Current State of Analysis and Comparison of Atmospheric and Altitude Correction Methods for Air Gaps and Clean Insulators

The dielectric strength of air gaps is affected by both: air density (determined by temperature and pressure) and humidity. In order to normalize external insulation strength of power equipment under different conditions, such effects need to be taken into account when external insulation is designed and tested. There are three main applications for atmospheric and altitude corrections: insulation coordination, equipment design and equipment testing. The existing correction methods for the different applications can lead to large differences in the applied correction factors and a need for harmonization between the standards was recognized. This paper presents the continued work of CIGRE WG D1.50 “Atmospheric and altitude correction factors for air gaps and clean insulators”, some…