The main type of electric motors used in the electric drive of technological processes are induction motors with a squirrel-cage rotor. With proper operation, they have a higher MTBF (Mean Time Between Failures). It was found that one of the common causes of engine failure is bearing wear and, as a result, increased rotor eccentricity. We used the oscillating amplitude of the rotor speed in the transient state as a diagnostic parameter. The paper presents a method for this troubleshooting, a block scheme and appearance of the experimental installation, and a single-line diagram of the transmitter for measuring rpm. The experience has established the optimal ADC sampling frequency for experimentation to be carried out. The results of studies of changes in the rotor speed oscillating from time to time under load at rotor eccentricity have been given.
Squirrel-cage induction motors are the main type of electric motors used for the electric motor drive of the working mechanism of industrial processes. The task of the electrical service of the enterprise is to control the engine power during operation and to prevent overloads or inefficient operations. In order to do that a non-contact method for determining the power of squirrel-cage induction motors is proposed. The method is based on the property of the mechanical characteristics of an induction motor, when with increasing the moment of resistance on the drive shaft, the rotor speed decreases in proportion to the load. Therefore, by measuring the rotor speed of the engine, it is possible to judge the degree of its load. To confirm this, experimental studies of axial fans were carried out. Linear supply voltage, winding current, active power, power factor and engine speed were used as the analyzed parameters of the motors. For more information about the state of the motor, in addition to analyzing the stator current, an analysis of the frequency of the supply voltage, as well as the input power, which is directly related to the current and supply voltage, was made. In the course of the experiments, a number of functional dependences of engine performance on its speed were obtained. It was established that tests are necessary for not only repaired engines, but also new ones to determine the optimal modes of its operation and identify production defects.
Service equipment of the heat sources taken by supervision consisted of centrifugal water pumps, blast air fans and exhausters. Robust and fail safe operation of the heat sources is impossible without the effective operation of this service equipment. Malfunctions of the service equipment resгде in disruption of heat supply, losses and emergencies. Consequently, to provide a robust operation of the equipment there were found the impending failure, classified and described. The main type of the electric engines used for the electric drive of the working organs of the service equipment are asynchronous electric drives with a short-circuited rotor which is mostly exposed to the external influence. In this work there are collected and analyzed reasons of fault inception of the service equipment as well as methods to define the complex parameter of technical state is developed and its functional dependence on failure interval is set. The acquired data may be used to define the readiness of the equipment for operation to the coming period as well as plan its maintenance operation and overhaul.
A squirrel-cage induction motor is the most common motor used to drive working machines in various technological processes, including in the agricultural sector. A sufficiently large resource is laid in them by the manufacturer, but in practice the engine serves much less, due to various factors, including imperfection of diagnostic systems. Failure analysis showed that one of the common causes of failure is increased bearing wear. An increase in the rotor eccentricity is the main diagnostic parameter of this malfunction, for the detection of which a diagnostic method was developed that allows using the indirect indicator, the rotor speed, to evaluate the technical condition of the engine bearings. To identify the dependence of diagnostic parameters on the technical condition, a virtual model of an asynchronous motor with rotor eccentricity was built. The model is implemented using a package of applied mathematical programs and allows you to simulate the operation of an induction motor in various modes, such as starting, idling, steady state with the ability to change the nature of the load. As a result, we obtained the dependences of the angular velocity of rotation of the rotor, stator current, and torque on the shaft versus time for various technical conditions of the engine.
The most common electric motor to drive working machines is an asynchronous one with a short-circuited rotor. It has a fairly large resource, provided proper operation. When analysing faults, it was found that the most common cause of failure is increased wear of bearings. The diagnostic parameter of this fault is an increase in the eccentricity of the rotor, to identify which we have developed a diagnostic method that allows us to evaluate the technical condition of the engine using an indirect indicator, the rotor speed. To make a diagnosis, it is necessary to process the data on the dynamics of change in the rotor speed of the engine and predict its operation for the forthcoming period. To simplify data processing, a program has been developed that is an automated system for analysing diagnostic parameters and can significantly reduce the laboriousness and time of diagnosis, eliminating the influence of the human factor. The developed programme was used to analyse the operation of asynchronous engines in poultry house ventilation systems, to predict their failure, as well as to plan maintenance and repair.
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