Reliability Of Electrical Machines Research Articles

Direct Thermal Management of Windings Enabled by Additive Manufacturing

The electrification and hybridization of ground- and air-transport, in pursuit of Carbon Net Zero targets, is driving demand for high power-density electrical machines. The power-density and reliability of electrical machines is ultimately limited by their ability to dissipate internally generated losses within the temperature constraints of the electrical insulation system. As the electrical windings are typically the dominant source of loss, their enhanced design is in the critical path to improvements in power-density. Application of metal additive manufacturing has the potential to disrupt conventional winding design by removing restrictions on conductor profiles, topologies and embedded thermal management. In this paper, a modular end-winding heat exchanger concept is presented, which enables effective direct cooling without occupying valuable stator slot cross-section. In addition, this arrangement eliminates the need for a good stator-winding thermal interface, thereby allowing mechanical or other less permanent winding retention methods to be used, facilitating non-destructive disassembly and repair. A prototype winding is fabricated and experimentally tested to demonstrate the feasibility of the concept, yielding promising results.

Monitoring Single-Phase LV Charging of Electric Vehicles

The paper presents the results of the monitoring process of the charging of an electric vehicle battery pack. Battery pack charging with a capacity of 58kWh was monitored in a single-phase 230V/50Hz circuit. The slow charging system used was configured to obtain a current of 10A. During monitoring, the focus was on the recognition of the charging, considering the impact of this process on power quality and, consequently, on the reliability of electrical machines. Research results show that the monitored charges are one-, two-, or three-stage processes. The variations in the currents, power, and higher harmonic contents were observed. The effects of such variations depend on the properties of the power grid at the point of connection of the charging system. Knowledge of the variation of the voltages, currents, and active and reactive power allows for the determination of the requirements of the measuring equipment used for charging the monitoring, including the selection of discrimination/averaging time of monitored quantities. The research results also indicate the need for continuous monitoring of the power quality in the power supply circuit of electrical loads, e.g., electrical machines. Continuous monitoring supports the diagnostics of electrical machines and allows the appropriate measures to increase their reliability.

Electrical Machinery Construction in Russia

The state of electrical machinery construction, which is an important basis of Russia’s electrical industry, is assessed. The article places focus on the competitiveness and self-sufficiency of domestic electrical machinery construction industry, its enterprises and production volumes. The production of electrical machinery around the world and the organizational interaction of its main manufacturers are also considered. The state of science in the field of electrical machinery construction is analyzed, and achievements in improving the energy efficiency, specific power capacity, and reliability of electrical machines are shown. Prospects for the development of adjustable-frequency motors, as well as machines operating under extreme loads that are used in electric transmission systems of urban, railway, marine transport, agriculture, and mining industry are discussed. Promising issues in the field of research activities aimed at development of new electrical machines and drive systems are considered. In conclusion, information is provided on the state of production at the enterprises of the Ruselprom Concern, one of the largest manufacturers of a wide range of electrical machines. The article is written in the form of answers Dr. Sci. (Eng.) L.N. Makarov, General Designer of Ruselprom Concern gave to the questions of P.A. Butyrin, Corresponding Member of the RAS, Dr. Sci. (Eng.), Editor-in-Chief of the journal Elektrichestvo.

Automated system for warming up traction electrical equipment of an electric locomotive

The successful operation of electric locomotives depends largely on the reliability of electrical machines. Reliability is the most important technical and economic indicator of the quality of the functioning of any technical device, in particular an electrical machine, which determines its ability to operate without fail with unchanged technical characteristics for a given period of time under certain operating conditions. In the presented scientific work, a detailed analysis of the causes of breakdown of traction electric motors is made. The aim of the study is to develop a technical solution to reduce the heating time, power consumption and to exclude or minimize the formation of condensation on the insulation of traction motors. The expediency of modernizing the positions of locomotive warming up before calling for repairs has been substantiated. This technical solution meets all the requirements for maintaining traction electrical equipment in good condition. The found technical solution is aimed at increasing the operational reliability of the insulation of traction electrical equipment, reducing the time of the heating process.

Methodology for the assessment of the operation reliability of pulling electric machines of city electric transport

One of the most commonly used means of the city’s electric traffic system is trolleybus that has a lot of advantages in comparison with fixed-route taxis, buses and trams. During trolleybuses operation, the most electric and mechanical load has an effect on the traction electric engines, on which the further effective operation of a trolleybus on a transfer line depends. Statistic data concerning the trolleybuses operations in Ukraine prove that reliability of traction electric engines has been reduced for subjective and objective reasons over the past 10-15 years. New developments and the use of technologies are therefore needed for more effective use of the known technical equipment, its modernization, reliability improvement and extending the service life. To determine the effectiveness of trolleybus operation on the route, the modern methods of reliability assessment of the traction electric engines are used, which allow to get adequate characteristics of the structure, functional links of parts and units. But some methods don’t meet the necessary requirements to ensure the reliability of traction electric engines operation. So the subject and the tasks of the research work are still relevant today. New solutions of characterization the reliability of traction electric engines guarantee reducing energy and resource consumption during operation, repair and production. A methodology is presented that allows assessing the operational reliability of electrical machines from the point of view of system analysis. Uncertainty of information data arising during the operation of electrical machines is considered. The decomposition of the goal for the efficient operation and maintenance of electrical machines has been carried out, which is reflected in the form of a "goal tree". The results obtained can be used as initial data for the formulation and solution of a number of problems of control over the operational reliability of electrical machines.

Calculation of residual technical resource and increase in reliability of electric machines

In this paper, we consider a probabilistic mathematical model for estimating the state of the traction motor of a trolleybus. The operation of electric motors in transport is inevitably associated with gradual wear and tear and the need for periodic repairs. For the effective construction of systems of preventive measures, control, testing, current and major repairs, the importance of the causes of the failure of electric motors is necessary.

The reliability increase of the electric drives for pumping units

Improving the quality and reliability of electrical machines is one of the most urgent problems of modern electrical engineering. Practical data show that the increase of service life and reliability of machines gives better results than the improvement of other technical and economic indicators: efficiency, power factor, utilization factor. The quantitative indicators of reliability can be best determined by the results of statistical processing of the information obtained when using the products. An algorithm of the load balancing based on the actual performance of pumping equipment and temporary changes in the connected load via the emergency shutdown of the pumps has been developed to improve the reliability operation and reduce inefficient energy losses. The main advantage of the proposed method is the analytical design models of optimization, which does not require numerical methods and iterative procedures. Such principles as active-preventative service and increasing personal responsibility for its quality and timeliness should be the basis for the organization of workposts service. Progressive forms of service are the technical re-equipment, modernization of equipment and improvement of production organization, as well as complex methods of the electric drive maintenance and application of the system of standardized tasks.

“Aging” characteristic of the insulation of the winding of electrical machines and equipment during service

To improve the reliability of electrical machines and equipment, it is necessary to change over to operating them based on their actual condition. This article examines the evaluation of the insulation of the windings of an electric drive and describes a method of determining the thermophysical characteristics of the insulation.