The analysis of on-line monitored results for capacitive type of equipment

At the end of 1998 some sets of online monitoring systems of capacitive type equipment, which are used to detect dielectric loss factor tanδ and capacitance C, were installed in one 500 kV substation and eight 220 kV substations in Beijing area. The detected results are transmitted through communication lines from substations to the Technical Center located in the Beijing Power Supply Company. Up to the present time the 9 systems have been worked for two years and been proved useful for the evaluation of insulation condition of capacitive equipment. Eight current transformers of rated voltage of 220 kV or 500 kV, the tang values of which were more than the permitted levels, were detected by these on-line monitoring systems. The factors that affect the measuring results of tanδ were carefully estimated through the analysis of each unit of on-line monitoring system. The emphasis was given to the temperature characteristic of current signal transducer. Finally, the analysis method of online monitoring data of capacitive type equipment was concluded