Investigation of electromagnetic force during short-circuit test in three-phase busbar system

Abstract

All busbar systems are subjected to electromagnetic forces which may cause permanent mechanical deformation and damage if large electromagnetic force occurs due to short-circuit current. Therefore, the predictions of electromagnetic force on the three-phase busbar system is very important, especially to analyze it effect on the mechanical structure of busbar system. In this paper, two finite element models of busbar system having different rated currents are presented. Each model of busbar system has different mechanical dimensions. The electromagnetic forces generated in conducting busbars are analyzed under short-circuit conditions. The electromagnetic force is obtained using transient analysis by applying Maxwell Stress equation. Higher peak short-circuit current contributes to the generation of higher electromagnetic force between parallel conductors. The finite element models predict the busbars will experience peak short-circuit current of 63kA and 73.5kA, thus, generating about 62.5242 N/mm and 67.8617 N/mm of electromagnetic forces respectively, in between the conducting busbars. Optimal design for the mechanical dimensions and supporting structure for the three-phase busbar system can be intensively simulated taking into account the maximum electromagnetic force allowable. The results indicate that the magnitude electromagnetic force can be reduced by 4%–7% when the dimensions of conducting busbar thickness and its spacing are increased by 1mm. The results obtained are useful for the mechanical design and determination of supporting structure of the busbar system.