scholarly journals Fault Identification of In-Service Power Transformer using Depolarization Current Analysis

2017 ◽  
Vol 7 (2) ◽  
pp. 559
Author(s):  
M.A. Talib ◽  
N.A. Muhamad ◽  
Z.A. Malek ◽  
B.T. Phung
Keyword(s):  
Power Transformer ◽  
Diagnostic Testing ◽  
Cost Effective ◽  
Power Transformers ◽  
Depolarization Current ◽  
Significant Information ◽  
Extended Application ◽  
Catastrophic Failures ◽  
Measurement Results

Preventive diagnostic testing of in-service power transformers require system outage and expert’s knowledge and experiences in interpreting the measurement results. The chemical oil analysis may cause significant variance to measurement results due to the different practices in oil sampling, storage, handling and transportation. Thus, a cost effective measuring technique by means of a simpler method that is able provide an accurate measurement results is highly required. The extended application of Polarization and Depolarization Current (PDC) measurement for characterization of different faults conditions on in-service power transformer has been presented in this paper. The oil sample from in-service power transformers with normal and 3 different faults type conditions were sampled and tested for Dissolved Gases Analysis (DGA) and PDC measurement. The DGA results was used to confirm type of faults inside the transformer while the PDC pattern of oil with normal, partial discharge, overheating and arcing were correlated to the oil sample conditions. The analysis result shows that depolarization current provides significant information to defferenciate fault types in power transformer. Thus this finding provides a new alternative in identifying incipient faults and such knowledge can be used to avoid catastrophic failures of power transformers.

Monitoring of Winding Deformation of Power Transformer by Using Nanosecond Pulses

2011 ◽  
Vol 128-129 ◽  
pp. 190-195
Author(s):  
Hua Lin Liu ◽  
Yin Bo Zhan ◽  
Xiao Lei ◽  
You Yuan Wang ◽  
Hua Rong Zeng ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Frequency Band ◽  
Low Voltage ◽  
Power Transformer ◽  
Test System ◽  
Power Transformers ◽  
Distribution Transformer ◽  
Frequency Method ◽  
Nanosecond Pulses ◽  
Measurement Results

As we know, the TF method is more sensitive to changes in the power transformers at higher frequencies. Although measurement based on low voltage impulse (LVI) is definitely faster than that based on swept frequency method (SFM), the available frequency band is narrow because of the typical microsecond impulse. In this paper, the characteristics of the nanosecond impulse in the frequency domain were investigated. A test System based on Nanosecond low voltage impulse was developed. The proposed method was applied to a 10kV/100kVA distribution transformer in the laboratory. Measurement results with two different impulses were compared.

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. .

Transformer Fault Classification from Polarization Current Measurement Results by Using Statistical Technique

2015 ◽  
Vol 754-755 ◽  
pp. 654-658
Author(s):  
Mohd Shahril bin Ahmad Khiar ◽  
Mohd Aizam Talib ◽  
Sharin bin Ab Ghani ◽  
Imran bin Sutan Chairul
Keyword(s):  
Power Transformer ◽  
Research Work ◽  
Statistical Technique ◽  
Fault Classification ◽  
Polarization Current ◽  
Depolarization Current ◽  
Measurement Results ◽  
Graphical Technique ◽  
Load Tap Changer ◽  
Transformer Fault

In general, the presence of moisture and other impurities inside the insulator or oil can cause the breakdown of the power transformer. Polarization and Depolarization Current (PDC) is one of the technique to assess the condition of insulation oil in power transformer and can be applied in many electrical apparatus such as power cables and on load tap changer as well as to estimate conductive and moisture content of the insulation. Basically, it is a technique that is based on time domain measurement and has been used since 1990. For this research, the PDC data will be analyzed using graphical method and statistical technique to classify the transformer faults into a proper range. Lastly, it will be validated with the results from previous research. The output of the research work revealed that in term of the sequence, the results obtain in both graphical technique and the statistical technique is identical with the results presented in previous research. Hence, the range of the faults started with partial discharge, followed by arcing and lastly is the overheating.

An update of novel identified cytogenetic and molecular biomarkers in the laboratory diagnosis of hematological neoplasia

2015 ◽  
Vol 39 (5) ◽  
Author(s):  
Tanja Hinrichsen ◽  
Stefanie Kuehner ◽  
Marion Subklewe
Keyword(s):  
Cancer Diagnosis ◽  
Blood Count ◽  
Diagnostic Testing ◽  
Cost Effective ◽  
Laboratory Diagnosis ◽  
Molecular Biomarkers ◽  
Routine Diagnostics ◽  
Novel Biomarkers ◽  
Excess Profit

AbstractCancer diagnosis and identification of novel biomarkers are a rapidly changing field and open new doors into personalized medicine. Particularly in the diagnosis of hematological neoplasia, the identification of novel biomarkers has become more important because of biological sub-classification, prognosis and targeted and individualized therapies. Therefore, techniques like blood count, morphology, cytochemistry, histology, immunophenotyping, cytogenetics and molecular genetics are essential and cannot be denied nowadays. In the last years, a broad spectrum of novel molecular biomarkers has been identified in the genetic and molecular characterization of myelodysplastic syndromes. Lots of these novel molecular biomarkers gained entry in the routine diagnostics and provide an excess profit for patients. However, to ensure a cost-effective, targeted and individualized diagnostic testing, application of existing techniques has to be weighed against each other to obtain the best possible combination of targeted diagnostics. This review summarized thus far the diagnostic-relevant morphologic, cytogenetic and molecular biomarkers in the laboratory diagnosis of hematological neoplasia.

