Insulation Materials Used in Transformer Manufacturing | Types & Applications

Why Are Insulation Materials Important in Transformers?

Transformer insulation materials separate conductive components, help control electrical stress, and provide mechanical support during manufacturing and operation.

Different materials perform different functions. The appropriate selection depends on the transformer design, voltage requirements, operating temperature, insulation system, and manufacturing process.

Common materials include electrical insulation paper, pressboard, polyester film, polyimide film, composite insulation materials, and adhesive-backed electrical insulation tape.

1. Electrical Insulation Paper

Electrical insulation paper is widely used in transformer winding systems, particularly in oil-immersed transformers.

Common types include:

• Kraft insulation paper: Used for conductor wrapping and winding insulation.

• Crepe paper: Flexible paper used around leads and irregular shapes.

• Diamond dotted paper (DDP): Resin-coated paper that can bond insulation layers during a specified curing process.

These materials are selected according to the winding structure, electrical requirements, and compatibility with the transformer insulation system.

2. Transformer Pressboard

Transformer pressboard is a rigid cellulose-based insulation material.

It can be processed into components such as spacers, cylinders, barriers, and support structures. In addition to electrical insulation, it helps maintain spacing and mechanical stability within the transformer.

Pressboard is different from adhesive insulation tape. It is generally used where thicker, formed, or load-bearing insulation components are required.

3. PET Polyester Film

PET film is a widely used electrical insulation material because of its dimensional stability, mechanical strength, and electrical insulation properties.

PET-based insulation tape can be used for:

• Winding and layer insulation

• Coil wrapping

• Margin insulation

• Component separation

• Insulation material fixation

For adhesive-backed PET tape, the adhesive type, total thickness, and application conditions also affect product performance.

4. PI / Polyimide Film

Polyimide (PI) film is used in electrical applications that require higher-temperature capability than many conventional polyester constructions can provide.

PI tape may be considered for selected transformer components and other electrical insulation applications with demanding thermal requirements.

The actual suitability depends on the complete tape construction, including the adhesive, thickness, and specified operating conditions.

5. Composite Insulation Materials

Composite materials combine two or more materials to achieve a balance of properties.

Examples include PET film laminated with non-woven insulation material and other film-based insulation laminates.

Depending on the construction, these materials can provide a combination of electrical insulation, flexibility, mechanical support, and resistance to handling damage.

PET composite non-woven tape can be considered for selected transformer barrier, wrapping, and insulation applications.

6. Electrical Insulation Tape

Electrical insulation tape is used in various transformer manufacturing processes, including wrapping, fixing, separation, and insulation protection.

Different tape types serve different purposes.

These are general application examples, not universal approvals. Each tape must be evaluated against the requirements of the intended transformer insulation system.

7. How to Choose the Right Transformer Insulation Material

Before selecting an insulation material, consider the following factors.

Electrical performance: Confirm the required breakdown voltage, dielectric strength, and insulation dimensions.

Temperature resistance: Evaluate the operating temperature and manufacturing process, including any heating, curing, or impregnation stages.

Mechanical requirements: Consider tensile strength, flexibility, dimensional stability, and resistance to handling damage.

Material compatibility: Confirm compatibility with transformer oil, varnish, resin, or other substances if the application involves contact or impregnation.

Dimensions: Check thickness, width, length, and the available installation space.

Manufacturing process: Determine whether the material will be manually applied, automatically wound, slit, laminated, or die-cut.

For adhesive-backed tapes, adhesion should also be tested on the actual substrate under relevant processing conditions.

8. Customized Transformer Insulation Tape from LY

Changshu Liangyi Tape Industrial Co., Ltd. is a source manufacturer specializing in industrial electrical insulation tapes.

Our production capabilities include:

Adhesive Coating → Rewinding → Slitting → Inspection → Packing

Our product range includes:

• PET / Mylar insulation tape

• PI / Kapton tape

• PET composite non-woven tape

• PET silicone tape

• Fiberglass cloth tape for electrical insulation

We can customize suitable tape products according to required widths, thicknesses, lengths, colors, adhesive systems, and roll specifications.

For transformer manufacturers, we also focus on finished-roll quality, including slitting accuracy, winding density, flatness, and roll stability.

Conclusion

Transformer manufacturing requires a coordinated insulation system rather than a single material.

Insulation paper and pressboard provide important winding and structural insulation functions, while PET film, PI film, composite materials, and electrical insulation tapes serve different applications.

The right choice depends on the electrical, thermal, mechanical, dimensional, and manufacturing requirements of the transformer.

Looking for transformer insulation tape? Contact LY with your required material, thickness, width, length, application, and quantity to discuss a customized solution.