Effect of test source parameters on flashover voltage of polymer insulators in clean fog test

One of the most important factors in artificial pollution test of insulators is the source parameter. Several researches have been performed for ceramic insulators; however fewer investigations for composite insulators have been done. In this paper it has been demonstrated that for a cascade setup, adding an output capacitor could improve the test setups for testing of composite insulators. Besides simulations, clean-fog test method was used to determine the flashover voltage (FOV) of composite insulators, which were selected from distribution overhead lines with different natural age level. Higher pollution values cause higher error and reduce the FOV in all cases. For a 1-year aged insulator, the error is less than 10%, but the maximum error for a 5-year aged and 10-year old are 22% and 40%, respectively. The error decreases depending on the hydrophobicity of silicon rubber. The less hydrophobic the insulator surface the greater the error in FOV