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. The mechanical properties vary for Machine
Direction (MD) and Transverse Directions (TD).
Polyester films are available in rolls of different width with or
without an adhesive coat. The Insulation
required for a Sandwich Bus (Busway) must have the following
properties:
Good dielectric properties Low loss Angle Good comparative tracking index Good thermal conductivity Chemically Stable Good thermal insulation class Low moisture absorption Fire retardant Flexible for ease of wrapping Low coefficient of friction Non-toxic Stability under thermal cycling High tensile strength Long life Low thermal expansion
Mylar Wrapping on Flat or Tubular Conductors
Comments
Post a Comment