Some problems of the IEC single sheet tester measurement method for electrical steel sheet from a view point of material evaluation

Abstract

A study is carried out based on the evaluation of IEC-standard. Two measurement results on N.O. magnetic steel sheets, one from S-SST (Stress load type single sheet tester developed in our research laboratory), another is from SST based on the IEC standard regulation, are compared and discussed. As a result of the measurements, both magnetization curves coincide mostly, but magnetic power loss determined by IEC method is larger than that achieved by S-SST. The differences between them may be caused by magnetic field strength evaluation for each measurement method, magnetizing current method for IEC-type-SST and H-coil method for S-SST. The effective magnetic path is regulated in IEC but actually this may be variable according to the type of magnetic sheet, the structure of the SST and of applied magnetic field strength. In order to discuss this point, a virtual magnetic path length is introduced by using the applied magnetic field strength.