Detection of Static Air-Gap Eccentricity in Three-Phase Squirrel Cage Induction Motor Through Stator Current and Vibrati
Three-phase squirrel cage induction motor being a core component of industrial drives needs fault detection strategies which can detect internal faults in very early stage of its development. This can result in enormous financial saving in industries. Sim
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Abstract Three-phase squirrel cage induction motor being a core component of industrial drives needs fault detection strategies which can detect internal faults in very early stage of its development. This can result in enormous financial saving in industries. Simulation studies with suitable mathematical models helps in identification of fault signatures in the diagnostic signal. The work presented in this paper addresses the issue of detection of incipient static eccentricity faults. Modelling of motor with static eccentricity fault is done and characteristic signatures were identified in frequency spectrum of stator current. These components were also identified in the vibration spectrum, by conducting a practical experimentation in three-phase squirrel cage induction motor with fabricated static eccentricity. The results validates the modelling approach and also demonstrates the suitability of vibration and stator current signal for the diagnosis of incipient static eccentricity faults.
Keywords Air-gap eccentricity Motor current signature analysis Vibration analysis Three-phase squirrel cage induction motor
1 Introduction A huge amount of world’s generating capacity is consumed by induction motor drives [1]. Induction motor drives are the major assets in process and energy industries. The asset management of electrical drives requires reliable condition monitoring, diagnostics and maintenance strategies. Static eccentricity is an internal fault in which position of minimum air-gap is fixed in space. In practical situations, inherent level of air-gap eccentricity always present due to manufacturing tolerances. Abnormal level of air-gap eccentricity has to be identified before leading to
S. Bindu (&) V.V. Thomas Manipal Institute of Technology, Manipal University, Manipal, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2018 A. Garg et al. (eds.), Advances in Power Systems and Energy Management, Lecture Notes in Electrical Engineering 436, https://doi.org/10.1007/978-981-10-4394-9_50
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secondary defects. The work presented here focuses on experimentation based on stator current and vibration analyses to diagnose static eccentricity in three-phase induction motor.
2 Diagnosis of Air-Gap Eccentricity Industrial case studies show that air-gap eccentricity occurs due to incorrect onsite installation of large motors and during re-installation following a repair or overhaul. Thermal bowing of the shaft can cause dynamic eccentricity. Air-gap eccentricity level of 25–30% is considered to be severe in large motors. A catastrophic failure can occur if the eccentricity is at a level such that the resultant unbalanced magnetic pull causes stator to rotor rubs [1, 2]. No single diagnostic signal exist which is able to detect probable faults in induction motors completely. Vibration and Stator Current and Temperature are the easily sensible diagnostic signals but each of these signals alone can detect only some specific faults. A general and reliable diagnostic
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