Tracked Changes. Specification for plastic films for electrical purposes. Specifications for individual materials. Requirements for balanced biaxially oriented polyethylene terephthalate (PET) films used for electrical insulation|Electrical resistivity, Thermal resistance, Corrosion resistance, Density, Electrical insulating materials, Polyethylene terephthalate, Elongation at fracture, Dissipation factor, Insulating films, Solid electrical insulating materials, Film splices, Plastics, Diameter, Thermal testing, Endurance testing, Grades (quality), Dimensional changes, Sag (deformation), Dielectric materials, Electrical testing, Defects, Designations, Permittivity, Plastic films, Deformation, Breakdown voltage, Thickness, Dielectric strength, Tensile strength, Width