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本文采用超星学习通线上教学平台,以 “高电压技术”课程为对象,实施了规模为120余人的线上线下混合式教学。基于线上教学和传统教学的优势互补,设计了“高电压技术”多个教学环节。归纳分析了混合式教学在各个教学环节取得的效果和问题,并根据学生反馈提出了持续性的改进措施。 相似文献
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模拟故障电弧引燃电缆的火源对电缆火灾模拟试验和防火性能评估十分重要,现有的电气火源大多基于化学燃烧,较难反映故障电弧引燃特点,为了模拟故障电弧引燃电缆,本文开发了一种基于电弧的火源。首先,本文分析了110 kV电缆发生接地线被盗或两侧交叉互联线被盗等故障时金属铠装层上的感应电压,其可高达数千伏。其次,对比研究了工频交流电压和20 kHz交流电压条件下金属护套对地电弧和雅各布天梯电弧的击穿前电压与维持电压,发现两者电弧击穿与维持特性接近。进一步提出了基于雅各布天梯电弧引燃电缆的电气火源模拟方法,并实验验证了该火源能够使110 kV电缆引燃和火焰蔓延。所得结论为:高频雅各布天梯电弧能够模拟故障电弧特点并有效引燃110 kV电缆。 相似文献
3.
Shuqun WU 《等离子体科学和技术》2019,21(7):74007-64
In this work, a typical pin-to-pin plasma synthetic jet in static air is excited by a pulsed DC power supply. The influences of the pulse rising time, the amplitude and the repetition frequency of the pulse voltage on the jet flow have been investigated. First, using a high-speed Schlieren imaging technique, the induced shock waves and the fast jet flow generated by the plasma synthetic jet are characterized. With a deposited energy of 44 mJ per pulse, the velocity of the shock wave and the maximum velocity of the jet flow reach 320 m s−1 and 100 m s−1, respectively. Second, when the applied voltage increases from 12.8 kV to 16 kV, the maximum jet velocity increases from 66 m s−1 to 93 m s−1. On the other hand, as the pulse rising time varies from 50 ns to 500 ns, or the pulse repetition frequency increases from 5 Hz to 40 Hz, the jet velocity induced by the plasma synthetic jet is weakly dependent. In addition, a comparative study of the plasma synthetic jets using three commercial pulsed power supplies (XJ-15, NPG- 18, and PG-30) is implemented. It reveals that the maximum jet velocity of 120 m s−1 is obtained in the case of PG-30, with the longest pulse rising time and the lowest breakdown voltage, while the maximum velocity of 33 m s−1 is detected in the case of NPG-18, even though it has the shortest pulse rising time and the highest breakdown voltage. 相似文献
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多路电弧的产生方法对提升材料处理或气体合成的效率具有重要意义,而目前产生多路电弧时通常需要多个电源,显著增加了应用成本。因此,本文重点对比研究了单电源驱动多路电弧的方法,设计了多对电极串联、多对电极并联(支路串联电容)以及多对电极并联(支路串联电容或电感)共三种电路结构,均实现了起弧与电弧稳定维持,并对击穿特性、电弧稳定电压电流特性进行了分析。结果表明:在多对电极串联时,多路起弧与电源输出电压紧密相关,即电极对数越多所需开路电压越高;在多对电极并联(支路串联电容)时,多路起弧与电源输出电流紧密相关,即电极对数越多则所需输出电流越大;在多对电极并联(支路串联电容或电感)时,电路中电感的磁饱和效应造成各元件电压电流的突变,影响各电弧的稳定与功率分配。本文对比研究了单电源产生多路电弧的三种方法,可有效降低应用成本,为电弧在材料处理与气体合成应用提供技术支撑。 相似文献
6.
