The Study on the Effect of Strand Transposition on Temperature Distribution in Cross Section of Evaporative Inner Cooled State Bar

Strand transposition is widely applied in large AC machine to reduce additional copper loss in stator bars, which can improve efficiency. Copper strands in stator bar cooled by different method have two structures. One kind of stator bar is cooled by air through outside faces, which contains only solid copper strands, the cross section has two structures distinguished by strand transposition or not. The other kind of stator bar is cooled by coolant through inside faces of the bar, which contains both solid and hollow strands. Thus the cross section of inner cooled stator bar in transposition part is regularly changed along the length direction as two kinds strand transposed at the same time. The number of cross sections is decided by the ratio of hollow copper strand and solid copper strand. According to different cross sections of evaporative inner cooled stator bar, this paper analyzes the influence of the strand transposition on cross section temperature distribution of inner cooled stator bar.