STUDY OF SOME INSULATING OILS AGING BY THERMAL CYCLING

The By gravimetric measurements and coupled thermal analysis techniques (DTG+TG+DTA) the aging of different sorts of insulating oil was studied by thermal cycling between -400C and 850C. The experimental results showed that, during the thermal cycling of the investigated mineral oils, their composition changes due to the volatilization of the volatile fractions (mass losses between 3.9% and 5.8%), unlike the investigated vegetable oil that showed a mass increase of approx. 0.66%. It has also been found that the mineral oils can be ensure a safe operation, without significant changes up to a maximum of 1000C, as long as investigating vegetable oil can be used without degradation risk up to 2000C.