| 摘要 |
PURPOSE:To stop an accident point accurately without reference to the state of the ground surface by connecting a DC power source between a cable and the mimic line of an open wire laid on the ground surface along the laying path of the cable. CONSTITUTION:The negative terminal of a DC power source flowing a direct current through a cable 1 is not grounded, but connected to the mimic earth line 5 of an open wire laid on the ground surface GL along the laying path of the cable 1. Then, a return-circuit current from an accident point 4 flows to the mimic earth line 5. For the purpose, the earth line 5 is disconnected and an ammeter 3 having a small resistance R detects the direction of the current. Since the direction of the current depends upon the position of the accident point 4 and the relative position of a detection point 5a, the disconnection of the earth line 5, measurement, recovery at the disconnection point, disconnection another point, measurement, etc., are performed repeatedly to spot the accident point as well as the conventional potential difference method. Thus, the accident point is spotted accurately without reference to the state of the ground surface. |
