Electrical Insulation Pressboard For Transformer

Transformer insulation pressboard is a rigid cellulose board used for barriers, spacers, cylinders and other structural insulation parts in oil-filled transformers. It offers good mechanical strength, dielectric insulation and oil compatibility.

What Is Transformer Pressboard?

Transformer pressboard is an electrical insulation board made mainly from high-purity cellulose fibers. In transformer manufacturing, it is used where insulation must do more than separate conductive parts. It must also hold shape, maintain spacing and support the internal structure of the transformer.

Public technical references describe transformer insulation pressboard as a key solid insulation material for oil-filled power transformers and distribution transformers, produced from pure or highly purified cellulose and valued for chemical purity, mechanical strength and oil impregnability.

In practical terms, transformer insulation pressboard is one of the core materials used to build the internal insulation system of a transformer.

Why Pressboard Is Used in Transformer Insulation

In transformers, insulation is not only an electrical issue. It is also a structural and mechanical issue.

That is why pressboard transformer insulation is widely used. Compared with thinner insulation papers, pressboard provides:

• higher mechanical strength

• better dimensional stability

• stronger support for internal parts

• good dielectric insulation

• good performance in oil-immersed transformer systems

Available Grades and Typical Supply Range

Our transformer pressboard is available in different grades, thicknesses and sheet sizes for different transformer voltage levels and applications.

B+  Quality

• used for 11KV transformer

• Thickness(mm): 0.8/1/1.5/2/2.5/3/4   

• Size(mm): 1000x2000

A Quality

• used for 35KV transformer

• Thickness(mm): 0.8/1/1.5/2/2.5/3/4   

• Size(mm): 1000x2000

A+ Quality 

• used for 110KV Transformer

• Thickness(mm): 0.8/1/1.5/2/ 2.5/ 3/ 4

• Size(mm): 1000x2000  1050X2000  1400X2500

G4 Quality (High density transformer pressboard)

• used for over 110KV Transformer

• Thickness(mm): 1-50

• Size: 1050X2000 2100x3200   2200x4400

Color: brown

Chengrui Insulation supplies transformer pressboard for oil-immersed transformer OEMs, repair workshops, and insulation parts processors. The material is commonly used for winding insulation, barriers, cylinders, rings, spacers, blocks, and other structural insulation parts inside power and distribution transformers.

Typical Applications of Transformer Insulation Pressboard

Transformer insulation pressboard is commonly fabricated into many pressboard components and parts used in transformer construction

• Barriers: Used to separate energized parts and maintain insulation distance inside the transformer.

• Spacers: Used to support winding geometry, maintain oil ducts and control internal clearances.

• Cylinders: Used around winding structures where shaped rigid insulation is required.

• End Rings: Used to support and stabilize winding ends.

• Structural Support Parts: Used for formed or machined insulation components that must provide both insulation and mechanical support.
  
  
  

Transformer Pressboard vs Presspaper

Buyers often confuse transformer pressboard with presspaper.

A practical distinction is:

• Presspaper is usually thinner and used for lighter insulation functions

• Transformer pressboard is thicker, stronger and better suited for structural insulation parts

  
  

How to Choose Pressboard for Transformer Insulation

When selecting pressboard for transformer insulation, start with the application, not just the material name.

1. Identify the Transformer Part

Is the material for a barrier, spacer, cylinder, end ring or another structural part?

2. Check Mechanical Requirement

Does the part need to resist deformation, maintain spacing or support winding geometry?

3. Confirm Oil-Filled Use

Most pressboard transformer insulation applications are closely linked to oil-filled transformer systems. Public manufacturer references strongly position pressboard in liquid-filled transformers.

4. Choose the Right Grade

Different voltage levels and transformer designs may require different grades such as B+, A, A+ or G4.

5. Confirm Thickness and Fabrication

Check whether you need standard sheets only or fabricated components such as rings, blocks or cylinders.

FAQ

Q1: Why is pressboard used in transformer insulation?

A: It is used because it combines mechanical strength, dielectric insulation and oil compatibility, which are essential in pressboard transformer insulation systems.

Q2: Is transformer insulation pressboard the same as presspaper?

A: No. Both are cellulose-based insulation materials, but transformer insulation pressboard is generally thicker and better suited for structural transformer parts, while presspaper is usually thinner and used for lighter insulation functions.

Q3: Is transformer pressboard suitable for oil-filled transformers?

A: Yes. Leading manufacturers specifically position transformer pressboard for oil-filled power and distribution transformers because of its oil impregnability and chemical purity.

We can supply insulation pressboard in standard sheets, different thicknesses (0.8-30mm), and cut-to-size parts according to customer drawings. For overseas buyers and distributors, we also provide sample sheets, packing confirmation, technical data, and export shipment support before bulk orders.