Magnetic Viscosity Measurement on Grain Oriented Steel

The phenomena of magnetic viscosity influences strongly the magnetizing characteristic especially at an active steep part of a hysteresis loop of transformer sheets made of a grain-oriented steel. The motivation for the viscosity measurement is the correct implementation of the Preisach hysteresis model. This article deals with the initial phase of determining the time constant of the flux density response to small steps of the field strength. Main relaxation parameters: the relaxation time and the time shift were calculated by the use of the curve fitting method. The relaxation time reaches 4 s for material M165-30S at the steepest part of the major hysteresis loop for the easy axis of magnetization and only 100 ms at the transverse magnetizing direction.