Leakage Current Measurement System Based On Virtual Instrument Of Iced Insulators' Flashover

The iced insulators flashover is one of the main faults of the EHV transmission lines in icing regions. Icing is especial form of pollution. The flashover of iced insulators is also caused by the leakage current. The variety and development of the leakage current is one of the main factors to cause the iced insulators flashover. Therefore, leakage current measurement on flashover process during the insulators icing has both important academic meaning and engineering value.During the insulators are carried out working voltage after it was iced, the surface states of iced insulators would variety according to the environment conditions. Therefore, The amplitude of leakage current would vary from several μA to 300~600mA. And it would last a long time because of the flashover development, it's difficult to data acquisition or logging the leakage current waveform by currently instruments. And so far, lots of investigation was conducted on the insulators' leakage current measurement and logging, but the investigation of the entireness process measurement and logging of the iced insulators flashover is also vacancy.Based on the currently laboratory investigation results and the iced insulators leakage current performance during icing process, in this paper a leakage current measurement system is designed with graphical programming language laboratory virtual instrument engineering workbench. Designs, manufacture and test for hardware and software of the whole system are finished.When signal-conditioning circuit is in consideration, attention is paid to design safeguard circuit and magnify circuit. A proper parameter data acquisition card is selected according to the signal-conditioning circuit. A common data acquisition card can be used on laboratory virtual instrument engineering workbench through designing the external interface between LabVIEW and common date acquisition card on the software design; Used the idea of the double buffer and direct memory access, a real time data acquisition and logging about the succession, big capacitance leakage current is realized; A digital filter is designed to filter high frequency signals. Finally, a kind of virtual instrument is designed to detect leakage current. It has high precision and high stability performance through comparison measurement between virtual instrument and oscillograph. It also can log and reading continues data while a common oscillograph can't. It offered a feasible way not only for iced insulatorsto detect leakage current during flashover on AC and DC, but also for polluted insulators.The iced insulators leakage current measurement results during flashover process in the multi-function artificial climate chamber of Chongqing University indicate that it cans acquisition and logging of iced insulator's leakage current and partial arc exactly.