| 摘要 |
PROBLEM TO BE SOLVED: To measure a steep signal waveform such as a lightning surge by a simple structure with high precision. SOLUTION: A lightning surge current discharged from a protective device 3 to a grounding wire 4 when a lightning surge is applied is detected by a detector 5. The detected signal vin is full wave rectified by an absolute value circuit 11 and is gain adjusted by an amplifier 12. The adjusted voltage v12 is supplied to comparators 13-1, 13-2 and a peak hold circuit 14. A PIC microcomputer 20, on the basis of output signals com1, com2 of the comparators 13-1, 13-2, allows two reference voltages ref1, ref2 output from D/A convertors 15-1, 15-2 to transition in accordance with the waveform of the voltage v12, samples the waveform of the voltage v12 with a constant voltage difference bref between the two reference voltages ref1, ref2 to determine a sampling time, multiplies the time by the first and second reference voltages ref1, ref2, converts the product into a current value, and calculates a time/current-value product. COPYRIGHT: (C)2007,JPO&INPIT
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