A Study of Pressure Development and Oil-immersed Transformer Tank Deformation During an Arcing Event Considering Strong FSI

Low impedance faults in an oil-immersed transformer are of great danger and unavoidable. Improvements of arc containment capacity of an oil-immersed transformer are therefore urgently required. Precise prediction of pressure development and transformer deformation during an arcing event greatly supports optimization of the transformer, however, are not available currently. This paper built a S-ALE model in regard to strong fluid-solid interaction between insulation oil and transformer tank. The developed model can well present pressure shock triggered by the arc and the propagation of the pressure wave. Stress field and deformation of the transformer tank show strong dependence on location of the arc and fluid channel inside the tank. Moreover, localized high stress and deformation gradients were generated due to both high energy release in an ultra-short time and local fluid resistance. An attempt to improve arc containment capacity of the tank was conducted via increasing allowable deformation of the tank during the arcing. A reduced stress on the connection bolts, indicating enhanced transformer performance, is achieved at a cost of increased tank deformation. The S-ALE model generated in this paper provides a powerful tool for design and optimization of the transformer tank. The effort on arcing protection of the transformer is meaningful and worth of further investigation.