| With the development of modern industry, the manufacture technology of large electric generator is getting more and more complete. To increase the utility of energy sources, it is necessary to pay full attention to the refurbish and upgrade of the generators, where the skin effect of stator bars is an important problem. At present, the refurbish and upgrade of the hydroelectric generator have been started. As the output of hydraulic turbine has reached the request, it becomes very important how to deal with the upgrade of the generator. By adopting the traditional way to rebuild the ventilation system is also an effective measure, but the results will not be significant. By changing the transposition of the stator bars in the generators to decrease their maximum temperature has been adopted by some power plants and good economic results have been obtained. International standards on this aspect are on preparing. Test and analysis for the stator bars temperature in Gezhouba power plant show that, by different transposition, temperature distribution in bars is different. The reason is in skin effect and circulating current among different layers. It may lead to 30~40℃ temperature difference. In this thesis, various transposition methods are studied and corresponding mathematical models were set up. On this basis, a program of strand current calculation and transposition analysis were made. Calculation results were verified by test. In such a way, optimal transposition scheme is obtained.
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