are compared with the measured ones. The error of the statistical method seems to be less than ten per cent if the coefficients are properly chosen. For larger machines, the finite element analysis indicates systematically smaller losses than measured.