Non-destructive measurement of the degradation of transformer insulating paper

Knowledge of the condition of power transformer winding insulation paper is fundamental to making optimum asset replacement decisions in the power industry. The ability to assess the aged condition of Kraft paper quickly and non-destructively using portable instrumentation would significantly increase the opportunities for gaining this knowledge. Insulation paper degrades over time in-service and its degree of polymerization (DP) reduces, eventually affecting its mechanical strength. At low DP levels the insulation may start to disintegrate and the risk of electrical breakdown increases. Currently-used methods of estimating DP are either approximate or destructive. The use of spectroscopy together with multivariate statistical analysis (MVSA) provides a powerful non-destructive evaluation of the condition of paper. From initial feasibility studies, we have developed a simple, portable system (TRANSPEC) using fiber-optics and broad-band spectroscopy that can measure the degree of polymerization of various aged transformer papers to a precision of approximately 30 DP units with a spatial resolution of 14 mm. The system can also measure the chemical composition and condition of the insulating mineral oil. MVSA regression models were constructed from library spectral data, and these models are used to predict the DP of other papers with parameters that fall within the range spanned by the set of calibration samples. Separating oil and moisture information from wetted paper is possible and will be reported in a separate publication. With a single TRANSPEC system, non-destructive in-situ analysis of the DP of insulating paper is possible, providing a rapid cost-effective method for transformer insulation condition assessment and monitoring, which correlates well with current destructive methods.     

绝缘油色谱分析在变压器故障查找中的应用

绝缘油气相色谱技术是检测变压器潜伏性故障的有效手段,文章通过2个实例,介绍了绝缘油气相色谱技术在2台静电除尘器变压器故障分析中的应用。     

油／气绝缘套管出线变压器现场试验方法

通过油／气套管和GIS连接的电力变压器是一种新型结构电力设备。对其进行介质损耗和电容测量试验,需要将SF6气室打开才能进行试验接线,现场处理难度大,并且容易在处理过程引起新的设备缺陷。文中介绍不打开SF6气室,对变压器进行介质损耗和电容测量的试验方法。理论分析和现场试验证明,该试验方法简单,测试数据可靠。     

变压器油中糠醛含量测试与分析

变压器油中糠醛浓度是绝缘纸老化程度的重要指标。介绍了液相色谱对绝缘油糠醛分析方法的依据，并建立了分析方法。通过数据表明测试糠醛的必要性。     

变压器匝间绝缘故障的分析

介绍了变压器匝间绝缘故障的起因和特点。阐述了诊断变压器匝间绝缘故障常用的绝缘油色谱分析和高压试验数据相结合的分析方法。结合实碌工作经验,提出了分析变压器匝间绝缘故障几点意见。     

变压器油抗氧化性能的热分析评价

通过差示扫描量热技术(DSC)，测定变压器油氧化放热峰的起始温度，并考察加入不同质量分数的抗氧剂(T501)后，它对变压器油氧化起始温度及抗氧化性能的影响最后的实验结果证明，差示扫描量热技术是一种快速评价变压器油抗氧化性能有效的新方法。     

Mechanism of increase of electrostatic charging tendency in insulating oil for oil‐immersed transformer

The mechanism of the increase in the electrostatic charging tendency (ECT) of insulating oil and causative compounds were investigated by accelerated deterioration tests with the addition of various compounds. Although the ECT of the insulating oil was almost constant when only sulfoxide compounds were added, a marked increase was observed when either hydrochloric acid or moisture, which was considered to be generated by the aging of insulating oil, was also added to oil containing sulfoxide compounds. It is assumed that the sulfonium ion, which is generated by the reaction between sulfoxide compounds and hydrogen ion, is the compound that directly contributes to the increase in the ECT. Hydrogen ions can be supplied from organic acids generated by the oxidation of hydrocarbons in aging insulating oil. It is considered that the increase in the ECT of insulating oil is caused by the generation of sulfoxides by the oxidation of sulfide, which are present in fresh oil (originating compounds), and the generation of sulfonium ions by a reaction between sulfoxide and hydrogen ions, which are formed during aging. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(4): 26–33, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21113     

变压器油色谱分析诊断技术

为了监测变压器运行状况,提出了对变压器采用气相色谱分析诊断技术和三比值法,介绍了它们的特点,论述了变压器油色谱分析在变压器潜伏性故障诊断上的应用效果,总结了变压器油色谱分析诊断技术在实际应用中需要注意事项.     

变压器油中气体含量异常问题的技术分析

通过对1台SFPSZ9/150000/220电力变压器油中气相色谱跟踪测试,结合高压电气试验,经综合分析查出了变压器油中气体含量异常的原因,并准确判断出故障部位.     

