Investigating the Quality of Power Supply to a Large Commercial Installation

2011 ◽  
Vol 367 ◽  
pp. 159-165
Author(s):  
B.A. Adegboye ◽  
M.G. Mele
Keyword(s):  
Power Factor ◽  
Power Supply ◽  
Harmonic Distortion ◽  
Poor Quality ◽  
Holding Company ◽  
The Poor ◽  
Three Phase ◽  
Commercial Installation ◽  
Maximum Voltage

The paper investigates the quality of power supply to the Corporate Headquarters of the Power Holding Company of Nigeria (PHCN), PLC, Maitama, Abuja. This was facilitated by the measurements conducted using the harmonitor 3000 power analyzer on the secondary terminals of the two (2) 1000kVA, 11kV three-phase transformers serving the Company. The data on the network consisting of voltages, currents, power factor and harmonic distortion were acquired by the Harmonitor. Analysis of these data shows that there is significantly high variation between the minimum and the maximum voltage and that the phase loads are unbalanced. There is low power factor and the total harmonic distortions (THD) on the phases and neutral are high. The causes of the poor quality of power supply were identified and recommendations proposed taking into cognizance the complexity and sensitivity of the equipment in the network.

Study of the Influence of Control System Parameters on the Quality of the Input Current of a Three-Phase Power Factor Corrector

2021 ◽  
Vol 2 (2) ◽  
pp. 29-35
Author(s):  
Dmitry A. Sorokin ◽  
◽  
Sergey I. Volskiy ◽  
Jaroslav Dragoun ◽  
◽  
...  
Keyword(s):  
Control System ◽  
Power Factor ◽  
Harmonic Distortion ◽  
Total Harmonic Distortion ◽  
Input Current ◽  
System Operation ◽  
Error Amplifier ◽  
Three Phase ◽  
Power Factor Corrector

The paper suggests a control system of a three-phase power factor corrector. The study of the control system operation is carried out and the expressions for calculating the permissible values of error amplifier factors are obtained. The influence of the error amplifier parameters on phase current quality is investigated. The dependence of total harmonic distortion input current on a combination of error amplifier parameters is obtained at a given value of power factor. The conditions under which the total harmonic distortion input current has the minimum value are found out. This article is of interest to power electronics engineers, who are aimed at developing a three-phase power factor corrector.

Power Quality Assessment in a Distribution Network

2009 ◽  
Vol 62-64 ◽  
pp. 53-59 ◽  
Author(s):  
B.A. Adegboye
Keyword(s):  
Quality Assessment ◽  
Power Quality ◽  
Power Factor ◽  
Textile Industry ◽  
Distribution Network ◽  
Harmonic Distortion ◽  
Three Phase ◽  
Blue Phases ◽  
Power Quality Disturbances

The paper explores power quality disturbances on a specified section of the distribution network of a Textile Industry in Kaduna State of Nigeria. The 33kV PHCN incoming to the industry is stepped down to 11kV by a 7.5MVA, 33/11kV three-phase transformer. This transformer supplies various 11/.415kV transformers present in the distribution network. Another 11kV PHCN incoming is used in event of any failure from the 33/11kV transformer. The paper focuses on Transformer No. 1, a 150kVA, 11/.415kV three-phase transformer operating at 0.9 power factor, located at printing and dying (P/D) building 1. Majority of the loads on it are inductive. Measurements were taken at the secondary terminal of this transformer by the use of the Harmonitor 3000 power analyzer, which generates the voltage and current waveforms, power factor, voltage and current total harmonic distortion and the apparent power of the red, yellow and blue phases of the transformer. Analyses of these data reveal the disturbances due to harmonics in the phases and neutral of the transformer. The effect of the harmonic current is seen as poor power factor of the transformer. Considering the observations and analyses of the power quality of the transformer 1 (P/D), the paper proposes some recommendations for improving the power quality of the distribution network under study.

