The impact of bearing shield wear on the power factor of ac electric motors

2020 ◽  
pp. 76-84
Author(s):  
Fedor M. Erkhan ◽  
Nikolay I. Korneychuk ◽  
Elena V. Bomeshko
Keyword(s):  
Power Factor ◽  
Air Gap ◽  
Research Purpose ◽  
Technological Equipment ◽  
Electric Motors ◽  
Measurement Tools ◽  
Useful Power ◽  
Support Surfaces ◽  
Rotor Bearings ◽  
The Impact

During the operation of AC electric motors, the seats under the rotor bearings are worn out. Wear of these surfaces leads to a change in the air gap between the rotor and the stator of the electric motor, which leads to an increase in the reactance and power loss. (Research purpose) The research purpose is in determining the maximum allowable amount of wear on the seats for the rotor shaft bearings of the support panels, in which their further use is impractical without restoring the seats. (Materials and methods) Electric motors of various technological equipment were chosen as the object of research. Universal control and measurement tools were used for micrometering. (Results and discussion) During the micrometering, it has been revealed for electric motors of the A2, A. 02, 4AS series that the wear of support surfaces made of aluminum alloys varies within 0,05-0,24 millimeter, and for surfaces made of cast iron within 0,06-0,20 millimeter. It was found that changing the air gap between the stator and the rotor leads to a change in the density of the magnetic flux distribution, and as a result, to a decrease in the power factor, efficiency and useful power on the motor shaft. (Conclusions) It is found that during the operation of asynchronous electric motors of various technological equipment, the wear of the support surfaces occurs within the range of 0,05-0,24 millimeter, which affects the power factor.

The Impact of Electricity Losses on the Reliability of Electrical Equipment in the Rural Power Grid of 0.4 kV

2021 ◽  
Vol 1 (42) ◽  
pp. 34-38
Author(s):  
Gennadiy Kudryashev ◽  
◽  
Aleksandr Tret’yakov ◽  
Oksana Shpak
Keyword(s):  
Power Grid ◽  
Electrical Equipment ◽  
Probability Of Failure ◽  
Operating Conditions ◽  
Research Purpose ◽  
Electricity Supply ◽  
Industrial Complex ◽  
Electric Motors ◽  
Agricultural Enterprise ◽  
The Impact

Rural networks are characterized by a large length and low load density. In the country, there are problems with the reliability of electricity supply to agricultural enterprises and the uninterrupted operation of electrical equipment. The average duration of consumer outages is up to 100 hours annually. In Western developed countries, it is statistically defined as an acceptable state of electricity supply, when for a medium- voltage network during the year, the total duration of interruptions is in the range of 15-60 minutes per year. The permanent functioning of the Russian agro-industrial complex is impossible without reliable and stable operation of rural electric distribution networks. (Research purpose) The research purpose is in studying the impact of electricity losses on the reliability of electrical equipment in the rural power grid of 0.4 kilovolt. (Materials and methods) The methods of ensuring reliability include: design features of the system, reliability of electrical equipment; provision of backup power, system management tools, organization of operation. The reasons for the decrease in reliability were: equipment failures, errors of operating personnel, excess of resource capabilities, deviation of the actual operating conditions of the equipment from the calculated ones. (Results and discussion) The article considers the issues of additional electricity losses in the low- voltage network of 0.4 kilovolts on the example of the power supply of an agricultural enterprise, caused by the flow of reactive energy. The article presents graphs of phase voltages and power consumption. Authors conducted experimental studies in a network of 0.4 kilovolts. The article presents the calculated reliability indicators of electrical equipment at an agricultural enterprise. The increase in reliability when installing a compensating device in the 0.4 kilovolt network are described. (Conclusions) The increase of reliability of electrical equipment is revealed, the probability of failure operation of the electric motors decreased by 3 percent; the probability of failure operation of the electric motors decreased by 19 percent; reducing the failure rate by 15 percent; decrease in failure rates by 14 percent.

