Short Circuit and Broken Rotor Faults Severity Discrimination in Induction Machines Using Non-invasive Optical Fiber Technology

Multiple techniques continue to be simultaneously utilized in the condition monitoring and fault detection of electric machines, as there is still no single technique that provides an all-round solution to fault finding in these machines. Having various machine fault-detection techniques is useful in allowing the ability to combine two or more in a manner that will provide a more comprehensive application-dependent condition-monitoring solution; especially, given the increasing role these machines are expected to play in man’s transition to a more sustainable environment, where many more electric machines will be required. This paper presents a novel non-invasive optical fiber using a stray flux technique for the condition monitoring and fault detection of induction machines. A giant magnetostrictive transducer, made of terfenol-D, was bonded onto a fiber Bragg grating, to form a composite FBG-T sensor, which utilizes the machines’ stray flux to determine the internal condition of the machine. Three machine conditions were investigated: healthy, broken rotor, and short circuit inter-turn fault. A tri-axial auto-data-logging flux meter was used to obtain stray magnetic flux measurements, and the numerical results obtained with LabView were analyzed in MATLAB. The optimal positioning and sensitivity of the FBG-T sensor were found to be transverse and 19.3810 pm/μT, respectively. The experimental results showed that the FBG-T sensor accurately distinguished each of the three machine conditions using a different order of magnitude of Bragg wavelength shifts, with the most severe fault reaching wavelength shifts of hundreds of picometres (pm) compared to the healthy and broken rotor conditions, which were in the low-to-mid-hundred and high-hundred picometre (pm) range, respectively. A fast Fourier transform (FFT) analysis, performed on the measured stray flux, revealed that the spectral content of the stray flux affected the magnetostrictive behavior of the magnetic dipoles of the terfenol-D transducer, which translated into strain on the fiber gratings.

Electroresistive method for monitoring the technical condition, quality, reliability and safety the supports of rolling of electrical machines

The necessity of monitoring the technical condition of the rolling supports of electric machines has been substantiated. It is proposed to use the electrical resistance of the bearing as an indicator of the technical condition the rolling support. The results of mathematical modeling of electrical resistance in the form of a function of resistance from factors of the internal environment of the bearing and modes of its assembly and operation in a rolling bearing are presented. An electroresistive method for monitoring the technical state the rolling support is proposed, which differs from the known methods by original algorithms for collecting information about the state of bearing parts, experimental studies have been carried out to confirm the efficiency of this method.

DIAGNOSTICS OF ROLLING EQUIPMENT SLIDING BEARINGS

Peculiarities of rolling bearings operation are analyzed. Methods of diagnostics of general purpose sliding bearings and rolling equipment are considered. Direct control of the maximum allowable wear of plain bearings during operation is proposed. It is advisable to provide remote information and consulting services to technical services of metallurgical enterprises for maintenance, repair and operation of crankshaft bearings. Bearings of electric machines of drives of rolls of rolling mills work in extremely difficult conditions with considerable overloads in the environment of the increased vibration. This leads to premature wear of the liner and its fatigue failure. The technical condition of bearings of electric machines of drives of rolls of rolling mills for the purpose of an exception of an emergency stop of production is carried out by indirect control of temperature and vibration. However, these controls do not guarantee an avoidance of an emergency. All problems with working plain bearings can be grouped into three groups: insufficient bearing capacity of the lubricating layer, unregulated clearance between the shaft and the liner, unsatisfactory technical condition of the bearing surfaces. Insufficient bearing capacity of the lubricating layer is more often associated with loss of lubricant properties due to improper maintenance of the lubrication system. The discrepancy between the size of the gap between the shaft and the liner to the normalized value arises from design, technological and operational reasons. Key words: plain bearing; failure; rolling equipment; direct wear control; remote information and consulting services

Aircraft Electric Machines

Current trend in aviation is to increase efficiency of all the aircraft’s systems. This leads to a reduction of fuel consumption which has also positive effect on emissions. One possibility how to reach this aim is to replace hydraulic and pneumatic system with an electrical power system. Because many on-board electrical loads are in the form of electrical drives, the special attention is given to electric motors and their electronic speed controllers / power converters. Furthermore, electric motors suitable for traction/propulsion are presented. Moreover, the various types of starter/generators suitable for on-board utilisation are compared in the paper.

