Obserwacja procesu starzenia izolacji uzwojeń maszyn elektrycznych z wykorzystaniem metody napięcia stałego

In majority of factories like cement mills, electric motors working there are subject to a considerable influence of weather conditions due to their location. A significant number of those machines are placed in the open air, and in some mills, in the period of increased air humidity, from November to March, the factory delays production and the planned repairs of production lines are implemented. In this period diagnostic tests of electrical machines are also carried out. Some of the tested motors have built-in heating systems what limits the soaking of the windings insulation, whereas others have no such heating systems and that is reflected in the received results. The article presents a short history (2001-2007) of conducting diagnostic tests of insulation of medium voltage electric motors with the DC voltage method. The results of the tests and their influence on limiting repairs as well as tendencies of changes in motors working in fairly difficult exploiting conditions are presented.