| 摘要 |
PURPOSE:To improve the accuracy of the fault finding effected by a DC resistance measurement performed when a fault such as disconnection of the cable or the like is occurred, by utilizing the cable structure. CONSTITUTION:Because a cable 32 has at least two kinds of metal portions which are insulated from each other, one of them is used as a feeder line, while the other is used as a resistance measuring line 35. The DC resistances for respective spans are to be Rl1 between a terminal station A and a m1 repeater, Rl2 between the m1 and m2 repeaters, and Rlmalpha>1 between the mm-1 and mm+alpha repeaters, and supporsed to concentrate on respective repeater parts 31. In this case, when there is a fault in the mm+1 span, the DC resistance measured from the side of the terminal station A is shown by the formula I. The ratio of the differences in the resistance values between the case where there is a fault in the repeating span adjacent thereto is shown by the formula II. If Rl1<Rl2<...Rlm, FR>1mm is established at arbitrary mm. Properly setting m1, m2..., Rl1, Rl2... permits FR to be set so as to be two or three times of 1/mm. |
