Transformer Insulation Materials
Electrical Insulating Pressboard
Pressed from 100% premium sulfate insulating wood pulp, Class A
Electrical insulating pressboard made from pure cellulose taken from long-fibred coniferous wood. High density and purity for coil end, layer, lead and structural insulation in oil-immersed transformers.
Class A (105°C)Thickness 0.8–3.0 mm and aboveDielectric strength in oil 30–40 kV/mm
- Temperature class
- Class A (105°C)
- Thickness
- 0.8–3.0 mm (>3.0 available)
- Density
- 1.0–1.3 g/cm³
- pH
- 6.0–9.0
Request a quotation or a sample. Tell us thickness, width, temperature class, quantity and delivery form. We reply within one business day.
Technical data
| Property | Unit | Value |
|---|---|---|
| Thickness | mm | 0.8–1.5 / 2.0–3.0 / >3.0 |
| Thickness tolerance | % | ±7.5 / ±5.0 |
| Density | g/cm³ | 1.0–1.2 / 1.1–1.25 / 1.15–1.3 |
| Tensile strength MD | MPa | ≥100 / ≥105 / ≥110 |
| Tensile strength CD | MPa | ≥75 / ≥80 / ≥85 |
| Dielectric strength in oil | kV/mm | 40 / 35 / 30 |
| Shrinkage MD / CD | % | ≤0.5 / ≤0.7 |
| Elongation MD / CD | % | ≥3.0 / ≥4.0 |
| Conductivity of aqueous extract | mS/m | ≤8.0 |
| pH value of aqueous extract | — | 6.0–9.0 |
| Ash content | % | ≤1.0 |
| Moisture content | % | ≤6.0 |
| Temperature class | — | Class A (105°C) |
Values are typical values or ranges from our product data. Bulk supply is subject to the approved specification, sample and test report. If a parameter you need is not listed here, ask our engineers for the full test report for that grade.
Key features
- Long-fibre coniferous pulp with a pure cellulose structure and no added adhesive.
- Controlled thickness tolerance and density grades for punching, machining and forming.
- High chemical purity to reduce oil contamination and ageing risk.
Applications
Coil end, layer, lead and structural insulation in oil-immersed power and distribution transformers.
Oil-Immersed TransformersDistribution TransformersReactors
Why it fits
Where the insulation has to carry mechanical load - end rings, spacers, lead supports - while staying oil-compatible.
Ordering information
To receive a quotation, please confirm:
- Product and grade
- Thickness and width (and roll or sheet size)
- Temperature class
- Quantity and delivery form (roll / sheet / die-cut / machined)
- Destination port and required delivery date
For machined parts, attach a drawing in PDF, DWG or STEP format. Datasheets, COAs and batch test data are available on request.
Related materials
Often specified together
Send your specification
Our export team reviews the application, the process and the existing specification before recommending a construction.