110~1900μm水雾对棒-板长间隙雷电冲击放电特性的影响

Influence of Water Spray with a Diameter of 110~1900μm on Lighting Impulse Discharge Characteristics of Long Rod-plate Gap

水雾–空气两相体放电涉及到水雾带电灭火、云中闪电及其发展、雨雾降低放电电压等研究领域。为此利用雾滴直径为110~1900μm的消防水雾以及1.0~2.5 m的棒–板间隙,研究水雾对棒–板长间隙雷电冲击50%放电电压U50的影响。试验表明,当水雾雾滴直径<300μm时,水雾对间隙U50的影响不明显;当水雾雾滴直径>300μm时,水雾间隙U50明显低于空气间隙U50。且水雾对棒–板长间隙U50的影响存在极性效应:在所试验的条件范围内,水雾正极性U50较空气间隙正极性U50最大降幅为2.3%,而水雾负极性U50较空气间隙负极性U50最大降幅达16.7%。对棒–板空气间隙中存在水雾的静电场仿真表明,水雾雾滴直径越大,空气间隙的电场畸变越严重,促进间隙放电的发生。

The research on water droplets-air two-phase mixture discharge involves the field of suppressing fires of electrical equipment using mists,initiation and growth of lighting in clouds,and decrease of surface flashover voltage caused by rain.Consequently,the influence of mist on the U50 of long rod-plate gap was studied using the mist with a diameter of 110~1900μm and a gap length of 1.0~2.5 m.When the droplets diameter of mist was less than 300μm,the influence of mist on the U50 of air gap was not distinct.When the droplets diameter of mist was greater than 300μm,the mist decreased the U50 of air gap clearly.Besides,the influence of mist on the U50 of air showed a polarity effect.The maximum decrease of positive polarity U50 of mist was 2.3%,compared with the positive polarity U50 of air;however,the maximum decrease of negative polarity U50 of mist was 16.7%,compared with the negative polarity U50 of air.The electrostatic field simulation of water droplets in the rod-plate air gap showed that,the greater the droplet diameter of mist was,the more serious the electric field distortion of the air gap was,which promoted the discharge.