| 摘要 |
PURPOSE:To locate an accident related to a steel tower and an accident occurrence section between steel towers by providing a current detecting means on both sides of the steel tower, and measuring a phase difference of the current detecting means. CONSTITUTION:Steel towers 130-134 are provided at a prescribed interval along a power transmission system 210, and optical current transformers CT 1a, 1b1, 1B2-1d2 are provided on an overhead ground wire 2 of a steel tower. Optical signal outputs of wavelengths lambda1, lambda2 of the CTs 1a, 1b1 are multiplexed 6b1 through optical fiber cables 3a, 3b1, respectively, and sent to a multiplexer 6b2 through an optical fiber cable 5b. An optical signal of a wavelength lambda2 of the CT 1b2 is also sent to the multiplexer 6b2, multiplexed with the optical signals of the wavelength lambda1 and lambda2, and thereafter, sent to t demultiplexer 7a of a transmission terminal station 100b which is provided on the steel tower 132. By the demultiplexer 7a, said optical signasl are demultiplexed to optical signals whose wavelength are lambda1, lambda2 and an optical signal whose wavelength is lambda3, and optical signals whose wavelength are lambda1, lambda2 are demultiplexed 7b. Subsequently, each signal is inputted to a discriminating circuit 7, for instance, a phase difference of the optical signals from the CT 1a and 1b1 is measured, and when the phase difference goes to 180 deg., it is decided that an accident is generated in the CT 1a and 1b1, accident information of its accident occurrence section is transmitted from the device 8 to an optical transmission device 9.
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