Effect of Arc Energy Absorber in a Wind Turbine Switch Unit

The effect of an arc energy absorber installed in a wind turbine switch unit has been investigated by computational fluid dynamics simulations based on results of an internal arc test. The absorber is assembled from several layers of perforated plates. The compact switch unit consists of an SF 6 insulated switch tank, a cable compartment, and a chimney, which directs hot gases upwards. The mechanisms determining the properties of arc absorbers are identified. These are heat transfer and gas-flow resistance. Pressure and temperature developments within all parts of the switch unit are analyzed depending on different locations of the absorber within the chimney and a different number of absorber layers. The heat collection of each absorber layer is determined, and the overall efficiency of the absorber is compared for all cases under investigation. The closer the absorber is to the heat source, the more efficient it is.