Abstract
In the paper presented the temperature of an oil-immersed transformer was measured, based on the principles of the fluorescence afterglow life. Three methods were used to calculate the fluorescence afterglow life τ by using the least squares method, the integral area ratio method and Prony algorithm. The leastsquare method, the integral area ratio method and the program of Prony algorithm are written using Matlab and C++. The Least-square fitting is susceptible to the influence of the DC component. When the DC location is different, the fluorescence afterglow life τ values vary widely. The integral area ratio method is not influenced by DC component, but it has low sensitivity. Prony algorithm is not affected by DC, it has high sensitivity. So Prony algorithm is selected as a way to obtain the fluorescence afterglow lifetime value τ.