Experimental verification of HVDC test sources requirements for pollution tests

This paper presents the results of tests conducted to verify the effect of the voltage source on the critical flashover voltage of DC insulators under pollution. Tests were performed under 3 pollution levels using voltage sources with different voltage drop x leakage current characteristics. A data acquisition system was used to record all current pulses above a certain pre selected current level and the corresponding voltage evolution during current pulse duration, which made possible a complete analysis of current pulses and voltage drops characteristics. The experimental results show that the present restrictions imposed on the DC voltage sources can probably be relaxed. Also from the experimental data collected it was found that the insulator tested presents a constant impedance x current characteristic. This characteristic can be useful in checking theoretical models for polluted insulator flashover