Ranprex® laminated wood and laminated pressboard are cellulose-based insulation materials commonly used in oil-immersed power and distribution transformers. These materials serve a dual purpose: providing both electrical insulation and mechanical support. While they are often interchangeable in applications like coil supports, rings, and lead rails, laminated wood frequently offers superior performance. This bulletin highlights the five key advantages of laminated wood over pressboard.

1. Superior Mechanical Properties

• Laminated wood is available in three construction styles: Parallel (P), Crosswise (C), and Tangential (T).
• These styles optimize properties like flexural strength, modulus of elasticity, compressive strength, and tensile strength.
• Example: P2R grade is ideal for lead structures due to high flexural strength; C2R is balanced for support blocks and rings.

2. Greater Density Options

• Laminated wood comes in four density grades: ultra-low, low, medium, and high.
• This allows for design flexibility and tailored mechanical performance.
• Laminated pressboard, by contrast, is only available in one commercial density.

3. Faster Dry-Out Time

• Laminated wood dries faster due to its fiber structure, reducing cycle times and heating costs.
• Pressboard’s layered structure impedes moisture removal, especially transversely.

4. Lower Cost

• Faster drying and reduced energy use contribute to lower overall processing costs.
• Laminated wood’s versatility also reduces the need for multiple material types.

5. Better Oil Absorption

• Laminated wood absorbs oil more effectively, enhancing dielectric performance and thermal stability.
• This is especially beneficial in transformer applications where insulation performance is critical.