The Triebenberg Laboratory-Designed for Highest Resolution Electron Microscopy and Holography

2001 ◽  
Vol 7 (S2) ◽  
pp. 894-895 ◽  
Author(s):  
Hannes Lichte ◽  
Dietrich Schulze ◽  
Michael Lehmann ◽  
Holger Just ◽  
Taher Erabi ◽  
...  
Keyword(s):  
Power Supply ◽  
Acoustic Noise ◽  
Poor Quality ◽  
Power Lines ◽  
The Poor ◽  
Main Challenge ◽  
Resolution Electron ◽  
Electron Microscopes ◽  
The City

Very often, the performance of modern electron microscopes is limited by the poor quality of the laboratory rather than by the specifications of the microscope. Therefore, with microscopes aiming at subangstrom resolution microscopy and highest performing holography methods, special measures have to be taken to reach the needed low level of AC-stray fields, vibrations, and acoustic noise. in an ”organically“ grown institute, this is very difficult to realize, if possible at all.• The Triebenberg Lab is newly built well outside the city of Dresden, in an area essentially free from disturbances, i.e. free from power lines, away from roads, trains and airplanes; fortunately, the site is shielded from wind by means of a dense belt of trees. The lab houses six microscope units each consisting of a microscope room, a room for peripheral devices (power supply, cooling units, computers, etc), and an office for up to three scientists. in view of the nearly ideal environment, the main challenge is to avoid any self-made disturbances which might arise by the operation of the lab. Therefore, without any compromise using the best art of engineering, we designed a special lab virtually free from disturbances. in the following, the main guidelines for the construction are sketched.

scholarly journals Current Interactions Mitigation in 3-Phase PFC Modular Rectifier through Differential-Mode Choke Filter Boost Converter

2021 ◽  
Vol 11 (4) ◽  
pp. 1684
Author(s):  
José Teixeira Gonçalves ◽  
Stanimir Valtchev ◽  
Rui Melicio
Keyword(s):  
Power Factor ◽  
Harmonic Distortion ◽  
Electrical Energy ◽  
Boost Converter ◽  
International Standards ◽  
Differential Mode ◽  
Driving Mode ◽  
Three Phase ◽  
Sinusoidal Shape

In this paper, a new way to mitigate the current interactions is proposed. The problem of current interactions arises when a modular three-phase (3-phase) rectifier (three single-phase modules) with boost converter for power factor correction (PFC) is used. A new differential-mode choke filter is implemented in the developed boost converter. The choke here is a specially made differential inductor in the input of the boost converter that eliminates the known current interactions. To prove the new concept, a study of the level of mitigation of the current interactions is presented. The control is operated in continuous driving mode (CCM), and the popular UC3854B circuit was used for this. The rectifier proposal is validated through a set of simulations performed on the PSIM 12.0 platform, as well as the construction of a prototype. With the results obtained, it is confirmed that the differential-mode choke filter eliminates the current interactions. It is observed that at the input of the rectifier, a sinusoidal alternating current with a low level of harmonic distortion is consumed from the grid. The sinusoidal shape of the phase current proves that a better power factor capable of meeting the international standards is obtained, and that the circuit in its initial version is operational. This proven result promises a good PFC operation, to guarantee the better quality of the electrical energy, being able to be applied in systems that require a high PFC, e.g., in battery charging, wind systems, or in aeronautics and spacecrafts.

An experience of performing spirometry by trained general practitioners

2020 ◽  
pp. 34-36
Author(s):  
M. A. Pokhaznikova ◽  
E. A. Andreeva ◽  
O. Yu. Kuznetsova
Keyword(s):  
General Practitioners ◽  
Quality Criteria ◽  
Poor Quality ◽  
Male Gender ◽  
Study Research ◽  
The Poor ◽  
Quality Of Research ◽  
Forced Expiratory Maneuver ◽  
Maximal Effort

