Abstract
This chapter describes optimal characterization of composites and nanocomposites materials that handle traditional transformer cores to design transformer core materials. It attempts to offer new designs for new transformer cores to control the magnetization parameters. This chapter draws attention to theories and effective nanoparticle structure that tackle the characteristics of transformer cores. It further sheds light on the effects of nanoparticles on magnetization loss of transformer core by using individual and multiple magnetic nanocomposites. The forecasting and recommendations of the magnetic characterization are also presented for 1-phase and 3-phase transformer cores.