The insulating medium of disc suspension insulators must possess the mechanical and electrical strength required for the transmission line and maintain thermomechanical stability under drastically changing atmospheric conditions. High-voltage insulators can withstand normal operating voltage, periodic internal overvoltages, and atmospheric overvoltages.
Suspension insulators can be assembled into insulator strings by simply connecting multiple insulator units mechanically. Under power frequency voltage, the external insulation strength of an insulator is often characterized by its leakage distance or leakage ratio. The leakage distance refers to the shortest distance or sum of the distances along the outer surface contour of the insulator between the poles under normal operating voltage. The voltage distribution uniformity of an insulator string depends on its main capacitance. Insulator strings with larger main capacitance are beneficial for reducing the voltage of insulators near the conductor side and grounding side, thereby reducing radio interference, reducing corona loss, extending service life, and increasing the flashover voltage of the entire string.
Key performance parameters of high-voltage insulators mainly include rated voltage, power frequency dry/wet withstand voltage, impulse withstand voltage, mechanical damage load, creepage distance, creepage ratio, and electrical breakdown strength.
