POWERBOARD AK for power transformers
- POWERBOARD AK is natural-coloured, hot-pressed pressboard made of 100 % unbleached sulphate cellulose (type B.3.1A according to IEC 60641-3)
- POWERBOARD AK is characterised by a high degree of purity and high mechanical strength
- POWERBOARD AK is virtually shrinkproof, dimensionally stable with extremely low compressibility, and is characterised by a very high oil absorption capacity
- Main applications for POWERBOARD AK are insulating cylinders, strips, spacers, washers and fittings in oil-insulated power transformers
Production and processing of pressboard
We use unbleached sulphate cellulose gained from Nordic, slow-growing coniferous wood for manufacturing pressboard. During the initial stage of pressboard production, the cellulose fibre must first be separated and squeezed in a grinding mill in aqueous suspension. This aqueous fibre mixture is then subjected to several purification processes to provide the basis for the natural purity of the final product right from the beginning. The mixture is then transferred to several consecutively arranged round screen cylinders of our paper-making machine to produce the fibre fleece.
During the production of KREMPEL-POWERBOARD AK the fibre fleece is rolled onto a so-called forming drum in multiple layers and couched. Once the desired number of layers and the thickness have been reached, the “roll” is cut. The resulting raw pressboard sheet is transferred automatically to a high performance press for good wet compression. Then the pressboard sheets are dried under pressure in a multi-plate hot press. This special manufacturing process gives our POWERBOARD AK its unique properties.
POWERBOARD AK is easy to process mechanically. All components necessary for coils, such as strips, spacers and pads, can be made by punching, drilling, milling or sawing.
POWERBOARD AK can be rolled easily to make insulating cylinders, however it is recommended to moisten the pressboard sheets before rolling.
Our high quality laminated board is made by laminating POWERBOARD AK. Various types are available for all kind of applications.
Technical data POWERBOARD AK
- Type B.3.1A according to IEC 60641-3-1
- POWERBOARD AK is manufactured in thicknesses from 1- 8 mm
- Testing of the following values is conducted in our test laboratories in accordance with IEC 60641-2
| Properties | Nominal thickness
mm |
Unit | POWERBOARD
AK |
| Tolerance thickness | ≤ 1,5
> 1,5 |
%
% |
± 7,5
± 5,0 |
| Density | ≤ 1,5
> 1,5 - 3,0 > 3,0 |
g/cm³
g/cm³ g/cm³ |
1,00 - 1,20
1,10 - 1,25 1,15 - 1,30 |
| Tensile strength MD | ≤ 1,5
> 1,5 - 3,0 > 3,0 |
MPa (N/mm²)
MPa (N/mm²) MPa (N/mm²) |
≥ 100
≥ 105 ≥ 110 |
| Tensile strength CMD | ≤ 1,5
> 1,5 - 3,0 > 3,0 |
MPa (N/mm²)
MPa (N/mm²) MPa (N/mm²) |
≥ 75
≥ 80 ≥ 85 |
| Elongation MD | 1,0 - 8,0 | % | ≥ 2,5 |
| Elongation CMD | 1,0 - 8,0 | % | ≥ 3,5 |
| Compressibility (C) | ≤ 1,5
> 1,5 - 3,0 > 3,0 - 6,0 > 6,0 - 8,0 |
%
% % % |
≤ 10
≤ 7,5 ≤ 5,0 ≤ 4,5 |
