变压器绝缘电阻不合格因素的初步研究及解决措施

绝缘电阻是变压器一项重要的测试项目,绝缘电阻的好坏直接关系到变压器的电气性能和寿命,本文对某变压器厂变压器绝缘电阻下降的原因进行分析研究。研究结果表明,水含量升高、极性物质增加、油品老化等因素可以造成变压器绝缘电阻的下降,通过检验变压器油介质损耗因数可以直观快速的判断绝缘电阻是否合格,通过白土吸附极性物质的方法进行处理,可降低变压器油的介质损耗因数从而降低变压器的绝缘电阻。     

浅析油浸式变压器的老化和寿命评估

在电力行业为了保证变压器的正常运行,要准确评估电力变压器的老化速度以及剩余寿命,本文以变压器绝缘老化机理为基础原理,并参考了近年国内外相关的研究,对油浸式变压器的老化以及寿命评估进行了深入的分析和研究,以供同仁参考。     

变压器绝缘纸老化特征产物检测方法研究

变压器内部绝缘纸的寿命决定了变压器的使用寿命,实现对其绝缘纸老化情况的检测分析具有重要的现实意义。本文研究运用顶空色谱法对变压器绝缘纸老化特征产物进行检测,可通过一次进样,同时实现对糠醛及甲醇的定量分析,且无需手动进行样品前处理,检测过程快速、准确且灵敏度高,为变压器纸绝缘系统的老化诊断提供了便捷的技术手段。     

免疫神经网络算法在机械设备橡塑绝缘件老化预测中的应用

机械设备中往往配备了大量的橡塑绝缘件,橡塑绝缘件和寿命关系到安全生产和经济效益。机械设备绝缘老化是影响寿命的主要因素,本文在介绍现有机械设备寿命诊断方法的基础上,利用现有的智能算法和计算法技术,提出了基于免疫优化的神经网络训练算法,对机械设备的绝缘老化数据进行综合分析、充分挖掘,对机械设备的绝缘老化给出定量的分析,用以预测机械设备的寿命。     

浅谈变压器纸绝缘老化判据和油中糠醛及相关组分检测

纸绝缘老化严重影响油浸式变压器寿命。通过对比各种判据,分析了油中糠醛及相关组分作为纸绝缘老化判据的优势,总结了影响其测量结果有效性的各项因素。同时,介绍了油中糠醛及相关组分含量检测方法,并给出了高效液相色谱法中萃取和色谱分离过程的参数范围。最后展望了糠醛及相关组分用于纸绝缘老化程度可靠评估的进一步研究方向。     

交直流复合电压叠加谐波电压下的绝缘纸电老化特性研究

换流变压器是特高压直流输电系统中的关键设备,而绝缘纸是换流变压器中重要的绝缘与散热材料。由绝缘设计与缺陷导致的绝缘问题占据了换流变压器故障的绝大多数,因此研究换流变压器绝缘纸的电老化特性具有重要意义。根据换流变压器阀侧绕组绝缘承受的电压类型,采用典型的油浸绝缘纸作为模拟换流变压器纸绝缘的试验材料,开展了绝缘纸在交直流复合电压叠加谐波电压下的长时耐压试验,研究了绝缘纸的电老化特性。试验结果表明,谐波电压对绝缘纸的电老化特性影响显著,随着谐波含量的增加,绝缘纸的电老化失效时间减小,且5次谐波对绝缘纸电老化失效时间的影响比3次谐波的影响更大。     

三种主要杂质对变压器油绝缘性能的影响及控制措施

杂质对变压器油的绝缘性能影响显著,有效控制油中杂质对变压器的安全运行至关重要。文章介绍了变压器油中三种主要杂质—水分、机械杂质与金属杂质的来源及危害,并提出了控制变压器油中这三种主要杂质的措施。     

变压器的短路故障分析及控制措施

变压器是电力系统中最关键的设备之一,它承担着电压变换,电能分配和传输,并提供电力服务。因此,变压器的正常运行是对电力系统安全、可靠、优质、经济运行的重要保证,必须最大限度地防止和减少变压器故障和事故的发生。但由于变压器长期运行,故障和事故总不可能完全避免,且引发故障和事故又出于众多方面的原因。如外力的破坏和影响,不可抗拒的自然灾害,安装、检修、维护中存在的问题和制造过程中遗留的设备缺陷等事故隐患,特别是电力变压器长期运行后造成的绝缘老化、材质劣化及预期寿命的影响,已成为发生故障的主要因素。同时,部分工作人员业务素质不高、技术水平不够或违章作业等,都会造成事故或导致事故的扩大,从而危及电力系统的安全运行……     

