Magnetic core short circuit testing techniques for electrical power generators

Power generators are exposed to high electrical, thermal and mechanical stresses during their operational life. Over time, this could lead to damages in the magnetic core isolation that can cause the formation of large eddy currents and local hot spots that gradually spread. Hence, it is recommended to regularly verify the isolation condition to avoid possible damage, which can lead to an unscheduled outage. This article analyses in detail the short circuit effects of magnetic core laminations of stators in power generators. The existing techniques for quantifying the size of the fault and its location are described. Advantages and disadvantages of these techniques for making maintenance decisions are established. Finally, experimental and finite element modelling results that illustrate the short-circuit eddy current problem are presented and discussed.