应用卡尔费休库仑法测定运行SF_(6)气体中的微量水分

Micromoisture Measurement of Operating SF_6 Gas by Karl Fischer Coulometry

SF_(6)气体微量水分测试是电气设备重要的状态检测试验,现行测试方法的结果存在差异时,需要引入一种辅助判断方法。文中首先介绍了卡尔费休库仑法的技术原理,着重利用不同方法间的比对分析了卡尔费休库仑法测试运行中SF_(6)气体微量水分的适用性,重点分析了测试过程中的影响因素及应对措施。结果表明:①卡尔费休库伦法的测试误差和重复性满足SF_(6)气体微量水分测试要求;②进样流速快慢均不利于测试准确性,可将进样流速控制在400~600 mL/min范围内;③保证测试准确性应至少进样3 L,当SF_(6)气体中水分含量过低则还应适当增加进样量;④故障SF_(6)气体中HF和H_(2)S组分性质活泼易影响测试结果,不建议在故障气室上应用卡尔费休库仑法。最后,通过不确定度评定和差异辅助判断,对方法的实际应用进行了验证。

The micromoisture test of SF_6 gas is an important state detection test of electrical equipment.In case of difference of the result of existing test method,it is necessary to introduce a kind of auxiliary judgment method.In this paper,the technical principle of Karl Fischer coulometry is introduced firstly,the applicability of operating SF_6 gas micromoisture which is tested by the Karl Fischer coulometry is analyzed by way of using the comparison among different methods,and the influencing factors and countermeasures in the testing process is particularly ana-lyzed.The results show that the test error and repeatability of Karl Fischer coulometry meet the micromoisture test requirement of SF_6 gas.Fast or slow injection flow rate is detrimental to the test accuracy and the injection flow rate can be controlled within the range of 400~600 mL/min.For assuring test accuracy,the injection volume shall be at least 3 L,the injection volume shall be increased appropriately in case of excessive low moisture in SF_6 gas.The active nature of HF and H_2S components in faulty SF_6 gas is likely to affect the test results.Therefore,the application of the Karl Fischer coulumetry methos is not recommended on the faulty gas compartment.Finally,the practical ap-plication of the method is verified by the uncertainty evaluation and difference auxiliary judgment.