| 摘要 |
PURPOSE:To ensure the monitoring of the lowering of oil level, by providing an optical fiber, whose core is partially exposed, in an expanding chamber, and utilizing the change in light transmittance. CONSTITUTION:In an expanding chamber 3, an optical fiber 91, whose core is partially exposed by stripping a part of a clad layer, is provided. The fiber 91 is taken out through an arm part 95 of an oil containing bushing. An light transmitter 97 is connected to one end of the fiber 91, and a light receiver 98 is connected to the other end. When an oil level is lowered, a material, i.e., an insulating oil 2, which is contacted with an exposed core 92 of the fiber 91 is transformed into a gas, e.g., nitrogen, on the oil surface. Therefore, light transmittance is changed, and the amount of light transmission at the exposed part 92 is changed. Since the amount of the received light of the light receiver 98 is changed, the lowering of the oil level can be always monitored positively by the change in the amount of the received light. |
