A Detection System of Gas Concentration Based on Low-Loss Fiber Loop Ring-Down Spectroscopy

In the engineering application of power transformers, due to phenomena such as overheating and partial discharge, the transformer may have a fault. Acetylene is one of the important characteristic components when the transformer is failure. The acetylene detection is significant to the diagnosis and evaluation of transformer operational condition. Therefore, a fiber loop ring-down system is built to detect acetylene in this paper. The fiber collimators at both ends of the gas cell are adjusted to reduce the loss of the gas cell system. The absorption line at 1531.6nm of the acetylene molecule was selected and the response characteristics of the system to the concentration of trace acetylene gas were studied through experiment. The ring-down waveforms at different concentrations of acetylene are measured. After fitting the peak value of waveforms, the corresponding ring-down time can be calculated and the quantitative relationship between ring-down time and concentration is also studied based on the least square method. The results show that there is a good linear dependence between the ring-down time and the concentration. The research results provide a new method for the online detection of dissolved gases in the transformer oil.