CSP04 - Fault diagnosis of electric motor by analyzing vibration and current spectrum

Abstract

As reliability of electric power system has been significantly improved in recent decades, electric motors are widely used in petroleum and chemical industries because they are rugged and reliable in severe condition. Motor consists of not only mechanical components such as rolling (or sleeve) bearing, cooling fan, shaft but electric components such as stator, rotor bar. When motor vibration occurs, the most effective way to figure out true source is vibration spectrum analysis. In general mechanical component damage is normally discovered by bearing defect frequency, and electrical component damage is closely related to the twice line frequency (2FL). However, when bearing defect frequency and twice line frequency (2FL) are very close or overlapped, its frustrating to distinguish true source of vibration before performing disassembly. In this case its not enough to determine probable causes by analyzing only one spectrum. This paper provides an analytical approach to investigate trouble source by analyzing vibration spectrum & motor current spectrum.