在电力系统中, 当受到强大的冲击电流时, 电力光缆将在高于导体最高工作温度10%的温度场环境下工作, 长时间的高温老化工况状态对光纤复合低压电缆(OPLC)光单元中的光纤造成极大的负效应, 严重地影响了整个电网的安全运行。针对上述问题, 为了研究单模光纤受热前后机械性能变化情况, 分析高温老化对光纤的损伤程度, 文章通过模拟高于以聚氯乙烯绝缘的OPLC导体温度10%的温度场环境, 测试了不同温度和老化时间段下单模光纤的断裂强度、断裂伸长率和光纤涂层剥离力等光纤机械性能, 基于测试数据, 运用线性拟合的统计方法, 研究了在该温度场环境下老化前后光纤机械特性的变化趋势。试验结果表明, OPLC中光纤的应力腐蚀敏感性参数比涂覆剥离力特性受热更敏感, 随着老化时间增长, 不同老化时长后涂覆剥离力比应力腐蚀敏感性参数的差值变化量更大, 耐热性能更差。基于机械性能的测试结果, 文章提出了增加光单元耐热层的优化意见。

In the power system, when the cable is subjected to strong impulse current, it will work in the temperature field higher than 10% of the conductor's maximum operating temperature. The long-term high-temperature aging condition has a great negative effect on the optical fiber in the optical unit of Optical Fiber Composite Low-Voltage Cable (OPLC), which seriously affects the safe operation of the entire power grid. Aiming at the above problems, in order to study the mechanical properties of single-mode fiber before and after heating, the damage degree of high temperature aging to optical fiber is analyzed. In this paper, the mechanical properties of single-mode fiber, such as breaking strength, elongation at break and stripping force of coatings, are tested at different temperatures and aging periods by emulating the temperature field of OPLC conductors 10% higher than that of polyvinyl chloride insulated conductors. Based on the test data, the change trend of mechanical properties of optical fiber before and after aging under this temperature field is studied by using the statistical method of linear fitting. The results show that the stress corrosion sensitivity parameters of optical fiber in OPLC are more sensitive to heat than the coating peeling force characteristics. With the increase of aging time, the difference between the coating stripping force and the stress corrosion sensitivity parameters is larger and the heat resistance is worse. Based on the test results of mechanical properties, the suggestion of adding heat-resistant layer of optical unit is proposed in this paper.