Corona Detection Experience in Commercial Production of Power Cables with Extruded Insulation

On the basis of extensive corona detection experience on full reel testing of cables it is proposed that, in addition to corona level, a characteristic designated as "corona factor" be determined on each reel length of high-voltage cable with extruded conductor and insulation shields. The corona factor establishes the relationship between discharges in the cable and voltage stress over a stress range up to several times the operating level. In addition, it is proposed that full reel power factor measurements be made to provide a check on the resistivity of the extruded shields. The use of a novel continuous corona discharge detector in the laboratory to locate defects in the cable core, with insulation semiconducting shield in place, is described.