Performance testing of high voltage generator- and motor insulation systems

High voltage rotating machines remain to play a significant role in generating electrical energy. One of the main causes for down times of these machines is related to problems in the winding insulation. The deregulated energy market leads to cost pressure on the producers of the insulations and the utilities. While manufacturers built insulations with increased electric field, utilities want to reduce costs through longer maintenance intervals and a higher lifetime of the machines. Improvements of insulations and a long failure- free lifetime can only be achieved when a complex mix of measures is applied. This paper describes a mix of techniques that are all suited to achieve a long lifetime of the insulations. Among them is a new method that allows testing of manufacturing quality of the insulation with only few material efforts, visual inspections, the measurement of loss factor and PD measurements.