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.

Monitoring of Petroleum-Related Environmental Contamination Using Fluorescence Fingerprinting

2006 ◽  
Vol 1 (2) ◽  
Author(s):  
P. Literathy ◽  
M. Quinn
Keyword(s):  
Environmental Contamination ◽  
Statistical Evaluation ◽  
Oil Pollution ◽  
Emission Spectra ◽  
Cost Effective ◽  
Petroleum Products ◽  
Danube River ◽  
Aromatic Components ◽  
Analytical Approaches

Petroleum and its refined products are considered the most complex contaminants frequently impacting the environment in significant quantities. They have heterogeneous chemical composition and alterations occur during environmental weathering. No single analytical method exists to characterize the petroleum-related environmental contamination. For monitoring, the analytical approaches include gravimetric, spectrometric and chromatographic methods having significant differences in their selectivity, sensitivity and cost-effectiveness. Recording fluorescence fingerprints of the cyclohexane extracts of the water, suspended solids, sediment or soil samples and applying appropriate statistical evaluation (e.g. by correlating the concatenated emission spectra of the fingerprints of the samples with arbitrary standards (e.g. petroleum products)), provides a powerful, cost-effective analytical tool for characterization of the type of oil pollution and detecting the most harmful aromatic components of the petroleum contaminated matrix. For monitoring purposes, the level of the contamination can be expressed as the equivalent concentration of an appropriate characteristic standard, based on the fluorescence intensities at the relevant characteristic wavelengths. These procedures are demonstrated in the monitoring of petroleum-related pollution in the water and suspended sediment in the Danube river basin

Green Synthesis and Spectroscopic Studies of Ag-rGO Nanocomposites for Highly Selective Mercury (II) Sensing

2018 ◽  
Vol 9 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Shubhangi J. Mane-Gavade ◽  
Sandip R. Sabale ◽  
Xiao-Ying Yu ◽  
Gurunath H. Nikam ◽  
Bhaskar V. Tamhankar
Keyword(s):  
Green Synthesis ◽  
Color Change ◽  
Limit Of Detection ◽  
Aqueous Media ◽  
Suitable Condition ◽  
Cost Effective ◽  
Spectroscopic Studies ◽  
Calibration Plot ◽  
First Time

Introduction: Herein we report the green synthesis and characterization of silverreduced graphene oxide nanocomposites (Ag-rGO) using Acacia nilotica gum for the first time. Experimental: We demonstrate the Hg2+ ions sensing ability of the Ag-rGO nanocomposites form aqueous medium. The developed colorimetric sensor method is simple, fast and selective for the detection of Hg2+ ions in aqueous media in presence of other associated ions. A significant color change was noticed with naked eye upon Hg2+ addition. The color change was not observed for cations including Sr2+, Ni2+, Cd2+, Pb2+, Mg2+, Ca2+, Fe2+, Ba2+ and Mn2+indicating that only Hg2+ shows a strong interaction with Ag-rGO nanocomposites. Under the most suitable condition, the calibration plot (A0-A) against concentration of Hg2+ was linear in the range of 0.1-1.0 ppm with a correlation coefficient (R2) value 0.9998. Results & Conclusion The concentration of Hg2+ was quantitatively determined with the Limit of Detection (LOD) of 0.85 ppm. Also, this method shows excellent selectivity towards Hg2+ over nine other cations tested. Moreover, the method offers a new cost effective, rapid and simple approach for the detection of Hg2+ in water samples.

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.

scholarly journals Semi-automated regional classification of the style of activity of slow rock-slope deformations using PS InSAR and SqueeSAR velocity data

Landslides ◽  
2021 ◽  
Author(s):  
Chiara Crippa ◽  
Elena Valbuzzi ◽  
Paolo Frattini ◽  
Giovanni B. Crosta ◽  
Margherita C. Spreafico ◽  
...  
Keyword(s):  
Rock Slope ◽  
Progressive Failure ◽  
Principal Component ◽  
Cost Effective ◽  
Displacement Rate ◽  
Machine Learning Classification ◽  
Management Perspective ◽  
Alpine Environments

AbstractLarge slow rock-slope deformations, including deep-seated gravitational slope deformations and large landslides, are widespread in alpine environments. They develop over thousands of years by progressive failure, resulting in slow movements that impact infrastructures and can eventually evolve into catastrophic rockslides. A robust characterization of their style of activity is thus required in a risk management perspective. We combine an original inventory of slow rock-slope deformations with different PS-InSAR and SqueeSAR datasets to develop a novel, semi-automated approach to characterize and classify 208 slow rock-slope deformations in Lombardia (Italian Central Alps) based on their displacement rate, kinematics, heterogeneity and morphometric expression. Through a peak analysis of displacement rate distributions, we characterize the segmentation of mapped landslides and highlight the occurrence of nested sectors with differential activity and displacement rates. Combining 2D decomposition of InSAR velocity vectors and machine learning classification, we develop an automatic approach to characterize the kinematics of each landslide. Then, we sequentially combine principal component and K-medoids cluster analyses to identify groups of slow rock-slope deformations with consistent styles of activity. Our methodology is readily applicable to different landslide datasets and provides an objective and cost-effective support to land planning and the prioritization of local-scale studies aimed at granting safety and infrastructure integrity.

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