On-Line Partial discharge Detection of Turbine Generator using GHz-Band Spatial Phase Difference Method

Abstract

Partial Discharge (PD) within voids in solid insulating system is a symptom and/or a direct cause of a deterioration of stator windings of a turbine generator. The bandwidth of the electromagnetic waves emitted from PD is very broad and ranges to GHz. We developed a new system based on “Spatial Phase Difference Method” for detecting microwave (GHz) emitted from PD. In this paper we applied this system to two off-line turbine generators in the overhaul and an on-line turbine generator which has two built-in antennas. On-line PD detection of the turbine generator is very useful for recognizing abnormal and/or deteriorated stator winding insulation without a machine outage. It was found that the detection system was able to detect microwave emitted from PD in operating turbine generator.