Applications of Diamond Dotted Polyester Film in Electrical Insulation Systems

In modern electrical equipment, insulation materials are no longer selected only for dielectric strength. Engineers also need materials that can provide mechanical stability, heat-activated bonding, dimensional consistency and reliable processing performance.

This is why diamond dotted polyester film is used in many transformer and electrical insulation systems.

Diamond dotted polyester film is an electrical insulation film made from polyester film coated with semi-cured epoxy resin in a diamond pattern. The polyester film provides insulation and mechanical support, while the diamond resin pattern provides bonding after heat curing.

Compared with ordinary polyester film, this material is more suitable for applications where insulation layers need to be bonded together during production.

For product specifications, you can visit our product page: Diamond Dotted Insulation Film.

Where Is Diamond Dotted Polyester Film Used?

Diamond dotted polyester film is mainly used in:

• power transformers and instrument transformers;

• dry-type transformers, oil-immersed transformers and SF₆ instrument transformers;

• interlayer insulation, interturn insulation and winding insulation;

• copper foil and aluminum foil winding insulation;

• motors, generators and electrical equipment;

• reactors, capacitors and switchgear insulation;

• EV drive motors, charging piles and energy storage equipment;

• wire and cable wrapping, electronic component insulation and bonding insulation structures.

Its core value is simple:

It provides electrical insulation and heat-activated bonding at the same time.

Applications:

1. Power Transformers and Instrument Transformers

Power transformers and instrument transformers are the most important application fields for diamond dotted polyester film.

In transformer winding structures, insulation materials must not only separate conductive layers, but also help maintain winding stability during manufacturing and operation.

Diamond dotted polyester film is commonly used for:

interlayer insulation;

interturn insulation;

winding insulation;

bonding insulation structures;

insulation between foil winding layers;

insulation liner for copper foil or aluminum foil windings.

In dry-type transformers, oil-immersed transformers and SF₆ instrument transformers, the diamond resin pattern can bond insulation layers together after heating. This helps improve winding compactness and mechanical stability.

For medium- and high-voltage instrument transformers, especially SF₆ instrument transformers, diamond dotted polyester film can be used as a high-performance insulation material where film insulation and controlled bonding are both required.

2. Foil Winding Insulation for Copper and Aluminum Coils

In low-voltage transformer coils, copper foil and aluminum foil windings are widely used.

During foil winding, insulation film is often placed between conductive layers as a liner or interlayer insulation material. The film must be thin, stable and strong enough to withstand winding tension.

Diamond dotted polyester film is suitable for this application because it provides stable polyester film insulation, heat-activated resin bonding and better resistance to short-circuit mechanical stress.

After curing, the resin dots help bond the insulation structure and winding layers together. This can improve the overall strength of the coil and help reduce movement between layers.

For transformer manufacturers, this is one of the key reasons to choose diamond dotted insulation film instead of ordinary smooth PET film.

3. Motors and Generators

Diamond dotted polyester film can also be used in motor and generator insulation systems.

Depending on the approved material grade and insulation system design, it may be used in B-class and selected F-class motor insulation structures.

In industrial motors, explosion-proof motors and generators, insulation materials are exposed to heat, vibration and mechanical stress. Materials used in these positions need good dielectric performance and reliable processing behavior.

Diamond dotted polyester film is useful when the insulation structure requires both film insulation and bonding support.

For motor applications where flexible composite paper is required, Chengrui also supplies NMN insulation paper, DMD insulation paper and NHN insulation paper.

4. Electrical Equipment, Switchgear, Reactors and Capacitors

Besides transformers and motors, diamond dotted polyester film can be used in different types of electrical equipment where internal insulation and bonding are required.

Typical applications include:

high-voltage and low-voltage switchgear;

reactors;

capacitors;

electrical component insulation;

internal insulation liners;

bonding and fixing insulation structures.

In these applications, the insulation material needs to maintain electrical separation while helping keep components stable inside the equipment.

The diamond resin coating provides bonding points after heat curing, while the polyester film base keeps good mechanical strength and insulation performance.

5. New Energy Applications

With the development of electric vehicles, charging systems and energy storage equipment, insulation materials are required to perform under more complex working conditions.

Diamond dotted polyester film can be used in selected new energy insulation systems, especially where polyester film insulation and bonding performance are needed.

Potential applications include:

EV drive motor insulation systems;

charging pile insulation parts;

energy storage equipment insulation;

battery-related electrical insulation structures;

customized new energy insulation components.

In these fields, material selection usually depends on temperature class, voltage level, mechanical design and processing method. Therefore, the final film specification should be confirmed according to the actual insulation system.

6. High-End Equipment and Special Insulation Components

Diamond dotted polyester film may also be used in high-end equipment where insulation performance, bonding reliability and material stability are important.

Typical fields include:

rail transit equipment;

aerospace-related electrical components;

special industrial insulation parts;

precision electrical equipment;

customized bonding insulation structures.

In these applications, materials are often selected not only by product name, but also by full insulation design.

For special insulation components, Chengrui can provide technical communication before quotation to help customers select the proper insulation material.

7. Other Extended Applications

Diamond dotted polyester film also has extended applications in some industrial and electronic insulation fields.

These may include:

wire and cable wrapping insulation;

electronic component insulation;

insulation encapsulation support;

industrial composite insulation structures;

bonding insulation layers;

customized electrical insulation parts.

For these applications, the key question is whether the customer needs heat-activated bonding.

If bonding is required, diamond dotted polyester film may be a better choice than ordinary PET film. If only basic insulation is needed, standard polyester film may be enough.

Why the Diamond Pattern Matters

The diamond pattern is one of the most important design features of diamond dotted polyester film.

If the entire film surface is coated with resin, air, gas or oil movement may be blocked between insulation layers. This can create processing problems in some transformer and electrical insulation systems.

The diamond resin pattern solves this issue by creating bonding points while leaving open channels between coated areas.

Diamond Dotted Polyester Film vs Ordinary Polyester Film

If your application only needs a stable PET insulation layer, ordinary polyester film may be suitable. If your application requires insulation layers to bond together during heating, diamond dotted polyester film is more suitable.

FAQ

Q1: What is diamond dotted polyester film used for?

A: Diamond dotted polyester film is mainly used for transformer interlayer insulation, interturn insulation, winding insulation, motor insulation, electrical equipment insulation and bonding insulation structures.

Q2: Why is diamond dotted polyester film used in transformers?

A: It provides polyester film insulation and heat-activated resin bonding. This helps improve winding stability while maintaining channels for air, gas or oil movement.

Q3: Can diamond dotted polyester film be used in SF₆ instrument transformers?

A: Yes. Diamond dotted polyester film is commonly used in SF₆ instrument transformers where film insulation and controlled bonding are required.

Q4: Can it be used for motors?

A: Yes. It can be used in selected motor and generator insulation structures, such as slot insulation, interturn insulation and phase insulation, depending on the approved insulation system design.