AGEING AND DEGRADATION OF ELECTRICAL MACHINES INSULATION
Catalin Rusu-Zagar, Petru V. Notingher, Cristina Stancu
Pages: 526-546 Published: 2 Jun 2014
Views: 2,245 Downloads: 4,645
Abstract: The ageing and degradation of electrical machines insulation are phenomena that determine the life-time of electrical machines in operation. The intensities of these phenomena depend on the nature and values of electrical, mechanical, thermal and environmental stresses that act (permanently or temporary) on the insulations. The paper presents an experimental study of the effects of thermal, mechanical and electrical stresses on the electrical characteristics of some paper mica, glass fibers and epoxy resin insulations. The samples (bars) were subjected to uni- and multifactor ageing using several laboratory setups and the variations of capacity and loss factor with the ageing time and applied voltage were measured. The results analyze shows that the Isotenax tape insulations have a better behavior than P722 tape insulations and that the multifactor stresses (electrical + mechanical + thermal) cause a more pronounced modification of the loss factor and capacity than the unifactor ones.
Keywords: electrical machines, epoxi-mica insulations, unifactor and multifactor ageing