| 摘要 |
PURPOSE:To achieve a high reliability, by mounting inside an oil-filed bushing a detector built by fastening a refractive index distribution type rod lens at both ends of a pipe having an opening on the side thereof. CONSTITUTION:Normally, as an oil surface of an insulating oil 7 is positioned in an expansion cylinder 3, a detector 10 is immersed into the insulating oil 7. Light reaches the detector 10 through an optical fiber 13 for transmitting light and is made incident on a rod lens 15. As the oil surface falls below the detector 10 in case of a oil leakage, light transmitted from the rod lens 15 reaches the rod lens 16 because a space in a pipe 18 is filled with a gas. The light incident on the rod lens 16 is focused at a spot with an action opposite to that on the light transmitting side to be incident on an optical fiber 14 for receiving light. The light is transmitted to a light receiver 12 through the light receiving optical fiber 14 to be used as abnormality detection signal. That is, normally, light is not detected with the light receiver 12 while light is detected in case of abnormality. Thus, constant monitoring is possible from a remote point by placing a light transmitter 11 and the light receiver 12 at an operation chamber or the like. |
