Detection of air-gap eccentricity faults in synchronous machines

近年来，与电机在线故障诊断(又称状态监测)相关的研究引起了人们的极大兴趣。故障预测，特别是在早期阶段，可以显著减少机器停机时间和维护。电机定子和转子之间的气隙不再均匀时，电机就会出现气隙偏心故障。气隙偏心大致可分为静态气隙偏心和动态气隙偏心两种。静态怪癖和动态怪癖往往并存。除非及早发现，否则偏心可能会导致定子与转子发生摩擦，导致电机因铁心和绕组损坏而发生重大故障。通常，与偏心有关的故障与大型机器有关。现有的偏心检测和监测技术大多局限于感应电机，因为它们通常具有很小的气隙。然而，同步电机偏心的早期和快速检测技术也可以使它们的设计具有更小的气隙。由于磁动力(MMF)要求的降低，这将大大降低机器的成本。它还将减少短路电流，从而减少断路器的尺寸和成本。因此，迫切需要开发诊断技术，最好是非侵入性的，以监测和检测同步电机中的这些故障。预计调查结果将为了解如何有效地检测同步电机的偏心提供新的线索。这将使众多同步机制造商和用户受益，并必将转化为加拿大工业利润的增加和生产率的提高。

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.