Comportarea ?n transformatoarele electrice a uleiurilor minerale ?n compara?ie cu uleiurile vegetaleBehaviour of Mineral Oils compared to Vegetable Oils in Electric TransformersFull text in Romanian

摘要

In order to evaluate the functionality of an insulating vegetable oil (natural ester) in electric transformers,comparative electric measurements were performed on a 30 /0.4 kV-40 kVA transformer. During the operation ofthe transformer filled with commercial mineral, the main electrical characteristics were determined, namely:applied voltage test (according to IEC 60076-3: 2013), measurement of partial discharges (according to IEC 60270:2015), measurement of capacities and of delta tangent (according to IEC 60076-1: 2011) as well as of insulationresistance (according to IEC 60076-1: 2011). These parameters were also determined under the same conditions onthe transformer filled with an experimental vegetable oil. The comparative measurements have highlighted thefact that, from the point of view of the applied voltage test (2 kV/rms) and of partial discharges, there are nodifferences in the behaviour of the two investigated oils. Determination of dielectric losses indicated that whenusing vegetable oil, tgδ = 3.94 % these are substantially lower than the investigated mineral oil (tgδ = 8.18 %).Themeasurement of dielectric losses show ed that they are significantly lower when using vegetable oil (tgδ = 3.94 %)than in the case of the investigated mineral oil (tgδ = 8.18 %). In addition, it was found that the insulation resistancewhen operating the electric transformer with vegetable oil is 2.5 times higher than in the case of mineral oil.