Electromagnetic Field and Force Analysis of Three-Phase Enclosure Type GIS Bus Capsule

With the aim to optimization design and condition monitoring of Gas Insulation Station (GIS), a 3-D finite element model has been developed for the computation of the electromagnetic field and forces in a three-phase enclosure type GIS bus capsule. The calculation takes into account the bus bar connectors' contact resistance by modeling equivalent contact bridges between contact interfaces and physical properties of the materials involved have also been considered. Using the field distributions, power losses and electromagnetic forces have been calculated, the calculation is more valid and accurate compared to those from closed-formulas. The influence of the operation current and short current on those quantities is also examined. The results show that the distributions of current density and electromagnetic force in the conductors and tank are not uniform. Electromagnetic force of plug-in connector obtained by closed-formulas calculation has obvious deviation, due to the current distributions are not considered. The electromagnetic forces of bus conductors and plug-in connectors are large enough to overcome hold forces exerted by the contact springs under short circuit conditions.