ORGANIZATIONAL AND TECHNOLOGICAL PRINCIPLES FOR CREATION INNOVATION CENTERS

2020 ◽  
Vol 4 (141) ◽  
pp. 40-46
Author(s):  
ZOYA MISHINA ◽  
Keyword(s):  
Research Purpose ◽  
Service Research ◽  
Industrial Complex ◽  
Technological Equipment ◽  
Technical Service ◽  
Agricultural Machinery ◽  
Efficient Operation ◽  
Technological Base ◽  
Reliability Of Operation ◽  
Production Areas

Timely conducting of all types of maintenance and routine repairs is possible only in the conditions of an innovative service center, equipped with the necessary equipment and having a complex of facilities to ensure favorable conditions for technical service. (Research purpose) The research purpose is in identifying opportunities for updating the technical service system in the agro-industrial complex by creating innovative service centers to ensure highly efficient operation of agricultural machinery and equipment. (Materials and methods) The system of maintenance in agriculture is characterized by a significant decrease in efficiency due to physical and moral wear of equipment of repair and technical enterprises, low level and insufficient qualification of personnel and managers of enterprises of the agro-industrial complex. The availability of existing enterprises of the agro-industrial complex with production areas is no more than 50 percent, technological equipment is no more than 47 percent, and technological equipment and equipment for jobs are 15 and 40 percent. (Results and discussion) The modernization of the infrastructure of technical service of agricultural machinery is aimed at updating the technological base of machine repair. Repair and technical enterprises do not have the necessary equipment to perform a number of maintenance and routine repairs. The process of developing technical service infrastructure is significantly behind the level of structural and technological complexity of agricultural machinery. Due to technological requirements, complex components and assemblies, such as engines, hydraulic equipment, fuel pumps of domestic and imported agricultural machinery should not be repaired in the conditions of farms. (Conclusions) The high technological level of innovative technical service centers serves as a condition for efficient operation of production, ensuring its stability and reliability of operation, flexibility and adaptability, high intensity and waste-free operation.

MODELING AND EXPERIMENTAL VERIFICATION OF AIR-THERMAL AND MICROWAVE-CONVECTIVE PRESOWING SEED TREATMENT

2020 ◽  
Vol 4 (41) ◽  
pp. 35-43
Author(s):  
ALEKSEY A. VASIL’EV ◽  
◽  
ALEKSEY N. VASIL’EV ◽  
DMITRIY BUDNIKOV ◽  
ANTON SHARKO
Keyword(s):  
High Frequency ◽  
Seed Treatment ◽  
Field Experiments ◽  
Research Purpose ◽  
Dense Layer ◽  
Technological Equipment ◽  
External Influence ◽  
Ultra High Frequency ◽  
Grain Processing ◽  
Seed Processing

The use of electrophysical influences for pre-sowing treatment of seeds is an effective way to increase their sowing quality. The use of these methods is limited by the fact that their implementation requires new technological equipment in grain processing lines. This problem is solved more easily when pre-sowing processing is performed using installations for active ventilation and grain drying. (Research purpose) The research purpose is in determining the possibility of using active ventilation units and ultra-high-frequency convective grain dryers for pre-sowing grain processing and to evaluating the effectiveness of such processing using computer modeling. (Materials and methods) It is necessary to ensure the uniformity of processing with external influence the seeds placed in a dense layer. Authors carried out pre-sowing treatment of seeds on real installations. Treated seeds were sown in experimental plots and the results of treatment were evaluated. (Results and discussion) The article presents graphs of changes in grain temperature and humidity during processing. To check the feasibility of pre-sowing treatment, authors performed modeling of air-heat and ultra-high-frequency convective seed treatment processes. Based on the results of field experiments, air-heat treatment stimulates the development of secondary plant roots, contributes to an intensive increase in the green mass of plants; ultra-high-frequency convective seed treatment allows increasing the number of productive stems in plants, the number of ears in one plant. (Conclusions) Technological equipment designed for drying and active ventilation of grain can be effectively used for pre-sowing seed processing. In the course of field experiments, it was revealed the possibility of controlling the structure of the crop using different types of external influence on seeds during their pre-sowing processing.

scholarly journals Optimization of Air Gap Length and Capacitive Auxiliary Winding in Three-Phase Induction Motors Based on a Genetic Algorithm

