Research of steep-front wave impulse voltage test effectiveness in finding internal fault of composite insulators

In order to verify the effectiveness of steep-front impulse voltage testing in finding the internal faults of composite insulators, some insulators with faults are modeled which include conductive channel, semi-conductive airy channel and partial little air bubbles that occur separately at different places. A steep-front wave impulse voltage test (steepness of wave front is 1000-4000 kV//spl mu/s) is respectively made for these faulty and normal insulators. At the same-time the internal electric field intensity and its distribution in the insulator is calculated by making use of infinite element analysis software in order to test whether breakdown has occurred. The result is consistent with the experimental one. The final result shows that steep-front wave impulse voltage testing plays a very effective part in finding severe faults of the insulator, however, tiny faults are not easy found using this method. The result of this research gives a reference to revise the steep-front wave impulse voltage test standard.