Diamond Dotted Insulation Polyester Film

Diamond Dotted Polyester Film for Transformer Interlayer and Interturn Insulation

Diamond Dotted Insulation Film also called Diamond Pattern Film (DPF), is an electrical insulation polyester film coated with modified epoxy resin in a diamond-grid pattern.

The polyester film provides electrical insulation, mechanical strength and dimensional stability, while the semi-cured epoxy resin dots provide heat-activated bonding during transformer manufacturing.

Unlike fully coated adhesive films, diamond dotted polyester film does not cover the entire surface with resin. The diamond pattern creates bonding points while leaving open channels between the resin areas. This helps support air, gas or oil movement inside the insulation structure, depending on the transformer design.

Diamond dotted insulation film is mainly used for interlayer insulation, interturn insulation and bonding insulation structures in SF₆ instrument transformers, power transformers and other electrical insulation systems.

Product Structure

Diamond dotted polyester film is made by coating modified epoxy insulating resin onto electrical-grade polyester film in a regular diamond pattern.

The resin is processed into a semi-cured state during production. At room temperature, the film remains easy to handle, cut and wrap. During the heating process, the resin softens and cures, bonding adjacent insulation layers together.

The diamond pattern is not only a coating design. It is used to control bonding distribution and maintain insulation medium channels between winding layers.

Grid Side Length: 9.4 mm

Grid Spacing: 6.5 mm

Technical Specifications

Why Use Diamond Dotted Polyester Film?

In transformer insulation systems, full-surface bonding is not always the best solution.

If resin covers the entire film surface, it may reduce the movement of air, gas or oil between insulation layers. This may increase the risk of trapped bubbles or uneven bonding in some transformer structures.

Diamond dotted insulation film solves this problem by using a patterned resin coating.

During heating, the epoxy resin dots bond the insulation layers together. At the same time, the uncoated areas between the resin dots remain as channels for air evacuation, gas movement or oil penetration.

This makes diamond dotted polyester film suitable for transformer designs requiring both:

electrical insulation;

heat-activated bonding;

controlled insulation medium channels;

improved winding stability.

Applications of Diamond Pattened Film

1. SF₆ Instrument Transformers

Diamond dotted insulation film is commonly used in SF₆ instrument transformers where insulation layers require both electrical insulation and controlled bonding.

The polyester film base provides insulation performance, while the diamond resin pattern supports bonding during the heat curing process.

2. Power Transformers

In power transformers, diamond dotted polyester film can be used for interlayer and interturn insulation where polyester film insulation and heat-activated bonding are required.

It helps improve insulation layer stability during transformer manufacturing and operation.

3. Interlayer Insulation

The film can be used between winding layers or insulation layers that require bonding after heating.

The diamond resin pattern helps bond adjacent layers while maintaining open channels between the resin areas.

4. Interturn Insulation

For transformer structures requiring thin film insulation between turns, diamond dotted polyester film provides a combination of dielectric insulation, mechanical support and resin bonding performance.

Curing Conditions

The film can be cured under either of the following conditions: At 90°C ± 5°C for 16 hours, or At 110°C ± 5°C for 6 hours.

Storage of Electrical polyester film

The DPF polyester film should be stored in a dry, ventilated, and clean environment at a temperature not exceeding 25°C. It must be protected from high temperatures and direct sunlight. The storage period is six months. If the storage period is exceeded, the adhesive strength should be tested, and the product may still be used if it meets the required standards.

Diamond Dotted Insulation Film vs Diamond Dotted Paper

Diamond dotted insulation film and diamond dotted paper are both diamond-pattern insulation materials, but their base materials and application focus are different.

Xuchang Chengrui Insulation Material Co.,Ltd. supplies electrical insulation materials for transformer manufacturers, motor manufacturers and insulation material distributors worldwide.

For diamond dotted polyester film, we support:

• customized roll width;

• customized roll length;

• export packing;

• sample support;

• technical communication before order;

• material recommendation according to transformer application.

Our related products include 6021 Polyester Film, Diamond Dotted Paper, Thermally Upgraded Diamond Dotted Paper and other transformer insulation materials.