Diagnostics three-phase asynchronous motors

The simplicity of the design of the asynchronous electric motors (AM) allows them to be widely used in industry. The AM fleet sometimes reaches 80% of the total load of the enterprise. According to statistics, more than 60% of AM failures are observed due to damage to the insulation of the AM stator winding. The reason is premature dynamic and thermal aging of the insulation, which leads to the failure of the conductive and grooved parts of the AM winding. As a result of a decrease in the dielectric properties of the insulation, damage occurs in the stator windings of AM, such as turn, phase-to-phase short circuits, which tend to develop into a short circuit. Short circuits in the stator windings of the AM are emergency and lead to a sudden disconnection of the AM from the power supply network by existing relay protection means, for example, current cut-off or thermal protection. Sudden, non-sanctioned disconnection of the electric motor from the power supply leads to the shutdown of technological equipment, damage to equipment, raw materials and economic losses. The aim of the work is to develop the principles of timely monitoring and prediction of the state of housing and interphrase insulation of stator windings of AM using the energy of capacitors with local compensation of reactive power. To achieve this goal, research was carried out at a laboratory institution with AM, in which branches of turns were made. The transient processes of capacitor discharge are considered and new methods for monitoring and predicting the residual insulation life are proposed. The new method is based on monitoring the condition of the insulation after each disconnection of the AM from the power supply, while using the energy that remains in the capacitors. The use of a change in the velocity characteristic of the constant discharge time of the capacitor made it possible to predict the residual service life of the AM. The personality of the study is that under the conditions of local compensation of reactive power, it is possible to use the energy remaining in the capacitors to diagnose and predict the state of insulation, as well as the change in the velocity characteristic of the capacitor discharge time constant, which is a criterion parameter for predicting the residual service life of the AM. The carried out studies confirmed the development of test diagnostics in conditions of reactive voltage compensation, which is a new direction in systems non-poisonous diagnostics, which requires continued research and applications in industry.

In order to improve the control result of three phase motor with power supplied by battery, it uses voltage vector control technology to control the three-phase motor excitation current and the torque current respectively. At the same time, according to the principle of rotor flux oriented, it get the aim of measuring and controlling the vector of three phase motor stator current. The research on the way of achieving the algorithm of the voltage space vector pulse width modulation is detailed introduced. By building the simulating model of three-phase asynchronous motor, it simulates the algorithm. As a result, it shows that the algorithm is reasonable, the control performance is better and application requirements of control for three-phase asynchronous motor with power supplied by battery is satisfied.

The timely detection of a critical state and forecasting the development of an emergency situation in the insulation of AM (asynchronous motor) windings is the main direction of increasing the economic efficiency of electrical engineering systems. One of the methods of reducing electricity losses is the compensation of reactive power, both complex and local. Asynchronous motors consume more than 60% of the produced electricity. Modern microprocessor devices, which are implemented in the automation of electrical engineering complexes, enable to combine local compensation of the reactive power consumed by synchronous motors with a diagnostic system for monitoring and predicting the residual life of an asynchronous motor and detecting a winding circuit in the stator windings of an electric motor. The purpose of the work is the analysis of the existing non-destructive test methods for diagnosing the state of the dielectric property of the insulation of AM windings, substantiating the direction of the development of diagnostic test methods and forecasting the decrease in the property of the body insulation of AM windings with the use of residual energy in the conditions of using a capacitor bank. To achieve the goal, the following tasks were solved: an analysis of the control methods of body and turn insulation was conducted; for the first time, the energy remaining in the capacitors after their disconnection was used in non-destructive test methods; it was proven that to predict the residual resource of the motor housing insulation, the time constant of the capacitor discharge decay can be effectively used as a criterion parameter, similarly, to detect a short circuit in the stator windings, the periodic voltage decay time on the capacitor can serve as a useful criterion; established interrelationships between changes in the resistance of the casing insulation of the windings and the time constant of the capacitor discharge. The most important result is the establishment of a unique relationship between the state of the case insulation and the value of the voltage decay time constant on the capacitor; change in period time and the number of turned-off turns in the AM stator winding. The most significant result is that the change in the time constant was used for the first time as a criterion parameter for predicting the residual life of the dielectric properties of the motor body insulation, and the change in the time period as a criterion parameter for the detection of a winding circuit. The significance of the study is that the value obtained after the first disconnection of the electric motor from the network is taken as the basic value of the constant decay time. Methods have been proposed and software developed for the device, which allows monitoring non-phase voltage modes of the network and current circuits during the operation of the electric motor, and when the electric motor is disconnected from the network - to control the value of the insulation resistance of the stator windings of the electric motor and the cable, as well as to predict the residual life of the electric motor

