| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect a cable failure without installing a device that requires an insulating current transformer or a controlling power supply at an intermediate connecting portion that connects an aerial line and a cable line, and to make easy a harmonious operation with a differential relay for protecting a transmission line. <P>SOLUTION: This system is constituted of a first differential protective relay 11 that obtains a differential quantity by bringing in current signals each obtained at both terminals of a transmission line TL and protects the transmission line, an optical sensor 6 that converts the current signals each obtained from a terminal of the cable line 2 and the intermediate connecting portion into optical signals and outputs the signals, an optical transmission line 7 that transmits the outputs of the optical sensor in cascade, a photoelectric transducing means 15 that outputs the differential quantity of electrical signal out of the optical signals transmitted through the optical transmission line, and a second differential protective relay 12 that protects the cable line by bring in the differential quantity outputted from the photoelectric transducing means. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
