PTFE蒸气对热态SF_6气体电击穿特性的影响  

Influence of PTFE Vapor on Dielectric Breakdown Property of Hot SF_6 Gas

作　　者：王流火 赵虎[2] 张晗[3] 王增彬 李兴文[4] 

机构地区：[1]广东电网有限责任公司电力科学研究院,广州510080 [2]西北工业大学自动化学院,西安710072 [3]中国南方电网超高压输电公司检修试验中心,广州510663 [4]西安交通大学电力设备电气绝缘国家重点实验室,西安710049

出　　处：《高电压技术》2017年第3期801-807,共7页High Voltage Engineering

基　　金：国家自然科学基金(51577143)~~

摘　　要：PTFE蒸气对SF_6断路器的开断特性有重要影响。为此研究了压力范围0.01~1.6 MPa、温度范围300~3 500K内PTFE蒸气对热态SF_6气体电击穿特性的影响。基于Gibbs自由能最小化的方法计算了不同混合比例和压力下SF_6与PTFE蒸气混合气体的平衡态化学组成随温度的变化;接着利用Boltzmann解析法计算分析了混合气体中电离与吸附反应系数随混合比例、温度、压力等因素的变化规律;然后通过混合气体在折合电场作用下自由电子产生与消失达到平衡的条件,确定了SF_6-PTFE混合气体的临界折合击穿场强随温度、压力、混合比例的定量关系。结果表明:在较低温度范围内,纯SF_6气体的电击穿特性明显优于SF_6-PTFE混合气体,然而在较高温度范围内,SF_6-PTFE混合气体的临界折合击穿场强高于纯SF_6气体。此外,提高压力能够将临界折合击穿场强随温度的变化推移至更高的温度范围。PTFE vapor has a crucial effect on the interruption performance of SF6 circuit breakers. Therefore, we analyzed the influences of PTFE vapor on the dielectric breakdown properties of hot SF6 gas at gas pressures of 0.01-1.6 MPa and gas temperatures up to 3 500 K, which represents the conditions prevailing during the dielectric recovery phase in a high voltage circuit breaker. By minimizing the Gibbs free energy under the assumptions of local thermodynamic and chemical equilibrium, we calculated the equilibrium compositions of SF6 mixtures with PTFE vapor, and analyzed the reduced ionization coefficient α/N, the reduced attachment coefficient η/N, and the reduced effective ionization coefficient （α-η）/N. Moreover, the critical reduced electric field strength （E/N）cr was determined by balancing the electron generation and loss processes. The results confirm the superior breakdown properties of pure SF6 at relatively low gas temperatures. However, （E/N）cr of SF6 mixtures with PTFE vapor are clearly higher than that of pure SF6 for high gas temperatures. In addition, it is also noted that the increase of gas pressure shifts the variations of （E/N）cr to higher gas temperatures.

关 键 词：SF6-PTFE混合气体 电击穿特性 喷口烧蚀 高压断路器 开断 电弧 

分 类 号：TM561.3[电气工程—电器]