浪涌保护器阀片热特性及其破坏机理研究

发布时间：2018-06-10 05:16

本文选题：浪涌保护器 + 氧化锌压敏阀片　；参考：《合肥工业大学》2017年硕士论文

【摘要】：以氧化锌压敏电阻为核心元件的浪涌保护器具有稳定电路电压、保护电器设备的作用,但由于压敏电阻自身的热效应会造成其热损毁,严重时引发火灾等事故。本文以浪涌保护器及其阀片为研究对象,针对浪涌保护器工作过程中的热损毁和失效问题,对浪涌保护器阀片热特性及其破坏机理进行研究。基于传热学理论,根据浪涌保护器的工作条件和氧化锌压敏电阻的热物理性能及电学性能,对浪涌保护器进行电-热耦合有限元建模,分析了浪涌保护器在正常工作状态下的温度场分布情况,研究表明浪涌保护器正常工作时整体温度场分布较均匀。分别讨论了氧化锌压敏阀片经8/20μs波形雷电流冲击、热损毁时的温度场分布和温升情况及压敏阀片老化过程中温度和漏电流的变化:经8/20μs波形雷电流冲击后压敏阀片的温度场均匀性降低,但其最大温升小于极限工作温升,阀片完好未损毁;热损毁时浪涌保护器整体结构解体,最高温度已超过1000K;阀片老化后其漏电流和最高温度均随电导率的增加(10-6~10-5S/m范围内)近似呈线性增加趋势。通过热稳定试验揭示多通道浪涌保护器脱扣弹片的不同步脱扣问题会加剧浪涌保护器的热损毁。对现有脱扣弹片结构进行优化,将中间通道脱扣弹片的预变形上翘斜度比边缘通道脱扣弹片的上翘斜度提高0.5度,以保证各弹片具有相同的预应力,同时设计了一套脱扣弹片预变形检测机构以确保脱扣弹片同步脱扣。通过分析测试氧化锌压敏阀片不同失效形式前后的微观结构及材料成分变化探讨其破坏机理:氧化锌压敏电阻的老化破坏倾向于造成晶粒间的挤压破坏,同时添加元素迁移并形成碎屑状物质散落在材料内部;氧化锌压敏电阻的冲击破坏倾向于造成晶粒破碎,同时还伴有添加元素的挥发,且发生穿孔破坏。
[Abstract]:The surge protector with zinc oxide varistor as the core element has the function of stabilizing the circuit voltage and protecting the electrical equipment. However, the thermal effect of the varistor itself will cause its thermal damage and lead to fire and other accidents. In this paper, the thermal characteristics of surge protector and its failure mechanism are studied in view of the thermal damage and failure of surge protector. Based on the theory of heat transfer, according to the working conditions of surge protector and the thermophysical and electrical properties of zinc oxide varistor, the electro-thermal coupling finite element model of surge protector is established. The temperature field distribution of surge protector under normal working condition is analyzed. The results show that the whole temperature field of surge protector is uniform when it works normally. The impact of 8 / 20 渭 s lightning current on zinc oxide varistor is discussed. The temperature field distribution and temperature rise during thermal damage and the change of temperature and leakage current during the aging of the pressure sensitive valve: the temperature field uniformity of the pressure sensitive valve is decreased after 8 / 20 渭 s wave lightning current impact, but the maximum temperature rise is less than the limit working temperature rise. The whole structure of the surge protector disintegrates and the maximum temperature exceeds 1000K. The leakage current and maximum temperature of the valve plate increase linearly with the increase of electrical conductivity in the range of 10 ~ (-6) N ~ (-5) S / m). The thermal stability test shows that the thermal damage of the surge protector will be aggravated by the non-synchronous release of the release shrapnel of the multi-channel surge protector. In order to ensure the same prestress of each shrapnel, the pre-deformed upwarping angle of the mid-channel tripping shrapnel is improved by 0.5 degree compared with that of the edge channel tripping shrapnel, and the structure of the existing tripping shrapnel is optimized, so as to ensure that each shrapnel has the same prestress. At the same time, a set of pre-deformation detection mechanism is designed to ensure the release of shrapnel simultaneously. By analyzing and testing the microstructure and material composition change of zinc oxide varistor before and after different failure modes, the failure mechanism of zinc oxide varistor is discussed: the aging failure of zinc oxide varistor tends to cause extrusion failure between grains. At the same time, the addition of elements and the formation of clastic material scattered in the material; the impact damage of ZnO varistor tends to cause grain breakage, but also accompanied by the volatilization of the added elements, and the perforation failure.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM862

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