Punctured insulator examination of a string insulator

This paper represents a punctured insulator detection method of a string insulator using a corona camera which can detect the ultraviolet light (partly corona phenomena) obtained from the high electric field stress of air around the tested insulators. It was found that the corona camera could detect the corona phenomena of the energized proper insulators at the inception and the higher voltage. In case of the energized improper insulators, the corona phenomena could be detected also at the inception voltage but it could not if the voltage of the improper insulator reached its punctured voltage. Using this normal principle, the punctured insulators connected with the good insulators of the string insulators can be detected.