Time varying magnetic fields under power transmission lines

The growing concern of the health effects of the magnetic fields resulting from the ac currents carried by the electrical power transmission lines necessitates a focus on the time varying nature of these fields. Effective values of these fields [1-9] do not reveal such valuable information. In this paper the time varying nature of the magnetic flux density (B) at ground level is under focus. Three-phase and 6-phase circuit, both compact and conventional designs are considered. At center line of tower, single 3-phase circuits produce almost vertical pulsating magnetic flux density vectors, double 3-phase circuits produce almost horizontal pulsating vectors and six-phase circuits produce almost rotating vectors.