排序方式: 共有28条查询结果,搜索用时 328 毫秒
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换流变阀侧绕组同时承受交流、直流、交直流叠加、极性反转等多种特殊电压形式,其许用场强却未得到同等关注。因此,采用针-板、板-板典型电极模型和脉冲电流法及宽频带电流传感器检测法,研究了变压器油在交流、直流、交直流复合电压条件下的局部放电起始过程;总结了该起始电压随电压类型变化的规律曲线,为换流变许用场强的提出奠定了基础。试验结果表明:针-板电极模型下局放起始电压基本只与交流、直流、复合电压的幅值有关,而与电压类型、复合电压分量所占比例无明显关系;板-板电极模型中,复合电压下交流局部放电起始电压受直流分量的影响很小。通过高速摄像仪记录复合电压下局部放电引发击穿的全过程并估算出了放电增长速率约为1.8km/s;利用扫描电镜观测放电通道表面形貌特征,进而采用表面能谱分析法检测其主要元素含量由高至低依次为C、O、Cu、Si。最后通过复合电压下油中局部放电产生随机分布气泡的仿真模型算出,气泡使局部放电场强严重畸变,不均匀系数f达1.6。 相似文献
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混凝土试件标养强度是评价混凝土拌合物检验批质量的重要指标,混凝土试件同条件强度是评价实体混凝土质量的重要指标,推定强度是构件是否需要处理的依据。 相似文献
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Direct current (DC) partial discharge (PD) test has drawn extensive attention from world-wide electric power research institutes in recent years. However, presently, no DC PD detection device on the market has the statistical function. Thus, we developed a test system for PD detection under DC voltage, which is characterized by strong anti-jamming capability, continuous high-speed real-time data acquisi- tion and effective, complete detection of DC PD signals. The DC PD mechanism, as well as the measuring principles, software system, and hardware design of the test equipment were introduced. Adopting typical electrode pairs, we tested the statistical spectrum of PD under DC voltage. The main difference in statistical spectrums between parallel plate electrodes and needle-plate electrodes was that the time interval between two consecutive discharges for needle-plate electrodes has obviously larger variation range than that for parallel plate electrodes, which could be the convincing proof for distinguishing the type of electrodes under DC PD. Practical results indicate that the proposed sys- tem can measure time domain signals of DC PD of oil-paper insulation effectively and promptly, and it can be used to determine and detect defects in DC power transmission equipment. 相似文献
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以PLC为核心的泵站自动控制系统,大大提高了泵站的综合自动化水平.本文主要介绍了日本三菱公司的FX2N系列可编程控制器(PLC)在泵站自动控制系统中的应用.解决了上位机(IFIX)与下位机(PLC)的通讯问题,以及多台FX2N系列的小型PLC如何进行数据采集,数据交换和通讯等问题.除此以外,还给出了此泵站控制系统的系统构成和系统功能. 相似文献
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