| 摘要 |
PURPOSE:To make it possible to realize the enhancement of noise resistance and the protection of a signal processing apparatus from surge, by simplifying the signal processing apparatus by dispensing with a synchronous circuit and using an optical fiber in signal transmission. CONSTITUTION:The surge wave generated from the failure point F at a distance lA from a terminal A and at a distance lB from a terminal B is propagated to both directions and propagated through an optical fiber while connected to a light signal by a sensor 2 and a photoelectric converter 6. On the basis of the signal propagation delay times in the optical fibers in the A-terminal side and the B-terminal side and time when the surge wave is generated, times of surge wave form signals from both terminals reaching a signal processing apparatus 8 are signal propagation delay times in the photoelectric converter 6 and the signal processing apparatus 8 and take the same value at both terminals. In this case, the center between terminals A, B is set to zero and the A-terminal side from the center to positive while the B-terminal side to negative and, when arrival time difference of surge wave form signals from both terminals is measured, the failure point F can be calculated.
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