Reduction of stray currents and magnetic fields from single-phase power distribution systems

This paper describes a simple, straightforward method for reducing stray currents and external magnetic fields from single-phase power distribution systems through the installation of a 1:1 current transformer. The current transformer magnetically couples the phase conductor and neutral conductors of a power cable, thereby forcing the return current to travel through the neutral rather than through other paths. Furthermore, if the phase conductor and neutral are sufficiently close together (preferably concentric), the magnetic field created by the return current in the neutral cancels the field created by the current from the phase conductor, thereby eliminating magnetic fields. This isolates the power cable from its environment while allowing it to remain solidly grounded. The current transformer may be applied to all sizes of power distribution systems, from underground residential distribution systems to wiring within buildings. This paper explains the theory behind this method, discusses possible practical applications of the method, and reports the results of a test installation by the City of Austin. These results show that the method can virtually eliminate stray currents and magnetic fields emanating from power distribution systems. However, more research should be done before the method is put into practice