Analysis of Armature-Winding Inter-Turn Short Circuit Fault in Multiphase Brushless Exciter

The paper establishes a mathematical model based on multi-loop method and tensor method for the multiphase brushless exciter widely used in the nuclear plant, and the inductances of the machine in the model are computed by FEM, which covers the influences of pole shape, cogging effect, spatial harmonics of the magnetic field. The model is then used to simulate the multiphase excitation system at normal and abnormal conditions including armature-winding internal short circuit, one of common faults in the exciter, which is of great importance for fault detection and improvement of the machine's reliability. In addition, the paper conducts associated fault experiments on a customized experimental prototype to verify the model. Simulated and measured results show that most electrical quantities of the system change significantly and the exciter needs a quick shutdown to avoid the associated windings' burning out when a metallic armature-winding inter-turn short circuit occurs in the multiphase brushless exciter.