Description
Ladder duct & Strip products provide a robust insulating solution for ducting within transformer enclosures and related equipment. The ladder configuration aids in directing airflow and supporting winding insulation, while the strip format offers versatile coverage for irregular surfaces and bundles. The product is manufactured by bonding specialized transformer board sticks onto insulating paper or a durable single-coated diamond-coated sheet to create a cohesive, rugged duct lining or wrap. This construction yields strong mechanical integrity and efficient oil impregnation pathways, contributing to improved thermal performance and reduced hot spots in high-load transformer applications.
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Typical composition and manufacturing notes
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Laminated structure using insulating base sheets bonded with transformer-grade adhesive systems
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Ducts and wraps designed for high compressive strength and dimensional stability
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Available in tape or reel formats with customizable joining methods to suit field installation
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Data Sheet
| Product name: Insulating press board (1-35kv) Thickness:1mm Test time :2024.4 | ||||||
| No. | Item | Unit | Requirements | Test Result | Test Method | |
| 1 | Thickness Tolerance | % | ±7.5 | 1.2 | IEC 60641-2:2004 | |
| 2 | Density | g/cm3 | 0.95-1.15 | 1.05 | ||
| 3 | Tensile strength | Lengthwise | N/mm2 | ≥55 | 59.8 | |
| 4 | Crosswise | ≥35 | 38.2 | |||
| 5 | Elongation | Lengthwise | % | ≥3.0 | 6.2 | |
| 6 | Crosswise | % | ≥4.0 | 5.4 | ||
| 7 | Shrinkage rate | Lengthwise | % | ≤0.7 | 0.51 | |
| 8 | Crosswise | ≤1.0 | 0.82 | |||
| 9 | Thickness | ≤5.0 | 4.5 | |||
| 10 | Ash content | % | ≤1.0 | 0.81 | ||
| 11 | Oil absorption rate | % | ≥15 | 19.2 | ||
| 12 | Water extraction PH | / | 6.0-9.0 | 7.43 | ||
| 13 | Water extraction Conductivity | mS/m | ≤8 | 7.6 | ||
| 14 | Electric strength (in oil) | KV/mm | ≥35 | 35.3 | ||
| 15 | Electric strength (in the air) | KV/mm | ≥10 | 10.2 | ||
| 16 | Water content | % | ≤8.0 | 7.9 | ||
| Test result: pass | ||||||
| Product name: Insulating press board (1-35kv) Thickness:1.5mm Test time:2024.4 | ||||||
| No. | Item | Unit | Requirements | Test Result | Test Method | |
| 1 | Thickness Tolerance | % | ±7.5 | 2.4 | IEC 60641-2:2004 | |
| 2 | Density | g/cm3 | 0.95-1.15 | 1.13 | ||
| 3 | Tensile strength | Lengthwise | N/mm2 | ≥55 | 60.5 | |
| 4 | Crosswise | ≥35 | 39.3 | |||
| 5 | Elongation | Lengthwise | % | ≥3.0 | 6.4 | |
| 6 | Crosswise | % | ≥4.0 | 5.5 | ||
| 7 | Shrinkage rate | Lengthwise | % | ≤0.7 | 0.54 | |
| 8 | Crosswise | ≤1.0 | 0.85 | |||
| 9 | Thickness | ≤5.0 | 4.2 | |||
| 10 | Ash content | % | ≤1.0 | 0.78 | ||
| 11 | Oil absorption rate | % | ≥15 | 19.6 | ||
| 12 | Water extraction PH | / | 6.0-9.0 | 7.49 | ||
| 13 | Water extraction Conductivity | mS/m | ≤8 | 7.7 | ||
| 14 | Electric strength (in oil) | KV/mm | ≥35 | 35.5 | ||
| 15 | Electric strength (in the air) | KV/mm | ≥10 | 10.4 | ||
| 16 | Water content | % | ≤8.0 | 7.8 | ||
| Test result: pass | ||||||
| Test Report | ||||||
| Product name:Insulating press board (1-35kv) Thickness:1.6mm Test time :2024.4 | ||||||
| No. | Item | Unit | Requirements | Test Result | Test Method | |
| 1 | Thickness Tolerance | % | ±7.5 | 2.1 | IEC 60641-2:2004 | |
| 2 | Density | g/cm3 | 0.95-1.15 | 1.14 | ||
| 3 | Tensile strength | Lengthwise | N/mm2 | ≥55 | 60.1 | |
| 4 | Crosswise | ≥35 | 37.3 | |||
| 5 | Elongation | Lengthwise | % | ≥3.0 | 6.4 | |
| 6 | Crosswise | % | ≥4.0 | 5.3 | ||
| 7 | Shrinkage rate | Lengthwise | % | ≤0.7 | 0.51 | |
| 8 | Crosswise | ≤1.0 | 0.88 | |||
| 9 | Thickness | ≤5.0 | 4.5 | |||
| 10 | Ash content | % | ≤1.0 | 0.86 | ||
| 11 | Oil absorption rate | % | ≥15 | 19.5 | ||
| 12 | Water extraction PH | / | 6.0-9.0 | 7.48 | ||
| 13 | Water extraction Conductivity | mS/m | ≤8 | 7.7 | ||
| 14 | Electric strength (in oil) | KV/mm | ≥35 | 35.5 | ||
| 15 | Electric strength (in the air) | KV/mm | ≥10 | 10.4 | ||
| 16 | Water content | % | ≤8.0 | 7.7 | ||
| Test result: pass | ||||||
Note:The product specifications provided are for reference purposes only. Please refer to the actual product for final specifications. We also offer various sizes and thicknesses to meet your specific needs. For further customization, please contact us.
We have a lots of Thickness for Products，Contact：jessie.feng@sidanm.com to
Application scenarios
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Transformer oil-impregnation support: enhances oil flow paths and supports impregnation efficiency in winding ducts.
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Duct lining for winding protection: provides a protective barrier during operation against mechanical abrasion and heat buildup.
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Tape/wrap solutions for irregular duct geometries: flexible formats enable precise coverage on bends and junctions.
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Customizable solutions for OEM builds: can be supplied as pre-cut lengths, continuous reels, or tailored to customer drawings.
FAQ (testing standards, quality, and installation)
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Q: What standards does Ladder Duct & Strip meet?
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A: Product families are designed to comply with applicable transformer insulation and electrical industry standards, including manufacturers’ internal specifications for thermal performance, mechanical strength, and chemical compatibility. (Consult SIDA QA for exact standard references per batch.)
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Q: How is thermal resistance verified?
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A: Thermal performance is evaluated via standardized heat-ageing/thermal conductivity tests on representative samples, with results logged in batch QC reports. Ask for the latest test report when ordering.
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Q: What installation guidance is recommended?
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A: Prepare a clean, dry substrate; remove oils or contaminants from metal ducts; apply recommended bonding adhesive if not pre-laminated; align tape or wrap to minimize gaps; seal seams to maintain barrier integrity.
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Q: Can the product be produced as customized widths or lengths?
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A: Yes. The product is available in tapes and reels, with customization options to meet customer requirements, including width, length, and cut-to-size packaging.
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Q: How should the product be packaged and shipped?
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A: Standard packaging uses reels or tensioned tapes, with protective wraps to prevent abrasion. Custom packaging options are available on request.
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