An acoustic emission method for on-line monitoring the contamination-causing flashover of insulator
This paper presents an acoustic emission (AE) monitoring method. When a partial discharge occurs, there is an instantaneous release of energy, some of which is emitted as acoustic energy. The pollution severities of insulators in-service can be monitored and accordingly threaten to the insulation of power grid is evaluated by detecting the sound signals. To prove this AE monitoring method, artificial contaminations experiments are carried out. The essential information about the relationship of AE signal and PD are obtained in different moments of the whole process of flashover. The studied method is a new way of AE technique in monitoring and characterizing defects of electrical power equipments in-service.
Early detection of weak points in MEEC distribution system
This paper is aimed at detecting the weak points in the distribution system of MEEC, "Middle Egypt Electricity Company". These include loose connections, polluted insulators and micro-roughness on line conductors and insulator hardware. The detection methodology is based on measuring ultrasound emissions from these weak points to warn against impending failures and subsequent supply interruptions. Laboratory testing made it possible to discriminate between loose-connection arcing, polluted-insulator "baby arcs" and sharp-edge corona according to the sound pattern. However, there can be occasions where sound pattern may prove confusing in discrimination between baby arcs and loose-connection arcing. In this case, recording of acoustic signals was found to be a useful tool for such discrimination.
Partial discharge. X. PD in gas-insulated substations-measurement and practical considerations
For pt.IX see ibid., vol.7, no.6, p.5 et seq. (1991). An overview of engineering practice related to partial discharge (PD) measurements in gas-insulated substations (GISs) is provided. The following questions are addressed: why measure PD in GIS?; in which phases of the life cycle should PD be measured?; what PD measurements are presently available?; and, what results can be expected under various measurement conditions?.<<ETX>>