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1
Kattel, Ruska, und Bhupendra Devkota. „PCBs Contamination among Distribution Transformers in the Kathmandu Valley“. International Journal of Environment 4, Nr. 1 (22.02.2015): 16–29. http://dx.doi.org/10.3126/ije.v4i1.12175.
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Transformer is the crucial part in any electrical system, however there are many risks associated with its use. Thus this study was focused on assessing the status of PCBs contamination and distribution of transformers in Distribution Centre-North of the Kathmandu valley along with PCBs contamination in them. Each transformer within the study area was closely observed to obtain information about all transformers. The dielectric oil samples from the transformers were collected, safely stored and analyzed in Test Kits (L2000DX Chloride Analyzer System, recommended by UNEP). Among 111 samples of transformer oil analyzed, 4 transformers were found PCBs contaminated and they were manufactured before 1990s. The total amount of PCBs contaminated transformer oil in these transformers was 479.6 Kg. Seven transformers were found leaking, four transformers located at residential area were found emitting a low frequency tonal noise, two transformers were located within school compound, nine transformers were located near water body and around 1.44 square meters of soil surface was found contaminated by transformer oil. Though there is no way to eliminate all the risk and consequences of operating oil filled transformers, scientific distribution and proper handling could be the reasonable approaches to reduce the risks.DOI: http://dx.doi.org/10.3126/ije.v4i1.12175International Journal of Environment Volume-4, Issue-1, Dec-Feb 2014/15, Page: 16-29
2
Okundamiya, M. S., E. Esekhaigbe, J. L. Owa und H. I. Obakhena. „Impacts of Ambient Temperature Change on the Breakdown Voltage of a Distribution Transformer“. International Journal of Emerging Scientific Research 2 (27.06.2021): 19–25. http://dx.doi.org/10.37121/ijesr.vol2.155.
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The aim of this paper is to determine the effects of ambient temperature variation on the breakdown voltage of a distribution transformer. Three different insulation oil samples (naphtha mineral, paraffin mineral and silicon base transformer oil) were collected from six distribution transformers (300 – 500 kVA) across two business units (Asaba and Ugbowo) of Benin Electricity Distribution Company during May and June, 2017. The oil samples were analysed using the 60 kV Megger OST60PB portable oil tester, to determine the trend of breakdown voltage of the oil insulation under varying temperature. A 3rd order polynomial model was deduced for each sample type with coefficient of determination within the range of 96.99 – 99.95 %. The observed average breakdown voltage is 43.6 kV (for naphtha base mineral transformer oil), 42.2 kV (for paraffin base mineral transformer oil) and 46.8 kV (for silicon base transformer oil) within the temperature range (26˚C – 32˚C). The result indicates that the breakdown voltages of the considered transformer oil types are satisfactory but the silicon base transformer oil has the best breakdown voltage.
3
Lu, Yun Cai, Li Wei, Wei Chao und Wu Peng. „The New Development Trend of Distribution Transformer“. Applied Mechanics and Materials 672-674 (Oktober 2014): 831–36. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.831.
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Firstly, this paper introduces the development of new materials, new technology and new manufacture in power industry of China, energy-saving, low noise and smart distribution transformers are widely used in countryside power grid reconstruction. In this paper, application status and development trend of different types of distribution transformers were introduced and compared in terms of new material and new structure, such as oil-immersed distribution transformer, amorphous core transformer(AMT), dry-type transformer, SF6 insulated distribution transformer, composite transformer and other types of distribution transformers. The development of distribution transformer is mainly based on energy saving, miniaturization, wound core and amorphous alloy nowadays, but the class-H dry-type transformer and tridimensional toroidal-core amorphous alloy transformer are the future direction of development. The technology application of smart distribution grid, power electronics technology and dynamic reactive power compensation technique will also affect the safety and economic operation of distribution transformer.
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Gafvert, U., A. Jaksts, C. Tornkvist und L. Walfridsson. „Electrical field distribution in transformer oil“. IEEE Transactions on Electrical Insulation 27, Nr. 3 (Juni 1992): 647–60. http://dx.doi.org/10.1109/14.142730.
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Yuchao, Ma, Mo Juan, Yu Jinshan, Li Xiang und Zheng Zhongyuan. „Study on Sound Field Distribution Rule for Tank Structures of Large Oil-immersed Transformers“. E3S Web of Conferences 233 (2021): 01021. http://dx.doi.org/10.1051/e3sconf/202123301021.
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Large oil-immersed transformers are an important part of the transmission and distribution network in power systems. Power transformers are the main noise source of substations. Because of the uneven manufacturing process, aging equipment, long-term operation, and close distance from sensitive points, the problem of transformer noise pollution has become increasingly prominent. In this paper, the transmission and analysis model is established for transformer sound waves on the interface between insulating oil and tank body according to the sound wave propagation rule in complicated medium, and the simplified acoustic simulation model is constructed for large oil-immersed transformers by simulating the vibration noise of transformer core with monopole sound source, with which, the sound field distribution rule inside and outside the transformer tank structure is obtained, and finally, the influence factors for noise distribution are given. The results of the study provide control basis for reducing transformer noise.
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Roza, Indra, Yussa Ananda, Lisa Adriana Siregar, Dharmawati Dharmawati und Junaidi Junaidi. „Analysis of Age Transformer Due to Annual Load Growth in 20 kV Distribution Network“. Journal of Renewable Energy, Electrical, and Computer Engineering 1, Nr. 1 (16.03.2021): 42. http://dx.doi.org/10.29103/jreece.v1i1.3685.
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Distribution transformer is a component in distributing electricity from distribution substations to consumers. Damage to distribution transformers causes continuity of customer service to be disrupted (power cut or blackout occurs). The length of the PLN electricity network requires a transformer to distribute electricity to serve consumers and how to maintain the transformer. The daily load curve of a peak load for housing, shops and factories / industries varies. Load served 200 kVA distribution transformer cannot serve the load on housing, shops and factories / industry. The method used is the replacement of a distribution transformer with a capacity of one stage greater or the replacement of a distribution transformer with a capacity of two levels larger. The distribution transformer carried out by the research is a capacity of 200 kVA replaced by 250 kVA. The ability of a distribution transformer cannot accommodate a load which will increase as an area is advanced. Observations made by calculating the age of the transformer by assuming the annual load growth (r) = 3% = 0.3. Annual peak load (P) = 1.8 p, u increase in oil temperature at peak load (θo = 96.21 0C; 84.16 0C). The increase in the hottest temperature above the oil cover, the increase in the temperature of the hottest place above the oil (θg = 20 0C; 20 0C). The ratio of the load loss to the nominal load excitation loss (Q = 3; 30). By assuming the values of these methods it can be estimated that the life of a distribution transformer is 20 kV, a capacity of 200 kVA is 18 years.
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Melnikova, O. S., und V. S. Kuznetsov. „Method of calculating the electric strength of oil channels of the main insulation of power transformers“. Vestnik IGEU, Nr. 5 (30.12.2020): 48–55. http://dx.doi.org/10.17588/2072-2672.2020.5.048-055.
