| 摘要 |
PURPOSE:To easily detect whether circumferential environment is contaminated or not by providing a transparent insulator of glass, etc., in the middle of an optical fiber calbe and detecting the contamination state of the circumferential environment from light passed through the transparent body. CONSTITUTION:For example, when contamination detection is carried out as to an enclosed switchboard, light from a light emitting device 2 is transmitted to a photodetector 3 through an optical fiber cable 4, transparent insulator 5, and then the optical fiber 4 again. If the inside of the enclosed switchboard 1 is contaminated with dust, gas, salt, etc., the transparent insulator 5 is also contaminated similarly and the quantity of light passing through the transparent insulator 5 decreases. Therefore, when the photodetector 3 detects the photodetection amount decreasing below a preset reference value, an alarm, etc., are generated and maintenance inspecting operation is performed in the early stage of the contamination. |
