GASSING OF THE ELECTRICAL INSULATING FLUIDS - A DETERMINANT FACTOR OF THE TRANSFORMERS SAFETY IN OPERATION

Abstract

The influence on the quality of the electrical insulating fluids on the safety in operation of the transformers has been evaluated. After processing the comparative experimental data obtained by gas chromatography technique on 5 different sorts of electrical insulating fluids (a sort of vegetable oil with high oleic content and with addition of 0.5% antioxidant "functional model" - compared with two commercial sorts of mineral oil, 1 mainly vegetable commercial oil, 1 commercial synthetic ester), thermal aged in contact with electrical insulating paper and copper for electrical use, at 110 ± 3 °C for 1000 hours in closed vessels (limited access to atmospheric oxygen) it has been found that at the transformers filled with mineral oils, the risk of explosion and fire is approx. 10 times higher than those filled with synthetic or vegetal ester. It has also been found that the ageing of the insulation paper is approx. 15 times slower in the synthetic and natural ester than in the mineral oils normally used in transformers.

Keywords

• transformer oils
• mineral oils
• synthetic esters
• natural esters
• explosion risk
• fire risk