Abstract: In the design of medium-voltage metal-enclosed gas-insulated transmission lines (GIL), factors such as transmission capacity,structural dimensions, and manufacturing costs need to be comprehensively considered, with a focus on the heat dissipation issue of low-pressure and large-capacity GIL. The insulating medium is a key component of medium-voltage GIL, directly affecting its insulation performance and heat dissipation performance. Taking a medium-voltage GIL with a current-carrying capacity of 2 500 A as an example, this paper elaborates on the basic structure and heat transfer mechanism of GIL. For insulating media such as SF₆ and N₂, the COMSOL software is used to simulate and calculate the temperature rise values under corresponding pressures, explore the temperature rise variation laws of GIL under different insulating media, and verify the results through experiments. By comparing the experimental and simulation data under the same working conditions, it is found that the variation trends are similar, but there are differences in specific calculation results. These differences are mainly due to the inability to accurately set parameters such as the heat transfer coefficient of the shell and the emissivity of the metal surface during simulation calculations, as well as the use of approximate simplified calculations.

    Key words: medium-voltage transmission equipment; metal-enclosed gas-insulated transmission line (GIL); insulating medium; temperature rise characteristic