Study on the Online Dissolved Gas Analysis Monitor based on the Photoacoustic Spectroscopy

Abstract

According to the principle of Photoacoustic Spectroscopy, HPAS-1000 Online Dissolved Gas Analysis Monitor is developed to monitor the dissolved gas in the power transformers online, which can directly extract the oil sample from the running transformer and measure the content of Hydrogen, Acetylene, Ethylene, Methane, Ethane, Carbon monoxide and Carbon dioxide dissolved in the oil sample in real time. Field Gas Monitor-INNOVA 1412 module is employed for it only takes a few milliliters of gas to achieve the measurement and the sensitivity of Acetylene, Ethylene, Methane, Carbon monoxide can reach to less than 0.5ppm. In order to separate the gas from the transformer oil a vacuum pump is used in the degassing module with TEFLON AF 2400 polymer membrane. For every fault gas has cross-interferences with each other including water vapor when measuring, INNOVA 1412 module should be calibrated by the fault gases of known standard concentrations before it can be used for measuring. Then several experiments were designed in order to study the characteristics of capillary negative pressure oil gas degassing system, and found the most efficient way of degassing. The experimental results show that, under the same conditions, the longer the degassing time, the higher the degassing efficiency; the greater the pressure difference, the higher the degassing efficiency; as the flow rate increases, the degassing efficiency increases first and then decreases, and the optimum flow rate is between 20ml/min and 30ml/min. Based on these results, the performance of HPAS-1000 Online Dissolved Gas Analysis Monitor is optimized, thus it subsequently passed the certification of CEPRI successfully and installed in the substations.