14. Mechanical properties of insulation and sheathing materials
The insulation tensile strength before aging is ≥6.5N/mm2, the elongation at break is ≥125%, the tensile strength of the sheath is ≥8.0N/mm2, and the elongation at break is ≥125%.
After aging at (150±2)℃ and 7×24h, the change rate of tensile strength before and after aging of insulation and sheath is ≤-30%, and the rate of change of elongation at break before and after aging of insulation and sheath is ≤-30%.
15. Thermal extension test
Under the load of 20N/cm2, after the sample is subjected to a thermal extension test at (200±3)℃ for 15min, the median value of the elongation of the insulation and sheath should not be greater than 100%, and the distance between the marked lines after the test piece is taken out of the oven and cooled The percentage of the median value of the increase to the distance before the specimen is placed in the oven shall not be greater than 25%.
16. Thermal life
According to EN 60216-1, EN60216-2 Arrhenius curve, the temperature index is 120 ℃. Time 5000h. Insulation and sheath elongation at break retention rate: ≥50%. Afterwards, a bending test at room temperature was performed. The diameter of the test rod is twice the outer diameter of the cable, and there should be no visible cracks on the surface of the sheath after the test. Required lifespan: 25 years.