Foreign trade relations between Ukraine and China: main directions of development

The article is devoted to the problems of developing foreign trade relations between Ukraine and China, as China ranks first in terms of trade among other trade partners of Ukraine. The article analyzes the reasons for China's interest in Ukraine and possible benefits for our country. The countries' export, import, foreign trade turnover, and foreign trade balance indicators are studied. The calculated indicators allowed us to state a positive trade balance for most goods, which indicates the advantage of exports over imports. The growth rates of exports and imports for the main product groups are calculated. It is concluded that the dynamics of international trade for ferrous metals, seeds, and fruits export growth rates are the highest, and electric machines and flour products - the lowest. The necessity of direct investments for further development in all spheres of the economy is substantiated. The structure of investment cooperation between Ukraine and China is analyzed, and conclusions are made about the number of direct investments coming from China. Based on the research and study of literature sources on the selected topic, the following conclusions were drawn on the prospects of foreign trade relations between China and Ukraine: it is advisable to study in detail the development of China's interests to adjust Ukraine's export policy to revive cooperation partners of Ukraine; as for the Ukrainian-Chinese trade relations, the following product groups have particular prospects for development: already positive in the foreign trade balance (corn, soybeans, barley, dairy products, honey), negative in the foreign trade balance (poultry, pork, fruits, vegetables) ) and products that do not require special state permits (sunflower oil and a wide range of food products). It is expedient to develop bilateral relations in mutually beneficial areas for both countries; there is a positive trade balance for most goods. For ferrous metals, seeds, and fruits, the export growth rates are the highest. For electric machines and flour products - the lowest, we need to emphasize the stabilization of exports of commodity groups, where export growth has increased. Ukraine needs to make tremendous efforts to join the «One Belt, One Road» initiative as a participant: because our country is only a watchdog. Also, you need to show more initiative and declare your desire to join the project «16 + 1»

Thermomechanical voltages in the insulation of traction electric machines of locomotive

In recent years, the production of locomotives in our country has increased significantly. At the same time, a lot of efforts are made to increase the power, reliability and efficiency of their work. One of the key components of any locomotive is electric traction machines, which are usually designed to the limit in order to obtain maximum torque and power density in the limited space of the rolling stock. Previously, this problem was solved by increasing the electromagnetic properties of materials, thermal conductivity of insulating materials. However, this path has exhausted the possibilities for increasing the efficiency of traction electric machines. As the design of traction electric machines improves, their level of functionality, reliability and durability increases, electric traction systems become more relevant and important for reducing the cost of materials, maintenance and ensuring traffic safety. The insulation state of the windings of traction electric machines mainly determines their reliability and performance, affects the service life and the cost of maintenance. Therefore, when designing a traction electric machine, it is important to take into account all operational factors that determine the optimal service life of a locomotive. The article discusses the effect of thermomechanical stresses in the insulation of traction electric machines on their reliability and durability.

Simulation of thermal processes in asynchronous traction electric motor of a locomotive

This article analyzes the problem of increasing the reliability of AC traction electric machines installed on traction rolling stock. In the course of the study, a finite element model of thermal processes was built, and the thermal state of an asynchronous traction motor (ATED) of a diesel locomotive was studied in the Solid Works program. The basic method for studying thermal processes in ATED was the finite element method (FEM), as well as the basic equations of heat transfer and the theory of heating a multicomponent solid. The constructed finite element model of the ATED rotor of a diesel locomotive makes it possible to determine the dependence of the temperature values of the rotor elements on the current flowing through them. The obtained values of the temperature distribution of the ATED squirrel-cage rotor are recommended to be taken into account in the design, manufacture and testing of AC electric machines of diesel locomotives.

Reactive inductor machines on transport

The experience of using reactive inductor machines (RIM) on vehicles is described. Over the past decade, the interest in RIM for the transport industry has significantly increased. One of the promising areas of RIM use is hybrid vehicles. A RIM has a simple design, high reliability and performance. It is capable of operating in motor and generator modes. The world experience in the development of vehicles with RIM has been promising in using this type of electric machines in electric power transmissions of locomotives.