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The most damage-sensitive unit of power transformers is the main insulation of the oil barrier type. The breakdown of such insulation occurs as a result of the breakdown of the oil channel near the high voltage winding. In accordance with traditional methods of calculating the dielectric strength of insulation, the value of the breakdown strength is determined by empirical formulas depending on the selected width of the oil channel. The existing methods do not consider the influence of the oil channel volume, of the electric strength the statistical characteristics of the oil, the design features of the insulation of power transformers, and do not contain recommendations for creating design models. Thus, to improve the calculation accuracy, it is relevant to develop the evaluation method of dielectric strength of the main insulation of power transformers taking into account the volume and parameters of the breakdown voltage distribution of transformer oil, design features. The research results of the breakdown tension in oil channels with different volumes of transformer oil were used. To improve the accuracy of the calculation and taking into account the design features, the model of the main insulation of power transformers was made in the ANSYS program. Boundary data and assumption of linear stress distribution of transformer coils were considered. A method for calculating the dielectric strength of oil channels of the main insulation of power transformers, considering the volume and parameters of the breakdown voltage distribution of transformer oil was proposed. Unlike the existing methods, when calculating the minimum breakdown strength in the model of the main insulation, the design features of power transformers are taken into account and assumptions are justified to improve the accuracy of the calculation. In accordance with the methodology, the parameters of the dielectric strength of the transformer oil in the oil channel of the high voltage winding of the transformer were calculated. It was concluded that with increase of relative value of breakdown tension, dielectric strength of oil channel is decreasing, and it corresponds to physical sense of breakdown. The method for calculating the dielectric strength of transformer oil can be used when choosing the main insulation of power transformers in design.
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Melnikova, O. S. „Impact of distribution of impurity particles on electric strength of transformer oil“. Vestnik IGEU, Nr. 6 (2019): 41–49. http://dx.doi.org/10.17588/2072-2672.2019.6.041-049.
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To extend the service life and ensure the operability of oil-filled transformer equipment, the attention is paid to the development of methods for monitoring the state of oil-barrier insulation. When monitoring the technical condition of transformer oil, the class of liquid purity is determined depending on the rated voltage of the equipment. However, the influence of the parameters of mechanical impurities on the breakdown voltage is not taken into account, thereby lowering the requirements for the quality of oil barrier insulation. This makes it relevant to study the influence of the size distribution of impurity particles on the electric strength of the internal insulation of power transformers and determine the parameters of particles of mechanical impurities to justify the underestimation of the quality indicators of transformer oil in operation. Methods of mathematical statistics were employed using the Gnedenko-Weibull distribution based on the standard values of liquid purity classes. To determine the maximum and minimum voltages, the standard values of the average breakdown voltages and the results of operational tests of transformer oil in a standard spark gap were used. The relation between the particle size of mechanical impurities and the breakdown voltage of transformer oil has been established. The particle size distribution of impurities has been obtained for 12 and 13 classes of liquid purity for power transformers with a voltage of 110–750 kV. The particle size range that defines the maximum and minimum breakdown voltages has been determined, and the values of limit concentrations of mechanical particles have been established. The obtained parameters of impurity particles which determine the maximum and minimum breakdown voltages of the operating oils can be used to evaluate the technical condition when diagnosing the internal insulation of power transformers in order to increase their operational reliability, as well as to adjust the regulatory requirements for the quality of operational transformer oil according to the content of mechanical impurities.
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Korenciak, D., M. Sebok und M. Gutten. „Thermal Measurement and its Application for Diagnostics of Distribution Oil Transformers“. ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 62, Nr. 6 (29.11.2019): 583–94. http://dx.doi.org/10.21122/1029-7448-2019-62-6-583-594.
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In the first part of the paper the theory of infrared radiation and the use of nondestructive measurement of electrical devices by means of thermovision are under analysis. In the second part of paper basic principles and application of non-contact temperature measurement are examined. In the third part of paper thermal processes in distribution oil transformer – temperature in dependence on height of oil transformer and temperature distribution in sectional plan of oil transformer – are considered. In the fourth part of paper, by means of the experimental measurements and subsequent analysis, practical thermal imaging and contact thermal measurements by optical detectors for the diagnosis of distribution oil transformers in the field of mechanical strength of windings are shown. In this paper, we wanted to show out the possibility of using thermal measurements in this field of analysis and detection of quality of winding for distribution oil transformer. It is possible to use these methods to localize places of faults, and they are also applicable for the diagnosis and detection of disorders of the quality of materials and other anomalies during operation of the equipment. By means of the experimental measurements followed by diagnostic analysis the practical use of thermovision and optical sensors for diagnostics of power oil transformers in field mechanical strength and quality of winding is demonstrated.
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Amrita, A. A. N., W. G. Ariastina und I. B. G. Manuaba. „Study of Transformer Lifetime Due to Loading Process on 20 KV Distribution Line“. Journal of Electrical, Electronics and Informatics 2, Nr. 2 (31.08.2018): 25. http://dx.doi.org/10.24843/jeei.2018.v02.i02.p01.
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Power transformer is very important in electric power system due to its function to raise or lower the voltage according to its designation. On the power side, the power transformer serves to raise voltage to be transmitted to the transmission line. On the transmission side, the power transformer serves to distribute the voltage between the main substations or down to the distribution voltage. On the distribution side, the stresses are channeled to large customers or lowered to serve small and medium customers. As the power transformer is so importance, it is necessary to protect against disturbance, as well as routine and periodic maintenance, so that the power transformer can operate in accordance with the planned time. Some factors that affect the duration of the power transformer is the ambient temperature, transformer oil temperature, and the pattern of load. Load that exceeds the maximum efficiency of the transformer which is 80% of its capacity will cause an increase in transformer oil temperature. Transformer oil, other than as a cooling medium also serves as an insulator. Increasing the temperature of transformer oil will affect its ability as an isolator that is to isolate the parts that are held in the transformer, such as iron core and the coils. If this is prolonged and not handled properly, it will lead to failure / breakdown of insulation resulting in short circuit between parts so that the power transformer will be damaged. PLN data indicates that the power transformer is still burdened exceeding maximum efficiency especially operating in the work area of PLN South Bali Area. The results of this study, on distribution transformers with different loads, in DS 137, DS 263 and DS 363, show that DS 363 transformer with loading above 80% has the shortest residual life time compared to DS 263 and DS 137 which loading less than 80%.
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Bustamante, Sergio, Mario Manana, Alberto Arroyo, Alberto Laso und Raquel Martinez. „Determination of Transformer Oil Contamination from the OLTC Gases in the Power Transformers of a Distribution System Operator“. Applied Sciences 10, Nr. 24 (13.12.2020): 8897. http://dx.doi.org/10.3390/app10248897.
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Power transformers are considered to be the most important assets in power substations. Thus, their maintenance is important to ensure the reliability of the power transmission and distribution system. One of the most commonly used methods for managing the maintenance and establishing the health status of power transformers is dissolved gas analysis (DGA). The presence of acetylene in the DGA results may indicate arcing or high-temperature thermal faults in the transformer. In old transformers with an on-load tap-changer (OLTC), oil or gases can be filtered from the OLTC compartment to the transformer’s main tank. This paper presents a method for determining the transformer oil contamination from the OLTC gases in a group of power transformers for a distribution system operator (DSO) based on the application of the guides and the knowledge of experts. As a result, twenty-six out of the 175 transformers studied are defined as contaminated from the OLTC gases. In addition, this paper presents a methodology based on machine learning techniques that allows the system to determine the transformer oil contamination from the DGA results. The trained model achieves an accuracy of 99.76% in identifying oil contamination.
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Djurdjevic, Ksenija, Mirjana Vojinovic-Miloradov und Slobodan Sokolovic. „Life cycle of transformer oil“. Chemical Industry 62, Nr. 1 (2008): 37–46. http://dx.doi.org/10.2298/hemind0801037d.