浅析变压器油颗粒度及处理措施

对超高压变压器来说,油中固体颗粒对其绝缘强度的影响越显突出。混入油中的固体颗粒悬浮在油中并随油流流动,在高压电场作用下不断运动,聚集在场强较高处,容易因极化定向排列成杂质"小桥",形成绝缘的薄弱环节,引起局部放电超标甚至造成绝缘击穿。对于超高压变压器生产制造企业来说,首先重视新油(指经真空滤油后,注入变压器油箱前的油)的清洁度,其次重视生产过程中产品清洁度的控制,如果产品清洁度控制不理想,注入油箱中合格的变压器油会被污染,造成油中颗粒度超过限值要求。分析杂质颗粒的来源、性质、数量、危害,对制定有效的控制和处理措施很有帮助,从而提高产品的可靠性。     

一种基于硬度保留率的低压电缆剩余寿命快速检测方法

正本发明属于电气设备绝缘诊断技术领域,涉及一种基于硬度保留率的低压电缆剩余寿命快速检测方法,对低压橡胶电缆的绝缘状态进行检测诊断与剩余寿命评估。首先利用硬度保留率评估电缆寿命;在对电缆绝缘材料进行加速老化试验,得到电缆硬度保留率随老化温度和老化时间变化的寿命方程;最后利用电缆的寿命方程得到电缆的剩余寿命     

Adsorption and surface properties of silica with transformer insulating oils

The presence of polar species in transformer insulating oil may cause degradation and electric discharges in the power transformer. Such oil polar fraction can originate either from the neat oil and/or from its oxidative degradation in the power transformer. The aim of this study is to examine the relation between the insulating oil and the electrical properties of its polar fraction in order to predict eventual failure in the power transformer.We investigate at ambient temperature the adsorption of the polar fractions of various transformers insulating oils (a new and two used oils) from the neat oils onto silica particles. The adsorbed amount was higher for the used oils as compared to the new one. Infrared spectra of the polar fraction indicate the presence of hydroxyl, aromatic and carboxyl functional groups that are found in the asphaltenes compounds. Microelectrophoresis study of the oil polar fraction covered silica particles gives negatively charged oil polar fraction. Such oil surface charge depends on the pH and results from the ionisation of the oil acidic surface groups. Finally, we obtain a good correlation between the amount of the oil polar fraction and the magnitude of the zeta potential at the water/oil-silica interface.     

金属减活剂的常见检测方法

变压器油在储存、运输和应用过程中不可避免的要与铜、铁等金属接触,这些金属对油品的氧化起到了催化作用。故现在普遍采用向变压器油中加入金属减活剂来抑制金属对油品的催化氧化作用。本文简单介绍了几种金属减活剂的常见检测方法。     

Origin of furanic compounds in thermal degradation of cellulosic insulating paper

The chemical components of cellulosic insulation (i.e., Kraft paper, cellulose, lignin, pentosans) used in electrical transformers were aged in transformer oil to determine the relative yield of furanic degradation products. The results show that the pentosans component of the paper give, by far, the highest yield of 2-furfural followed by cellulose, levoglucosan, and lignin. However, the pentosans did not produce any detectable quantities of either 5-hydroxymethyl-2-furfuraldehyde or 2-furfurol, both of which are known to be produced by the degradation of Kraft paper. α-Cellulose was found to give 3 times as much 2-furfural as levoglucosan, which is a degradation product of cellulose, suggesting another pathway to 2-furfural production from cellulose than exclusively through the commonly quoted mechanism in which levoglucosan is the intermediate. It was also found that the production of 2-furfural from levoglucosan appears to be accelerated by acidic conditions in oxidized oil. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2541–2547, 1998     

Low temperature thermal degradation of cellulosic insulating paper in air and transformer oil

The thermal degradation of cellulose in the form of Kraft insulating paper has been studied in air for up to 140 h and in transformer oil for up to 3500 h in the temperature range 60–120 °C using measurements of the degree of polymerization (DP) and (in oil) analysis of furanic degradation products. Degradation was faster in air than in oil. The DP decreased from the original value of 1.2 × 10³ to a limiting value in the range of 300–900 depending on temperature and degradation conditions. The variation of the DP with degradation time was consistent with two mechanisms, one in which the first‐order rate constant decreased exponentially with time, and another in which only a limited number of chain bonds were scissionable. The degradation rate was first order in scissionable bonds. The major furanic degradation products were 2‐furaldehyde, 5‐hydroxymethyl‐2‐furaldehyde and furfuryl alcohol. Their concentrations continually increased over the timescale of the experiments. © 2001 Society of Chemical Industry     

