Coast-Down Time as a Mechanical Condition Indicator.

摘要

This initial report presents the development of a theoretical expression, and input for that expression, to predict the behavior of vertically mounted electric motors during coastdown. The coast-down behavior of four motors, equipped with grease-lubricated deep-groove ball bearings and operated at steady state under design conditions, is studied. The coast-down time (speed/time curve) is predictable by expressing the torque (M) on the rotor as a function of the speed (N) of the rotor in a quadratic of the form M = A + BN + CN2. It is demonstrated that the predictive capability developed herein can be used effectively to determine whether a motor is being operated under the desired design conditions. More experimental data will be obtained to confirm or refine the predictive technique. Mechanical problems will be introduced into the motor in an attempt to determine the effect on the coast-down curve. (Author)