| Values of Resistivity in Three Materials (Unit: Ω・m) | Properties of Different Insulating Materials | ||
| Oil | Insulation Paper | Oil immersed pressed paper | |
| A1 | 1012 | 1012 | 1012 |
| A2 | 1012 | 5 × 1012 | 1013 |
| A3 | 1012 | 5 × 1013 | 1014 |
| A4 | 1012 | 5 × 1014 | 1015 |