Research on the effect of rotor broken bar position on induction machine

In the past two decades, there have been many investigations on fault diagnosis in squirrel-cage induction machines, because it is presently one of the most widely used machines in industry. The broken rotor bar position has a big impact on the cage induction machine, which was overlooked in the past. Based on the multi-loop method, research has been carried out on the broken rotor bar position and its impact. First the relation between the broken rotor bar position and the fault characteristic in stator current caused by rotor winding fault are quantitatively analyzed in this paper, and the regularity is generalized. Then it is pointed out that for a machine with broken rotor bar fault, when further broken bars occur in some positions, the machine´s asymmetry will rise, the impact on operation will be greater, and the fault characteristic of stator current will increase; however, when the further broken bars are in some other positions, the machine´s asymmetry will decline, the impact on operation will be less, and the fault characteristic of stator current will decrease. The criterion to judge the fault extent is proposed, which is through the asymmetry of the machine caused by broken rotor bars.