Analyses And Solution Research On Large-scale Steel-rolling Synchronous Motor's Damper Bar Fault

One of hot-rolling mill main driving motor is an AC-AC variable-frequency variable-speed non-salient pole synchronous motor from SIEMENS, the motor power is 12000 kW, which is now the largest single unit capacity in China. During the routine inside check of the motor, the damper bar's looseness and crack fault was found in the rotor damper windings, and it was deteriorating, so that the motor's operating status became more severe. The damper bar's crack fault of synchronous motors is infrequent, so we have not enough experience to solve the problem. This paper is of great significance to ensure the hot-rolling production, safeguard the motor, and avoid non-planned off-line maintenance time. Also, it introduces the characteristic of the damper bar's fault and its key repair technology, which can provide reference for synchronous motors's design and manufacturing.This paper focuses on the research of the damper bar's crack fault of large-scale steel-rolling synchronous motors. It introduces the motor's fault conditions, and some other synchronous motor's fault conditions in China, analyzing the characteristic of the damper bar's fault of synchronous motors. Through the research on the mechanism of the damper bar's crack and the analyses of the primary cause of the damper bar's crack, this paper also conducts the reasoning of the damper bar's fault developing trend.According to the fault developing mechanism, through the monitoring of motor's operating parameters, which includes some outside attributes, such as voltage, current and temperature, through the inspection of the damper bar's fault developing trend and the motor's dynamic performance, such as the motor's vibration, quantitative index of the damper bar's fault can be made, so as to evaluate the motor's status in different phases and predict the fault developing trend. In the meanwhile, based on the phenomenon and characteristic of the motor's fault, this paper carries out the research on the pointed repair scheme of the damper bar's fault of synchronous motors, sets forth the process of repairing and concludes the key points of the repair technology.