Research Of Acetylene Concentration Dissolved In Transformer Oil Measurement Instrumentation Based On Spectrum Absorption

With the rapid development of the electric power projects and electrization of industrial corporations, more and more transformers have been used. When in operation, transformer oil will perhaps produce some malfunction gases, so malfunction gases' real time supervision is very important to the secure operation of transformer.In this article, using the spectrum absorption method, the malfunction gas in the transformer oil is on-line detected remotely with high sensitivity, and the optical signal transmitted by optical fiber. The transformer's work state can be watched. This method offers long life, high sensitivity, no influence of surroundings gases, no electromagnetic induction and so on. It can be used in the hazardous or foul environment. In order to realize fiber detecting, the fault gas dissolved in the transformer oil must be separated by the macromolecule membrane. Experiment indicates that Polyflon membrane is an excellent medium for the main malfunction gas (acetylene) permeation. It needs a long time for the malfunction gas to permeate to reach a balanced state. A measuring method under unbalanced state based on equal time interval sampling is proposed. It not only decreases the difficulty in designing the gas cell, but also increases the real-time of measurement.In the paper, the center absorption wave, the absorption shape, the gap between the adjacent lines and the intensity of absorption line are analyzed using quantum mechanics knowledge and molecular spectrum theory. It gives the theoretic description of the Beer-Lambert law.The designs of the light path, circuit and gas cell are based on the theoretic analysis in the paper. For the signals are very weak, the lock-in amplifier is employed to extract the signals in the circuit design. It can inhabit the noise in the most and maximize the signal-to-noise.The feasibility of theoretic analysis and system design is proved by the experiments. The results of the experiments are given in the end of the paper.