Acoustic diagnoses of AC corona on the surfaces of insulators

Electrical partial discharge (PD) detection methods have been applied over a very wide range of circumstances. However in some applications, electrical methods are not very effective, typically as a result of excessive interference (electromagnetic interference). Such interference can be controlled in a research or factory setting, but is often beyond control in a field setting. The acoustic method is one of the nondestructive diagnostic methods used to measure, detect and localize PD in insulation systems of power facilities. Acoustic methods can be made immune to electromagnetic interference. In this paper an ultrasound detector system plus fibre-optic transmission system is used to detect corona on surface of an insulator string under high voltage AC at laboratory conditions. The results will show and benefits of using two systems for detecting corona will be presented.