The values for relative permittivity, known as dielectric constant, of insulation are taken from standard IEC 60287-1-1 Ed.2.1 where available with the following additions:
The dielectric constant depends on the temperature. In the range of normal operating temperatures for cables, this dependency for impregnated paper, PE and XLPE is negligible. PVC mixtures, on the other hand, show a strong temperature dependency.
| Material | Value |
|---|---|
| PE | 2.3 |
| HDPE | 2.3 |
| XLPE | 2.5 |
| XLPEf | 4.0 (U_n <= 30kV) 3.0 (U_n > 30kV) |
| PVC | 8.0 |
| EPR | 3.0 |
| IIR | 4.0 |
| PPLP | 2.8 |
| Mass | 4.0 |
| OilP | 3.6 (self-contained U_n <= 150kV) 3.5 (self-contained U_n > 150kV) 3.7 (pipe-type oil-filled) 3.6 (pipe-type external gas pressure) 3.4 (pipe-type internal gas pressure) |
| PP | 2.21 |
| SiR | 3.2 |
| EVA | 2.95 |
| XHF | 3.1 |
