The preferred size of the nominal diameter of the conductor diameter conductor shall comply with the R20 number system in GB/T321-2005.

1. The temperature index test shall be carried out on the unimpregnated enameled wire specimen with a nominal diameter of 1.000 mm and a grade 2 film thickness in accordance with GB/T4074.7-2009.

2. The temperature index shall not be less than the specified value of the relevant product standard, and the failure time at the lowest test temperature shall be not less than 5000h.

3. When requested by the user, the manufacturer shall provide proof that the enameled wire meets the temperature index requirements.

4. Note: The temperature index for the extrapolated life of 20000h is only for unimpregnated enameled wire samples, not as part of the insulation system.