Chapter # 3 INSULATING MATERIAL 3.5 Polyester Film Polyester films/tapes have been used for the insulation of conductors in the manufacture of motor and transformers. Polyester films are used as slot insulation in the motor manufacturing industry. They are now being used as an insulating material in the sandwich bus for interphase and phase to earth insulation. While polyester films are available for a wide range of thermal class of insulation, Class B should be sufficient to meet the specification requirements of Busbar Systems . Mylar is the most commonly used insulation in sandwich Busways. It is the trade name for BoPET (Biaxially-Oriented Polyethylene terephthalate). The films are available in thickness varying from 12 µM (0.5 mil) to 500 µM (20 mil). Wrapping of Polyester films on Busbars is highly automated. Th
