充油电气设备.分析游离气体和溶解气体用气体和油的取样.指南

[中文适用范围]： 本国际标准涉及从气体收集继电器中取样游离气体的技术，以及从充油设备（例如电力和仪表变压器、电抗器、套管、充油电缆和充油罐式电容器）中取样油的技术。描述了三种游离气体取样方法和三种油样取样方法；方法之间的选择通常取决于可用的设备以及分析所需的油量。在分析溶解在油中的气体之前，必须首先将它们从油中提取出来。描述了三种基本方法，一种使用真空萃取（托普勒和部分脱气），另一种通过将载气鼓泡通过油样（汽提）来置换溶解的气体，最后一种通过油样之间的气体分配和少量载气（顶部空间）。萃取后的气体通过气相色谱进行定量分析；描述了一种分析方法。来自气体收集继电器的游离气体无需经过预处理即可进行分析。确保气体提取和分析设备（一起视为单个系统）性能的首选方法是对实验室制备的含有已知气体浓度（“油中气体标准”）的油样进行脱气，并定量分析分析提取的气体。描述了两种制备油包气标准品的方法。对于色谱仪的日常校准检查，可以方便地使用含有适当已知量的每种气体组分的标准气体混合物，其比例与从变压器油中提取的气体的常见比例相似。所描述的技术一方面考虑了与工厂验收测试相关的分析所特有的问题，其中石油的气体含量通常非常低，另一方面考虑了工厂中的监测设备所带来的问题。现场，样品的运输可能通过非加压空运进行，并且工厂和检查实验室之间的环境温度可能存在相当大的差异。 [外文原描述]： Deals with the techniques for sampling free gases from gas-collecting relays and for sampling oil from oil-filled equipment such as power and instrument transformers, reactors, bushings, oil-filled cables and oil-filled tank-type capacitors. Three methods of sampling free gases and three methods of sampling oil are described; the choice between the methods often depends on the apparatus available and on the quantity of oil needed for analysis. Before analysing the gases dissolved in oil, they must first be extracted from the oil. Three basic methods are described, one using extraction by vacuum (Toepler and partial degassing), another by displacement of the dissolved gases by bubbling the carrier gas through the oil sample (stripping), and the last one by partition of gases between the oil sample and a small volume of the carrier gas (head space). The gases are analysed quantitatively after extraction by gas chromatography; a method of analysis is described. Free gases from gas-collecting relays are analysed without preliminary treatment. The preferred method for assuring the performance of the gas extraction and analysis equipment, considered together as a single system, is to degas samples of oil prepared in the laboratory and containing known concentrations of gases ("gas-in-oil standards") and quantitatively analyse the gases extracted. Two methods of preparing gas-in-oil standards are described. For daily calibration checks of the chromatograph, it is convenient to use a standard gas mixture containing a suitable known amount of each of the gas components to be in a similar ratio to the commons ratios of the gases extracted from transformer oils. The techniques described take account, on the one hand, of the problems peculiar to analyses associated with acceptance testing in the factory, where gas contents of oil are generally very low and, on the other hand, of the problems imposed by monitoring equipment in the field, where transport of samples may be by un-pressurized air freight and where considerable differences in ambient temperature may exist between the plant and the examining laboratory. The main changes with respect to the previous edition are listed below. Since the publication of the second edition of this standard, a number of new gas extraction methods have been developed and are commercially available, such as mercury-free versions of the standard Toepler and partial degassing methods, which are referenced to in Annex C of the present edition. The head space method, based on a new concept for the extraction of gases from oil is introduced as a full method in this third edition, and reference is made to a simplified version of it also in Annex C (shake test method). More sensitive chromatographic techniques have also been developed since the last edition, and are presented in this third edition.