The Color Change of the Thermoplastic Polyolefin Used in the Outer Sheath of a Low-Voltage Power Cable Does Not Mean Tensile Strength Loss

Power cables used outdoors age prematurely due to ultraviolet radiation. Their ampacity should be decreased accordingly to take a good performance. The mechanical strength of the cables may decrease and the color of the outer sheath of cable insulation changes when exposed to outdoor UV radiation. It is of great concern to know how the elongation strength of a cable varies with the exposure time to prevent cable break. To evaluate their UV resistance, UV chamber tests are performed. The determination of the color of the cable insulator is also an important part of the test. In this study, Thermoplastic Polyolefin (TPO) insulation to be used in the outer sheath of low-voltage power cables is aged in a Q-SUN Xenon light test chamber. 240-, 480-, and 720-hour test durations are chosen in the experiments. All elongation at break tests are made with a Zwick/Roell Z010 Tensile Tester and a gray scale is used for assessing the color change. It has been found that the color change of Thermoplastic Polyolefin does not reflect the elongation at break and tensile strength value changes much and the elongation at break value of Thermoplastic polyolefin is not a monotonous function of UV exposure time.