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The consumption of electric power is constantly increasing due to industrialization and population growth. This results in much more severe operating conditions of transformers, the most important electrical devices that make integral parts of power transmission and distribution systems. The designed operating life of the majority of worldwide transformers has already expired, which puts the increase of transformer reliability and operating life extension in the spotlight. Transformer oil plays a very important role in transformer operation, since it provides insulation and cooling, helps extinguishing sparks and dissolves gases formed during oil degradation. In addition to this, it also dissolves moisture and gases from cellulose insulation and atmosphere it is exposed to. Further and by no means less important functions of transformer are of diagnostic purpose. It has been determined that examination and inspection of insulation oil provide 70% of information on transformer condition, which can be divided in three main groups: dielectric condition, aged transformer condition and oil degradation condition. By inspecting and examining the application oil it is possible to determine the condition of insulation, oil and solid insulation (paper), as well as irregularities in transformer operation. All of the above-mentioned reasons and facts create ground for the subject of this research covering two stages of transformer oil life cycle: (1) proactive maintenance and monitoring of transformer oils in the course of utilization with reference to influence of transformer oil condition on paper insulation condition, as well as the condition of the transformer itself; (2) regeneration of transformer oils for the purpose of extension of utilization period and paper insulation revitalization potential by means of oil purification. The study highlights advantages of oil-paper insulation revitalization over oil replacement. Besides economic, there are advantages concerning environmental protection, starting from unrecoverable resources (petroleum) saving through power and energy saving to waste reduction. Adequate management of transformer oil life cycle, meaning timely and technologically updated regeneration process, prevents waste production. Regeneration by means of synthetic adsorbents in laboratory conditions as well as on site has ensured and provided satisfactory results with reference to oil quality improvement. It has also confirmed and substantiated the necessity of regeneration implementation before the paper insulation is damaged.
13
Stanisic, Stevan, Milica Jevtic, Bhaba Das und Zoran Radakovic. „Fem CFD analysis of air flow in kiosk substation with the oil immersed distribution transformer“. Facta universitatis - series: Electronics and Energetics 31, Nr. 3 (2018): 411–23. http://dx.doi.org/10.2298/fuee1803411s.
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In practice of loading of oil-immersed distribution transformers, there is a need to have lumped thermal model, requiring no big computational resources and computational time. One such model is presented in international transformer loading guide (IEC 60076-7), where heat transfer inside the transformer is modeled. In case of indoor transformer operation, this model does not consider transient thermal phenomena in the room. We developed a lumped model that includes heat transfer in the transformer room. In scope of the research, we also built FEM CFD (finite element method, computational fluid dynamics) model of air flow and heat transfer. The purpose of FEM CFD was to make a better insight into air flow, i.e. to study the simplifications introduced in lumped model and suggest potential improvements. This paper presents results achieved with FEM CFD. The considered case was the transformer with natural oil and natural air flow (ONAN).
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Liu, Wei Jia, Xin Wang, Yi Hui Zheng, Li Xue Li und Qing Shan Xu. „The Assessment of the Overload Capacity of Transformer Based on the Temperature Reverse Extrapolation Method“. Advanced Materials Research 860-863 (Dezember 2013): 2153–56. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.2153.
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The assessment of the overload capacity of transformer has a certain practical significance. In this paper, a temperature reverse extrapolation method is proposed to assess the overload capacity of transformer. Firstly, the top oil temperature is monitored by the online monitoring system. Secondly, the temperature distribution model and the calculation methods of hot spot temperature in the PTP7 (Power Transformers. Part 7: Loading guide for oil-immersed power transformers) guide are analyzed. Then, a new method called temperature reverse extrapolation which can calculate the overload factor of transformer is composed. And based on the overload factor, two meaningful data about overload capacity are obtained. Finally, an assessment system of transformer overload capacity based on the online monitoring is developed.
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Muhamad, Nor Asiah, und Hanafiah Kamarden. „Simulation Study on HST Distribution for ONAN Oil-Filled Transformer“. Applied Mechanics and Materials 785 (August 2015): 269–73. http://dx.doi.org/10.4028/www.scientific.net/amm.785.269.
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Advanced monitoring system and preventive maintenance introduced on serviced transformer successfully reducing the equipment malfunction and breakdown rate. However, faults that occur and developed inside the transformer can be very unpredictable. One of the measures can be taken is to analyse the hottest spot temperature (HST) of the transformer, because high temperature will affect transformer insulation system performance and its life-span. HST distribution study on the transformer surface body can give better understanding on how HST will behave at inner and outer transformer surface tank, so that it can be correlated to the actual temperature inside the transformer. Therefore, this paper presents a simulation study on 100 KVA ONAN oil-filled type of distribution transformer with three types of HST intensity. Result shows that temperature distribution projectile is tending to go upwards in the insulation oil and inward into the winding. Moreover, location of HST can be identified by comparing the temperature distribution plot with and without HST.
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K.C., Laxman, und Bhupendra Devkota. „PCBs Contaminantion of Transformer Oil and its Occupational Health and Safety Status in the Kathmandu Valley, Nepal“. International Journal of Environment 3, Nr. 4 (15.12.2014): 12–23. http://dx.doi.org/10.3126/ije.v3i4.11727.
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Electrification in Kathmandu valley had started in 1911 and the use of polychlorinated biphenyls (PCBs) probably started since 1940s (Devkota, 2005). This research work was undertaken to find out the degree and extent of PCBs contamination in transformer oil and to explore its impacts on occupational health and safety issues of the workers and on the environment. The research was focused on Distributions Centers of the Nepal Electricity Authority (NEA) in the Kathmandu valley, NEA Lainchaur workshop and welding workshops of the Kathmandu valley. The samples of transformer oil were collected, safely stored and analyzed using L2000DX Chloride Analyzer, PCBs contamination at >50 ppm level was found in 184 distribution transformers with total volume of PCBs contaminated transformer oil to be 67566.3 Kg. The knowledge on impacts of PCBs contaminated transformer oil on human health and environment was better among NEA employees than among employees of welding workshops, though not satisfactory. Due to very low awareness, the workers come in contact with the transformer oil regularly and many health impacts such as eye problems, skin related complication, weakness and respiratory problems might be due to this exposure; however, exact impacts could not be verified scientifically.DOI: http://dx.doi.org/10.3126/ije.v3i4.11727 International Journal of EnvironmentVolume-3, Issue-4, Sep-Nov 2014Page : 12-23
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Wan, Tao. „The Temperature Distribution of Oil-Immersed Transformer Starting with Heavy Load in Cold Regions“. Advanced Materials Research 1079-1080 (Dezember 2014): 553–57. http://dx.doi.org/10.4028/www.scientific.net/amr.1079-1080.553.
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When the large oil-immersed transformer start with heavy load in cold regions, due to the high viscosity of the oil at low temperatures, the flow of the oil is extremely slow in the early start of heavy load, resulting in a negative heat radiation. At the same time, the winding and the core are rapidly increasing heat in the early start of heavy load. Rapid increase in heat and the lack of heat dissipation caused a series of problems. In this paper, we study the process of heating and cooling when the large oil-immersed transformer start with heavy load in cold region and takes a transformer of 31.5MVA as example to build a three-dimensional model ,the model is based on the actual size of the transformer. We use the finite volume method to calculate three-dimensional temperature field distribution changing with time when the oil-immersed transformer startup with heavy load in - 35 °C,-30 °C and-25 °C three cases. The results show that the viscosity coefficient of transformer oil is very high at low temperatures. In the early start of the transformer, because of the poor fluidity of the oil, the heat cannot be dissipated in time and the transformer local overheating near the winding. Then we analyzes the damage of local overheating for a short period of time in the transformer, especially the damage of the oiled paper's insulation At last ,we analysis of the causes of transformer internal local overheating and give some measures to avoid local overheating when oil-immersed transformer start with heavy load in cold regions.KEYWORDS: oil-immersed transformer, cold regions, start with heavy load, FVM, three-dimensional temperature distribution
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Husin, M. A., Nordiana Azlin binti Othman, N. A. Muhammad, H. Kamarden und M. S. Kamarudin. „Top oil heat distribution pattern of ONAN corn oil based transformer with presence of hot spot study using FEMM“. Bulletin of Electrical Engineering and Informatics 8, Nr. 3 (01.09.2019): 753–60. http://dx.doi.org/10.11591/eei.v8i3.1602.
