In-service monitoring of thermal generator stator insulation condition

The monitoring and assessment of the stator insulation condition of a large hydrogen-cooled steam turbine generator are described. The results are based upon the analysis and interpretation of readings taken using the partial discharge analysis (PDA) method. Although meaningful partial discharge (PD) data has already been obtained from the use of PDA on smaller thermal generators, the application of the system on a large thermal generator (rated more than 500 MW) is a novel one. The installation of the PDA system on a 25-year old, 530-MW steam turbine generator is described, and the results of the initial set of tests are presented.