Vibration Data and Analysis of A Large rating Induction Motor with Bent Shaft: Some Aspects

Abstract

Operation of many equipment in an energy intensive industry are very critical. The no-provision of standby can increase this criticality multi-fold. The motor under study for this paper is one such equipment where the development of bend in rotor shaft was observed during diagnosis of a breakdown event due to high bearing temperature protection. This is a 1.7 MW Induction Motor of a petrochemical industry. Due to non-availability of spare motor, the motor with developing bentshaft-problem was kept under operation with increased monitoring. The incipient stage detection of the motor vibration due the bent-shaft lead to additional condition monitoring. The vibration data sampled over a period of nearly four and half years with changed bearings is analyzed and reported in this paper. Attempt is made to monitor the defect in the motor with the change in vibration levels as a function time of operation of the motor with the help of vibration trends. Over the period of observation, the average vibrations showed an increasing trend in the range of 0.2 mm/s to 0.6 mm/s with the bent shaft, although these values are well within the acceptable upper limit. Finally, the vibration data is compared with those of replaced (new) motor. © 2020 IEEE.