Avoiding Current-Induced Bearing Filure in Electric Motor-Driven Paper Mill Systems

摘要

Atypical paper mill may contain hundreds of electric motors. These motors are used in applications as varied as boiler feedwater pumps and paper rewinders at the end of the papermaking process. The leading failure mode for motors has always been and continues to vbe bearing failure. The vast majority of bearing failures in electric motor-driven paper mill systems are due to mechanical and thermal causes. These include misalignment of the motor and load, vibration, incor-rect lubrication, excessive radial or axial loading, lubricat contamination, or inad-equate maintenance. A failure mode that has received a great deal of interest recently is failure due to electrically induced bearing currents. In these cases, bearings prematurely fail because of electrc current flowing through the motor or driven-equimpment bearings.