Application of coast-down monitoring technique for vertical shaft motors

The application of a technique to predict the coast-down behavior of vertically mounted electric motors is described. The technique gives an estimate of the coast-down time, as well as a determination of the shape of the speed/time curve, to be expected when the motors are equipped with grease-lubricated, deep-groove ball bearings and operated free of installation and assembly errors. Thus, a practical means to assess the mechanical condition of vertically mounted electric motors is provided by comparing their actual (measured) coast-down behavior with that predicted by the technique.