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Transformer thermal modelling is a crucial aspect to be considered as this may help the determination of heat capacity of transformer. This paper present, simulation study on Oil Natural Air Natural (ONAN) transformer heat distribution pattern with and without presence of hot spot temperature (HST). This paper aims to compare the effects of different HST value at different locations inside the transformer unit as well as to evaluate the top oil thermal behaviour of corn oil as cooling mechanism in a transformer. To achieve aforementioned objectives, three HSTs were introduced to the 30 MVA transformer winding to find the total heat build-up in the top of the transformer tank. The outcome of thermal properties is examined using x-y temperature plot. From the results found that the location of HST affects overall transformer’s temperature. HST at the top of the winding give a significant effect compared to when HST is at the bottom of the winding. It is also evident that the usage of corn oil reduced the temperature distribution of the transformer. The findings suggest that the temperature distribution study especially on transformer is important to monitor in-service transformer in a non-invasive manner.
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Sun, Ruibang, Xing Yang, Juncai Wang, Peng Chen und Liusuo Wu. „Experimental Study on Axial Temperature Profile of Jet Fire of Oil-Filled Equipment in Substation“. Processes 9, Nr. 8 (21.08.2021): 1460. http://dx.doi.org/10.3390/pr9081460.
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With the widespread use of substations around the world, oil jet fire accidents from transformer oil-filled equipment in substations caused by faults have occurred from time to time. In this paper, a series of transformer oil jet fire experiments are carried out by changing the external heat source (30 cm and 40 cm) and the inner diameter of the container (5 cm, 8 cm and 10 cm) to study the axial centerline temperature distribution of the transformer oil jet fire plume of the transformer oil-filled equipment in the substation. The experiment uses K-type thermocouple, electronic balance and CCD to measure and assess the temperature distribution of the axial centerline of the fire plume of the transformer oil jet. The result demonstrates that the axial centerline temperature of the fire plume increases with the external heat release rate and the inner diameter of the container. In addition, a novel axial temperature distribution prediction model of the transformer oil jet fire plume is established. This model can effectively predict the oil jet fire plume temperature of transformer oil- filling equipment in substations, and provide help for substation fire control.
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Hasan, Mushtaq I., Adnan A. Ugla und Hassan S. Kadhim. „Improving the thermal performance of electrical transformers using hybrid mixture of (transformer oil, nanoparticles, and PCM)“. Al-Qadisiyah Journal for Engineering Sciences 13, Nr. 3 (30.09.2020): 175–82. http://dx.doi.org/10.30772/qjes.v13i3.704.
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In this paper, an experimental electrical distribution transformer was studied and a new technique was proposed to improve the performance of a new mixed cooling consisting of pure transformer oil, paraffin wax and nanoparticles. The experiment was carried out on a small transformer that was done by taking a model with dimensions (15 * 10 * 10) cm to facilitate calculations. Paraffin wax absorbs the heat generated in the transformer due to the smelting process that can be used to cool electrical appliances. Nanoparticles have good thermal properties and lead to increased oil insulation to thermal improvements in transformer oil with dispersal of solid nanoparticles and their effects on transformer cooling. Three types of solid nanoparticles were used in this experiment (Al2O3, TiO2, and Sic) with a different volume concentration (1%, 3%, and 5%) and 4% paraffin wax as a certified added percentage for each process. The obtained results showed that when mixing paraffin wax and solid nanoparticles with transformer oil, the transformer cooling performance is improved by reducing the temperature. The best selected nanoparticles were found to be Sic and the reason for this is that Sic has a higher thermal conductivity compared to (Al2O3 and TiO2). The proposed hybrid oil reduces the temperature by 10 ° C (in the case of PCM and Sic) and it is possible to improve the cooling performance of electrical transformers.
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Das, Anu Kumar, Aniket Shivaji Chavan, Dayal Ch Shill und Saibal Chatterjee. „Jatropha Curcas oil for distribution transformer – A comparative review“. Sustainable Energy Technologies and Assessments 46 (August 2021): 101259. http://dx.doi.org/10.1016/j.seta.2021.101259.
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Yahaya, Muhammad, Norhafiz Azis, Amran Mohd Selva, Mohd Ab Kadir, Jasronita Jasni, Emran Kadim, Mohd Hairi und Young Yang Ghazali. „A Maintenance Cost Study of Transformers Based on Markov Model Utilizing Frequency of Transition Approach“. Energies 11, Nr. 8 (02.08.2018): 2006. http://dx.doi.org/10.3390/en11082006.
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In this paper, a maintenance cost study of transformers based on the Markov Model (MM) utilizing the Health Index (HI) is presented. In total, 120 distribution transformers of oil type (33/11 kV and 30 MVA) are examined. The HI is computed based on condition assessment data. Based on the HI, the transformers are arranged according to its corresponding states, and the transition probabilities are determined based on frequency of a transition approach utilizing the transformer transition states for the year 2013/2014 and 2012/2013. The future states of transformers are determined based on the MM chain algorithm. Finally, the maintenance costs are estimated based on future-state distribution probabilities according to the proposed maintenance policy model. The study shows that the deterioration states of the transformer population for the year 2015 can be predicted by MM based on the transformer transition states for the year 2013/2014 and 2012/2013. Analysis on the relationship between the predicted and actual computed numbers of transformers reveals that all transformer states are still within the 95% prediction interval. There is a 90% probability that the transformer population will reach State 1 after 76 years and 69 years based on the transformer transition states for the year 2013/2014 and 2012/2013. Based on the probability-state distributions, it is found that the total maintenance cost increases gradually from Ringgit Malaysia (RM) 5.94 million to RM 39.09 million based on transformer transition states for the year 2013/2014 and RM 37.56 million for the year 2012/2013 within the 20 years prediction interval, respectively.
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Hasan, Mushtaq Ismael. „Improving the cooling performance of electrical distribution transformer using transformer oil – Based MEPCM suspension“. Engineering Science and Technology, an International Journal 20, Nr. 2 (April 2017): 502–10. http://dx.doi.org/10.1016/j.jestch.2016.12.003.
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Ab Ghani, Siti Soleha, und Nor Asiah Muhamad. „Review on Dissolved Fault Gases in Monitoring Bio-Oil Filled Transformer“. Applied Mechanics and Materials 818 (Januar 2016): 69–73. http://dx.doi.org/10.4028/www.scientific.net/amm.818.69.