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4407
Author(s):  
Mbika Muteba
Keyword(s):  
Genetic Algorithm ◽  
Design Process ◽  
Power Factor ◽  
High Speed ◽  
High Efficiency ◽  
Air Gap ◽  
Element Analysis ◽  
Three Phase ◽  
High Torque ◽  
Cage Induction Motor

There is a necessity to design a three-phase squirrel cage induction motor (SCIM) for high-speed applications with a larger air gap length in order to limit the distortion of air gap flux density, the thermal expansion of stator and rotor teeth, centrifugal forces, and the magnetic pull. To that effect, a larger air gap length lowers the power factor, efficiency, and torque density of a three-phase SCIM. This should inform motor design engineers to take special care during the design process of a three-phase SCIM by selecting an air gap length that will provide optimal performance. This paper presents an approach that would assist with the selection of an optimal air gap length (OAL) and optimal capacitive auxiliary stator winding (OCASW) configuration for a high torque per ampere (TPA) three-phase SCIM. A genetic algorithm (GA) assisted by finite element analysis (FEA) is used in the design process to determine the OAL and OCASW required to obtain a high torque per ampere without compromising the merit of achieving an excellent power factor and high efficiency for a three-phase SCIM. The performance of the optimized three-phase SCIM is compared to unoptimized machines. The results obtained from FEA are validated through experimental measurements. Owing to the penalty functions related to the value of objective and constraint functions introduced in the genetic algorithm model, both the FEA and experimental results provide evidence that an enhanced torque per ampere three-phase SCIM can be realized for a large OAL and OCASW with high efficiency and an excellent power factor in different working conditions.

Tinnitus Impact: Three Different Measurement Tools

2003 ◽  
Vol 14 (04) ◽  
pp. 181-187 ◽  
Author(s):  
Christopher D. Bauch ◽  
Susan G. Lynn ◽  
Donald E. Williams ◽  
Michael W. Mellon ◽  
Amy L. Weaver
Keyword(s):  
Quality Of Life ◽  
Severity Index ◽  
Assessment Tools ◽  
Symptom Checklist ◽  
Tinnitus Handicap Inventory ◽  
Measurement Tools ◽  
Medical Population ◽  
High Level ◽  
The Impact

The impact of tinnitus and overall levels of distress were measured with three assessment tools for patients with tinnitus. The Tinnitus Handicap Inventory (THI), the Symptom Checklist-90-Revised (SCL-90-R) and an activities limitations questionnaire were administered to 53 audiology patients reporting tinnitus. Forty-three percent of these patients experienced either quality of life reductions associated with tinnitus, substantial perceived handicap, and/or a high level of distress. Results from the General Severity Index (GSI) of the SCL-90-R indicated that 25% of these patients displayed distress greater than that of the general medical population. The SCL-90-R can be a useful tool for audiologists working with tinnitus patients in assessing needs for referral for psychological or psychiatric counseling.

scholarly journals Effectiveness of a Power Factor Correction Policy in Improving the Energy Efficiency of Large-Scale Electricity Users in Ghana

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2582 ◽  
Author(s):  
Samuel Lotsu ◽  
Yuichiro Yoshida ◽  
Katsufumi Fukuda ◽  
Bing He
Keyword(s):  
Energy Efficiency ◽  
Power Factor ◽  
Large Scale ◽  
Regression Discontinuity ◽  
Power Factor Correction ◽  
Energy Crisis ◽  
Regression Discontinuity Design ◽  
The Government ◽  
Power Factor Improvement ◽  
The Impact

Confronting an energy crisis, the government of Ghana enacted a power factor correction policy in 1995. The policy imposes a penalty on large-scale electricity users, namely, special load tariff (SLT) customers of the Electricity Company of Ghana (ECG), whose power factor is below 90%. This paper investigates the impact of this policy on these firms’ power factor improvement by using panel data from 183 SLT customers from 1994 to 1997 and from 2012. To avoid potential endogeneity, this paper adopts a regression discontinuity design (RDD) with the power factor of the firms in the previous year as a running variable, with its cutoff set at the penalty threshold. The result shows that these large-scale electricity users who face the penalty because their power factor falls just short of the threshold are more likely to improve their power factor in the subsequent year, implying that the power factor correction policy implemented by Ghana’s government is effective.

