Why electric motors fail, and what to do about it when they do

摘要

Richard Hale, Managing Director of the Deritend Group offers some useful advice on how to look after electric motors. Electric motors fail for a number of reasons wholly unrelated to their age and to the hours that they have been operating. Problems with power supplies, overheating, contamination, insufficient or unsuitable lubrication and unusual loads can all play their part in impairing the efficient operation of motors, leading to premature, and usually costly, failure for the motor user. Addressing these factors is crucial, therefore, for any enterprise that is seeking to extend motor life, reduce downtime costs and improve OEE. In any study of the factors that cause motors to fail, the logical place to start is the power supply. With a properly conditioned and regulated power supply, the output to the motor should be a perfect sine wave on each phase at the motor's rated voltage and frequency. However, this is rarely achieved, and the result can be a host of problems including: harmonics, which cause overheating and decreased efficiency; overvoltage and undervoltage, the former reducing efficiency and power factor, while the latter increases current and causes overheating; voltage imbalances, which cause overheating and reduce efficiency.