In service insulating liquid are subjected to thermal and electrical stress, consequently decompose produce oxidation by products. The oxidation by products is affecting electrical and physical properties of the liquid, reducing their cooling efficiency and ability to act as insulating liquid. Heavily oxidised oil has low cooling property, leading to transformer overheating damaging solid insulation system and transformer failure. Clearly such oil is not fit for the purpose and remedial action is required. While there are several options available to the equipment owner, to rectify the situation, but making correct decision is technically and economically important since it may affect life of the system. Among these options are; reclaiming the oil, replacing the oil, recondition the oil or retain the oil. In order to be able to make such decision and make sure correct decision is made, the oil must be tested and certain limits for test results are required. Additionally risk analysis, cost analysis and benefit of each option should be considered to be able to select the best available option.
Prof. Pahlavanpour and Dr Eklund
Nynas Naphthenics Ltd
Wallis house, 76 North Street