A Non-Contact Technique for Determining Harmonic Currents Present in Individual Conductors of Overhead Lines

This work derives the relations between harmonic or fundamental currents in overhead three-phase circuits and the magnetic fields measured under the lines. These relations are used to calculate harmonic currents in each conductor from the magnetic field data. Calculated and experimental field patterns are shown, and a specific technique for field measurements and current calculations is outlined. Laboratory results indicate that a good level of accuracy is attainable with this non-contact technique.