变压器油色谱分析与故障判断及处理

阐述变压器油气体色谱分析与变压器内部故障之间的内在联系，通过色谱分析监测变压器的运行状况，并介绍变压器油气体色谱超标在线脱气处理方法。     

硅油与矿物油用作变压器油的性能比较

从安全运行可靠性、运行寿命、煅烧性、热老化性、环境保护等几方面将用作变压顺绝缘油的硅油与矿物油作了对比。结果表明,硅油用作变压器绝缘油,运行寿命长、电绝缘性能好、使用量少、无毒、无污染,各方面性能明显优于矿物油。     

Effects of elevated temperature and crude oil on the properties of a hydrogenated nitrile butadiene rubber elastomer

The stability and durability of hydrogenated nitrile butadiene rubber (HNBR) material in crude oil environments are of great importance for petroleum equipment to resist leakage and to ensure reliability. In this paper, an HNBR material was fabricated, and the degradation of the HNBR material was investigated in simulated crude oil environments. One crude oil and three temperatures (50 °C, 75 °C, and 100 °C, based on actual crude oil operations, were used in this study. Weight changes for the HNBR specimens were monitored after exposure to the environments over time. Optical microscopy was used to show the topographical changes on the specimen surfaces. Attenuated total reflection Fourier transform infrared (ATR‐FTIR) spectroscopy was employed to study the surface chemistry of the HNBR material before and after exposure to the simulated crude oil environments at selected times. Mechanical property tests (tensile and compressive stress–strain tests, tear strength test, and compression set test) were conducted to assess the changes in mechanical properties of the HNBR specimens before and after exposure to the environments. The test results show that the physical–mechanical properties of the HNBR material changed significantly. The temperature and the crude oil had a direct effect on the degradation of the mechanical properties. The ATR‐FTIR test results indicate that the surface chemistry changed via chain crosslinking in the material after exposure to the environments over time. The degradation mechanisms of the HNBR material after exposure to the crude oil could be due to the presence of chain crosslinking, chain mobility, and backbone scission. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44012.     

TRANSFER PLASMAS DESTROY PCB FLUIDS

High voltage, ac transfer arcs were used as a reaction zone to destroy polychlorinated biphenyls dissolved in transformer fluid. The extremely high temperature of the arc is of sufficient magnitude that it destroys both the PCB's and the oil in which the PCB's are dissolved.

Although fast pyrolysis is the major destructive mechanism, several other features of the process are unique. For example, the transfer arc discharge is submerged. The arc is created beneath the surface of the transformer oil at a water interface. Furthermore, the water phase is part of the electrical circuit; but it also participates in the reaction chemistry of the plasma arc. Water vapor created by the discharge reacts with the carbon and acetylene formed by pyrolysis to produce hydrogen and carbon monoxide. This retards carbon buildup within the system.

The presence of the water phase also provides a convenient adsorption medium for acid gases (HC1) which are formed by pyrolysis of the PCB's, These gases are infinitely more soluble in the water phase than they are in the transformer oil through which they would have to pass to escape the submerged reaction zone. As a result, this new technology provides a convenient small-scale destruction for oils contaminated with PCB     

Aromatic and aliphatic hydrocarbon balance in electric transformer oils

Laboratory-scale NMR studies of transformer oils reveal the presence of highly branched aliphatic and aromatic hydrocarbons with evidence of proportional balance in both aged and new oils. The primary to secondary proton ratios of aged oils were determined to be approximately 1, whereas the ratio ranged from 1.120 to 1.194 in new oils. Analyses indicate that several transitions in the chemistry of oil components contributed to the observed composite peaks and did not allow the identification of specific compounds beyond their functional groups. Resonances of non-hydrocarbons are observed for concentrations between 2 and 4 ppm, while the aromatic families occur at concentrations between 9 and 6 ppm. No consistent trend is observed between oil aging and the evolution of oil chemical composition. However, the color numbers, 0.50-1.82, increase with the oil age and the direction of color change matches that of increasing turbidity from new (T34 and T44) to old oils (T14 and T24). This implies that turbidity may be a dependable method of indexing the aging of transformer oils.     

加氢柴油精密蒸馏工艺生产10#变压器油

文章介绍了广东某企业生产10#变压器油的新工艺,该企业通过工艺改进,提高了10#变压器油的产品质量,减少了三废排放,简化了生产流程,降低了生产成本,寻找到了一条降本增效、环保安全的有效途径。