Temperature Rise Comparison of Switchgear in SF6, N2, and Air

Based on the heat conduction equation, fluid flow governing equation and radiation heat transfer equation, a multi-physics coupled mathematical model is established, the convection heat transfer problem between solid and fluid is solved by wall function. The three dimensional thermal field in a type of switchgear filled respectively with SF6, N2, and air are calculated and analyzed to discuss the feasibility of using air or N2 as the substitution of SF6 by the finite volume method. The results show that the temperature fields in three gases are similar in the switchgear. The temperature rise of current-carrying loop is the highest in SF6 and is the lowest in the air. So the conclusion could be made that air or N2 can replace SF6 as the insulating gas of switchgear on the perspective of temperature rise.