Measurement Of Electrical Steels Magnetic Properties At Very High Flux Densities Using Improved Sst

Fundamental knowledge of the magnetic properties of electrical steels is essential to design a reliable and efficient transformer. It also helps predict the transformer performance under extreme operating conditions such as the high flux density scenario. However, the current relevant IEC standards on methods of measurement of electrical steels' magnetic properties only cover the flux densities up to 1.80 Tesla, and indeed those methods are unable to measure the steel characteristics when approaching deep saturation. In this paper, an improved single sheet tester (SST) with magnetic flux waveform control is introduced to measure the AC magnetic properties of electrical steels at high flux densities up to their nominal saturation magnetization. It utilizes the B-coil instead of the standard SST secondary winding to measure the flux density, which largely reduces the error caused by the air flux when the steel is in saturation. The performance of this improved SST is verified by measuring magnetic properties of high-permeability grain-oriented (HGO) 3% silicon steel at 50 Hz up to 2.0 T. The necessity of using H-coil in saturation is also investigated and discussed here. The improved SST would then contribute to a better understanding of the electrical steel behaviours in deep saturation.