What is electrical laminated wood?
Electrical laminated wood is an insulating and supporting material widely used in transformers and mutual inductors. It has the advantages of moderate specific gravity, high mechanical strength, easy vacuum drying and easy mechanical processing. Its dielectric constant is close to that of transformer oil, and its insulation is reasonably matched. It can be used for a long time in transformer oil at 105°C. Electrical laminated wood has been widely used in oil-immersed transformers to manufacture upper and lower pressure plates, lead brackets, iron yoke pads and other parts, and in mutual inductors to make clamps. It replaces steel plates, insulating paperboards, epoxy paperboards, and epoxy glass cloth boards in these applications, thereby reducing the weight and material costs of transformers. Electrical laminated wood is a single board made of high-quality birch wood by steaming, peeling and drying. It is coated with special insulating glue and made at high temperature and high pressure.
Detailed explanation of transformer laminated wood quality standards
1. Material requirements for transformer laminated wood
The main materials of transformer laminated wood are epoxy resin and wood. Epoxy resin should comply with GB/T8815-2002 standard, and wood should comply with GB/T 5849-1986 standard. Epoxy resin should have good electrical insulation performance, heat resistance and mechanical strength, and wood should have good pressure resistance and mechanical strength.
2. Size requirements for transformer laminated wood
The size of transformer laminated wood should comply with GB/T 11718-1989 standard, and the length, width, thickness and tolerance of the pressing block should meet the standard requirements. At the same time, the angle, flatness, parallelism, verticality and other aspects of the pressing block should also meet the standard requirements.
3. Surface quality requirements for transformer laminated wood
The surface of the transformer laminated wood should be flat, smooth, without obvious bumps and scratches, and uniform in color. There should be no defects such as cracks, bubbles, pitting, stains, etc.
4. Insulation performance requirements for transformer laminated wood boards
The insulation performance of transformer laminated wood boards shall comply with the GB/T 1408.1-2006 standard, the insulation resistance shall comply with the standard requirements, and the insulation dielectric loss tangent shall comply with the standard requirements. At the same time, transformer laminated wood boards shall also undergo arc resistance tests and be able to withstand a certain arc breakdown capacity.
5. Other requirements for transformer laminated wood boards
Transformer laminated wood boards shall also comply with the relevant requirements in the GB/T 16915.1-2017 standard, such as environmental protection requirements, safety requirements, etc.
Electrical Laminated Wood Technical Parameters
|
Executive Standard: GB/T 20634.3-2008 /IEC61061-2:1998 |
|
Number |
Item |
Unit |
Value |
|
DLW101 |
DLW201 |
DLW202 |
DLW301 |
|
1 |
Appearance |
- |
Smooth Surface, Neat Cutting Edge,
No Delamination of Section |
|
2 |
Density |
g/cm³ |
1.2-1.3 |
1.1-1.2 |
1.1-1.2 |
1.0-1.1 |
|
3 |
Flexural Strength at Perpendicular Lamination |
A-Direction |
MPa |
≥80 |
≥65 |
≥65 |
≥55 |
|
B-Direction |
≥80 |
≥65 |
≥65 |
≥55 |
|
4 |
Impact Strength |
A-Direction |
KJ/m2 |
≥15 |
≥13 |
≥13 |
≥10 |
|
B-Direction |
≥15 |
≥13 |
≥13 |
≥10 |
|
5 |
Interlaminar Shear Strength |
MPa |
≥9 |
≥8 |
≥8 |
≥7 |
|
6 |
Electrical Strength at Perpendicular Lamination
（Transformer Oil at 90℃） |
Kv/mm |
≥9 |
≥8 |
≥7 |
≥7 |
|
7 |
Breakdown Voltage at Parallel Lamination
（Transformer Oil at 90℃） |
kv |
≥50 |
≥50 |
≥50 |
≥50 |
|
8 |
Pollution of Liquid Dielectric |
- |
≤0.1 |
|
9 |
Shrinkage after Drying |
A-Direction |
％ |
≤0.3 |
≤0.3 |
≤0.3 |
≤0.3 |
|
B-Direction |
≤0.3 |
≤0.3 |
≤0.3 |
≤0.3 |
|
Thickness- |
≤3 |
≤3 |
≤3 |
≤3 |
|
Direction |
|
10 |
Water Content |
％ |
≤6 |
≤6 |
≤6 |
≤6 |
|
11 |
Oil Absorption Rate |
％ |
≥5 |
≥8 |
≥8 |
≥10 |
|
Suggestions on the Application of Laminated Wood Insulation in Transformer |
Voltage Rating |
≥110KV |
≤110KV |
66-35KV |
≤35KV |
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