Determination of frequency dependant permeability of nonlinear ACSR core

Aluminum Conductor Steel Reinforced (ACSR) steel core is made of a nonlinear ferromagnetic material and usually, its permeability values are not known. Hence those values must be determined by measurements. For such measurements, two samples of torus transformer were constructed. Applying well known methods, for different primary currents and different frequencies, numerous hysteresis loops were measured and recorded on digital phosphor oscilloscope. Due to unknown, undesired external electromagnetic fields, a lot of electromagnetic noise was present in the recorded data and those disturbances were eliminated applying an appropriate numerical procedure. From the set of recorded and numerically processed hysteresis loops, normal magnetization curve was obtained, defining at the same time, static and dynamic permeability as a function of magnetic density vector magnitude. The influence of different frequencies was investigated as well.