Evaluation of the cause of overload failure in rotating equipment

Overloads are a major cause of failure with wound armature rotating equipment. The reason for this is: 1. Rotating equipment, because of the nature of its application is often subjected to mechanical or electrical overloads and thus overheating. 2. The insulation system in a wound armature is subject to large centrifugal forces due to high rotational speeds and/or large diameters. This combination of high temperatures and large forces can result in premature failure of the equipment. Often the deciding factor which determines whether a motor or generator endures or fails the overload is the type of magnet wire in the armature. Much has been learned from actual field usage and experience about the suitability of existing types of magnet wires for applications of this type. There have also been a number of test methods proposed to predetermine how a magnet wire will perform in this application. The results of some of these tests agree with actual performance, others do not. This paper is a study of the performance of various types of magnet wire in an actual overloaded wound armature rotating equipment. It also discusses a laboratory test which can explain and predict the performance of a magnet wire in this application.