ABSTRACT
All materials used in the construction of electrical machines can be divided into three groups:
1. Active materials, i.e., electric conductors (magnet wires), superconductors, electrical steels, sintered powders and PMs
2. Insulating materials 3. Construction materials
All current conducting materials (with high electric conductivity), magnetic flux conducting materials (with high magnetic permeability), and PMs are called active materials. They serve in the excitation of the EMF and MMF, concentrate the magnetic flux in the desired place or direction, and help to maximize the electromagnetic forces. Ferromagnetic materials are divided into soft ferromagnetic materials, i.e., with a narrow hysteresis loop, and hard ferromagnetic materials or PMs, i.e., with a wide hysteresis loop.
