The influence of water and pollution on diagnosing defective composite insulator by electric field mapping

The electric field mapping was applied to detect 110 kV detective composite insulators in our laboratory. Two kinds of conductive internal defects were simulated on 110 kV composite insulators for determining the sensitivity of the method. The influence of water and pollution on electric field mapping was also investigated. Results indicated that some kinds of defects in composite insulators could be found by electric field mapping when insulators are in dry condition. The existance of water and dirtiness will severely affect the field distribution, causing diagnostics to be difficult. But very severe conductive faults in composite insulators may still be found out by this measuring method.