An Electromagnetic Detector of Insulator Surface Discharge

Over the past years many attempts have been made to develop means of monitoring possible leakage currents on polluted insulator surfaces in high-voltage power systems and warning against prospective flashovers. The literature offers a number of those detectors whose operation is based on measuring one of the following parameters: the maximum leakage current amplitude, the frequency of leakage current surges, and the conductance of the contaminating layer (usually assessed after deenergizing the system). A new principle of pollution assessment is introduced whereby the electromagnetic emission from the leakage current on the insulator surface is received, amplified, processed, and then used to activate an automatic alarm system. The advantages and limitations of the new detector are presented. Laboratory results of the detector output under various conditions of applied voltage and contaminants are given. A correlation between leakage current amplitudes and detected EM signals is established which allows a comparative evaluation of the detector.