The primary 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 causing damage or destruction under specified long-term and short-term mechanical loads; not showing significant degradation after long-term operation under specified mechanical, electrical loads, and various environmental conditions; and not producing noticeable corona discharge phenomena under operating voltages in the insulator fittings to avoid interference with radio or television reception. As insulators are widely used, their connecting fittings are also required to be interchangeable. Furthermore, technical standards for insulators demand various electrical, mechanical, physical, and environmental condition tests based on different models and usage conditions to verify their performance and quality.