Partial discharge testing of generator insulation

Progressive degradation of high-voltage generator insulation whether due directly to the erosive effects of internal or slot discharge, or to other debilitating factors such as heat and vibration, may be detected and monitored as a function of time by in-situ partial-discharge tests. This paper describes new diagnostic test techniques for assessing the condition of generator insulation with a minimum of service interruption. An improved means of coupling or data acquisition is described, as well as a versatile single-channel pulse height analyzer with characteristics adequate for a field application of this type. Some typical test data are given. These studies were sponsored by the Canadian Electrical Association and are presented with their permission.