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The combination of solid insulation (usually cellulose paper) and liquid insulation (usually mineral oil) yield good dielectric properties at fair cost. However, arising concerns on environmental effect of mineral oil when leakage and its risk of fire has force researches for alternative fluids. One of the suitable options for replacement of mineral oil is biodegradable oil that is plant-based, high biodegradability, non-toxicity and high fire point. Some refining and modification to crude vegetable oils resulting to suitable transformer dielectric fluid such as BIOTEMP®, ENVIROTEMP® FR3 and PFAE (palm fatty acid ester). Application of these oils in small scale distribution transformers give positive feedback so far, hence, led to development of biodegradable oil-based large power transformer. Monitoring of the oil for power transformer is important to ensure its reliability and avoid unnecessary cost of failure. Dissolved Gas Analysis (DGA) is one of the methods for oil monitoring of transformer. This method analyzes oil condition to detect incipient faults so that relevant actions can be made before actual failures occur. This paper will review the hydrocarbon gases or known as faults gases for monitoring and faults diagnosis for mineral and biodegradable oil-filled transformer. Past works about DGA on biodegradable oil such as sunflower, soybean, and corn oil are analyzed. Any different on gases production of oil through different tests will be discuss further in this paper.
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Meitei, Sorokhaibam Nilakanta, Kunal Borah und Saibal Chatterjee. „Modelling of Acoustic Wave Propagation Due to Partial Discharge and Its Detection and Localization in an Oil-Filled Distribution Transformer“. Frequenz 74, Nr. 1-2 (28.01.2020): 73–81. http://dx.doi.org/10.1515/freq-2019-0050.
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AbstractPartial discharge (PD) is the main cause of the insulation decay and hence periodical testing of the insulation condition of a distribution transformer is necessary. This paper presents a model of PD acoustic wave propagation, detection, and localization in an oil-filled distribution transformer using finite element method supported by COMSOL Multiphysics software. Using an acoustic module and AC/DC module of COMSOL Multiphysics software, oil filled distribution transformer, and the acoustic piezoelectric sensor are simulated to analyze and detect the PD inside the transformer. PD is numerically simulated in the transformer windings, core, and oil ducts that produce acoustic wave signal. The distribution of the acoustic pressure wave inside the model transformer is analyzed first. Next, the acoustic piezoelectric sensors are modelled at four different locations of the model transformer to detect the pressure acoustic wave signal induced due to PD in the transformer. Finally, using an artificial neural network (ANN), the localization, and identification of PD in various parts of the transformer have been analyzed. The results obtained for location and detection are quite encouraging.
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Yue, Guo Liang, Yong Qiang Wang, Jie He und Hong Liang Liu. „Research of Temperature Field in Oil-Immersed Transformer Considering the Oil Speed“. Advanced Materials Research 912-914 (April 2014): 1041–45. http://dx.doi.org/10.4028/www.scientific.net/amr.912-914.1041.
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In this paper, we have Elaborated the mathematical model of temperature field and flow field of the oil-immersed transformer, and analysis its structure of thermal .We established a temperature finite element model of an oil-immersed transformer using the method of flow-solid-thermal coupling. Using the software of ANSYS, simulating on a 250MVA oil-immersed transformer, we obtain the steady-state temperature distribution and the winding hottest locations. Analyze the effect of oil-speed to the temperature field and location of the hot spot temperature of oil-immersed transformer. The results show that when oil flow rate is increases in the normal range, Transformer temperature rise corresponding slowly, and its location hottest temperature slightly pulled accordingly. The fiber measure different speeds Oil immersed transformer winding hot spot temperature to provide a basis for positioning.
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Liu, Qiang, Ramamoorthi Venkatasubramanian, Shanika Matharage und Zhongdong Wang. „Effect of Oil Regeneration on Improving Paper Conditions in a Distribution Transformer“. Energies 12, Nr. 9 (01.05.2019): 1665. http://dx.doi.org/10.3390/en12091665.
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Managing a large fleet of ageing assets has become a technical challenge faced by many electricity utilities in developed countries. Asset managers are increasingly interested in techniques that can help extend the useful lifetime of a transformer. Oil regeneration is one of such techniques. In this paper, oil regeneration experiments were performed on a 6.4/0.4 kV retired distribution transformer to investigate the effect of oil regeneration on improving paper conditions. Oil regeneration was conducted in two stages, with the first stage aimed at ‘cleaning the oil’ and the second stage targeted at ‘cleaning the paper’. Oil samples were collected at regular intervals throughout the process and paper samples were obtained from the transformer before and after each oil regeneration stage. It was found that oil regeneration restores oil parameters, including moisture and acidity, similar to those of new oils at the end of stage 1. Analysis of paper samples indicated a reduction in paper moisture at the end of stage 2 by nearly 40%, while low molecular weight acids (LMA) in paper exhibited a reduction by around 30% on average. It is found that the extended oil regeneration period, i.e., stage 2, is necessary to improve the paper condition and hence to reduce the paper ageing rate.
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Wang, Yong Qiang, Jie He, Lun Ma, Liu Wang, Ying Ying Sun, Tao Wan und Jian Fei Dang. „Research of the Temperature Field Distribution Based on FVM for Oil-Immersed Transformer“. Advanced Materials Research 1079-1080 (Dezember 2014): 510–14. http://dx.doi.org/10.4028/www.scientific.net/amr.1079-1080.510.
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Thehottest spot temperature (HST) of windings of oil-immersed transformer is animportant factor that affects load capacity and operation life of transformer,and is closely related to the transformer load, top oil and environmenttemperature. HST, when operating at high temperature and overload, may lead totransformer failure which will affect the normal operation of the power system.In order to calculate the transformer hot spot temperature accurately, we takea 33MVA-500KV transformer as an example, and establish a three dimensionalmodel, get its internal temperature distribution based on Fluent simulationsoftware. At last, we comparative and analysis the accuracy of FVM calculation andIEEE guidelines recommend model combined with online monitored values. Theresults show that the FVM method with higher accuracy relative to the IEEEguidelines model, proved that using the FVM can accurately calculate the HST ofoil-immersed transformer.
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KROPOTIN, V. O., S. S. GIRSHIN, V. N. GORYUNOV, E. V. PETROVA, V. M. TROTSENKO und A. O. SHEPELEV. „SIMULATION OF STATIONARY THERMAL REGIME OF OIL TRANSFORMER USING ANSYS“. Actual Issues Of Energy 3, Nr. 1 (2021): 037–42. http://dx.doi.org/10.25206/2686-6935-2021-3-1-37-42.
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With the expansion of the electric power system, the number of distribution plants increases, the most common in which are oil-immersed transformers. the increase in the number of transformers leads to an increase in energy losses, which depend on many factors, including the temperature of the windings. at the same time, temperature is one of the most important parameters that determine the service life of a transformer. the paper discusses a digital model of the thermal regime of an oil-immersed transformer with natural cooling based on the ansys software, focused both on the tasks of calculating energy losses and on assessing the load capacity. the simulation results are compared with the heating rates. the use of thermal regime models when calculating power losses can significantly increase the accuracy of calculations.
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Adejumobi, I. A. „Dielectric Strength, Breakdown Voltage and Acidity Test with Respect to Transformer Insulating Oil“. Advanced Materials Research 62-64 (Februar 2009): 120–25. http://dx.doi.org/10.4028/www.scientific.net/amr.62-64.120.
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This paper presented the qualitative assessment of transformer insulating oil. The breakdown voltage, dielectric and acidity tests were electrically and chemically carried out on sixteen samples of transformer insulating oil collected from various serving distribution transformers in Ilorin Metropolis in Nigeria, through the supply authority. The adequacy of the obtained results was determined by comparing experimental values with America Society for Testing and British Standard (BTA4705) pre-requisites. About seventy five percent (75%) of the tested samples failed at least one of the tests, indicating inadequacy in the routine checks. Economic impacts of the obtained results and major causes and prevention of insulation oil degradation were also presented.
