Proposal for a General Atmospheric Correction Method of Breakdown and Withstand Voltages of Air-Gap Insulated Configurations Based on a Streamer–Leader Differentiated Model of the Breakdown Process

Abstract

Current atmospheric correction methods for breakdown and withstand voltages in long air-gap configurations show deviations in comparison to measurement data when applied to correct for unusual or atypical atmospheric conditions (i.e., altitudes above 2000 m a.s.l.). The corresponding standards IEC 60060 and IEC 60071 show inconsistencies, although both are being based upon the same measurements and empirical models. In its first part, the concept paper at hand presents the current knowledge and problems of atmospheric correction. In the second part, the authors outline the possible steps for a necessary new investigation as well as the algorithm of a hypothetical correction method. The proposed research is based upon the recent knowledge that any breakdown process in air-gap insulation consists of the sub-processes streamer and leader. While their characteristics seem to be independent of configuration and voltage form, their ratio and proportion varies, which, in turn, defines the value of breakdown voltage. Therefore, the authors propose a sub-process differentiated, measurement-based evaluation of the atmospheric influences air pressure, air humidity, air conductivity and temperature. The main goal is to develop a generic physical model of the breakdown process.

Keywords

• atmospheric correction
• breakdown voltage
• withstand voltage
• streamer
• leader
• air-gap insulation
• high voltage testing
• insulation co-ordination