Wet Bar Detection and Maintenance of Water-Cooled Stator Bars of Turbine Generators

摘要

Detection method for water leakage in stator bars of large-capacity direct water-cooled turbine generators has been developed. Detection of water permeation into insulation layer of stator bars which are designed to have internal electrodes in the ground wall insulation at the end portion was difficult with a conventional capacitance measuring method. Some of authors developed a new method specializing in diagnosis for the bars with internal electrodes, which was named as PMM or PMT (Potential Mapping Method (or Test)) and published in 2003. After the publication the new method has been successfully applied to several generators. This paper outlines the principle of the PMM, the information obtained from measured data, the application experience and the concept on application of the PMM to maintenance.