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To study the aging characteristics of low-voltage cables at lower temperatures ( below 50 ℃), this paper conducts accelerated aging experiments on low-voltage cables at different lower temperatures, and studies the breakdown characteristics of aged samples. An accelerated aging at power frequency of low-voltage cable samples was carried out at 0 ℃, 20 ℃ and 50 ℃ for 7 days, 14 days and 21 days respectively, and the aging voltage was 1 kV. The breakdown experiment and scanning electron microscope observation were carried out on the aged samples, and the mechanical properties of the unaged samples were tested at 0 ℃, 20 ℃ and 50 ℃. The breakdown test results show that the breakdown strengths of the samples aged for 21 days are 20 ℃, 50 ℃, 0 ℃ from high to low. The SEM results show that the densities of micropores in the aged samples are 0 ℃, 50 ℃ and 20 ℃ from large to small, while the pore size is 50 ℃, 20 ℃ and 0 ℃ from large to small. The tensile results show that the elastic modulus and tensile strength of the samples at 0 ℃ and 20 ℃ are much higher than those at 50 ℃. The electric field simulation results show that the electric field strength at the tip of the microvoid of the 0 ℃ aged sample is about 3 times that of 20 ℃ and 50 ℃. The analysis shows that the microvoid tip has a high field strength at 0 ℃, and the microvoid grows rapidly along the electric field direction (radial direction), resulting in the lowest breakdown strength of the sample. The electric field strengths of the microvoid tip at 20 ℃ and 50 ℃ are significantly lower than that at 0 ℃, and the mechanical strength of the sample insulation at 50 ℃ is significantly lower than that of 20℃, resulting in higher radial failure rate of the sample than 20 ℃, and lower breakdown strength of the sample at 50 ℃ than 20 ℃. The breakdown strength of low-voltage cable samples is closely related to the failure characteristics of the microstructure of the insulation in the radial direction, and the number and density of radial micropores have a greater influence on the breakdown field strength than the pore size.

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Study on Breakdown Characteristics of Low Voltage Cables in Substation at Lower Temperatures

  • 会议论文

  • 发表日期：

    2025年

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  • Menglin Dong,
  • Kangle Li,
  • Hui Chen

摘要

To study the aging characteristics of low-voltage cables at lower temperatures ( below 50 ℃), this paper conducts accelerated aging experiments on low-voltage cables at different lower temperatures, and studies the breakdown characteristics of aged samples. An accelerated aging at power frequency of low-voltage cable samples was carried out at 0 ℃, 20 ℃ and 50 ℃ for 7 days, 14 days and 21 days respectively, and the aging voltage was 1 kV. The breakdown experiment and scanning electron microscope observation were carried out on the aged samples, and the mechanical properties of the unaged samples were tested at 0 ℃, 20 ℃ and 50 ℃. The breakdown test results show that the breakdown strengths of the samples aged for 21 days are 20 ℃, 50 ℃, 0 ℃ from high to low. The SEM results show that the densities of micropores in the aged samples are 0 ℃, 50 ℃ and 20 ℃ from large to small, while the pore size is 50 ℃, 20 ℃ and 0 ℃ from large to small. The tensile results show that the elastic modulus and tensile strength of the samples at 0 ℃ and 20 ℃ are much higher than those at 50 ℃. The electric field simulation results show that the electric field strength at the tip of the microvoid of the 0 ℃ aged sample is about 3 times that of 20 ℃ and 50 ℃. The analysis shows that the microvoid tip has a high field strength at 0 ℃, and the microvoid grows rapidly along the electric field direction (radial direction), resulting in the lowest breakdown strength of the sample. The electric field strengths of the microvoid tip at 20 ℃ and 50 ℃ are significantly lower than that at 0 ℃, and the mechanical strength of the sample insulation at 50 ℃ is significantly lower than that of 20℃, resulting in higher radial failure rate of the sample than 20 ℃, and lower breakdown strength of the sample at 50 ℃ than 20 ℃. The breakdown strength of low-voltage cable samples is closely related to the failure characteristics of the microstructure of the insulation in the radial direction, and the number and density of radial micropores have a greater influence on the breakdown field strength than the pore size.