Determination of the Insulation Condition in Synchronous Generators: Industrial Methods and A Case Study

Electrical machines, and especially Synchronous Generators (SGs), take a significant position in power generation plants and industry production lines, and their unscheduled outages may have very negative repercussions. One of the main reasons for their failure relies on the degradation of their stator and rotor insulation systems. Although there are several industrial methods that are commonly used for diagnosing the health of such parts, some critical aspects remain unsolved. This article reviews the different diagnostic methods and techniques that are most commonly used in practice to determine the condition of these two insulation systems in SGs, emphasizing their respective drawbacks and analyzing their variants. Consequently, a case study on an SG operating in a power plant in Greece that illustrates the application of all of these methods is presented.