The article discusses the experience of teaching and conducting spirometry of general practitioners as part of the RESPECT study (RESearch on the PrEvalence and the diagnosis of COPD and its Tobacco-related aetiology). A total of 33 trained in spirometry general practitioners performed a study of 3119 patients. Quality criteria met 84.1% of spirometric studies. The analysis of the most common mistakes made by doctors during the forced expiratory maneuver is included. The most frequent errors were expiration exhalation of less than 6s (54%), non-maximal effort throughout the test and lack of reproducibility (11.3%). Independent predictors of poor spirogram quality were male gender, obstruction (FEV1 /FVC<0.7), and the center where the study was performed. The number of good-quality spirograms ranged from 96.1% (95% CI 83.2–110.4) to 59.8% (95% CI 49.6–71.4) depending on the center. Subsequently, an analysis of the reasons behind the poor quality of research in individual centers was conducted and the identified shortcomings were eliminated. The poor quality of the spirograms was associated either with the errors of the doctors who undertook the study or with the technical malfunctions of the spirometer.

Supply Chain Integration: Establish the Appropriate Challenges in Improving Integrated SC in an Innovative Approach of IBS

2016 ◽  
Vol 1 (3) ◽  
Author(s):  
Ani Saifuza Abd Shukor ◽  
Muhammad Fadhil Muhammad ◽  
Shamsida Saidan Khaderi ◽  
Faridah Muhammad Halil
Keyword(s):  
Supply Chain ◽  
System Integration ◽  
Publishing House ◽  
Structured Interview ◽  
Poor Quality ◽  
Supply Chain Integration ◽  
Project Environment ◽  
The Poor ◽  
International Publishing

The shift to an integrated IBS construction approach requires enhanced supply chain integration to improve the productivity as well as the poor quality of human behavioual aspect in IBS project. This paper is to identify the challenges at each tier between players to facilitate supply chain integration among the IBS players. Findings adopted from semi-structured interview revealed the critical attitude issues of human factors, lack of interaction and sharing knowledge between interdisciplinary people. The findings of this study is useful to improve integration of supply chain and enhance innovation and sharing interaction between players in the IBS Malaysian construction project environment.© 2016. The Authors. Published for AMER ABRA by e-International Publishing House, Ltd., UK. Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia.Keywords: Construction Environment; Industrialised Building System; Integration and Supply Chain 

scholarly journals Hybrid Three-Phase Rectifiers with Active Power Factor Correction: A Systematic Review

Electronics ◽  
2021 ◽  
Vol 10 (13) ◽  
pp. 1520
Author(s):  
José Teixeira Gonçalves ◽  
Stanimir Valtchev ◽  
Rui Melicio ◽  
Alcides Gonçalves ◽  
Frede Blaabjerg
Keyword(s):  
Power Factor ◽  
Power Distribution ◽  
Harmonic Distortion ◽  
International Standards ◽  
Pwm Converter ◽  
High Power Factor ◽  
Three Phase ◽  
Sinusoidal Input ◽  
Converter Topologies ◽  
Future Direction

The hybrid three-phase rectifiers (HTR) consist of parallel associations of two rectifiers (rectifier 1 and rectifier 2), each one of them with a distinct operation, while the sum of their input currents forms a sinusoidal or multilevel waveform. In general, rectifier 1 is a GRAETZ (full bridge) (can be combined with a BOOST converter) and rectifier 2 is combined with a DC-DC converter. In this HTR contest, this paper is intended to answer some important questions about those hybrid rectifiers. To obtain the correct answers, the study is conducted as an analysis of a systematic literature review. Thus, a search was carried out in the databases, mostly IEEE and IET, and 34 papers were selected as the best corresponding to the HTR theme. It is observed that the preferred form of power distribution in unidirectional hybrid three-phase rectifiers (UHTR) is 55%Po (rectifier 1) and 45%Po (rectifier 2). For the bidirectional hybrid three-phase rectifiers (BHTR), rectifier 1 preferably takes 90% of Po and 10% of Po is processed by rectifier 2. It is also observed that the UHTR that employ the single-ended primary-inductor converter (SEPIC) or VIENNA converter topologies in rectifier 2 can present sinusoidal input currents with low total harmonic distortion (THD) and high Power Factor (PF), even successfully complying with the international standards. The same can be said about the rectifier that employs a pulse-width (PWM) converter of BOOST topology in rectifier 2. In short, the HTR are interesting because they allow using the GRAETZ full bridge topology in rectifier 1, thus taking advantage of its characteristics, being simple, robust, and reliable. At the same time, the advantages of rectifier 2, i.e., high PF and low THD, are well used. In addition, this article also points out the future direction of research that is still unexplored in the literature, thus giving opportunities for future innovation.

