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, there should be no breakdown or surface flashover; under the action of specified long-term and short-term mechanical loads, no damage or destruction should occur; 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 significant 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. Moreover, the technical standards for insulators vary by model and usage conditions, mandating various electrical, mechanical, physical, and environmental condition tests to verify their performance and quality.