Strength analysis of the bushing system supporting set for a medium power turbo-generator using the multiphysics method

In this paper, a comprehensive stress analysis of the bushing support system for a medium-power turbo-generator is presented, using the multiphysics approach. For evaluation of the system response, the finite element method (FEM) is utilized for three types of loads: electromagnetic, thermal, and mechanical. The electromagnetic and thermal loads are computed for both rated and fault conditions. In addition, mechanical loads, including bolt pre-tension, weight, and seismic acceleration are applied. All various loads are combined through a standard method, and the subsequent stress distribution is analyzed for all components based on the appropriate stress criteria. Since the bushings are used in transferring electrical currents from the stator windings to the casing outlet, allowable creepage and air electrical distances, by standard regulations, should be observed. Consequently, the support structures are required to be constructed from non-conductive materials or designed to meet the specified minimum distances. In this study, EPGM composite material is selected for the supports due to its non-conductive properties and ability to withstand the worst conditions. The structural design of supports is optimized to ensure their durability under the worst conditions. Finally, the safety factors for all components are calculated and then compared to the permissible limits.