Heat Transfer in Gas-Insulated Bus Bars

Numerical prediction and experimental verification of the temperature rise for a single-phase and a three-phase gas-insulated bus bar with current flow are investigated. Various heat generation rates possibly produced in the gas-insulated bus bar are calculated. To estimate the power loss caused by eddy current, the magnetic field analysis is carried out. The heat balance calculation solving the differential form of an energy balance equation with empirical relations is conducted by using the 5^th order Runge-Kutta method. The various cases representing different geometries and current values are investigated by conducting the heat balance calculation. Three-dimensional numerical flow field analysis using finite volume method is performed for the different type of the bus bars. From the flow field analysis based on laminar natural convection, the temperature gradient in the current flowing direction caused by contact heat source is found for both single-phase and three-phase bus bars. In the experiments, temperature rises in each of conductor, contact part, and external tank are measured for a full-scale gas-insulated bus bar. The comparisons of the predicted values of the heat balance calculation and the numerical analyses to results of the experiments are made. From the comparisons, it is concluded that the temperature rise of a bus bar can be predicted quite well by performing laminar natural convection flow analyses.