The primary function of insulators is to achieve electrical insulation and mechanical fixation, for which various electrical and mechanical performance requirements are specified. For example, under the influence of the specified operating voltage, lightning overvoltage, and internal overvoltage, no breakdown or surface flashover occurs; under the specified long-term and short-term mechanical loads, no damage or destruction is caused; after long-term operation under specified mechanical, electrical loads and various environmental conditions, no significant deterioration is observed; the metal fittings of the insulators do not produce a noticeable corona discharge under operating voltage to avoid interference with radio or television reception. Since insulators are widely used, the connecting metal fittings are also required to be interchangeable. Furthermore, technical standards for insulators dictate that various electrical, mechanical, physical tests, and environmental condition variations be conducted based on the model and usage conditions to verify their performance and quality.