Magnetic properties in axial 50 Hz fields of steel core wire for overhead-line conductors

As a result of the spiralling of the power-frequency current around the core of a steel-cored overhead-line conductor, a longitudinal alternating magnetic flux is set up in the steel core. This flux produces active and reactive power losses, which give rise to increases in the effective resistance and inductance of the conductor. Results are given of experimental work to determine the effects of conditioning, galvanisation, preforming, stranding, temperature and tensile stress on the magnetic characteristics of three sizes of 85ton grade 0.55%-carbon-steel wire. It is shown how the increase of resistance and inductive reactance of the conductor can be calculated for conditions in service.