Development of capacitance measuring robot for water-cooled stator winding of turbine generators

Direct water cooling of stator winding is widely adopted on large capacity turbine generators. In the case of water permeation into stator winding insulation, the di-electric strength drops steeply due to wet-heat deterioration. A robot capable of measuring water-cooled winding capacitance without removing the rotor has been developed, confirming good results in the field and contributing to the assurance of generators with high reliability. This paper outlines the capacitance measuring robot including following contents: (1) Background of the development of the capacitance measuring robot, (2) Development of the capacitance measuring robot, (3) The extent of generator disassembling and test schedule, (4) Field measurement results and evaluation, (5) Effects of applying the robot. (author)