Development of partial discharge monitor for turbine generators

A new partial discharge (PD) monitor has been developed. It continuously monitors electrical condition of stator winding insulation of the turbine generators in service. Wires of a resistance temperature detector (RTD) preinstalled between top and bottom coils of a stator slot are used as a RF coupler so that no new device installed inside a generator is required. Electromagnetic noise occurring around the generator is rejected by detection with multiple sensors and signal processing software. Results of in-service measurements show negative load and temperature dependence of PD characteristic. It is expected that the dependence is a symptom of degradation of the insulation system.