Explain the factors affecting permeability and hysterisis loss.
Factors affecting permeability and hysterisis loss: When the initial permeability is high, the hysterisis loss is low and vice versa. This permeability and the hysterisis loss based upon the physical condition and chemical purity of sample. The crystals of a ferromagnetic material while cold worked experience deformation with a result of that the material has very poor magnetic properties. Because of the internal strains on the domains, greater magnetic field is needed to provide a definite magnetization. Thus the permeability reduces and the hysterisis loss is increased. A material, that has suffered magnetic damage because of cold work, may be heated to a adequately high temperature while the magnetic properties will be restored. The lowest hysterisis loss and highest magnetic permeability which can be obtained are restricted by the impurity content of the materials. Impurities affect the regular geometric pattern of the crystal and are harmful to the magnetic properties. The major impurities in the magnetic materials used for electrical machinery and transformer cores are carbon, oxygen, nitrogen and sulphur. Carbon is most detrimental and the amount of carbon is maintained to a low value of 0.01 percent in commercial materials.