Electrical Engineering ⇒ Topic : Steinmetz Hysteresis Law

Steinmetz Hysteresis Law

To eliminate the need of finding the area of hysteresis loop for computing the hysteresis loss, Steinmetz devised an empirical law for finding the hysteresis loss. He found that the area of hysteresis loop of a magnetic material is directly proportional to 1.6 the power of the maximum flux density established i.e

where η is a constant called hysteresis coefficient. Its value depends upon the nature of material.The smaller the value of η of a magnetic material, the lesser is the hysteresis loss. The armatures of electrical machines and transformer cores are made of magnetic materials having low hysteresis coefficient in order to reduce the hysteresis loss. The best transformer steels have η values around 130, for cast steel they are around 2500 and for cast iron about 3750.

If V is the volume of the material in m³ and f is the frequency of reversal of magnetisation, then,