The reliability of a low-voltage asynchronous electric motor is primarily determined by the reliability of the stator winding insulation. Common reasons for the failure of the insulation system are the unsatisfactory quality of the enameled wires and electrical insulating materials used for imperfection and violation of the technological process of winding and insulating work, and the discrepancy between operating modes. In the vast majority of cases, failures occur due to damage to the inter-turn insulation as the weakest element. This causes the need to study the insulation system resistance to the formation of defects. The results of assessing the stability of the insulation of winding wires to defect formation are obtained, taking into account the features of the operational loads characteristic of frequency-controlled drives with pulse-width modulation of the output voltage and the influence of the inter-turn insulation defectiveness level on its reliability indicators is also studied. The authors have developed the measures to reduce the defectiveness of inter-turn insulation at the manufacturing stage and during operation. This will ensure a minimum level of insulation defects and increase the resource of asynchronous electric motors by reducing the number of failures.
To support modern requirements for an induction electric drive of pipeline valves, the most promising is the organization of a filed oriented control system, the setting of which is extremely difficult without the parameters of the equivalent circuit of an induction machine. This article provides a technique of setting a field oriented control system for induction electric drive of pipeline valves based on equivalent circuit parameters, estimated by falling phase current curve. The main aim of the research is to test the functioning of an induction filed oriented electric drive using a load stand, the setting of which is made on the basis of parameters previously estimated by falling phase current curve. Methods. To achieve the goal of the research, theoretical and experimental research methods were used. Theoretical research methods include the theory of electric drive, the theory of automatic control systems, the theory of electrical machines. Experimental research were carried out using a load stand that provides the required level of load on the shaft of the tested induction machine. Results. Suggested the technique of setting a field oriented control system for induction electric drive of pipeline valves based on equivalent circuit parameters, estimated by falling phase current curve. Relative values of deviations of current, speed and torque are obtained at the nominal level of load on the shaft of an induction machine. The applicability of the proposed technique using a loading stand was confirmed.
To cool solar panels in hot season, it is necessary to use special cooling devices. The most optimal way of cooling is the use of liquid cooling, realized by means of a pump. This article provides an overview and evaluation of ways to cool solar panels using various devices. The relevance of the research is caused by the need to reduce the temperature of solar panels in order to increase the output power in the hot season. The main aim of the research is to compare and choose the most optimal way to cool solar panels. Methods: comparative analysis, mathematical modeling in the ANSYS environment. Results. Comparative characteristic of TEM, radiators, fans and liquid cooling is given, an example of cooling a solar panel using liquid cooling to spray a liquid flow of 29 l/min is calculated. The panels will cool down from 45 to 35 °C in 4,7 minutes. For one EasySunSolar solar panel with a capacity of 100 W, costing $100, taking into account electrical work, an additional heat sink module will cost about $50.
To support modern requirements for an induction electric drive of pipeline valves, the most promising is the organization of a filed oriented control system, the setting of which is extremely difficult without the parameters of the equivalent circuit of an induction machine. This article provides a technique of setting a field oriented control system for induction electric drive of pipeline valves based on equivalent circuit parameters, estimated by falling phase current curve. The main aim of the research is to test the functioning of an induction filed oriented electric drive using a load stand, the setting of which is made on the basis of parameters previously estimated by falling phase current curve. Methods. To achieve the goal of the research, theoretical and experimental research methods were used. Theoretical research methods include the theory of electric drive, the theory of automatic control systems, the theory of electrical machines. Experimental research were carried out using a load stand that provides the required level of load on the shaft of the tested induction machine. Results. Suggested the technique of setting a field oriented control system for induction electric drive of pipeline valves based on equivalent circuit parameters, estimated by falling phase current curve. Relative values of deviations of current, speed and torque are obtained at the nominal level of load on the shaft of an induction machine. The applicability of the proposed technique using a loading stand was confirmed.
In the present work, Al7075 based hybrid composites was developed using stir casting technique. Al7075 hybrid composites with different weight percentage of Mica, Graphite and E-glass fiber were developed to study the effect of these reinforcements on microstructure and mechanical properties, E-Glass fiber is kept constant at 0, 2, 4%, Mica is varied from 1-3% in steps of 1 and Graphite varied from 1-5% in steps of 2. It can be seen that the three peaks corresponding to Al were seen at 38º, 46º and 65º 2θ angles and small peaks related to all the three reinforcement mica, graphite and E-glass fiber were observed in the XRD pattern. Grain size analysis was examined using Clemex Image-Analyzer software, it was observed that decrease in grain size of Al7075 matrix was found to decrease with the increase in reinforcements, Hardness was found to increase with increase in reinforcement content whether it could E-glass fiber from 0% - 4% or mica from 1% - 3% or graphite content from 1% - 5%. Ultimate tensile strength increased with the increase in reinforcement content both before and after heat treatment.
