| 摘要 |
<p>PROBLEM TO BE SOLVED: To solve the problem where, since metal sheaths of respective phases are cross-bonded to each other with cross-bonding wires at insulating joints of respective phases of a power cable line and ammeters are attached to the respective cross-bonding wires at all the insulating joints, in order to detect the abnormality of a corrosion-protective layer of the power cable, a large number of ammeters are necessary, and further, a large quantity of communication cables, such as optical fiber cables, are necessary for transmitting the current data to a monitoring center, so that the power cable line system is not economical. SOLUTION: Metal sheaths 2 at normal joints 4 of respective phases are respectively connected to each other with conductors 11 but are not grounded. The metal sheaths 2 at terminal joints 5 of the respective phases on both ends of a cable line are grounded collectively 10, and ammeters are attached to the respective collective grounds 10. With such a constitution, in order to detect the abnormality of a corrosion-protective layer of a power cable, since the ammeter 9a are attached only to the respective collective grounds 10 at the terminal joints 5 of both the ends, i.e., the ammeters are attached to only two positions, so that the power cable system can be very economical.</p> |
