METHOD FOR DETECTING LIGHTNING DAMAGE ON POWER TRANSMISSION LINE TOWER

摘要

PURPOSE:To elevate the accuracy with a less erroneous discrimination even allowed for a sizable margin in the discrimination of difference in the phase by use of pulses from the second one on in the detection of lightning damage on power transmission towers checking a phase difference of a dynamic current by pulses corresponding to the zero-cross point thereof. CONSTITUTION:Light pulse P and Q obtained from a dynamic current detectors 1 and 1' are converted into electrical pulses with light-electricity conversion circuits 8 and 8' to trigger FFs 9 and 9' with the rise thereof. With the coming of the first pulse, an output signal from the FFs 9 and 9' is provided to open an AND gate 10. The second pulses P and Q open AND gates 11 and 11' and are input one-shot multivibrators (M) 12 and 12'. The Ms 12 and 12' are triggered with the rise of the second pulses and pulses equivalent to the phase of 90 deg. are putout. Even if there is a difference in the phase between the second pulses, an AND gate 13 is opened to allow the pulses to be input into a FF14. The output thereof serves to indicate the coincidence of the second pulse, namely, being the lightning-damaged power transmission tower.