Applying the Recovery Voltage Method (RVM) to Study the Degradation of High Power Transformer Insulation

2014 ◽  
Vol 911 ◽  
pp. 260-265
Author(s):  
Doina Elena Gavrilă ◽  
Ilies Ciprian ◽  
Horia Catalin Gavrilă
Keyword(s):  
High Power ◽  
Power Transformer ◽  
Dielectric Strength ◽  
Power Transformers ◽  
Polarization Spectrum ◽  
Accelerate Ageing ◽  
Solid Part ◽  
Recovery Voltage ◽  
Transformer Insulation ◽  
Solid Insulation

Good operation of power transformers is very important because they are among the most expensive equipment in the network generation, transmission and electricity distribution. It became necessary regular monitoring of such systems and determinate the life of a transformer, it preventing breakdown and corresponding loss occurrence.Ageing in the insulation system of power transformers is determinate by influence of air, moisture, temperature, mechanical and electrical stresses and insulation contamination. One of the most important ageing indicators in transformers is the water content in the solid part of the insulation. The water reduces drastically the dielectric strength of solid insulation, accelerate ageing in paper and can cause water vapor bubbles.In RVM method a voltmeter determines the recovery voltage (RV) after charging the insulation with a DC voltage. By subsequent relaxation and repeated charging for varied times the so called polarization spectrum can be created. RV range provides an indication on the condition in which there is the insulation of transformer. The paper analyzes measurements on two high power transformers in operation, determining the moisture content of solid insulation.

scholarly journals Frequency Domain Diagnostics of Transformer Insulation

2019 ◽  
Vol 10 (4) ◽  
pp. 353-359
Author(s):  
M. Gutten ◽  
M. Šebok ◽  
D. Korenčiak ◽  
P. Brnčal ◽  
M. Kubiš ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Chromatographic Analysis ◽  
Single Phase ◽  
Power Transformer ◽  
Operating Temperature ◽  
Power Transformers ◽  
Insulating Paper ◽  
Recovery Voltage ◽  
Transformer Insulation ◽  
Diagnostic Measurement

The first part of paper deals with the base information about diagnostics of power transformers. In this part are presented differently insulating methods, for example method of recovery voltage method, method of polarization and depolarization currents and chromatographic analysis.The second part of paper deals use of method of frequency domain spectroscopy for oil power transformers. This method is used in analysis insulating condition of power transformer with system of oil-paper. It was found, that the results of these tests are highly impacted by the operating temperature during the experimental measurement. Moisture and conductivity between insulating paper and oil in an insulating system are highly dependent from temperature.In the other part, the paper presents experimental results of the frequency diagnostic measurement for a real single-phase traction transformer 110/27 kV at different operating temperatures and states (with oil and without).Finally in the last part, the paper presents comparing frequency insulating measurements among several the same single-phase transformers 110/27 kV.

scholarly journals Monitoring and diagnostics of power transformer insulation

2006 ◽  
Vol 10 (4) ◽  
pp. 43-54 ◽  
Author(s):  
Dragan Kovacevic ◽  
Slobodan Skundric ◽  
Jelena Lukic
Keyword(s):  
Power Systems ◽  
Power Transformer ◽  
Cost Effective ◽  
Service Condition ◽  
Life Extension ◽  
Power Transformers ◽  
Knowledge Rules ◽  
Critical Components ◽  
Monitoring And Diagnostics ◽  
Transformer Insulation

Liberalization of the energy market drives utilities to a more cost-effective power system. Power transformers are the most complex, important, and critical components of the transition and distribution power systems. Insulation system is the key component of life extension, better availability and higher reliability of a transformer. In order to achieve both decreasing operational cost and reliable service condition-based maintenance is needed. Monitoring and diagnostics methods and techniques, for insulation condition assessment of power transformers, are described. Date base and knowledge rules diagnostics management system, in internet oriented environment, is outlined. .

scholarly journals Streaming Electrification Phenomenon of Electrical Insulating Oils for Power Transformers

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3225 ◽  
Author(s):  
Maciej Zdanowski
Keyword(s):  
Power Transformer ◽  
Flow Speed ◽  
Power Transformers ◽  
Pipe Material ◽  
Mineral Oils ◽  
Electrostatic Charges ◽  
Volume Charge Density ◽  
Electrostatic Charging ◽  
Flow Through ◽  
Transformer Insulation

The subject matter of this study was the problem of the ECT (electrostatic charging tendency) of mineral insulation oils during their flow. The electrostatic charges generated may lead to partial discharges, and as a consequence, to the breakdown of a power transformer insulation system. In this study, the results of the ECT of mineral oils used in transformers were compared. The method of streaming electrification of insulation liquids using a flow-through system was used. The influence of flow speed, temperature, and the pipe material on the values of the electrification current and volume charge density qw were analyzed. The results obtained in this study should be taken into account regarding the operation of power transformers.