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Orjiewulu, J. C., D. C. Chukwuemeka, C. E. Jesusblessing und A. Ibrahim. „DESIGN AND IMPLEMENTATION OF AN AUTO-TEMP CONTROL SYSTEM FOR DISTRIBUTION TRANSFORMER“. Open Journal of Engineering Science (ISSN: 2734-2115) 1, Nr. 2 (09.09.2020): 1–19. http://dx.doi.org/10.52417/ojes.v1i2.142.
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Unreliability and interruptions facing power supply are evidence of the excessive heat generated in power systems, as a result of the inefficiency of oil cooling medium employed in distribution transformers. The design and implementation of a prototype automatic temperature control system is to be employed as a method towards solving the above stated problem of excessive temperature rise in distribution transformers. The prototype design consists of a PIC microcontroller programmed in C language, an LM35 temperature sensor, an electric fan and other diverse electronic component. It operates a mechanism that detects temperature rise in the transformer and automatically turns on the cooling fan at extreme temperature conditions. A 16x2 LCD is employed as the medium for temperature display unit of the transformer. The resulting prototype functions in a way that it has the ability to detect every 1ºC rise and reduction in the temperature of the transformer. Thus, at extreme temperature conditions, the automatic temperature control system diminishes the excessive heat generated in the transformer to the appropriate working temperature condition.
Orjiewulu, J. C. | Department of Electrical Electronics Engineering, University of Benin, Benin City, Edo State, Nigeria.
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Tien, Nguen, und K. H. Gilfanov. „Thermal modelling of oil-filled power transformer TM - 160/10“. Power engineering: research, equipment, technology 21, Nr. 5 (17.12.2019): 141–51. http://dx.doi.org/10.30724/1998-9903-2019-21-5-141-151.
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The results of modeling the thermal characteristics of the dry and oil-filled power transformer TM-160/10 in idle and short circuit modes are presented. The electrical, geometric and thermal characteristics of the TM-160/10 transformer are determined. Computer modeling is performed in the software package ANSYS 17.1. The 2D distributions of temperature and density of heat flows in the transformer in the longitudinal and transverse sections are determined. It is shown that the use of transformer oil for cooling the transformer significantly reduces the temperatures in the active part. The temperature distribution occupies the range of 67-91 °С. Accordingly, the temperature of the most heated part is 91 °C and also corresponds to the low voltage winding. The dependence of the most heated point of the transformer on the operating mode was studied. A formula is proposed for calculating the maximum temperature of a transformer as a function of power loss.
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Sutan Chairul, Imran, Yasmin Hanum Md Thayoob, Young Zaidey Yang Ghazali, Mohd Shahril Ahmad Khiar und Sharin Ab Ghani. „Formation and Effect of Moisture Contents to Kraft Paper’s Life of In-Service Power Distribution Transformer“. Applied Mechanics and Materials 793 (September 2015): 114–18. http://dx.doi.org/10.4028/www.scientific.net/amm.793.114.
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Examples of solid and liquid electrical insulations for power transformer are mineral oil and cellulose based paper. As transformers performed their function to step-up or step-down voltage level, its’ insulations will be degraded. Paper insulation is considered the most critical component in a transformer insulation system because it is not easily replaced if compared to oil where it is easily reconditioned in-order to remove water and contaminants. Studies show that temperature, moisture contents and oxygen contributed to paper insulation degradation. Moisture and furanic compound were produced from these deterioration processes. This paper is focused on the formation and effect of moisture to Kraft paper’s life. Levels of moisture contents were obtained from in-service power distribution transformers. These data then is used to assess the Kraft paper’s life by means of Weibull plot. This study shows that level of moisture contents can be used to assess the life of Kraft paper insulation.
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Saker, A., und P. Atten. „Potential distribution along single negative creeping streamer in transformer oil“. IEE Proceedings A Science, Measurement and Technology 140, Nr. 5 (1993): 375. http://dx.doi.org/10.1049/ip-a-3.1993.0058.
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Li, Guang Hua, Hong Lei Liu und De Jian Wang. „Heat Transfer Model and Analysis of Oil-Immersed Electrical Transformers with Heat Pipe Radiator“. Advanced Materials Research 516-517 (Mai 2012): 312–15. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.312.
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This paper has formulated a heat transfer model for analyzing the cooling properties of a heat pipe cooling device of oil-immersed electrical transformer. Based on the model, the oil temperature field of a 30 KVA oil-immersed transformer has been numerical simulated, and experiments also had been conducted. Results showed that the numerical simulation has good agreement with experiment results. Results also showed that heat pipe radiator is feasible for oil-immersed electrical transformer cooling. The model can be used to analyze the oil temperature distribution properties in an oil-immersed electrical transformer with heat pipe cooling device, and provide theoretical guide for transformer design and improvement.
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Ivankov, V. F., А. V. Basova und І. V. Khimjk. „ANALYTICAL AND CFD-CALCULATION OF THE HEAT CONDITION OF FOIL WINDINGS OF OIL DISTRIBUTING TRANSFORMERS“. Tekhnichna Elektrodynamika 2020, Nr. 6 (21.10.2020): 77–86. http://dx.doi.org/10.15407/techned2020.06.077.
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An analytical method of calculating the thermal condition of foil windings of lower voltage oil distribution transformers has been developed. At known oil temperatures in the tank, this technique provides the identification of heat-recoil ratios on winding surfaces, taking into account their design features and heat loads, as well as calculating the excess esexcesses of the average temperature of the winding and its most heated point above the oil and over the cooling environment. In order to calculate the excess temperature of the winding over the oil by the method of separating variables using the final cosinus-conversion Fourier obtained the solution of the edge problem for the Poisson equation with heterogeneous boundary conditions on the surfaces of the rectangular section winding with anisotropic properties and with its uneven distribution of losses. In addition, an alternative approach has been developed to determine the thermal state of an axisymmetric transformer model by numerical CFD modeling of the system of equations of motion and continuity of the Navier-Stokes coolant. This allows you to obtain the distribution of the oil velocity field and absolute temperatures, both of the oil in the tank, and of the foil and ball windings of the transformer using the minimum empirical data on the physical properties of the oil and the heat transfer of the tanks. The methods are verified by known experimental data for transformers TM-1000/35 and TM-630/10. References 11, figures 4, tables 2.
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SRINIVASAN, M., und A. KRISHNAN. „ASSESSING THE RELIABILITY OF TRANSFORMER TOP OIL TEMPERATURE MODEL“. International Journal of Reliability, Quality and Safety Engineering 19, Nr. 05 (Oktober 2012): 1250024. http://dx.doi.org/10.1142/s0218539312500246.
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The hot spot temperature (HST) plays a most important role in the insulation life of the transformer. Ambient temperature and environmental variable factors involved in the top oil temperature (TOT) computations in all transformer thermal models affects insulation lifetime either directly or indirectly. The importance of the ambient temperature in transformer's insulation life, a new semi-physically-based model for the estimation of TOT in transformers has been proposed in this paper. The winding hot-spot temperature can be calculated as function of the TOT that can be estimated by using the ambient temperature, wind velocity and solar heat radiation effect and transformer loading measured data. The estimated TOT is compared with measured data of a distribution transformer in operation. The proposed model has been validated using real data gathered from a 100 MVA power transformer. For a semi-physically-based model to be acceptable, it must have the qualities of: adequacy, accuracy and consistency. We assess model adequacy using the scale: prediction R2, and plot of residuals against fitted values. To assess model consistency, we use: variance inflation factor (VIF) (which measure multicollinearity), condition number. To assess model accuracy we use mean square error, maximum and minimum error values of semi-physically-based model parameters to the existing model parameters.
