Degradation of insulating materials due to
- Degradation in surface quality (pollution).
- Excessive temperature.
- Partial discharge in the vacuoles (micro pockets) inside the insulating materials.
- Accidental reduction in electrical insulation (presence of animals, tree branches, tools left by carelessness on a bus bar, etc.).
- Destruction due to external causes (hit by a shovel, etc.).
- Over voltages causing a breakdown in equipment insulation (switching surges or lightning strike).