High voltage surges can have various sources, both internal and external to the power system, such as lightning strikes, switching operations, faults, capacitor switching, and harmonics. Lightning strikes can induce high currents and voltages in overhead lines, transformers . An overvoltage refers to an abnormal increase in electrical voltage above the nominal levels of the network. This increase, which can last from microseconds to extended periods, is capable of causing serious damage to electrical installations and devices if not properly controlled. It is a very common issue in Power systems. All the equipment and insulators used in substations and transmission lines.
[PDF Version]