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Alqudsi, Alhaytham, und Ayman El-Hag. „Application of Machine Learning in Transformer Health Index Prediction“. Energies 12, Nr. 14 (14.07.2019): 2694. http://dx.doi.org/10.3390/en12142694.
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The presented paper aims to establish a strong basis for utilizing machine learning (ML) towards the prediction of the overall insulation health condition of medium voltage distribution transformers based on their oil test results. To validate the presented approach, the ML algorithms were tested on two databases of more than 1000 medium voltage transformer oil samples of ratings in the order of tens of MVA. The oil test results were acquired from in-service transformers (during oil sampling time) of two different utility companies in the gulf region. The illustrated procedure aimed to mimic a realistic scenario of how the utility would benefit from the use of different ML tools towards understanding the insulation health index of their transformers. This objective was achieved using two procedural steps. In the first step, three different data training and testing scenarios were used with several pattern recognition tools for classifying the transformer health condition based on the full set of input test features. In the second step, the same pattern recognition tools were used along with the three training/testing scenarios for a reduced number of test features. Also, a previously developed reduced model was the basis to reduce the needed number of tests for transformer health index calculations. It was found that reducing the number of tests did not influence the accuracy of the ML prediction models, which is considered as a significant advantage in terms of transformer asset management (TAM) cost reduction.
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Guney, Ezgi, und Okan Ozgonenel. „An Eco-Friendly Gas Insulated Transformer Design“. Energies 14, Nr. 12 (21.06.2021): 3698. http://dx.doi.org/10.3390/en14123698.
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Electricity companies around the world are constantly seeking ways to provide electricity more safely and efficiently while reducing the negative impact on the environment. Mineral oils have been the most popular transformer insulation, having excellent electrical insulating properties, but have many problems such as high flammability, significant cleaning problems, and are toxic to fish and wildlife. This paper presents an alternative approach to mineral oil: a transformer design that is clean and provides better performance and environmental benefits. A 50 kVA, 34.5/0.4 kV gas insulated distribution transformer was designed and evaluated using the COMSOL Multiphysics environment. R410A was used as insulation material. R410A is a near-azeotropic mixture of difluoromethane (CH2F2, called R-32) and pentafluoro ethane (C2HF5, called R-125), which is used as a refrigerant in air conditioning applications. It has excellent properties including environmentally friendly, no-ozone depletion, low greenhouse effect, non-explosive and non-flammable, First, the breakdown voltage of the selected gas was determined. The electrostatic and thermal properties of the R410A gas insulated transformer were investigated in the COMSOL environment. The simulation results for the performance of oil and SF6 gas insulated transformers using the same model were compared. The gas-insulated transformer is believed to have equivalent performance and is an environmentally friendly alternative to current oil-based transformers.
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Yahaya, Muhammad, Norhafiz Azis, Amran Mohd Selva, Mohd Ab Kadir, Jasronita Jasni, Mohd Hairi, Young Yang Ghazali und Mohd Talib. „Effect of Pre-Determined Maintenance Repair Rates on the Health Index State Distribution and Performance Condition Curve Based on the Markov Prediction Model for Sustainable Transformers Asset Management Strategies“. Sustainability 10, Nr. 10 (25.09.2018): 3399. http://dx.doi.org/10.3390/su10103399.
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This paper presents an investigation of the condition state distribution and performance condition curve of the transformer population under different pre-determined maintenance repair rates based on the Markov Prediction Model (MPM). In total, 3195 oil samples from 373 transformers with an age between one and 25 years were tested. The previously computed Health Index (HI) prediction model of the transformer population based on MPM utilizing the nonlinear minimization technique was employed in this study. The transition probabilities for each of the states were updated based on 10%, 20% and 30% pre-determined maintenance repair rates for the sensitivity study. Next, the HI state distribution and performance condition curve were analyzed based on the Markov chain algorithm. Based on the case study, it is found that the pre-determined maintenance repair rates can affect the HI state distribution and improve the performance condition curve. The 30% pre-determined maintenance repair rate gives the highest impact, especially for the transformer population at state 4 (poor). Overall, the average percentage of change for all HI state distributions is 16.48%. A clear improvement of HI state distribution is found at state 4 (poor) where the highest percentage can be up to 63.25%.
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Shutenko, O. V., und S. H. Ponomarenko. „CORRECTION OF TRANSFORMER OIL BREAKDOWN VOLTAGE MAXIMUM PERMISSIBLE VALUES BY THE MINIMUM RISK METHOD“. Bulletin of the National Technical University "KhPI". Series: Energy: Reliability and Energy Efficiency, Nr. 1 (1) (30.12.2020): 105–14. http://dx.doi.org/10.20998/2224-0349.2020.01.16.
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The method of correction of maximum permissible values of breakdown voltage of transformer oils in order to minimize possible economic damage in case of making erroneous decisions during diagnostics of the condition of transformer oils according to the results of periodic tests is proposed. An algorithm for statistical processing of the periodic test results is described, the use of which allows forming arrays with homogeneous values of the indicators under a priori limited measuring information. Analysis of distribution laws of breakdown voltage values for the transformer oils suitable and unsuitable for operation according to the values of this indicator is done. According to the results of the analysis, it was found that the breakdown voltage values of oils with different states have Weibull distribution. It was determined that the values of mathematical expectations of breakdown voltage of serviceable oils with the ageing of transformer oils shifts to the area of low values. It means that the breakdown voltage maximum permissible values of oils for the given distributions should be different. It is confirmed by the previously known fact that for unimodal distributions, the maximum permissible values of indicators that provide a minimum of risk are in an interval bounded by the mathematical expectation of the indicator distributions with different states. A decisive rule is formulated and an average risk function is compiled to adjust the maximum permissible breakdown voltage values of transformer oils. Based on the minimisation of the average risk function by Newton's method, the maximum permissible values of the breakdown voltage of oils have been determined. The made comparative analysis has shown that the correction of maximum permissible values of breakdown voltage of oils allows decreasing the risk values by 1.52÷19.13 times in comparison with risks, which provide the use of maximum permissible values, regulated in standards. It was found that the maximum permissible values of the breakdown voltage of oils, providing a minimum value of average risk, are not constant. They vary depending on the values of faulty decision prices and the probabilities of occurrence of different defective and defect-free oil states of transformers.
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Murata, Koichi, und Shinji Yasuda. „The Latest Technique of Portable Oil-Dissolved Gas Analyzer for Distribution Oil-Immersed Transformer“. IEEJ Transactions on Power and Energy 112, Nr. 3 (1992): 214–19. http://dx.doi.org/10.1541/ieejpes1990.112.3_214.
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Khan, Yasir, und Muhammad Iftikhar Khan. „Enhancing Service Life of Power Transformer through Inhibiting the Degradation of Insulating oil by New Approach“. International journal of Engineering Works 7, Nr. 10 (17.10.2020): 369–74. http://dx.doi.org/10.34259/ijew.20.710369374.
