Merits of high temperature HV insulation system for rotating machines

Present HV insulation systems utilize the well-accepted global VPI methods that have been in place since the mid 60´s. These systems have been rated class F and in most continuous duty applications have been operating at class B temperatures. The exceptional operating performance of these systems also has hampered attempts to introduce new systems with cost effective materials. Due to the competitive nature of HV machines, nontechnical assessments have been made in favor of certain materials despite ample test data. User groups have generated standards specifying materials or process techniques that prevent progress in developing new materials that can withstand higher operating temperatures and stress levels. This paper attempts to evaluate the merits of operation at higher temperature with a system that has been introduced over 15 years, with additional testing conducted over the past four years