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为研究干式空心电抗器匝间绝缘的电老化规律,进行了干式空心电抗器匝间绝缘模型试样的起始局部放电电压及击穿试验。采用恒定电压法及阶梯电压法进行了局部放电发生后干式空心电抗器匝间绝缘的电老化寿命试验,求得两种老化方式下的电老化反幂寿命方程。分析并试验验证了两个寿命方程存在差别的原因,并修正了局部放电发生后恒定电压下干式空心电抗器匝间绝缘模型试样的电老化反幂寿命方程。研究结果表明:发生局部放电时,干式空心电抗器匝间绝缘的电老化规律不符合反幂寿命模型,耐压寿命指数N及常数C随着试验电压的升高而增大;各种过电压下可能出现的局部放电对干式空心电抗器匝间绝缘材料的危害很大,可以通过改进制造工艺提高起始局部放电电压、选用耐局部放电能力强的绝缘材料作为匝间绝缘或者加装过电压抑制装置限制过电压幅值等方法延长干式空心电抗器匝间绝缘的使用寿命。 相似文献
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本文介绍了66 kV干式空心电抗器的短路故障情况,依据其结构特点及现场检查,初步判断第7、8绕包封层间绝缘击穿.对该设备解体检查分析,发现包封层表面鸟类排泄物、毛絮等积污明显,有沿鸟类排泄物的爬电痕迹,第7、8绕包封层存在贯穿性过火过烟痕迹,其包封内各层导线有不同程度烧蚀,烧蚀点附近导线包覆绝缘膜韧性良好.推断包封层表面积污发生污湿放电,逐渐累积恶化后损坏包封股间、层间绝缘,导致电抗器短路.据此,提出检查电抗器防腐蚀涂层,例行检修增加通风道清理项目,改造电抗器格栅,增强防鸟性能等运检预防措施,以保障设备安全运行. 相似文献
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交联聚乙烯(cross-linked polyethylene,XLPE)电缆本体与附件构成的异质绝缘的电树枝化严重威胁电缆及附件的安全运行。为探明不同温度下XLPE-硅橡胶(silicone rubber,SIR)异质绝缘的交/直流电树枝及局部放电特性,分别在30、50和70℃下,对XLPE-SIR进行交/直流下的电树枝实验及局部放电检测。结果表明,局部放电特征量与电树枝发展阶段密切相关,其中放电量变化率相关性最强;异质绝缘界面对电树枝发展起阻碍作用;交/直流下试样击穿路径不同,推测这与实际界面的非理想接触状态及交/直流下界面附近电荷分布与局部放电差异有关;此外,温度升高不仅促进电树枝的引发与生长,同时对交流电树枝形态有显著影响。结果可为高压交/直流XLPE电缆附件处的绝缘老化状态监测与评估提供一定理论依据。 相似文献
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户外干式空芯电抗器绝缘结构电场数值计算与分析 总被引:3,自引:1,他引:2
分析了户外干式空芯电抗器表面发生的树枝状放电。利用有限元法,对电抗器绝缘结构进行了电场计算,得出:绝缘结构中最大场强及其出现的位置;绝缘开裂对电场分布的影响;以及最大场强值与结构因素的关系。说明绝缘开裂是产生表面树枝状放电的主要原因之一。 相似文献
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干式空心电抗器的故障分析及运维措施 总被引:1,自引:0,他引:1
通过对500kV变电站发生的几起干式空心电抗器故障的分析,指出干式空心电抗器在运行中出现的线圈受潮、温度分布不均衡、局部放电过热、绝缘烧损等现象,会逐步演变成事故,甚至烧毁设备,其中线圈匝间绝缘击穿是造成干式空心电抗器故障的主要原因,同时指出了故障设备在设计、制造中存在的缺陷。提出了干式空心电抗器的日常检修、维护建议和措施。 相似文献
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《IEEJ Transactions on Electrical and Electronic Engineering》2017,12(Z2):S10-S15
Inorganic fillers were added to epoxy resin for preparing micro and nano filler/epoxy composite, and then the breakdown strengths, depths of erosion caused by partial discharge, and electrical tree experiments of composites were investigated. It was found that the loading of micro fillers usually decreases the short‐time breakdown strength (breakdown under a continuously rising voltage) of the composites. On the contrary, it increases the ability to withstand long‐time electrical aging (erosion or breakdown caused by electrical tree under a discontinuously rising voltage or constant voltage) of the composites. The effect of inorganic fillers in suppressing the electrical tree or erosion channel propagation in the composite is different during the process of withstanding short‐time breakdown and long‐time electrical aging. Defects are introduced during the mixing of fillers and epoxy resin, which play a role to decrease the short‐time breakdown strength and accelerate long‐time electrical aging. It is concluded that micro and nano inorganic fillers can suppress the electrical tree channel propagation and erosion caused by partial discharge, whereas defects play the opposite role in composites. Two opposite effects of inorganic fillers and defects exist simultaneously during the process of electrical aging and breakdown; whereas inorganic fillers play a primary role in long‐time electrical aging, defects play a primary role in short‐time breakdown. 相似文献
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聚合物纳米复合材料因其优良的电气绝缘性能在电介质绝缘领域得到了广泛应用。为了获得性能优良的环氧树脂绝缘材料,将采用硅烷偶联剂进行表面处理后的纳米Al N颗粒加入环氧树脂绝缘材料中,采用溶液共混法制备了Al N质量分数分别为0%、0.5%、1%、3%、5%、7%的Al N/环氧树脂复合材料,研究了不同Al N质量分数对Al N/环氧树脂复合材料绝缘性能的影响。结果表明,树脂基体和Al N填料之间实现了有效的结合,提高了环氧树脂的热稳定性;Al N的加入一定程度上减小了复合材料的体积电阻率,并且增大了复合材料的介质损耗因数,但对复合材料电气绝缘性能的影响较小;当纳米Al N颗粒质量分数为3%时,Al N/环氧树脂复合材料的交流击穿电场强度最大。因此,添加适量纳米Al N颗粒能够提高干式变压器环氧树脂的电气绝缘性能。 相似文献
