Insulation Material and Kraft Paper.
Transformer Board STB 3.1
Transformer Board STB 3.1 is a pre-compressed, high-density pressboard made from 100% high purity, unbleached sulphate kraft wood pulp. It is very flat, hard and rigid in character, having good physical, mechanical and electrical properties, which make it ideal for manufacture of various machined components such as radial and axial spacres, runners, blocks, strips, rings, etc. used in production of power transformers upto 765 kV class.
Transformer Board STB 3.1 is in full conformity with IEC 60641-3-1:1992, Type B.3.1.
Standard Thickness : 0.80, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0, 6.0 & 8.0 mm
Standard Size : 1400 mm (W) * 2500 mm (L)
2100 mm (W) * 3200 mm (L)
4200 mm (W) * 6400 mm (L)
Finish : Matt with mesh marks on both sides
Colour: Natural
Specification of Transformer Board STB 3.1 conforming to IEC 60641-3-1:1992, Type B.3.1
| PROPERTY | UNIT | MIN./MAX or RANGE | TYPICAL VALUES |
| Thickness Tolerance
<=1.6 mm > 1.6 mm |
% | Max | +-7.5 |
| Apparent Density
<=1.6 mm >1.6 mm – 3.0 mm >3.0 mm – 6.0 mm |
g/cm2 | Range | 1.00 - 1.20
1.10 - 1.25 1.15 - 1.30 |
| Tensile Strength Machine Direction
<=1.6 mm >1.6 mm -3.0 mm >3.0 mm-6.0 mm |
MPa | Min | 100
105 110 |
| Elongation
Machine Direction Cross Machine Direction |
% | Min | 3.0
4.0 |
| Compressibility C
<=1.6 mm >1.6 mm-3.0 mm >3.0 mm-6.0 mm |
% | Max | 10.0
7.5 5.0 |
| Reversible Part of Compressibility C
<=1.6 mm >1.6 mm-3.0 mm >3.0 mm-6.0 mm |
% | Min |
0.5 0.7 5.0 |
|
Shrinkage Machine Direction Cross Machine Direction Thickness |
% | Max |
0.5 0.7 5.0 |
| Cohesion between Plies (Visual Test) | Pass/Fail | - | Pass |
| Moisture Content | % | Max | 6.0 |
| Ash Content | % | Max | 1.0 |
| Conductivity of Aqueous Extract
<=1.6 mm >1.6 mm-3.0 mm >3.0 mm – 6.0 mm |
mS/m | Max |
5.0 6.0 8.0 |
| pH of Aqueous Extract | - | Range | 6.0 - 9.0 |
| Oil Absorption
<=1.6 mm >1.6 mm – 3.0 mm >3.0 mm – 6.0 mm |
% | Min | 11.0
9.0 7.0 |
| Electrical Strength in Air/Oil
<=1.6 mm >1.6 mm – 3.0 mm >3.0 mm – 6.0 mm |
kV/mm | Min | 12/40
11/35 10/30 |
Transformer Board PC
Transformer Board PC is a pre-compressed high density pressboard made from 100% high purity, unbleached sulphate kraft wood pulp. It is very flat, hard and rigid in character, having good physical mechanical and electrical properties, which make it ideal for manufacture of various machined components used in production of distribution transformers.
Transformer Board PC is in full conformity with Mill’s standard.
Standard Thickness : 0.80, 1.0, 1.5, 2.0, 3.0 & 4.0 mm
Standard Size : 1000 mm (W) * 2000 mm (L)
Finish : Matt with mesh marks on both sides
Colour : Natural
Specification of Transformer Board STB 3.1 conforming to IEC 60641-3-1:1992, Type B.3.1
| PROPERTY | UNIT | MIN./MAX or RANGE | TYPICAL VALUES |
| Thickness Tolerance | % | Max | +-7.0 |
| Apparent Density | g/cm3 | Range | 1.00 - 1.25 |
| Tensile Strength Machine Direction
MD CMD |
MPa | Min | 90
50 |
| Elongation
MD CMD |
% | Min | 2.5
3.5 |
| Shrinkage
MD CMD Thickness |
% | Max |
1.0 1.4 6.0 |
| Cohesion between Plies (Visual Test) | Pass/Fail | - | Pass |
| Moisture Content | % | Max | 5.0 - 9.0 |
| Ash Content | % | Max | 1.0 |
| Conductivity of Aqueous Extract
0.8 - 1.6 mm 1.6 mm - 3.0 mm >3.0 mm – 6.0 mm |
mS/m | Max |
5.0 6.0 8.0 |
| pH of Aqueous Extract | - | Range | 6.0 - 9.0 |
| Oil Absorption | % | Min | 9.0 |
| Electrical Strength in Air/Oil
0.8 - 1.6 mm >1.6 mm – 3.0 mm >3.0 mm – 6.0 mm |
kV/mm | Min | 11/35
10/30 9/24 |