Ageing and Breakdown Due to Accumulative of Charges on Insulation Surface
- During discharges of solid or liquid or solid gas or solid-vacuum interfaces certain quantity and charge (electron) gets deposited on the solid insulator surface.
- Charge deposited can stay there for long durations (days and weeks) and presence of two charges increases the surface of conductivity and freely increasing the discharge magnitude in subsequent discharges.
- Increase in discharge magnitude in subsequent discharges causes damage to the dielectric surface.
- Discharging characteristic changes with life of insulation for clean surface Vi – discharge characteristics depends on nature of dielectric, its size and shape and discharge consists of a small number of discharges. After some time erosion causes the discharges to decrease in number and also in magnitude. With the passage of time phenomenon becomes complex because of the charges on the surface induced conductively add to the charge accumulation in bulk due to partial discharge.