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Cylinders and end-rings made from precompressed pressboard are suitable for use in liquid-filled power, distribution, and traction transformers.

High purity, mechanical strength, and oil impregnability make the components optimally adaptable to the electrical field conditions in the transformer. In areas with high field strength, the shape retention and good dielectric properties of these components prove their worth. The excellent mechanical properties of the insulation material provide the required safety in the event of a short circuit.

These insulation components are produced using special processing procedures, which guarantee high compaction and dimensional stability.


  • Shape 0: without axial chamfer
  • Shape A: axial chamfer one-sided outside
  • Shape J: axial chamfer one-sided inside
  • Shape AJ: axial chamfer both sides once inside, once outside
  • Shape AA: axial chamfer on both sides outside
  • Shape JJ: axial chamfer on both sides inside
  • 10 mm / -5

Our customers are increasingly using complete insulation systems, known as insulation kits (preassembled insulation sets), which provide significant benefits in terms of cost and effectiveness.

Why Hitachi Energy?

  • More than 150 years of experience in insulation
  • Complete range of insulation products for liquid-filled transformers; comprehensive range for dry-type
  • Material excellence
  • Advanced technology to scan the quality of pressboard
  • Approved supplier to major utilities worldwide
  • Global footprint

Product scope

  • Power, distribution and traction transformers
  • Insulation of windings in transformers
    • Cylinders with strips and distance elements
    • Cylinder with angle ring
  • Insulation class A (105° C) material according to VDE 0530 Part 1
  • 100% sulfate pulp
  • Natural colored
  • Precompressed pressboard, even fibre orientation, hard and dimensionally stable
  • High purity and mechanical strength
  • Low shrinkage and compressibility
  • Good compatibility with liquid dielectrics

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