Mineral insulating oil in transformers

Nearly all load bearing transformers in electric power delivery systems around the world are filled with liquid. The liquid functions both as an electrical insulation and as a heat transfer fluid. The liquid in almost all of these units is transformer oil, petroleum-based insulating oil refined specifically to meet the requirements of this application. Transformers in electric power distribution and transmission systems are expected to function reliably and efficiently and to do this for many years. The quality of the oil in a transformer plays an important role in performing this function, and the characteristics of transformer oil have been examined and reported on for decades. This article discusses some of these characteristics and the relationships between these characteristics and the production and in-service performance of mineral transformer oil. Transformer oil is used around the world, but the emphasis here is on practices in the United States     

变压器绝缘电阻试验中容易忽视的几个问题

介绍了绝缘电阻受温度及外界电磁场干扰等因素的影响 ,提出了解决办法 ,避免一些错误判断给生产运行带来影响     

在线色谱在电力变压器油分析中的应用分析

本文介绍色谱在线监测技术的基本原理和关键组成,通过实例对色谱在线监测和实验室离线分析进行数据比对。数据表明,在线监测技术可以反映变压器运行状态和故障发展的趋势。     

变压器油色谱分析技术的发展及最新动态

从色谱仪气路系统、脱气方法、数据处理及变压器故障诊断技术和色谱在线监测装置的研制与应用等方面,介绍了国内外变压器油色谱分析技术的发展过程及最新动态。     

Breakdown of transformer oil

Some of the factors affecting the dielectric strength of transformer oil are investigated. These factors include the stabilization phenomenon, oil and electrode pretreatment, the effect of oil velocity, the effect of a capacitance parallel to the test cell, and the effects of electrode area and gap spacing. The experimental apparatus and procedure are described, and the results are presented for each of the above factors. Suggestions for future research are offered     

State of water in hydrocarbon liquids and its effect onconductivity [transformer oil]

The humidity or the dissolved water in insulating oils influences conduction and breakdown phenomena. The corrections between the amount of dissolved water and the electrical properties have been investigated. However, the effect of water has been based only on the total amount of water because in the past there was no way to observe the state of water in oil in an electrical field. With the availability of Fourier transform infrared (FTIR) spectroscopy to characterize water clusters, the effect of water in transformer oil can be reassessed based not only on the amount of water, but also on the state of water. In this paper, IR spectra of water in several liquid hydrocarbons and conduction current were measured at the same time. The selection of the liquid hydrocarbons was made on the basis of the degree of polarizability of the liquids. Because the water molecules combine with the polar structures by hydrogen bonding, the state of water depends on the polarizability of the oil. As a result, there is a difference in conduction phenomena depending on whether water is free or combined with the polar structure of the liquid     

Technical report-particles in transformer oil

Attention is drawn to a parameter that plays a crucial role in determining the breakdown strength of transformer oil, yet which tends to be ignored. This parameter is the settling time, which can mean either the time interval between two consecutive measurements or the time for which an oil sample is stored before measurements begin. The term is used here in the former sense. Research carried out with Bruce profile electrodes and for gap spacings of 1 and 4 mm showed that settling times between measurements of 1 and 5 mm gave widely differing breakdown strength results. The breakdown strength with 1-min settling time was inferior to that for a settling time of 5 min. A particle counting analysis performed on two oil samples supports the hypothesis that short settling times do not allow either the bubbles from the previous breakdown to be dissolved or the decomposition products to settle under the influence of gravity, thereby increasing the probability of breakdown     

六氟化硫气体绝缘变压器及其监督的探讨

本文简述了六氟化硫气体变压器的结构。在对六氟化硫气体变压器生产、安装、运行和试验进行了调研的基础上 ,提出六氟化硫气体变压器运行监督的要求。特别是对六氟化硫气体的分析试验要求。     

变压器绝缘油硫腐蚀分析方法

采用ASTM D1275-B腐蚀性硫检测方法和扫描电子显微镜技术,研究变压器绝缘油硫腐蚀的分析方法。对变压器绝缘油进行腐蚀性硫检测,判断油中有无腐蚀性硫;对硫腐蚀的铜片进行形貌和能谱分析,测量腐蚀产物中硫含量和腐蚀产物层的厚度。测量结果表明,硫腐蚀程度随硫含量和产物层厚度的增加而增大。变压器绝缘油硫腐蚀的形貌和能谱分析,弥补了腐蚀性硫检测方法在判断硫腐蚀程度方面的不足,该方法可以判断硫腐蚀程度,还能够判断腐蚀性硫检测结果的准确性,因此ASTM D1275-B法结合扫描电子显微镜技术是分析变压器绝缘油硫腐蚀的有效方法。