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-Nowadays, it is a global trend to build refinery or chemical plants with an isolated system in a place distant from the center of a city. In the refinery or chemical plants equipped with an isolated system, induced motors mostly take the load, and the scale of high-voltage electric motors reaches from several kW up to several MW. Therefore, it is needed to examine the effects of electric motors on the power system closely in the stages of planning and designing a plant to build a stable power system. This study is aimed to investigate how to decide rated voltage in consideration of stability which has not been considered in the stages of planning and designing so far in order to secure stability for the power system.

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-In this study, samples from the site where there occurred unbalanced current when cable routing were analyzed, and the simulation program for electric power system analysis, PSCAD/EMTDC, was used to calculate the current unbalance on cable routing. Based on electromagnetic finite element analysis(FEA), electromagnetic parameters enabled the interlocking with COMSOL for the calculation of allowable current ampacity and magnetic filed distribution. This then led to modeling unbalanced current between common modes using the unbalanced current analysis program, thereby comparing and discussing the results from both. The analyzed model is a common mode 2 parallel circuit, which is a basic model for cable routing, and by arranging cables in various ways, the arrangement with the least current unbalance was suggested, which would, in the future, prevent earth faults and extend life for the whole cable.

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