Dissolved Gas Analysis in Camellia Insulating Oil during Thermal Ageing Test

Vegetable insulating oil, one of the environmental friendly dielectric liquids, has been widely utilized with oil-filled transformers during the past two decades. As like mineral-oil filled transformers, thermal ageing is also critical for evaluating the performance of vegetable-oil filled transformers. The detection of the dissolved gases and clarification of the gas production regularity are necessary for understanding the thermal aging mechanism of vegetable insulating oils. In this work, experiments were conducted to simulate the thermal ageing process of camellia insulating oil, and to find out the composition variation regularities of characteristic dissolved gases by various thermal ageing temperature and duration. The results shown that CO and CO
2
, but also H
2
and C
2
H
6
were the main characteristic gases produced during the thermal ageing of camellia insulating oil, meanwhile the percentage composition of C
2
H
6
tended to increase with the increased thermal ageing duration, while H
2
showed an opposite tendency. The acid value variation of the oils recorded during the test tended to be increased with extended thermal aging durations.