Distinction device null of the imported noise in part discharge

摘要

PURPOSE:To measure internal electric discharging with high accuracy by amplifying the voltage of detection impedance and performing waveform conversion into a rectangular wave, then comparing the pulse width of the rectangular wave with a border value for discrimination, and removing an external noise. CONSTITUTION:A power source Vac, the impedance Z, a body 1 to be tested, and an earth wire 2 are connected in series and a current transformer 3 provided to the earth wire 2 detects a current. Then the detected current is amplified by an amplifier 4 and converted into one rectangular wave by a waveform converter 5 equipped with a detecting circuit and a comparator. Then a discrimination device 7 decides whether the pulse width T of this rectangular wave is longer than the border time T0 to decide partial discharging when T0T or the external noise when T0T, and a counter 6 counts only the partial discharging. The partial discharging caused in a transformer, etc., is accurately measured.