Current detector for surge arrester diagnostic and overvoltage assessment in high voltage substations

摘要

The present invention relates to an apparatus for sensing and measuring theHV surge arrester current. It comprises two toroidal current transformers arranged coaxially with respect to the earth wire of the surge arrester, means for sensing the current signals emitted by the said transformers and for converting the said current signals in digital signals, and means for transmitting the said digital signals to an information network and analog state signals by relay activation. The two toroidal current instrument transformers are associated, respectively, one to means for sensing the normal leakage current, and the other to means for sensing the impulsive current, the latter comprising a circuit (TRIGGER) discriminating between "switching" and "lightning" signals, in which the basis for discrimination is a signal duration threshold, of about 35 µs.