Relevance of Corrections with atmospheric Conditions of High Voltages used for Insulation Testing

The disruptive voltages used to test the self-restoring insulations are influenced by the actual atmospheric conditions in which they are performed. The main factors of influence are atmospheric pressure and humidity, the ambient temperature having an indirect role on the first parameters. As a result, different standards have been elaborated in order to specify the correction factors, based on the data collected during experiments. A procedures' unification to satisfy the multitude of real cases (electric field structures, voltage levels and distances between electrodes) is in itself a difficult approach. The work summarizes the currently used procedures for determining the atmospheric correction factors and presents their sensitivity with the atmospheric parameters registered for over 25 years in a laboratory located at low altitude, during of carrying out industrial tests of some insulator strings with rated voltages between 110 kV and 400 kV.