*1.2.5 Corona discharge resistance and material degradation*

The ionization of air in the form of an electrical discharge is known as corona discharge. This ionization occurs when the electric field crosses the threshold value of air breakdown. Partial or surface discharge is also a kind of corona discharge because it is half discharged to bridge between the electrodes [12]. Corona discharge appears in the form of a lightning color. In high voltage laboratory, corona discharge can be originated using a simple rod to plane electrodes with an air gap between them. Extensive research work has been studied on the appropriate electric field stress to set up corona discharge [12]. Corona discharge depends on the following parameters:


Corona discharges can damage the insulation significantly. With the growing demand for high voltage power supplies, it is becoming common that the insulating materials face severe corona discharges. Corona discharge produces an eminently energized plasma of charged species and emits UV light. These plasma discharges emit charged particles on the surface of insulation and deteriorate the surface physically and chemically. The increase in temperature and humidity can accelerate the corona discharge intensity.