Failure Mechanism Analysis of Electromagnetic Relay under Mechanical Impact

2013 ◽  
Vol 473 ◽  
pp. 39-45 ◽  
Author(s):  
Guo Wei Zhao ◽  
Yong Chen ◽  
De Yong Li ◽  
Bin Tang
Keyword(s):  
Failure Mechanism ◽  
Magnetic Circuit ◽  
Impact Damage ◽  
Engineering Application ◽  
Air Gap ◽  
Mechanism Analysis ◽  
Mechanical Impact ◽  
Electromagnetic Relay ◽  
Electromagnetic Relays ◽  
The Impact

The aim was to analyze failure mechanism of electromagnetic relay caused by mechanical impact. The principle of electromagnetic relays was studied and the effect of mechanical impact on electromagnetic relays was analyzed in this paper. Based on the established magnetic circuit model, the relationship of the magnetic field strength, the electromagnetic attraction and the impact damage degree was studied. Then, the damage intensity of mechanical impact on magnetic circuit was decided. Afterwards, the structure of electromagnetic relays was improved, and the mechanical impact simulation was studied by ANSYS. The results show that the uncontrollability of electromagnetic relay is mainly caused by air gap, which is aroused by mechanical impact; in addition, the size of air gap is inversely proportional to electromagnetic attraction force. Moreover, the improved structure of relays can increase impact resistance and broaden the scope of engineering application of electromagnetic relay.

scholarly journals The Psychological Impact of COVID-19 Among Pakistani Adults in Lahore

2021 ◽  
Vol 9 ◽  
Author(s):  
Saima Majeed ◽  
Elizabeth Maria Schwaiger ◽  
Abia Nazim ◽  
Ivan Suneel Samuel
Keyword(s):  
Online Survey ◽  
Family System ◽  
Nuclear Family ◽  
Psychological Impact ◽  
The Novel ◽  
Snowball Sampling ◽  
Measurement Tools ◽  
Novel Coronavirus ◽  
Restrictive Measures ◽  
The Impact

Background: In the wake of the worldwide spread of the novel coronavirus and the resultant restrictive measures, mental health has become a crucial issue. Physical health is not the only aspect of humans that is at risk. Globally, the rates and severity of mental illness are being significantly impacted by this pandemic. Two scales have been validated to measure the impact of coronavirus disease 2019 (COVID-19) on the levels of anxiety and obsessional thinking in clinical and non-clinical populations. The present study was designed to investigate the levels of anxiety and obsessions related to COVID-19 in the general public of Lahore, Pakistan.Materials and Methods: Data were collected via snowball sampling from May 9 to May 19. An online survey consisting of a demographic profile and two scales, Coronavirus Anxiety Scale (CAS) and Obsession with COVID-19 Scale (OCS), was sent through email, WhatsApp, and Facebook groups to adults (18 years and above) of Lahore, Pakistan.Results: A total of 240 individuals (20% men and 80% women) recorded their responses. The majority belonged to a nuclear family system (60%), and their education level ranged from high school to Ph.D. The cut-off score for probable dysfunctional coronavirus anxiety and obsession levels was not met within this sample (CAS, M = 3.24, SD = 4.21; OCS, M = 4.14, SD = 3.15), suggesting that the general population of Lahore, Pakistan is not suffering from dysfunctional anxiety or obsessions related to COVID-19. Forty-seven participants' score on OCS and 35 participants' scores on CAS were above the cut-off, i.e., ≥7 and ≥9, respectively. The results of the correlation analysis showed a significant positive relationship (**p < 0.619) between anxiety and obsessions related to COVID-19.Conclusion: One important, yet surprising, conclusion of this study is that the average adult in Lahore does not show much anxiety or obsessions related to COVID-19. Other studies around the world using these measurement tools have indicated significantly high levels of both anxiety and obsessions related to COVID-19. These findings may demonstrate the resilience of Pakistanis or perhaps the lack of understanding of the seriousness of the situation.

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