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This article discusses possible ways of technical diagnostics of high-voltage electric equipment of substations and electric networks by means of mathematical apparatus of the theory of indistinct sets and indistinct relations. It is shown that on the basis of indistinct expert estimates it is possible to do a prediction for possible causes of failures if some estimates of the available symptoms of...
This paper proposes mathematical models of moisture in paper-oil insulation systems for use in power transformers. This work is important because it helps shed light on the phenomenon of moisture migration in power transformer insulation systems, and also serves as a tool to underpin decisions by maintenance engineers in response to the occurrence of phenomena that may impair the performance of transformers...
This paper presents a methodology to design hermetically sealed shell type oil immersed distribution transformers with minimum evaluated cost according to the IEC standards. Distribution transformer model and design constraints are implemented as a user friendly software using MATLAB. An objective function for total evaluated cost is optimized subjected to ten constraints according to IEC 60076 in...
Transformers have emerged as an integrated part of a power system. Any fault in the transformer can cause a severe outage, which therefore necessitates continuous monitoring and diagnostics of its operation. The renewed thrust in smart power system networks along with the development of advanced methods in the monitoring and diagnostics has resulted in a major impetus for research in the related domain...
The efficient energy policies and its inherent practices are promoting new operating modes of the transformers. Independently of the practices, the temperature remains one of the most relevant limiting factors, being thus essential to predict accurately its distribution and magnitude. Addressing this specific challenge, the thermal hydraulic network models (THNMs) are enhancing our comprehension,...
Power transformers are to be monitored frequently to avoid catastrophic failures which are more or less related to internal faults. Many techniques and tools are developed world wide and most of these techniques rely on expert's analysis and are well affected by environmental conditions which lead to misinterpretation of the test. In this paper a new fuzzy logic algorithm (FLA) based technique is...
In order to increase the efficiency of the loosely coupled inductive power transfer system, the leakage inductances of the loosely coupled transformer need to be compensated. But the compensated capacitors may make the system enter into multi-resonant state. Thus the transfer characteristics of the system are analyzed and simulation of the transfer function is given. From the simulated curved surface,...
Two winding insulation breakdown failures in Extra High Voltage transformers are investigated. The discovered cause, partial discharge development between winding turns, which is normally considered rare, is studied through lab simulation. Simplified winding samples are tested under a combination of various environmental conditions, including the electric field, temperature and humidity. Studies revealed...
Power transformers always vibrate while working. The vibration detected in the tank is different at different parts of the transformer, with different frequencies and amplitudes. The difference in the vibration pattern depends on the working conditions and the age of the transformer. Mechanical faults produce differences in this vibrational pattern caused by either, failures in the winding, in the...
"SieFormer" is an acronym of Siemens Transformer and belongs to a new family of products developed to satisfy the demands of the customers of the 21st century. It encompasses features such a low losses, low partial discharge with high reliability in terms of short-circuit withstand ability and life expectancy. This combined with the ease in operation and maintenance contributes to a high...
At Shinkansen substations in Japan that receive electric power from an extra-high voltage system, we have been using modified Woodbridge connected transformers for traction power supply since the inauguration of the Sanyo Shinkansen, which commenced commercial operations in March 1972. However, this transformer is of a rather complicated structure. Therefore, we studied a new type of transformer,...
Transformer is one of the most important equipment in electricity grid since problems in transformer will influence electrical power system stability. Therefore early knowing on transformer abnormality and ability to evaluate the problems can avoid damage on the transformer. Among methods of transformer abnormality monitoring is thermography Monitoring. In PLN P3B Jawa Bali thermographic monitoring...
This article illustrates AREVA T&Dpsilas position in terms of their productspsila end of life management. In order to manage the equipments that have reached the end of useful life, this study describes complete dismantling operation diagram, recycling routes and waste management.
The international trend is for power utilities having major capital equipment with service ages in excess of their assigned lifetimes. The key role for the asset manager in this situation is to be able to define the risks for future operation. This will then permit criticality based decisions for managing future operating and capital expenditure. The first step is to define relevant failure modes...
Frequency response analysis (FRA) is a diagnosis method to detect troubles of a transformer, which are deformation and displacement of winging and so, by detecting change of a transfer function compared with that measured when the transformer is normal. However, identification of the troubles detected by FRA is not clear. In this paper, firstly, identification method of the troubles is investigated...
Hot spot temperature (HST) is the most important parameter in the operation of power transformers. The HST has to be held under a prescribed limit. HST has a considerable effect on the insulation aging. Therefore detecting, monitoring and removing the HST could be a very important and necessary action for Utilities. A new design of oil spraying and its effect, along with a thermal management in a...
This paper is concerned with the development of a new type of power supply for high power RF applications for CW operation. Losses are reduced by the use of zero current switching. This allows for a high operating frequency and minimised transformer and filter size. Preliminary practical results have been found to be promising, with design of the resonant circuit and isolating transformer being fundamental...
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