气压及温度衰减对C4F7N分解组分影响规律研究

Influence of pressure and temperature on C4F7N decomposition components

C4F7N以其显著的绝缘能力和低GWP值成为目前有望代替SF 6作为绝缘介质的气体之一。但是,C4F7N在绝缘击穿过程中会分解成低碳低氟的小分子,引起绝缘强度发生变化,给设备及其所在电力系统的安全可靠运行带来潜在威胁。本文建立化学动力学模型研究C4F7N分解组分在绝缘击穿过程中的演化规律,获得C4F7N分解组分的变化特性以及温度衰减、气压的影响规律。结果表明:绝大部分C4F7N分解组分随着温度的降低迅速复合为C4F7N,因此C4F7N具有良好的绝缘自恢复特性;较高的温度衰减速度降低了C4F7N的复合速率,使得同一温度下的C4F7N摩尔分数有所下降,不利于绝缘强度恢复过程;气压的提升促进了C4F7N的复合过程,使其摩尔分数在更高温度下接近于1,有利于绝缘强度恢复。研究结果可以为C4F7N作为绝缘介质的可行性研究奠定理论基础。

Owing to the excellent insulation performance and low GWP,C4F7N has become one of the promising gases to replace SF 6 as insulation medium.However,it will decompose to small fraction under dielectric breakdown and thus decrease the insulation strength,which is a potential threat to the safety operation of power system.Therefore,this paper builds a chemical kinetic model to study the variation characteristic of C4F7N decomposition components during dielectric breakdown,with the influence of pressure and temperature on C4F7N decomposition components obtained.The study shows that most fractions will recombine to C4F7N with temperature decreasing,so C4F7N has a great insulation-recovery property.High temperature decreasing rate causes a drop of C4F7N recombining rate and leads to the declination in the molar fraction of C4F7N at same temperature,which is harmful to insulation-recovery process.The growth of pressure promotes the recombination of C4F7N,making its molar fraction close to one at higher temperatures,which is helpful in the insulation-recovery process.This study is hopeful to lay a theoretical basis for the application of C4F7N as insulation medium.