The relationship of the measured A-C permeability at low inductions to the dynamic hysteresis loop geometry

Expressions relating a-c permeability and core loss to the dynamic hysteresis loop geometry are derived. It is shown that for inductions of 5 kilogauss or less, the a-c permeability associated with an iron-core inductor represented by a resistance in parallel with an inductance is equal to the slope of the major axis of the dynamic hysteresis loop. If the iron-core inductor is represented by a resistor in series with an inductor, the a-c permeability is not easily interpreted. To calculate the permeabilities and the core loss, it is necessary to measure the peak magnetic induction, the peak magnetic field, and the phase angle between them. This was done for several different materials at frequencies of 60 and 400 cps (cycles per second) and the results are compared to modified Hay bridge measurements. The two methods in most cases agree to within about 5%.