The main function of insulators is to achieve electrical insulation and mechanical fixation, for which various electrical and mechanical performance requirements are specified. This includes not experiencing breakdown or surface flashover under specified operating voltages, lightning overvoltages, and internal overvoltages; not producing damage or destruction under specified long-term and short-term mechanical loads; and not showing significant deterioration after long-term operation under specified mechanical, electrical loads, and various environmental conditions. The fittings of the insulator should not produce significant corona discharge under operating voltages to avoid interference with radio or television reception. Since insulators are widely used, their connecting fittings are also required to be interchangeable. Furthermore, technical standards for insulators stipulate various electrical, mechanical, physical, and environmental condition tests, depending on the model and usage conditions, to verify their performance and quality.