为了探索脉冲电应力作用下高压绝缘栅双极型晶体管(IGBT)器件绝缘材料的局部放电特性,建立高频高压脉冲作用下的局部放电测量平台,系统研究了电压幅值、脉冲重复频率、上升沿时间和脉宽对聚酰亚胺薄膜局部放电特性的影响规律。结果表明:随着电压幅值从3 kV增加至11 kV,脉冲上升沿处的局部放电信号幅值逐渐增大,而放电时延逐渐减小;随着脉冲重复频率从50 Hz增大至100 kHz,上升沿的放电时延逐渐增大但局部放电信号幅值几乎不变;随着上升沿时间从136 ns增大至300 ns,放电时延逐渐增大且更加分散,局部放电信号幅值逐渐减小且更加紧密;与脉宽为1μs的情况相比,脉宽为500 ns时局部放电信号幅值更大且放电时延更小。该结果可为高压大功率电力电子装置中固态开关的绝缘老化和状态监测提供重要科学依据。 相似文献
7.
本文采用"超星学习通"线上教学平台,以"高电压技术"课程为对象,实施了规模为120余人的线上线下混合式教学.基于线上教学和传统教学的优势互补,设计了"高电压技术"多个教学环节.归纳分析了混合式教学在各个教学环节取得的效果和问题,并根据学生反馈提出了持续性的改进措施. 相似文献
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Shuqun WU 《等离子体科学和技术》2018,20(10):105402
An atmospheric-pressure microplasma plume of diameter 10 μm is generated inside a long tube. The length of the microplasma plume reaches as much as 2 cm. First, with the assistance of an air dielectric barrier discharge (DBD), the ignition voltage of the microplasma decreases from 40 kV to 23.6 kV. Second, although the current density reaches as high as (1.2−7.6)×104 A cm −2 , comparable to the current density in transient spark discharge, the microplasma plume is non- thermal. Third, it is interesting to observe that the amplitude of the discharge current in a positive cycle of applied voltage is much lower than that in a negative cycle of applied voltage. Fourth, the electron density measured by the Stark broadening of Ar spectral line 696.5nm reaches as high as 3×1016 cm−3 , which yields a conductivity of the microplasma column of around 48 S m−1 . In addition, the propagation velocity of the microplasma plume, obtained from light signals at different axial positions, ranges from 1×105 m s −1 to 5×10 5 m s−1 . A detailed analysis reveals that the surface charges deposited on the inner wall exert significant influence on the discharge behavior of the microplasma. 相似文献
9.
Shuqun WU 《等离子体科学和技术》2020,22(11):115402
In order to demonstrate the modulation of terahertz wave propagation in atmospheric pressure
microplasmas, in this work, the band structure and the transmission characteristics of a onedimensional
collisional microplasma photonic crystal are investigated, using the transfer matrix
method. For a lattice constant of 150 μm and a plasma width of 100 μm, three stopbands of
microplasma photonic crystal are observed, in a frequency range of 0.1–5 THz. Firstly, an
increase in gas pressure leads to a decrease in the central frequency of the stopband. When the
gas pressure increases from 50.5 kPa to 202 kPa, the transmission coefficient of the THz wave
first increases and then decreases at high frequency, where the wave frequency is much greater
than both the plasma frequency and the collision frequency. Secondly, it is interesting to find that
the central frequency and the bandwidth of the first THz stopband remain almost unchanged for
electron densities of less than 1015 cm–3, increasing significantly when the electron density
increases up to 1016 cm–3. A central frequency shift of 110 GHz, and a bandgap broadening of
200 GHz in the first stopband are observed. In addition, an atmospheric pressure microplasma
with the electron density of 1 × 1015–6 × 1015 cm–3 is recommended for the modulation of THz
wave propagation by plasma photonic crystals. 相似文献
10.
在航空领域中,线缆电弧引发的电气火灾是一项严重的安全隐患。随着多电/全电飞机的发展,航空电气系统对电气设计、安装提出了更高的安全要求。本文对航空线缆电弧故障引发电气火灾的原因、机理、检测、预防和扑灭进行了综述。调查统计了欧洲空中航行安全组织公开数据中由线缆电弧引发的飞机火灾事故并分析其原因,介绍了电弧引燃线缆机理研究的近况,然后结合目前国内外飞机实际情况,讨论了航空线缆电弧引发电气火灾的预警技术和灭火技术。针对航空线缆绝缘失效以及布线不当易引发电气火灾问题提出了预防建议,强调了发展高可靠性且能作用于飞机所有电气设备电弧探测技术、火灾预警技术和灭火系统的重要性,同时也提出探测电弧火源引发航空线缆的机理研究仍存在挑战。 相似文献