| 摘要 |
PURPOSE:To detect only reflected pulses from a real accident point by sending pulses to an accident phase and a health phase, inputting reflected pulses from those phases to a balanced circuit, and detecting pulses outputted by the balanced circuit. CONSTITUTION:A power cable 1 has the accident phase 2 and health phase 3, which have joints B and C respectively. If there is an accident point Q in the accident phase 2 far away from the joint B, reflected pulses are generated in the accident phase 2 by the joint B and accident point Q and reflecting pulses are generated in the health phase 3 only by the joint C. Consequently, the output of the balanced circuit 5 is the difference between two signals and there are only the reflected pulses from the accident point Q in the accident phase 2. Thus, reflection from the joints and a Y branch is canceled to detect only the reflected wave from the real accident occurrence point.
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