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Dissolved Gas Analysis (DGA) is one of the most effective methods in condition monitoring and fault diagnosis of oil immersed transformers. To facilitate the DGA data interpretation, investigation of fault gas generation under laboratory simulated faults using immersed heating method is often conducted. However, with immersed heating method, it is difficult to generate a stable thermal fault with...
Ageing of paper insulation within oil immersed power transformers is the determining factor for the transformer expected life. A thermal diagram as shown in the IEC 60076-2:2011 standard specified a hot spot factor method to estimate the hot spot temperature based on heat run test data. The hot spot factor is split into a Q factor, which depends on loss distribution within winding, and an S factor,...
Dissolved Gas Analysis (DGA) method is one of the most effective techniques to monitor the condition of transformers. In this method, free gas leakage condition is required as any leakage of dissolved gases might distort the DGA results and mislead the diagnosis of transformer fault. In this paper, a mass transfer model based on two-film theory is built to simulate the gas leakage process from transformer...
Aging of power transformers is one of the biggest challenges electrical utilities face. As transformers are commissioned, their insulation system composed of liquid (oil) and solid (paper and pressboard) insulations will deteriorate over time, jeopardizing longevity and reliability of transformers. As a means for optimizing capital expenditure without undermining the reliability of electricity supply,...
Paper ageing is an irreversible process, which has made paper insulation a lifetime determining factor for transformers. Chemical indicators in oil such as carbon oxide gases and 2-FAL, are used to indicate the ageing state of paper as it is difficult to obtain paper samples to measure DP or tensile strength. Methanol amount in oil was recently found to be an early-ageing indicator for paper. In this...
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