The main function of insulators is to achieve electrical insulation and mechanical fixation, for which various electrical and mechanical performance requirements are specified. For instance, under the specified operating voltage, lightning overvoltage, and internal overvoltage, no breakdown or surface flashover should occur; under the specified long-term and short-term mechanical loads, no damage or destruction should take place; after long-term operation under specified mechanical, electrical loads, and various environmental conditions, no significant deterioration should occur; the hardware of the insulator should not produce noticeable corona discharge under operating voltage to avoid interference with radio or television reception. Since insulators are widely used, their connecting hardware is also required to be interchangeable. Moreover, the 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.