Experimental investigation into VHF electromagnetic radiation from power system arcs

Research suggests that electromagnetic radiation in the form of atmospheric radio waves (or sferics) originate from power system apparatus when transient currents occur. This can be during events such as switching or faults where an arc forms part of the current path causing nonlinearities. The frequency spectrum of these sferics is known to exist from the VLF to the UHF region. This paper describes an experimental investigation into the properties of the origin, propagation and signature of VHF electromagnetic sferics induced by power system arcs. Arcing experiments involving an arcing welder and 132 kV switching events are used to investigate the outlined sferic processes. Demodulation, Fourier transform and short time Fourier transform (STFT) techniques are applied to further describe the power system induced sferic and to attempt discriminate it´s presence from background noise and other signals