Insulator aging tests with HVAC and HVDC excitation using the tracking wheel tester

An experimental study was conducted, using a Rotating Wheel Tracking and Erosion Tester (RWT) with the aim to compare the aging performance of different insulators under AC and DC (both polarities) excitation. The procedures of the standard were adapted to perform AC and DC (both polarities) tests on 6 practical insulators from different manufacturers, representing different materials and specific creepage distances. The results obtained confirm the extreme severity of the test, especially for the silicone rubber insulators. The DC tests turned out to be more severe than the AC tests. The formation of a brown deposit on the insulator surface was observed and investigated.