PRE-COMPRESSED PRESSBOARD

Pre-compressed pressboard is a specialized material primarily utilized in the electrical industry, particularly for power and distribution transformers. This board serves as an essential component for providing electrical insulation and is manufactured from pure cellulose fibers derived from softwood pulp, ensuring high purity and mechanical strength without the use of fillers or bonding agents.

Characteristics and Specifications

  • Material Composition: Made exclusively from virgin softwood sulfate pulp, pre-compressed pressboard features high chemical purity and low conductivity. The manufacturing process involves refining the pulp in water to achieve suitable fiber length and bonding ability, followed by pressing under heat and pressure to enhance its properties

Physical Properties:

  • Density: High density contributes to its rigidity.
  • Thickness: Available in various thicknesses, typically ranging from 0.80 mm to 8 mm.
  • Dimensional Stability: Exhibits low compressibility and shrinkage, making it suitable for high voltage applications

Electrical Properties:

  • It possesses excellent electrical strength, making it ideal for use as spacers in transformer windings that are subjected to electromagnetic forces during operation.
No Properties Units Specifications Value Obtained
1 Thickness mm 2.85-3.15 3.09
2 Apparent Density g/cm3 1.10-1.25 1.23
3 Tensile Strength Index MD MPa 105 min 139
4 Tensile Strength Index CMD MPa 80 min 98
5 Elongation MD % 2.5 min 4.9
6 Elongation CMD % 3.5 min 4.8
7 Compressibility in Air % 7.50 max 4.19
8 Rev. Compressibility in Air % 50.00 min 55.33
9 Shrinkage in Air MD % 0.50 max 0.27
10 Shrinkage in Air CMD % 0.70 max 0.30
11 Shrinkage in Air PD % 6.00 max 2.40
12 Ply Bond Resistance N/30mm 250 min 729
13 Moisture Content % 6.00 max 2.40
14 Oil Absorption % 9.00 min 11.91
15 Conductivity of aqueous Extract mS/m 6.0 max 5.1
16 pH of aqueous Extract Range 6.0-9.0 7.0
17 Ash Content % 0.70 max 0.27
18 Electric Strength in Air KV/mm 12.0 min 15.4
19 Electric Strength in oil KV/mm 35.0 min 49.6