On-line detection of partial discharges in statorwindings of large turbine generators

Power utilities aim at the production of electrical energy at low cost and with a high availability. To achieve this for turbine generators, two aspects are of major importance: (i) minimal costs for maintenance and (ii) reduction of in-service failures. This can only be realized when effective tools are available to assess the condition of a generator. In The Netherlands, common tools are: (i) on- and off-line diagnostics for statorwindings, (ii) ultrasonic inspection of retaining rings, (iii) video endoscopes for visual inspections, and (iv) expert-systems to calculate the risk-of-failure for stator- and rotorwindings. This paper describes one of these tools in detail, namely on-line partial discharge monitoring of statorwindings.