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 action of specified operating voltage, lightning overvoltage, and internal overvoltage, no breakdown or surface flashover should occur; under the action of specified long-term and short-term mechanical loads, no damage or destruction should be produced; 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 any noticeable corona discharge under operating voltage to avoid interference with radio or television reception. Since insulators are widely used, the connecting hardware is also required to be interchangeable. Additionally, the technical standards for insulators stipulate that various electrical, mechanical, physical, and environmental condition tests should be conducted on the insulators, depending on the model and usage conditions, to verify their performance and quality.