Calculation and Analysis of the Strands Short-Circuit in Stator Transposition Bar for Large Generators

The transposition of the stator bar is an important technique in the large generator design. Under the excitation of vibration and thermal effect, the insulation of strand is easily damaged, which leads to short-circuiting fault, and adversely impacts the generator's secure operation. To better protect the generator, there is a need for detailed research of the characteristics of stator transposition bar under the strands short-circuit condition. In this paper, we proposed a 3D finite numerical method (FEM) for calculating the strand short-circuit current. In the proposed method, the whole model of stator transposition bar is divided into multiple piecewise segments, and each segment is coupled together by the circuit. Based on this method, the electromagnetic properties of the 308° stator transposition bar under the strands short-circuit fault condition are analyzed. Then, the properties of the strand short-circuit current is studied. Finally, the calculated results are compared with the measured data. The results show that the calculation of the strand short-circuit current with high precision and the strand short-circuit current jump is one of the characteristics of strands short-circuit fault in stator transposition bar.