Detection of air-gap eccentricity faults in synchronous machines

近年来，与在线电机故障诊断（也称为基于状态的监测（CBM））相关的研究引起了人们极大的兴趣。故障预测，特别是在早期阶段，可以大大减少机器停机时间和维护。当电机定转子间的气隙不均匀时，会发生气隙偏心故障。气隙偏心可以大致分为两种类型，即静态气隙偏心和动态气隙偏心。静态和动态偏心倾向于共存。除非及早发现，否则偏心可能会导致定子与转子之间的摩擦，从而由于铁芯和绕组损坏而导致机器的重大故障。通常，与偏心相关的故障与大型机器有关。偏心检测和监测技术主要局限于感应电机，因为它们通常具有非常小的气隙。然而，同步电机偏心的早期和快速检测技术也可以使其设计具有更小的气隙。这将大大降低成本的机器由于减少磁动力（MMF）的要求。它还将减少短路电流，从而减少断路器的尺寸和成本。因此，必须开发诊断技术，最好是非侵入性的，以监测和检测同步机中的这些故障。预计研究结果将为了解如何有效地检测同步电机的偏心提供新的思路。这将使许多同步电机的制造商和用户受益，并必将转化为加拿大工业的利润增加和生产力提高。

Recently, research related to on-line electric machine fault diagnosis (also known as Condition Based Monitoring (CBM)) has generated considerable interest. Fault prognosis, particularly at the incipient stage, can reduce machine downtime and maintenance considerably. Air-gap eccentricity faults occur in electrical machines when the air-gap between stator and rotor is no longer uniform. An air-gap eccentricity can be broadly classified into two types, namely, the static air-gap eccentricity and the dynamic air-gap eccentricity. Static and dynamic eccentricities tend to co-exist. Unless detected early, eccentricity may result in stator to rotor rub, causing a major breakdown of the machine due to core and winding damage. Normally, eccentricity related faults are associated with large machines. The detection and monitoring techniques available for eccentricity have been mostly restricted to induction machines because they usually have very small airgap. However, early and quick detection techniques of eccentricity for synchronous machines can also lead to their design with much smaller airgap. This will substantially reduce the cost of the machine due to a decrease in magneto motive force (MMF) requirements. It will also reduce short circuit currents and hence circuit breaker size and cost. It is therefore imperative that diagnosis techniques, preferably non-invasive in nature, are developed to monitor and detect these faults in synchronous machines. It is expected that the results of the investigation will shed new light in understanding how to effectively detect eccentricity of synchronous machines. This will benefit numerous manufacturers and users of synchronous machines and will surely translate into increased profit and enhanced productivity for Canadian industry.