A new Method to Estimate the Remaining Life of Power Transformers Using the Analysis of Dissolved Gases in Oil

Any power transformer is expected to serve at least for 30 years according to the current standards. Therefore, the insulation life time should be in a good match with it to prevent unwanted failure or damage of transformers as a result of insulation failure. Based on the analysis of dissolved gases in oil, a new method is proposed for the estimation of remaining life of power transformer. In this method, status of the insulation is classified in three general groups based on the CO and CO2 contents of the oil. Then, having the H2, CH4, C2H6 and N2 contents of the oil, the condition of the insulation is determined more accurately by using the aforementioned classification and four fuzzy estimators. The fuzzy logic is employed to improve the accuracy of the estimated status for the insulation, obtained from the method based on the amount of dissolved gases in the oils. The proposed method is applied on different sets of samples obtained from several transformers with certain insulation conditions. The estimated status for the insulation of each transformer showed a good agreement with corresponding set of data for the same transformer.