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Oil reclamation is a transformer insulation reconditioning technique which may be used as on-line or off-line. However, there is a need of evidence showing the effect of this process on conditions of the paper insulation, which indeed affects the life span of a transformer. This research work focuses on oil reclamation experiment on an old retired distribution transformer. Electrical testing and post-mortem analysis of the transformer were conducted, aimed at investigating the design aspects and collecting information on the insulation conditions prior to the oil reclamation. Temperature and moisture sensors were installed to monitor the conditions within the transformer during the oil reclamation [2]. The experimental process of transformer Oil reclamation was performed into two phases, with regular oil sampling to analyze the changes in key oil parameters, namely acidity number (AN), moisture and breakdown voltage (BV). This was accompanied by paper sampling at the end of each reclamation cycle to study the effects of oil reclamation on properties, particularly moisture, LMA and degree of polymerization. The transformer which was used for the entire experimental process was about 45 years old, 200kVA, 1100 / 415-240V distribution transformer. In order to study the long-term effect of oil reclamation, oil samples were collected from an on-site reclamation exercise performed in a laboratory-accelerated thermal ageing experiment. Oil samples collected before and after the reclamation were aged alongside new oils for comparison [4]. Through the regular monitoring and measurement of oil parameters (AN, moisture and BD strength) over 144 hours and paper parameters (LMA, moisture and DP) at specific stages of phase 1, it was observed that the transformer oil-paper insulation system was significantly improved. The entire research work was performed into two phases (phase 1 and phase 2). The “phase 1” was aimed to improve and restore the oil parameters comparable to the parameters of new oil as specified in “IEC-60296” and its effect on the paper insulation. “Phase 2” was aimed to compare the life span of reclaimed oil filled transformer with the transformer in which aged oil has been replaced by new oil[6]. Effective study of oil reclamation was analyzed through laboratory accelerated aging experiment and real time application on a 45 years old transformer. Through the regular monitoring and measurement of oil parameters (AN, moisture and BD strength) over 144 hours and paper parameters (LMA, moisture and DP) at specific stages of phase1, it was observed that the transformer oil-paper insulation system was significantly improved [15].
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Cong, Haoxi, Minhao Zhang und Qingmin Li. „Study on Sulfide Distribution in the Operating Oil of Power Transformers and Its Effect on the Oil Quality“. Applied Sciences 8, Nr. 9 (07.09.2018): 1577. http://dx.doi.org/10.3390/app8091577.
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Corrosive sulfides in transformer oil could react with copper wire to produce cuprous sulfide, causing insulation failure. At present, both the quantitative measurement method and distribution of sulfur components in operating oil are not clear yet. In this paper, the existing types and contents of sulfides in oil samples with different alkyl groups and different voltage levels were investigated. With quantitative testing methods, the distribution of sulfur composition in the operating oil was analyzed. Results showed that the thiophene sulfide in transformer oil existed mainly in the form of benzothiophene with an unsaturation of 6 and dibenzothiophene with an unsaturation of 9. The content of monosulfide sulfide with unsaturation of 3 or 6 was the highest. The disulfide existed basically in the form of Dibenzyl disulfide (DBDS). The influence of sulfides on the oil quality were analyzed on this basis. Results showed that the existence of sulfides would increase the moisture content in oil. The absorbed moisture could cause the decrease of the breakdown voltage and rise of the dielectric loss. The above study could provide some engineering practice for understanding the sulphide distribution in transformer oils and further prevent the sulfur corrosion faults.
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Gomathy, V., und Dr S. Sumathi. „IMPLEMENTATION OF SVM USING SEQUENTIAL MINIMAL OPTIMIZATION FOR POWER TRANSFORMER FAULT ANALYSIS USING DGA“. INTERNATIONAL JOURNAL OF COMPUTERS & TECHNOLOGY 10, Nr. 5 (20.08.2013): 1687–99. http://dx.doi.org/10.24297/ijct.v10i5.4153.
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Reliable operations of power transformers are necessary for effective transmission and distribution of power supply. During normal functions of the power transformer, distinct types of faults occurs due to insulation failure, oil aging products, overheating of windings, etc., affect the continuity of power supply thus leading to serious economic losses. To avoid interruptions in the power supply, various software fault diagnosis approaches are developed to detect faults in the power transformer and eliminate the impacts. SVM and SVM-SMO are the software fault diagnostic techniques developed in this paper for the continuous monitoring and analysis of faults in the power transformer. The SVM algorithm is faster, conceptually simple and easy to implement with better scaling properties for few training samples. The performances of SVM for large training samples are complex, subtle and difficult to implement. In order to obtain better fault diagnosis of large training data, SVM is optimized with SMO technique to achieve high interpretation accuracy in fault analysis of power transformer. The proposed methods use Dissolved Gas-in-oil Analysis (DGA) data set obtained from 500 KV main transformers of Pingguo Substation in South China Electric Power Company. DGA is an important tool for diagnosis and detection of incipient faults in the power transformers. The Gas Chromatograph (GC) is one of the traditional methods of DGA, utilized to choose the most appropriate gas signatures dissolved in transformer oil to detect types of faults in the transformer. The simulations are carried out in MATLAB software with an Intel core 3 processor with speed of 3 GHZ and 2 GB RAM PC. The results obtained by optimized SVM and SVM-SMO are compared with the existing SVM classification techniques. The test results indicate that the SVM-SMO approach significantly improve the classification accuracy and computational time for power transformer fault classification.
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Li, Yan, Yong Teng Jing und Longnv Li. „Calculation and Analysis of Winding Temperature Rise for ODAF Power Transformer“. Advanced Materials Research 516-517 (Mai 2012): 1580–83. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.1580.
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The AutoCAD, Gambit and ANSYS software are used to establish transformer oil flow-temperature rise model and mesh generation based on finite volume method, fluid mechanics and numerical heat transfer. A method that calculates temperature rise distribution of transformer winding regional wire and oil by FLUENT software, and a numerical example is given for an actual transformer.
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Bokes, Peter. „Average temperature of oil-filled transformer windings with partial cooling ducts“. Journal of Electrical Engineering 72, Nr. 1 (01.02.2021): 35–39. http://dx.doi.org/10.2478/jee-2021-0005.
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Abstract An effective one-dimensional model is presented that describes the temperature profile of a winding of an oil-filled distribution transformer with an arbitrary number of partial cooling ducts. An analytical solution of the model is applied to a specific example — a low voltage winding of a 400 kVA distribution transformer with one or two partial cooling ducts. Starting from the exact solution, a simple and practical formula for the temperature rise of similar windings has been derived that is suitable for transformer designers.
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Fu, Qiang, Meng Jun Wang, Wei Su, Yi Hua Qian und Guo Hua Lu. „Research on Monitoring of Moisture Content in Transformer Oil by Using Sensors“. Advanced Materials Research 684 (April 2013): 486–90. http://dx.doi.org/10.4028/www.scientific.net/amr.684.486.
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The moisture distribution in the transformer and variation mechanism of moisture in oil is analyzed in this paper, and using relative saturation and temperature as characteristic parameters, a detail scheme of on-line monitoring moisture content in transformer oil is put forward. The polyimide-based capacitive humidity sensor and temperature sensor are employed in on-line monitoring moisture content in oil. Computer is utilized to sample and analyze the data that sensors send out. The experiment on test transformer confirms that the sensors can work reliably, and reflect the moisture content in transformer oil accurately. The method that the paper proposes can realize the purpose of on-line monitoring.
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Okabe, Shigemitsu, und Takeshi Kawashima. „Charge Distribution with Return of Positive Charge in Oil Filled Transformer“. IEEJ Transactions on Power and Energy 122, Nr. 2 (2002): 331–32. http://dx.doi.org/10.1541/ieejpes1990.122.2_331.
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Józefczak, Arkadiusz, Tomasz Hornowski und Andrzej Skumiel. „Temperature Dependence of Particle Size Distribution in Transformer Oil-Based Ferrofluid“. International Journal of Thermophysics 32, Nr. 4 (07.12.2010): 795–806. http://dx.doi.org/10.1007/s10765-010-0895-5.
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