| Resilience (Crev) | ≤ 1,5
> 1,5 - 8,0 |
%
% |
≥ 45
≥ 50 |
| Shrinkage MD | 1,0 - 8,0 | % | ≤ 0,5 |
| Shrinkage CMD | 1,0 - 8,0 | % | ≤ 0,7 |
| Shrinkage thickness | 1,0 - 8,0 | % | ≤ 5,0 |
| Moisture content | 1,0 - 8,0 | % | ≤ 6,0 |
| Ash content | 1,0 - 8,0 | % | ≤ 0,7 |
| Conductivity
of aqueous extract |
≤ 1,6
> 1,6 - 3,0 > 3,0 - 6,0 > 6,0 - 8,0 |
mS/m
mS/m mS/m mS/m |
≤ 5,0
≤ 6,0 ≤ 8,0 ≤ 10,0 |
| PH-value of aqueous extract | 1,0 - 8,0 | 6 - 9 | |
| Oil absorption | ≤ 1,6
> 1,6 - 3,0 > 3,0 - 6,0 > 6,0 - 8,0 |
%
% % % |
≥ 11
≥ 9 ≥ 7 ≥ 6 |
| Dielectric strength in air | 1,0 - 8,0 | kV/mm | ≥ 12 |
| Dielectric strengtht in oil | ≤ 1,6
> 1,6 |
kV/mm
kV/mm |
≥ 45
≥ 35 |
| All values stated are to be seen as typical values. We reserve the right to introduce changes within the framework of further technical development. We do not accept any obligations or liabilities in respect of this information. Status: 10/2010
|
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Technical data LAMINATED BOARD
- POWERBOARD AK-CG Bonding with a casein adhesive corresponds to type LB 3.1A.1 according to IEC 60763-3-1
- POWERBOARD AK-PG Bonding with a polyester-resin adhesive corresponds to type LB 3.1A.2 according to IEC 60763-3-1
- POWERBOARD AK-PHG Bonding with a phenol-resin adhesive based on type LB 3.1A.1 according to IEC 60763-3-1
- Testing of the following values is conducted in our test laboratories in accordance with IEC 60763-2sformers
| Properties | Unit | POWERBOARD
AK-CG |
POWERBOARD
AK-PG |
POWERBOARD
AK-PHG |
| Tolerance thickness
≤ 12 mm |
% | ± 5,0 | ± 5,0 | ± 5,0 |
| Tolerance thickness
> 12 mm |
% | ± 4,0 | ± 4,0 | ± 4,0 |
| Density | g/cm³ | 1,15 - 1,30 | 1,15 - 1,35 | 1,15 - 1,35 |
| Bending strength MD | MPa
(N/mm²) |
110 | 130 | 110 |
| Bending strength CMD | MPa
(N/mm²) |
100 | 115 | 100 |
| Compressibility (C) | % | ≤ 3,5 | ≤ 3,0 | ≤ 3,5 |
| Resilience (Crev) | % | ≥ 60 | ≥ 60 | ≥ 60 |
| Shrinkage MD | % | ≤ 0,5 | ≤ 0,4 | ≤ 0,5 |
| Shrinkage CMD | % | ≤ 0,7 | ≤ 0,6 | ≤ 0,7 |
| Shrinkage thickness | % | ≤ 6,0 | ≤ 4,0 | ≤ 6,0 |
| Moisture content | % | ≤ 8 | ≤ 6 | ≤ 8 |
| Conductivity
of aqueous extract |
μS/cm | ≤ 15 | ≤ 10 | ≤ 15 |
| PH-value of aqueous extract | 6,0 - 10,0 | 5,0 - 8,0 | 6,0 - 10,0 | |
| Oil absorption | % | ≥ 6 | ≥ 6 | ≥ 6 |
| Dielectric strength in oil | kV/mm | ≥ 8 | ≥ 8 | ≥ 8 |
| All values stated are to be seen as typical values. We reserve the right to introduce changes within the framework of further technical development. We do not accept any obligations or liabilities in respect of this information. Status: 10/2010 | ||||
Variants supplied
| Variant | POWERBOARD AK | POWERBOARD
AK-CG |
POWERBOARD
AK-PG |
POWERBOARD
AK-PHG |
| Thickness (mm) | 1 - 8 | 9 - 30 | 10 - 120 | 10 - 120 |
| Standard sizes (mm x mm) | 2200 x 4200
1100 x 4200 2200 x 2100 1100 x 2100 |
2050 x 1050
4100 x 1050 |
2050 x 1050 | 4150 x 2150 |
| Other sizes and blanks are available on request. | ||||
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