Multifactor-surface-tests of organic insulating materials in the early stage of degradation

Ageing due to multifactor stresses of the surface of organic materials has to be divided into two different stages named “early” and “late” stage of ageing. While standardized tests such as the inclined plane test or the rotating wheel dip test aim at verifying only the performance of insulating materials in the late stage of ageing, growing interest of scientists recently focuses on the early stage of ageing, characterized by a loss of hydrophobicity and an increase of leakage current as well as the appearance of surface partial discharges. To assess the phenomena in the early stage of ageing several new test facilities and diagnostic tools have been developed and applied, such as the “inverse” climatic chamber generating continuous condensation, the cold fog chamber and the “modified” rotating wheel dip test arrangement. This paper presents some new test results of polymer resin materials achieved in above mentioned test facilities and enables a comparison and assessment of the efficiency and the advantages of relevant test procedures