Diamond Dotted Presspaper (DDP)
Diamond Dotted Presspaper is Composed of electrical insulation paper with diamond-shape epoxy resin dotted in both sides. The epoxy resin used in D.D.P. contains a kind of incubative hardener material. It is a dry and crisp material at normal temperature (below 35° C or 95° F). This flexible material has good dielectric properties and good mechanical properties after heat-solidification. It is suitable as insulation material for coils and between layers of coil in the oiled–liquid power and distribution transformers.
Essential for transformer insulation systems, particularly in oil-immersed power and distribution transformers.
| Property | Unit | Standard Value | ||
|---|---|---|---|---|
| Thickness | mm | 0.08±0.005 | 0.12±0.007 | 0.17±0.01 |
| Tensile strength MD | Mpa | ≥75 | ≥80 | ≥78 |
| Tensile strength CMD | Mpa | ≥37 | ≥38 | ≥35 |
| Tear-resistance | mN | ≥500 | ≥1000 | ≥1500 |
| Breakdown voltage | V | ≥800 | ≥1100 | ≥1400 |
| Moisture content | % | 4.0 - 8.0 | ||
| Thickness of adhesion | mm | 0.02±0.0125 | ||
| Bonding strength | Kpa | 350 | ||