Steady-state heating of gas insulated busbars

The alternating current flowing in the busbars of gas insulated switchgears (GIS) or substations generates Joule-heat both in the busbars and - due to eddy currents - in the metal enclosure. Besides heat conduction, the steady-state temperature of the conducting parts highly depends on the heat transfer between them and the encompassing gas insulation. The flow of the gas inside and outside the equipment that is, natural convection together with radiation determines the transferred heat. Such conjugate heat transfer problems can be treated numerically by finite element simulations. This paper compares the results of uni- and bidirectional coupling of electromagnetic and flow field simulations of a high voltage, gas insulated, three-phase busbar. It also discusses the influence of radiation on the results.