Optimized, emission free production process for main wall insulation with enhanced lifetime properties

The Micadur® insulation system, introduced in 1958 and based on the VPI (vacuum pressure impregnation) technique, has extended field experience with thousands of hydro and turbo generators in service. A significant step forward for the further improvement of this continuously evolving insulation system was the introduction of the Tube VPI technology, developed and patented by Alstom in the late 1990's, which has since been in use for the production of main insulation of turbo generator bars up to rated voltages of 27 kV. This technology has also significantly improved the EHS (Environmental, Health and Safety) situation inherent to the conventional methods of impregnation. In this report, it is shown how an existing and well-proven process technology can be used by tapping the full potential to improve the performance of the insulation of rotating electrical machines without the need to change the well-proven insulation materials that has been used for years.