Influence of slot radial magnetic field on circulating current in stator transposition strands of large turbogenerator

In large turbogenerators, the stator bars are made of several parallel strands which are connected together in end region. Because of the disparity of electromotive force between every two strands in the same bar, circulating current flows around a close-cycle and inevitably leads to useless circulating current losses, generating heat. Thus the transposition must be used in strands to avoid the circulating current, such as 540° transposition, void transposition, incomplete transposition, extended transposition, twin transposition bars and mixed transposition bars. How to ascertain the appropriate transposition type among so many transposition types depends on the calculation of circulating current.