Offline and Online Methods for Stator Core Fault Detection in Large Generators

Fault diagnosis techniques play a crucial role in large turbogenerators. Due to the fact that it can cause catastrophic damage to the machine in a very short time, the development of new and more efficient methods represents a huge challenge for the researchers. Following this, the aim of this paper is to present two real-scale experimental devices manufactured to study interlaminar short-circuit faults in the stator of large generators. The first one is based on a stack of laminations in which faulty sheets can be inserted. In the second device, a special attention is given to the development of a partial exciter of a real 125-MW turbogenerator. Experimental online and offline results are presented and show that the measurement of flux density at the level of the external key bar can provide information about a short circuit between laminations.