地表紫外辐射对棒-板间隙正极性直流放电的影响

Effect of Terrestrial Solar UV Radiation on Positive DC Discharge of Point-plane Gap

揭示地表太阳紫外辐射对电力系统外绝缘放电特性的影响对于强紫外辐射地区外绝缘设计和运行有着重要的意义,但是目前并没有相关的系统研究。为此,利用人工紫外光源模拟大气环境中的紫外辐射,在实验室研究了紫外辐射对棒板间隙正极性直流放电特性的影响。试验结果表明地表太阳紫外辐射对棒板间隙正极性直流击穿电压和电晕放电均无明显影响。分析认为,这是由于到达地表的太阳紫外辐射的波长范围为290～400 nm,且辐射照度≤200 W/m2,无法电离空气和铜、铁电极,对电弧的发展过程也没有明显影响。虽然这一波段的部分光子能量高于铝的逸出功,但由于铝在空气中极易氧化,形成氧化膜(Al2O3),这层氧化膜阻止了紫外光子从铝电极表面电离出电子。因此,太阳紫外辐射对暴露在空气中的铜、铁、铝电极的正极性直流放电均无明显影响。所做工作填补了相关领域的空白,可为强紫外辐射地区的外绝缘设计提供技术支持。

It is important to reveal the effect of terrestrial solar ultraviolet radiation （TSUVR） on the discharge perfor mance of external insulation for the design and operation of power system in regions where have strong TSUVR. Consequently, we use an artificial UV lamp to imitate TSUVR in experiments to research this effect on positive DC dis charge. It is found that TSUVR has no obvious effect on breakdown voltage and corona of air-gap positive DC discharge. That is because the wavelength of TSUVR is in the range of 290 - 400 nm, and its intensity is less than 200 W/m2, and air, Cu, and Fe can not be photoionized under TSUVR. There is no obvious effect of TSUVR on arc propagation due to ener gy. Although a part of the photons in TSUVR has higher energy than the work function of A1, A1 could be easily oxidized, and the oxide film （A1203） prevents A1 from being ionized by TSUVR. Therefore, TSUVR has no obvious effect on posi tive DC discharge performance of air gap. This research will support the design of external insulation in the regions with strong TSUVR.