Reduction of power system magnetic field by configuration twist

The low-frequency magnetic field in the vicinity of helical three-conductor arrangements carrying symmetric three-phase alternating current is studied by analytical numerical and experimental methods. New approximate and simple closed-form expressions are derived for all three components of the three-dimensional field vector as function of current, distance, pitch and conductor spacing. Comparison is made with numerical results. Measurements on an experimental helical arrangement have also been performed for verification.