Comparative Study on Effect of Temperature & Moisture on Transformer Insulation Conductivity

2013 ◽  
Vol 284-287 ◽  
pp. 1126-1130 ◽  
Author(s):  
Abubakar Abdull Suleiman ◽  
Rubiatul A. B. Zainir ◽  
Nor Asiah Muhamad ◽  
Nouruddeen Bashir
Keyword(s):  
Power Transformer ◽  
Electrical Power ◽  
Power Transformers ◽  
Effect Of Temperature ◽  
Power Networks ◽  
Tests And Measurements ◽  
Sample Data ◽  
Effects Of Temperature ◽  
Insulation Breakdown ◽  
Transformer Insulation

It has been acknowledged that the insulation of the power transformers is the main cause of their failures. This can easily be attributed to the fact that all power transformers connected to electrical power networks bears loads and the load causes temperature rise and degradation of the cellulose paper. The by-product of the degradation includes moisture. The high temperature and moisture combine to accelerate the rate of insulation breakdown by increasing the material conductivity, σ and also increase the aging rate of the transformer. This paper has reviewed some transformer assessments and tests as sample data to study the effects of temperature and moisture on power transformer insulation conductivity. The results from the tests and measurements were analyzed and presented accordingly. The analyses of results found that irrespective of the assessment technique used, be it FDS, PDC or RVM, conductivity of the transformer insulating materials increases with any increase in both temperature and moisture content.

scholarly journals ANALYSIS ON DEGRADATION AND DEFORMATION OF TRANSFORMER INSULATION SYSTEM

2014 ◽  
pp. 75-81
Author(s):  
T. MANIVANNAN
Keyword(s):  
Frequency Response ◽  
Power Transformer ◽  
Good Condition ◽  
Dielectric Strength ◽  
Response Analysis ◽  
Insulation System ◽  
Distribution Transformers ◽  
Insulation Degradation ◽  
Transformer Winding ◽  
Transformer Insulation

Performance of insulation system of power transformer is essential to ensure better performance of power network. Most of the power and distribution transformers in service are aged and, have experienced several thermal and electrical stresses due to varying loading conditions, in addition to ageing. The rate of degradation and hence, the useful life of the insulation system mainly depends on the variation of operational stresses. Due to the progress in insulation degradation, the dielectric strength of the insulating oil and paper over transformer winding may reach to a point such that it could not withstand any small abnormal currents and voltages. In order to maintain the quality of system operation it is necessary to keep the transformer in good condition. This needs appropriate maintenance based on reliable diagnostics. In this paper experimental results on the application of frequency response analysis (FRA) for the diagnosis of power transformers. Frequency Response of Transformer, also serves for assessing the deformation process.

A Solid-State On-Load Tap Changer for the Power Transformers of 10—0.4 kV Distribution Networks

Vestnik MEI ◽  
2020 ◽  
Vol 6 (6) ◽  
pp. 82-90
Author(s):  
Dmitriy I. Panfilov ◽  
◽  
Mikhail G. Astashev ◽  
Aleksandr V. Gorchakov ◽  
◽  
...  
Keyword(s):  
Solid State ◽  
Physical Model ◽  
High Speed ◽  
Power Transformer ◽  
Voltage Control ◽  
Power Transformers ◽  
Control Algorithms ◽  
Load Voltage ◽  
Tap Changer ◽  
Load Tap Changer

The specific features relating to voltage control of power transformers at distribution network transformer substations are considered. An approach to implementing high-speed on-load voltage control of serially produced 10/0.4 kV power transformers by using a solid-state on-load tap changer (SOLTC) is presented. An example of the SOLTC circuit solution on the basis of thyristor switches is given. On-load voltage control algorithms for power transformers equipped with SOLTC that ensure high reliability and high-speed operation are proposed. The SOLTC performance and the operability of the suggested voltage control algorithms were studied by simulation in the Matlab/Simulink environment and by experiments on the SOLTC physical model. The structure and peculiarities of the used simulation Matlab model are described. The SOLTC physical model design and its parameters are presented. The results obtained from the simulating the SOLTC operation on the Matlab model and from the experiments on the SOLTS physical model jointly with a power transformer under different loads and with using different control algorithms are given. An analysis of the experimental study results has shown the soundness of the adopted technical solutions. It has been demonstrated that the use of an SOLTC ensures high-speed voltage control, high efficiency and reliability of its operation, and arcless switching of the power transformer regulating taps without load voltage and current interruption. By using the SOLTC operation algorithms it is possible to perform individual phase voltage regulation in a three-phase 0.4 kV distribution network. The possibility of integrating SOLTC control and diagnostic facilities into the structure of modern digital substations based on the digital interface according to the IEC 61850 standard is noted.

The Heating System of Agricultural Facilities Using Excess Heat Power Transformers

2020 ◽  
Vol 67 (1) ◽  
pp. 42-47
Author(s):  
Anatoliy I. Sopov ◽  
Aleksandr V. Vinogradov
Keyword(s):  
System Design ◽  
Heat Supply ◽  
Cooling System ◽  
Power Transformer ◽  
Electric Heating ◽  
Heating System ◽  
Power Transformers ◽  
Large Power ◽  
Excess Heat ◽  
Power Centers

In power transformers, energy losses in the form of heat are about 2 percent of their rated power, and in transformers of large power centers reach hundreds of kilowatts. Heat is dissipated into the environment and heats the street air. Therefore, there is a need to consume this thermal energy as a source of heat supply to nearby facilities. (Research purpose) To develop methods and means of using excess heat of power transformers with improvement of their cooling system design. (Materials and methods) The authors applied following methods: analysis, synthesis, comparison, monographic, mathematical and others. They analyzed various methods for consuming excess heat from power transformers. They identified suitable heat supply sources among power transformers and potential heat consumers. The authors studied the reasons for the formation of excess heat in power transformers and found ways to conserve this heat to increase the efficiency of its selection. (Results and discussion) The authors developed an improved power transformer cooling system design to combine the functions of voltage transformation and electric heating. They conducted experiments to verify the effectiveness of decisions made. A feasibility study was carried out on the implementation of the developed system using the example of the TMG-1000/10/0.4 power transformer. (Conclusions) The authors got a new way to use the excess heat of power transformers to heat the AIC facilities. It was determined that the improved design of the power transformer and its cooling system using the developed solutions made it possible to maximize the amount of heat taken off without quality loss of voltage transformation.

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