Harmonic Composition of Low-Frequency Electromagnetic Emissions Associated with High-Voltage Transmission

Electric-field-strength measures of the spectrum between 10 and 200 kHz were obtained under dry conditions near a 500-kV transmission line. Comparison of the magnitudes of electric field strength between the odd and even harmonics of 60 Hz revealed a marked asymmetry. The ratio of odd to even harmonic field strength ranged from 19 to 3.3. A primary source of these emissions may be produced by components within the power systems with nonlinearities that are best described by odd functions.