Tracking and erosion properties evaluation of polymeric insulating materials

Abstract

With excellent electrical properties, low weight and easy processing, polymeric materials were widely used as external insulating materials for indoor and outdoor electrical applications. However, with the presence of humidity and contamination in the operation environment, surface tracking may happen to polymeric insulating materials which influences the long term reliability of the insulation and equipment, and may even lead to a fire hazard. Therefore, resistance of tracking and erosion of polymeric insulation materials is a very critical property which has been attracted more and more attention in recent years. This study attempts to evaluate the tracking and erosion resistance performances of different polymeric materials. For this purpose, tracking and erosion resistance was determined in accordance with IEC 60587 by inclined-plane method in this work, using constant tracking voltage. End-point criterion A was applied, meanwhile track distances of end-point B was also measured. Test tolerance time, maximum currents, erosion depth, length of track from the lower electrode and the leakage currents on the surface of the specimens was recorded and analyzed. Five kinds of commercialized polymeric insulation materials were evaluated and compared. SMC, BMC, GPO3 and glass fiber reinforced PPA were evaluated with AC 2.5kV and 3.5kV. HTV silicone rubber was tested with AC 2.5kV, 3.5kV and 4.5 kV. The experimental results indicated that tracking and erosion resistance of different polymeric insulating materials were successfully evaluated and ranked by inclined-plane tracking and erosion test, and the ranking of resistance should be HTV-1, BMC, SMC, HTV-2, GPO3 and glass fiber reinforced PPA. Besides, the influence factors of the dry-band arcing and leakage current on the materials surface during the test were also discussed.