Electric rotating machinery represents a class of equipment that is very complex and, therefore,
subject to many different types of failure. The ac windings are subject to the same
types of failures as transformers, and protection must be provided to remove faulted machines
to preserve system integrity as well as to limit the damage to the equipment. Machines
are also subject to faults in the magnetic lamination insulation that can lead to heating
and eventual significant damage. Machines are also subject to the problems associated
with overheating and the loss of life of insulation that accumulates due to overheating.
Therefore, the cooling media that control the heating of current-carrying windings
and the magnetic steel circuits are possible causes of machine failure that must be considered