Comparative performance of woven glass and polyester film backed micaceous tapes for the insulation of high voltage AC stator windings of rotating electrical machines

Film backed materials are currently used as the main dielectric for many ranges of high voltage industrial machines with voltages up to 13.8 kV. Details of some of the development work and some of the salient points regarding manufacture of windings and service experience are outlined. From the data presented it is evident that polyester film backed micapaper performs equally as well as equivalent glass backed material for machine windings operating up to the normal Class `F´ temperature limits. Long-term aging, electrical stressing and thermal cycling tests demonstrate that the overall performance is better with polyester film backed tapes