Identification of Reasons for Short Circuit Development and Bulge Deformations in Salient Pole Field Winding- A Case Study

Recent studies have identified that insulation failures in rotor and stator winding are the main root cause for internal failures of electrical generators. The insulation failure of windings is a combined effect of thermal degradation, high electrical stresses and mechanical stresses due to vibrations. The cost of subsequent failures is very high and severely effects on the reliability of electricity supply. In recent past rotor pole bulging and inter turn short circuit development have been noticed in a 60 MW Barge Mounted Power Plant. This research focuses on identifying root cause for the failures and suggest remedial measures. First, operational data and design parameters have been analyzed together with a visual inspection of defective rotor poles. Then, temperature distribution in the rotor pole has been simulated to analyse thermal behavior of the rotor poles and windings. It has been identified that high temperature in the winding is the root cause for observed insulation failures.