Study On Absorptive Spectrum Optical Fiber Methane Gas Sensor

Abstract Operation safety of large-scale transformer in electrical power system is of practical significance. This thesis was concentrated on highly sensitive on-line remote sensing of fault gases for transformer isolation oil on the basis of optical fiber. Optical fiber gas sensor has found a wide range of applications by virtue of it~ various technical merits. In this paper, the development of optical fiber gas sensors was thoroughly reviewed, from which some drawbacks and application limitations of on-going optical fiber gas-sensing techniques were extracted. The article used the method of spectrum absorption to measure gas concentration, transmitting optical signal by optical fiber. Harmonic detection technique of gas concentration sensing based on infrared absorption phenomena of gases was presented. This was a novel optical fiber methane sensor. This method offered high selectivity, long life, no influence of surroundings gases, no electrical induction and so on. It adapted to be used in the foul and hazardous environment. On the basis of near-infrared absorption spectrum of methane, an experimental setup was established, employing laser diode and silicon optical fiber whose low-loss transmission windows encompass absorption spectrum of methane under exploration. Close attentions were paid to such problems as light path design, gas chamber manufacturing, light source drive, modulation and its stability. The work with crucial importance is to optimize the design of light path and electronic circuitry of the system so as to maximize the signal-to-noise ratio through noise inhibition. In the end of this article, correctness of all principles and design was proved, and the result of experiment was given.