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Figure 5.11 B–H characteristic of a magnetic material
Flux density,
where A is the cross-sectional area of the core. The magnetizing force is
expressed in terms of ampere-turns per unit length. That is, magnetizing force
H is given as
Where l is the length of the flux path.
5.4 HYSTERESIS LOSS AND EDDY CURRENT LOSS IN MAGNETIC MATERIALS
Magnetization of the magnetic material in opposite directions due to
application of alternate magnetizing force, involves certain amount of work
done. The work done is represented by the area of the hysteresis loop. The
hysteresis loop area depends upon the nature of the magnetic material. In
selecting the material for the core of any electrical machine and equipment, a
study of the hysteresis loop is made. For example, if we want that high flux
should be produced by applying a low magnetizing force, and the loop area
also be small then we must use a material whose hysteresis loop area should
be as shown in Fig. 5.12 (a). A certain percentage of silicon when added to
steel provides this kind of B–H characteristic. Silicon steel is used as the core
material of transformers, as will be studied in a separate chapter. In Fig. 5.12
