The main function of insulators is to achieve electrical insulation and mechanical fixation, for which various electrical and mechanical performance requirements are stipulated. For instance, under specified operating voltages, lightning overvoltages, and internal overvoltages, they should not experience breakdown or surface flashover; under specified long-term and short-term mechanical loads, they should not cause damage or destruction; after long-term operation under specified mechanical, electrical loads, and various environmental conditions, they should not show significant degradation; the metal fittings of insulators should not exhibit noticeable corona discharge under operating voltages to avoid interference with radio or television reception. As insulators are widely used, their connecting metal fittings are also required to be interchangeable. Furthermore, technical standards for insulators dictate that various electrical, mechanical, physical, and environmental condition tests must be conducted on the insulators depending on their models and usage conditions to verify their performance and quality.