Products for the Electrical Industry

POLIFIBRA Folien offers a wide range of films and multilayer composites, which are used for Insulation and other applications in the Electrical sector.

Where electric power is used, insulation is necessary. The "Appropriate Insulation" is a critical factor in ensuring the most efficient functionality of High-Voltage machines, Transformers and Motors.

On the following pages you will find an overview of our portfolio in the electrical sector:

General Notes
When choosing the right film or the film composite, different priorities have to be considered. [more]

Polyester films
POLIFIBRA manufacture a wide range of insulating films that are based on Polyester films [more]

Composite films
POLIFIBRA manufacture composite polyester films, which are UL and IEC / CEI Approved [more]

Prepregs / coated films
Polifibra produce films that incorporate reinforcing fibers that are impregnated with resin [more]

Heat stabilized films
These films are polyester films which have been “Heat Stabilized”, to limit further shrinkage. [more]

Caps and tubes
These Spirally Wound Tubes and Caps are used for Electrical Insulation on Motor Lead Wires. [more]

FAQ

1. What is a prepreg in electrical insulation?

A prepreg is a reinforcing or carrier material pre-impregnated with resin that is activated under heat and pressure. In electrical machines, prepregs act as an insulating layer and as a bonding layer between winding packages or laminated cores at the same time. Polifibra supplies heat-activatable composite films (PREPREGS) for exactly this application.

2. Which applications does prepreg have in electrical engineering?

Prepregs are used wherever layers have to insulate and bond at the same time: stator windings, rotor bandages, transformer windings, pole shoes and coil formers. They replace separate adhesives and allow reproducible winding and impregnation processes.

3. What temperature is required to process prepregs?

Typical activation and curing temperatures are between approx. 120 °C and 180 °C, depending on the resin system. The exact values depend on the resin used and on the thermal class of the machine. Polifibra matches the system individually to the winding and oven process of the customer.

4. Which standards do Polifibra insulation composites meet?

The composite films are UL certified and tested to IEC/CEI standards. They can therefore be used in internationally listed machines and in equipment that requires UL or IEC conformity documentation.

5. What is a foil winding in a transformer and which film is used?

In foil windings, a wide metal strip (usually Cu or Al) is layered with a thin insulating film instead of a winding wire. The insulating film provides electrical separation between the layers and thermal stability. Polyester and PI based films from the Polifibra range are the typical choice.

6. What is modern insulating paper in transformers made of?

In many applications, classic cellulose insulating paper has been replaced by polyester and aramid films and by composite systems, which offer a higher thermal class, better mechanical stability and more consistent properties. Polifibra supplies the matching films, including multilayer composites.

7. What is a multilayer composite film and when does it make sense?

A composite film combines several materials (for example PET + aramid + PET) into a laminate. Dielectric strength, mechanical load capacity and temperature resistance can be set specifically this way, which is useful for high voltage and high temperature machines where single layers are not sufficient.

8. Which film thicknesses and widths are available for winding machines?

Polifibra converts insulating films to the widths and core diameters required by the winding machine. Thicknesses typically range from a few µm up to the three digit µm range, and custom dimensions are produced to drawing.

9. Are Polifibra insulating films heat stabilized?

Yes. Polifibra explicitly supplies heat stabilized films that do not shrink during the winding and baking process. This is mandatory whenever dimensions and insulation distances have to be maintained exactly after heat treatment.

10. Can insulation composites be converted to customer drawings?

Yes. Polifibra produces slit rolls, caps, tubes and die cut parts to customer specification, including the composite structure, UL listing and suitable packaging for automated further processing.
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