Opportunities and precautions in measurement of power loss in electrical steel laminations using the initial rate of rise of temperature method.

A system has been developed for measuring localized power loss of electrical steel laminations based on the initial rate of rise of temperature method. Hardware and software components were designed and developed individually to make an accurate measuring system. Three experiments were carried out to calibrate the system and quantify its accuracy over a wide measurement range. The application of the measuring system was demonstrated in two cases of measuring localized power losses near bolt holes in laminations and near artificial lamination edge burrs in a 300 kVA, 3 phase transformer core. The experimental results show that the developed system can measure localized power loss over a wide range with uncertainty of measurement less than ± 2%, but precautions are necessary when interpreting measurements in regions where the magnitude of the loss varies significantly over distances of less than a few centimeters