| 摘要 |
PURPOSE:To know automatically the generation of a leakage oil accident by providing in series plural leakage oil detectors on an optical transmission line which is provided along an OFF cable, and separating and fetching backscattering light which is reflected by the optical transmission line, by an optical directional coupler. CONSTITUTION:A light emitting part 5 is connected through an optical directional coupler 3 to the incident end of an optical transmission line 1 which is provided along an OF cable, the pulse light is made incident on the optical transmission line 1 through the coupler 3 from this light emitting part 5, and this pulse light is made to pass through successively to each optical fiber 2 and each leakage oil detector 4 which is provided in series. By the propagation of this pulse light, backscattering light is generated in the optical transmission line 1. This backscattering light is fetched by the coupler 3 and its optical intensity is detected. In such a case, if leakage oil is generated in one OF cable connecting part, and an OF oil has adhered to a liquid sensor 4a of the corresponding detector 4, when passing through the detector 4, a leakage oil adhering loss is added to the backscattering light, its optical intensity is lowered and fetched, and by detecting this optical intensity drop, a position where the leakage oil is generated can be known instantaneously. |
