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) online and offline diagnostics for stator windings; (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 rotor windings. This paper describes one of these tools in detail, namely the online partial discharge monitoring of stator windings