High voltage technology is applied in power transmission because, under the same transmission power, the higher the voltage, the smaller the current. This way, high voltage transmission can reduce the current during transmission, thereby reducing the heat loss caused by the current and reducing the material cost of long-distance transmission. Studying the insulation characteristics, dielectric strength, and discharge mechanism of dielectrics under various applied voltages in order to reasonably solve the insulation structure problems of electrical equipment is an important content of high-voltage technology. In engineering, AC power supply voltages of 1000 volts and above are referred to as high voltages. The types of high voltage involved in high voltage technology include DC voltage, power frequency AC voltage, millisecond level switching overvoltage, microsecond level lightning overvoltage, nanosecond level nuclear electromagnetic pulse (NEMP), etc. Since the 20th century, with the increasingly widespread application of electricity, the coverage of the power system has become larger and the amount of electricity transmitted has also increased. This requires the continuous improvement of the transmission voltage level of the power system. On a global scale, transmission lines have experienced the development of high voltage at 110, 150, and 230 kV, ultra-high voltage at 287, 400, 500, 735-765 kV, and ultra-high voltage at 1000 kV and 1150 kV (industrial test lines). DC transmission has also experienced development of ± 100, ± 250, ± 400, ± 450, ± 500, and ± 750 kV. These stages are closely related to the high voltage technology solving the problems of corona phenomenon in transmission lines, protection and limitation of overvoltage, as well as the impact of electrostatic and electromagnetic fields on the environment