Up to 38% of asynchronous motor (AM) failures are caused by damage to the stator insulation. Despite the wide variety of methods, the reliability of determining the inter-turn short circuits of stator windings under operating voltage still remains at a low level. The existing methods for diagnostics of asynchronous motor failure of the interturn short circuit of stator winding have been examined. New diagnostic methods for individual parameters developed in the course of the previous study are described. A new diagnostic method is formulated, on the basis of which the research work is carried out. The method will allow us to constantly monitor the technical condition of the stator winding, and identify its damage at an early stage of their development. Diagnostics can be performed without dismantling the engine and without removing it from the working process. The microprocessor unit is implemented for diagnostics of the technical condition of AM introducing this method. Moreover, the software and hardware complex is implemented for diagnostics of the technical condition for AM. The results of experiments on a laboratory stand with inter-turn AM closures are presented, which confirm the higher reliability of monitoring.
The article considers the important problem of technical and economic optimization of the operating modes of the first rise section of water supply systems. At the same time, the task is to minimize the costs associated with the excessive operation of pumps, while providing the protection of the pipeline from freezing in harsh natural operating conditions. To solve this problem, a computer simulation model was developed for the first rise section, equipped with a pump performance control system. The main differences of the developed model are: integrated approach to the analysis of parameters of various physical nature, assessment of the object economic indicators, possibility of simulating non-standard control algorithms. Preliminary studies of the model have shown the possibility and feasibility of its application for calculating the optimal parameters and operating modes of the object under consideration. Based on the simulation results, it was revealed that to calculate the control action by level, it is advisable to use the PID law, for temperature—PD law, for flow rate—PI law. To calculate the main control action, it is proposed to simultaneously calculate the actions in terms of level and temperature, followed by bringing the larger of them to the value of the setpoint for the flow rate maintained by the flow controller. The studies of the proposed management concept for the first rise section have shown its high technical and economic efficiency. In particular, the savings in electricity consumption are estimated at about 55.2% while providing pipeline frost protection.
OBJECT. The work is aimed at solving an important problem of increasing the economic efficiency, the level of resource saving and accident-free operation of the first rise section of the centralized water supply systems of small and medium-sized settlements. At the same time, the task is to minimize the cost of electricity associated with the excess performance of pumps, while ensuring the protection of the pipeline from freezing in conditions of negative ambient temperatures. METHODS. To solve this problem, an optimal method for controlling electric drives of first rise pumps at the request of the end user of water was developed, which differs from the existing ones by analyzing the state of the thermal parameters of the pipeline. The method is based on the calculation of control actions based on the water level in the storage reservoir or the water pressure in the pipeline UL and the water temperature at the end of the pipeline UT, followed by the calculation of the optimal pump supply setpoint, which is then maintained by the frequency control method. The Matlab® Simulink simulation model was used to determine the optimal laws for calculating control actions and evaluate the effectiveness of the proposed solutions. RESULTS. Based on the simulation results, it was found that it is advisable to use the PID law for calculating the control effect for the UL level, the PD law for the UT temperature, and the PI law for the flow rate. The parameters of the technological process and the level of power consumption in the control process were also evaluated. CONCLUSIONS. Studies of the proposed concept of managing the first rise section have shown high technical and economic efficiency, in particular, the savings in electricity consumption are estimated at about 22 % while ensuring the protection of the pipeline from freezing.
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