This standard specifies the test methods for dielectric strength (the maximum breakdown voltage per unit thickness) and voltage endurance of insulating adhesive tapes under power frequency (typically 50 Hz) conditions. The core principle involves applying a progressively increasing power frequency AC voltage to a sample attached between electrodes until it breaks down or withstands a preset voltage for a specified duration, thereby evaluating its electrical insulation performance and reliability. This method is applicable for assessing various types of insulating tapes widely used in fields such as electrical engineering and new energy batteries. Conducting this test requires a specialized high-voltage breakdown tester, which typically includes a high-voltage generator, an electrode system (such as unequal-diameter cylindrical electrodes), and voltage measurement and control units. During operation, a thickness gauge must also be used to accurately measure the sample's thickness for calculating the dielectric strength.