Abstract – The rotor and stator windings used in large motors and generators are generally reliable with a life of 20 years or more. However, in an effort to reduce cost to remain competitive, many machine manufacturers have had to develop novel winding designs and manufacturing methods. They have also had to reduce material usage. The result has been windings that operate at higher electrical, thermal and mechanical stresses. Unfortunately, in some cases the consequence of the new manufacturing methods and higher design stresses has been premature failure of the windings. This paper reviews several case studies of premature deterioration or failure of recently made machines. The case studies will include premature stator winding deterioration due to:
- Stress relief coating malfunction
- Insufficient spacing between high voltage components
- Poor installation within the stator slot
- Poor stator endwinding support
Ways to avoid these premature winding problems such as better specifications, increased vigilance during manufacture and on-line monitoring are briefly reviewed.