Electric field measurement on time domain generated by corona on insulators on distribution systems

Radiofrequency interference and TV interference are becoming a problem in urban and rural areas. This interference is generated by high voltage transmission lines as well as distribution lines. The RF noise can be produced by polluted or damaged insulators and by metal parts of the distribution lines. The corona effect on the surface of the dielectric material produces high frequency electromagnetic fields during the ionisation and during the recombination periods. Fields of different intensity are produced by positive and negative voltages. The insulator flashover (leakage current) also produces electromagnetic fields. A new technique to measure these fields is developed. This technique measures the radiated fields in the time and frequency domains. This permits characterisation of the radiated field and thus identification of the type of the source. Several measurements were performed by varying the type of the RF generator, i.e. new and broken insulators. A digitising oscilloscope was used to observe the electric field on a monopole antenna and the AC voltage applied to the insulator