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Electrical grade cellulose pressboard sheets for solid insulation in oil-immersed power and distribution transformers
Overview
Electrical grade pressboard (also called transformer board or presspahn board) is a solid insulation material made from high-purity, long-fibre cellulose pulp. It is the primary solid insulation used inside oil-immersed power and distribution transformers.
Pressboard is used as barriers, spacers, cylinders, end rings and structural insulation. Its porous fibre structure absorbs transformer oil completely, and the oil-impregnated board gives high dielectric strength over the life of the transformer.
Hitech Insulation supplies pressboard as full sheets, cut-to-size strips and blanks, or as finished machined and moulded components made to customer drawings in our Chennai units. Uniform density, low shrinkage and consistent thickness keep electrical clearances and winding heights accurate.
We supply transformer manufacturers, repairers and OEMs in Tamil Nadu, across South and North India, and export to overseas customers.
Technical Specifications
| Specification | Value |
|---|---|
| Base Material | High-purity cellulose fibres (electrical grade) |
| Thickness | Standard sheet thicknesses; custom thickness on request |
| Density | 0.9 – 1.2 g/cm³ |
| Dielectric Strength (in oil) | ≥ 15 kV/mm |
| Operating Temperature Class | Class A – 105°C |
| Moisture Content | ≤ 6% |
| Oil Compatibility | Excellent (mineral transformer oil) |
| Surface Finish | Smooth / calendered |
| Supply Form | Full sheets, cut-to-size, strips, machined components |
| Processing Options | Cutting, punching, CNC machining, drilling, bonding |
Applications
- Solid insulation barriers in power and distribution transformers
- Phase and winding separation, cylinders and wraps
- Radial spacers, axial strips and support blocks
- End rings and yoke insulation
- Lead and bushing insulation supports
Why Choose This Product
High dielectric strength after oil impregnation
Good mechanical rigidity with low deformation
Uniform thickness for reliable electrical clearances
Compatible with standard transformer insulation systems
Easily machined into custom transformer components
Need Custom Specifications?
Our engineering team can customize this product to your exact requirements. Get in touch for a detailed quote.
Electrical Grade Pressboard Sheets – FAQs
What is electrical grade pressboard used for?
What is the difference between pressboard and pre-compressed pressboard?
Can Hitech Insulation cut pressboard to size or machine components?
Do you supply pressboard outside Tamil Nadu and outside India?
Related Products
Pre-Compressed Pressboard
High-density pressboard for critical transformer insulation and load-bearing applications
Moulded Pressboard Components
Hot-moulded pressboard insulation components for complex transformer geometries
Transformer Insulation Component Kits
Pre-assembled pressboard insulation kits for transformer manufacturing