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In this paper we develop a kinetic model for the growth of electrical tree structures in solid polymeric insulation that allows for combined electrical and mechanical stresses. We present an energy balance analysis during the tree growth process and show the total tree extension driving force is not a material constant due to the existence of a damage process zone around the tree tip and the dissipated heat and the trapped energy remaining in the damage process zone. We derive both the tree growth rate equation and life formula of tree propagation to breakdown, based on the specific tree growth mechanism and the fractal nature of tree structures. We perform electrical tree growth tests in epoxy resin samples with and without mechanical residual stresses, and present results which show that the proposed model can give predicted tree propagation times to failure in good agreement with the experimental data of the tree growth subjected to a combined electrical and mechanical stress 相似文献
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Imai T. Sawa F. Nakano T. Ozaki T. Shimizu T. Kozako M. Tanaka T. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2006,13(2):319-326
This paper focuses on the electrical insulation properties of a newly prepared composite material by nano- and micro-filler mixture. Nano- and micro-filler mixture composites were made by dispersing nano-scale layered silicate fillers and micro-scale silica fillers in epoxy resin. To investigate the effects of nano- and micro-filler mixture, the thermal expansion coefficient and insulation breakdown properties by a needle-plate electrode method were measured for the filler mixture composite and the conventional filled epoxy. The filler mixture composite had almost the same thermal expansion coefficient as the conventional filled epoxy. In a continuous voltage rising test, the filler mixture composite had 7% higher insulation breakdown strength than the conventional filled epoxy. Moreover, under constant AC voltage (10 kV at 1 kHz), the filler mixture composite had an insulation breakdown time of more than 20,000 minutes whereas the conventional filled epoxy had a breakdown time of 830 minutes. Electron microscope observation showed that the area surrounded by dispersed micro-scale silica fillers were also filled with the nano-scale layered silicate fillers. Furthermore, the estimate of spacing between the fillers and the filler/epoxy interface area showed a more densely-packed structure of the filler mixture composite than the conventional filled epoxy. The morphological feature of the filler mixture composite seems to improve its insulation breakdown strength and time. 相似文献
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X射线具有较大的能量,能使电介质发生电离,进而可以影响局部放电的发生与发展过程。首先介绍X射线激励固体绝缘内部气隙、油纸绝缘内部气隙和油隙等典型缺陷局部放电的宏观现象,综述X射线能够为绝缘体中的气隙放电提供给初始电子,减小放电统计时延,降低局部放电起始电压的机理。其次,阐述近年来X射线激励下GIS绝缘子中气隙缺陷、环氧树脂浸渍绝缘中气隙缺陷和油纸绝缘系统等绝缘结构中的局部放电现象和特性。最后,总结现有X射线激励下局部放电检测技术的应用场景,给出该技术的发展和应用前景。 相似文献
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环氧树脂广泛应用在电机绝缘领域,向树脂中添加微米氧化铝可以减缓绝缘老化的侵蚀,为了进一步提升氧化铝/环氧树脂复合材料电气性能,本文引入偶联剂协同低温等离子体复合改性方法对氧化铝填料进行表面处理。将偶联剂包覆改性后的微米氧化铝置于重复脉冲低温等离子体中分别进行0~9min表面改性处理,其次将氧化铝掺杂进环氧树脂中制备复合材料。观测氧化铝填料外表的形貌、官能团及结构变化,对复合材料局部放电起始电压进行测试分析。结果表明,偶联剂和低温等离子体复合改性能有效提升氧化铝填料表面活性官能团的含量,为氧化铝与树脂基体的紧密键合提供了基础,进而提升了氧化铝/环氧树脂复合材料的电气性能。在复合改性中等离子体处理时间为3min时,氧化铝填料表面含氧基团的含量相对于单一偶联剂改性增长了3.32%,表面偶联剂的接枝率提升了24.5%,复合材料的电气性能提升了7.9%。 相似文献
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为研究玻璃纤维、碳纳米管共掺杂环氧树脂复合材料的绝缘性能,制备了纤维不同掺杂量和排布方式时的玻璃纤维-碳纳米管环氧树脂复合材料,并分别测试了其介电常数、介质损耗因数及交流短时击穿电压,研究了掺杂工艺参数对复合材料绝缘性能的影响。研究发现,玻璃纤维掺杂量在15~20wt%、纤维束间距在1.0~1.2mm时,复合材料介电常数和介质损耗因数均达到最小值,分别为3.63和0.0303;而其交流短时击穿电压在40wt%掺杂量、1.5mm纤维束间距时,达到最大值39.6k V。与单向排布方式相比,正方形网格排布的复合材料击穿电压更高。研究表明,玻璃纤维的引入改善了碳纳米管-环氧树脂复合材料的绝缘性能,玻璃纤维、碳纳米管与环氧树脂之间的界面效应在复合树脂绝缘性能的改善中发挥主要作用。 相似文献