In most aging turbine generators, windings failures are caused by the deterioration of the insulation. Vibration is always there due to interaction between mechanical and electromagnetic forces between the rotor and the stator. Structures might become loose due to thermal cycling and start to rub against each other, causing further deterioration and partial discharge. These partial discharge are arcing events that give rise to hot spots. If unattended to, hot spots might lead to fire and explosion especially in the case of large, hydrogen cooled Generators.