The influence of the stress level on electro isolating oil state from the electric power transformers

The paper has three parts. The first part presents the characteristics of the power transformers that make the object of the analysis and their loading characteristics (load curve, over-voltages, over-currents). The second part shows the state characteristics of the electric insulating oil for each transformer under analysis, in terms of some essential state indicators: dielectric rigidity, tangent to the angle of losses and concentration of the seven essential gases (H2, CH4, C2H6, C2H4, C2H2, CO and CO2). The third part of the paper makes an analysis of the level of correlation between the power transformer straining degree and the state characteristics of the electric insulating oil. Based on the results obtained proposals are made regarding the ways of reclaiming and replacing or the electric insulating oil in power transformers depending on the transformer degree of straining.