Operational Performance of Fluoronitrile-Carbon Dioxide Mixture as Insulating Medium in 110 kV Live-Tank Circuit Breaker: Theoretical View

This study presents a theoretical feasibility assessment of replacing SF<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> with a 6% C<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub>F<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub>N/94% CO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> mixture in a standard 110 kV live-tank circuit breaker. Motivated by the increasing global pressure to eliminate high-GWP fluorinated gases, the work integrates three complementary analytical approaches: insulation coordination using an adapted Vishnevsky method, comparative gas-dynamic evaluation of the self-blast double-volume interrupter, and electrostatic field analysis in COMSOL Multiphysics. Results indicate that the alternative mixture requires increased internal insulation distances yet provides comparable electric field distribution and enhanced mass flow rate at higher initial pressure. These findings suggest that C<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub>F<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub>N/CO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> may offer preliminary suitability as an eco-friendly insulating medium; however, reduced dielectric safety margins and the absence of arc-related validation highlight the need for further experimental and computational research before practical deployment in high-voltage switching devices.