Photoacoustic detection of dissolved gases in transformer oil

This paper investigates the applications of photoacoustic spectrometry (PAS) to analyze dissolved gases in transformer oil. An inexpensive experimental device with an electric Pulse infrared light and six filters has been developed to detect six main fault gases in transformer oil, namely, CH4, C2H6, C2H4, C2H2, CO, and CO2. The method of choosing the characteristic wavelengths for the above Six fault gases is discussed in detail. A weighted least-square error method is proposed to analyze the measured data and to determine the component concentrations of dissolved gas in oil. Two sample sets of gas mixtures are analyzed by the experimental device for the purpose of verification. The PAS measurements are compared with the true values and the values measured by a conventional 'as chrornatograph (GC) method. The comparison results show that PAS is an effective way ofanalv/in- dissolved gases in transformer oil, which exhibits some advantages in the gas detection Such as consuming no gas. separating no gas, high accuracy, high stability, and rapid measurements. Copyright (C) 2007 John Wiley & Sons, Ltd.