The longitudinal and transverse inhomogeneity of power losses at the magnetic induction amplitude of 1.5 and 1.7 T and frequency of 50 Hz and the magnetic induction at the magnetic field intensity of 1000 A/m were investigated on sheets made of cold-rolled grain-oriented silicon steel. It has been ascertained that the power losses and magnetic induction change in the longitudinal and transverse direction, leading to greater total detected differences on the surface of high-permeability grade M2H specimens than on the surface of standard grade Eo 10 specimens.

Due to good experience with the single strip tester using a self-compensating magnetic circuit, a single sheet tester based on the same principle was constructed. It was utilized for comparative loss measurements on specimens of different dimensions which give important hints for iron testing.

The influence of stress on components of the complex permeability of grain oriented transformer sheets has been investigated. Results show the best quality factor Q = μ′μ″ may be attained at optimal tensile stress. From this point of view, and with respect to magnetostriction, a suitable surface coating on sheets must be chosen.