Ageing of mineral oils-a diagnostic study

Simulated laboratory experiments on the effects of copper/oil ratio and temperature considering the aspects of oxygen availability are presented. It is shown that copper/oil ratio is the most significant factor in accelerating the thermo-oxidation aging process. Laboratory experiments for representing aging corresponding to that in the field are reported. The data so produced are extrapolated for life prediction in service. It is shown that it is possible to estimate the life of an oil with the help of Myer's index. It is important to determine experimentally a range of gas levels for the oil to be used during factory tests. Gas values exceeding this range are considered to be indicative of incipient faults for new transformers after factory tests.<
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