Premature Wear and Recurring Bearing Failures in an Inverter-Driven Induction Motor—Part I: Investigation of the Problem

This paper provides an analysis about early incipient and recurring failures in three-phase induction motor bearings when driven by pulsewidth modulation (PWM) inverters, focusing on a real industrial process. The potential problems preliminarily defined were first discussed on a theoretical basis and afterward experimentally assessed by means of vibration, stator current, and common-mode current data acquisition and analysis. Over the investigation, it was concluded that the presence of common-mode currents at the verified levels could cause damages to the motor bearings, which was confirmed when the machine stopped working due to another bearing failure.