Oil immersed electrical insulation pressboard is specially developed for oil-immersed transformers. Compared with ordinary electrical pressboard, it features higher purity, denser fiber structure and stable oil absorption compatibility. In oil-immersed transformers, paper and oil work together: the pressboard provides mechanical support and main insulation, while transformer oil fills gaps and dissipates heat. Poor compatibility between board and oil will precipitate impurities and accelerate oil aging, which may cause severe long-term failures.
Our oil immersed pressboard adopts high-purity unbleached sulfate wood pulp, without harmful fillers or additives. Even after long-term immersion in transformer oil, it will not contaminate the oil. Test data shows that after soaking in No.25 transformer oil for 30 days, the medium loss increment of oil is less than 2%, far better than the industry standard 5%. A manufacturer of oil-immersed transformers once used cheap pressboard, which precipitated impurities and degraded oil quality after two years of operation. After switching to our oil immersed pressboard, oil stability improved greatly and maintenance cycles were extended. For oil transformer manufacturers, the slight price difference of pressboard is negligible compared to the value of the whole transformer; stable reliability is the top priority.
Specification Parameters
|
Parameter Item |
Technical Index |
|
Thickness Range |
0.5～5mm |
|
Density |
1.0～1.25 g/cm³ |
|
Maximum Width |
1600mm |
|
Temperature Resistance Class |
Class A (105℃) |
|
Medium Loss Increment in Oil |
≤2% |
|
Vertical Breakdown Voltage (In Oil) |
≥40 kV/mm |
Application Fields
- Blocks, support strips and angle rings for oil-immersed transformers
- Insulation cylinders and partitions of oil transformers
- Oil-filled insulation parts for current transformers and capacitors
- Winding support structures of power transformers
- All insulation components for oil-immersed electrical equipment
Quality Control
Quality control standards for oil immersed pressboard are stricter than ordinary boards, as they directly determine transformer service life and safety. We only use high-purity sulfate wood pulp, no recycled paper or inferior fillers. During production, pressure and temperature are tightly controlled to achieve uniform density and tight fiber bonding. Finished products go through extra oil compatibility testing besides standard thickness, density, strength and breakdown voltage inspections: every batch is soaked in standard transformer oil at constant temperature for 30 days to test oil medium loss and acid value change; non-compliant batches are scrapped. Oil absorption uniformity testing is also carried out to avoid bulging and deformation caused by uneven oil uptake. All test records are traceable to raw material and production batches.
Packaging & Transportation
Oil immersed pressboard is extremely moisture-sensitive, so we adopt high-grade moisture-proof packaging. Inner layers are vacuum-sealed with PE moisture-proof film, lined with hard cardboard to prevent bending deformation, and packed in thick cartons or wooden pallets. Desiccants are placed inside each package. Export sea freight orders add extra aluminum foil vacuum packaging and fumigated pallets. Each package is labeled with clear "Moisture Proof" marks and product info. Trade terms EXW and FOB Wenzhou Port are available with complete export documents. Store in dry and ventilated warehouses and unpack right before use to minimize air exposure time.
Factory Strength
We have years of experience in deep processing of electrical pressboard, and oil immersed pressboard is our flagship product. Full processing lines from raw sheet slitting to stamping forming are in-house. We can fabricate blocks, support strips, angle rings, insulation cylinders, fan-shaped plates and other custom parts from your drawings. Annual capacity reaches 1,000 tons with stable monthly output to fulfill large orders on schedule. Our technical team is familiar with transformer standards and processing techniques, able to optimize part layouts and improve material utilization to lower your procurement costs. Our products are supplied to domestic transformer factories and exported to South America, Southeast Asia, the Middle East, validated by years of field operation.
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