Suppression of partial discharges in high-voltage rotating machines

Partial discharge in high-voltage electric rotating machines is unfavorable to the long-term operation of the machines and is associated with insulation failure. Throughout this history of manufacturing these machines, materials and techniques have been developed to suppress the onset of partial discharge, so that a number of modern solutions are available to manufacturers and repair shops. This paper is specifically intended as an introduction to classic design issues and solutions, providing information on the properties of materials used in the suppression of PD and on their selection for and application to high-voltage rotating machines. It also reviews a selection of recent material developments.