Usability of India’s government statistics1

2020 ◽  
pp. 1-17
Author(s):  
Vikas Kumar
Keyword(s):  
National Sample ◽  
Poor Quality ◽  
Sample Surveys ◽  
Sources Of Information ◽  
Cross Sectional ◽  
Jammu And Kashmir ◽  
The Poor ◽  
Government Statistics

The quality of metadata is a crucial determinant of usability/interpretability of data. This paper draws attention to the poor quality of India’s government statistics and the paucity of metadata necessary to understand the problems. The paper suggests that there has been a decline in India both in terms of the availability and quality of metadata for key government sources of information including maps, decennial population censuses and National Sample Surveys amidst growing sophistication in the understanding of metadata. The poor quality of metadata impairs cross-sectional as well as inter-temporal comparisons and policymaking apart from concealing biases and lapses of government statisticians. The paper draws on the experience of three states – erstwhile Jammu and Kashmir, Manipur and Nagaland – where government statistics have been affected by serious errors that are not well-understood due to the lack of adequate metadata.

Numerical Analysis of Masonry under Compression via Micro-Model

2011 ◽  
Vol 243-249 ◽  
pp. 1360-1365 ◽  
Author(s):  
Wei Rong Lü ◽  
Meng Wang ◽  
Xi Jun Liu
Keyword(s):  
Joint Strength ◽  
Ultimate Load ◽  
Poor Quality ◽  
Micro Model ◽  
Element Analysis ◽  
Mortar Joint ◽  
The Poor ◽  
The Finite Element Analysis ◽  
Brick And Mortar

The micro-model, which the brick and the mortar model are separated, is used to analyze masonry. Meanwhile, the mortar is divided into three layers along the thickness direction to obtain the internal mechanical behavior of mortar, and the vertical mortar joint strength is taken as 50% strength of the horizontal mortar joint for considering the poor quality of vertical mortar joint. The compressive ultimate load and failure mode of masonry taken from the finite element analysis result, especially the vertical cracks throughout all bricks and mortar and change of brick and mortar strain, are in agreement with the experimental results. It shows that the micro-model and method adopted in paper are able to effectively apply in nonlinear structural analysis for masonry.

A ‘Galilean’ science of language

2014 ◽  
Vol 50 (3) ◽  
pp. 671-704 ◽  
Author(s):  
CHRISTINA BEHME
Keyword(s):  
Language Evolution ◽  
Relevant Literature ◽  
Child Psychology ◽  
Scientific Work ◽  
Poor Quality ◽  
The Poor ◽  
Recent Scholarship ◽  
Basic Understanding ◽  
Sixth Decade

The Science of Language, published in the sixth decade of Noam Chomsky's linguistic career, defends views that are visibly out of touch with recent research in formal linguistics, developmental child psychology, computational modeling of language acquisition, and language evolution. I argue that the poor quality of this volume is representative of the serious shortcomings of Chomsky's recent scholarship, especially of his criticism of and contribution to debates about language evolution. Chomsky creates the impression that he is quoting titbits of a massive body of scientific work he has conducted or is intimately familiar with. Yet his speculations reveal a lack of even basic understanding of biology, and an unwillingness to engage seriously with the relevant literature. At the same time, he ridicules the work of virtually all other theorists, without spelling out the views he disagrees with. A critical analysis of the ‘Galilean method’ demonstrates that Chomsky uses appeal to authority to insulate his own proposals against falsification by empirical counter-evidence. This form of discourse bears no serious relation to the way science proceeds.

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