Research and Analysis of Insulating Gas in Unified Test Conditions

In order to study the insulation mechanism of SF₆ substitute gas, it is suggested to calculate the dielectric strength of insulating gas from the molecular structure. The dielectric strength of a typical gas is modeled by a power frequency breakdown test under a uniform electric field. The molecular parameters of insulating gases are calculated by the density functional theory method, and the effect of molecular structure parameters on the breakdown voltage of power frequency is studied. Based on the molecular structure parameters, which are closely related to the breakdown voltage of power frequency, a model of pressure and distance variation of AC breakdown voltage of insulating gas is established. The breakdown voltages of insulating gases (CF₃SO₂F) are also derived from the proposed model. The calculated breakdown voltage of power frequency of two gases is compared with the experimental value. The average error is just 2.6%. This model provides a basis for the future search for potential alternative insulating gases.