Investigation of Temperature,Electric Field and Thermal Aging Effect on Conductance Characteristics of Fluorinert-Paper Composites

Traditional oil-paper composites insulation is widely employed in the insulation systems of various power equipment. However, its inherent characteristics such as flammability, explosiveness of its insulation oil and nonenvironmental friendliness, impose certain limitations on its long-term application. This paper presents a new fluorinertpaper composite insulation material fabricated by vacuum impregnation of NOMEX insulating paper with an eco-friendly fluorinert liquid (FC-40), a non-flammable liquid with no flash point, for 48 hours. The effects of temperature, electric field strength, and thermal aging on the conductivity characteristics of the composite insulation were investigated. The research results indicate that the conductivity of the fluorinert-paper composite increases with rising temperature and exhibits a sharp increase beyond 60° C. The conductivity increases slightly within the range of 5 to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$15 \text{kV} / \text{mm}$</tex>, and increases sharply after the field strength exceeds <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$15 \text{kV} / \text{mm}$</tex>.Furthermore, the fluorinert-paper composite consistently exhibits lower conductivity than oil-paper insulation both before and after thermal aging. This study concludes that the fluorinert-paper composite possesses superior electrical conductivity, providing a theoretical foundation for developing advanced insulation systems in power equipment.