The article considers indirect control devices for the mechanical coordinate’s measurement of a three-phase asynchronous electric motor, which detects the temperature of the stator winding conductors and the basic frequency of stator voltage. Characteristics of mechanical coordinate’s simulation of the asynchronous motor are provided to assess the accuracy of the mechanical coordinate’s measurement in the dynamic modes.

Three-phase induction motors (TIMs) play a key role in industrial production lines. Due to their robustness and versatility, TIMs are commonly used to drive different devices like fans, conveyors, sieves, and compressors. However, these devices are often exposed to mechanical and electrical faults. Among them, failures in stator winding insulation lead to severe damage to the TIMs and can cause operational interruptions. Therefore, several approaches have been developed to monitor electrical faults in induction motors. The acoustic emission (AE) stands out as an efficient non-invasive technique (NIT) for TIM diagnosis. In this work, the AE analysis was applied to detect winding insulation faults and identify which electrical phase was affected. To achieve this proposal, a TIM was subjected to insulation faults in each of the three electrical phases, and the acoustic signals were acquired by four piezoelectric sensors attached to the motor. These signals were processed using a new technique, which calculates the energy of a specific range of the signal spectrum and assigns the energy values of each piezoelectric sensor to a coordinate axis (x, y). By ploting the values for each fault condition, this technique allows the detection of insulation faults and correctly identifies the affected phase by clustering the resulting values. Finally, the proposed methodology presented satisfactory results in winding insulation diagnosis.

According to the three-phase squirrel-cage asynchronous motor rotor broken bar fault, presented with parameters identification method of asynchronous motor parameter identification to monitoring and diagnosis of rotor resistance variation of rotor bar breaking principle. Choose a three-phase squirrel-cage asynchronous motor in three working points of experiments, results show that the method is correct and feasible. This method is based on the three-phase squirrel-cage asynchronous motor steady state model parameter equation, using the method of least squares identification parameters, and consider the effects of temperature on the parameters, by the parameter variation in diagnosis of broken rotor bar fault. Advantages of simple scientific method, this method can also be used in conjunction with other methods and, on the three-phase squirrel-cage asynchronous motor rotor has no fault diagnosis.

Three-phase asynchronous motor is widely used in petrochemical industry, but they are generally installed in harsh environments. Traditional maintenance and fault diagnosis are difficult to detect the potential faults of three-phase asynchronous motors effectively. It is a common method to detect the state of three-phase asynchronous motor based on temperature and humidity. Considering the characteristics of temperature and humidity data, this paper introduces a CM-RSL model based on deep learning. The model comprises the Random Forest (RF) algorithm for detecting data anomalies resulting from electromagnetic interference, a Support Vector Machine (SVC) classifier for identifying anomalies caused by sensor failure, and Long Short-Term Memory (LSTM). The CM-RSL model is used to analyze whether there is abnormal interference in the temperature and humidity data of the three-phase asynchronous motor, and then estimate the working condition of the connected motor. In the concluding phase, the proposed model underwent evaluation using long-term real-time temperature and humidity data from 32 three-phase asynchronous motors, collected through temperature and humidity sensors. The results demonstrate that the CM-RSL model effectively identifies the sources of disturbances leading to anomalies in the temperature and humidity data of three-phase asynchronous motors, achieving an accuracy rate exceeding 98%.

This paper presents a novel method for detecting stator winding inter-turn short circuit fault in a three-phase induction motor by vibration signature analysis using non-electrical contact type microelectromechanical systems (MEMS) accelerometer. The present work detects inter-turn short circuit by vibration analysis in a three-phase induction motor running under different load conditions. Theoretical analysis of stator winding under inter-turn short circuit condition has been presented. Experimental investigations have been carried out to detect inter-turn short circuit fault by vibration signature analysis using a MEMS accelerometer with three-phase induction motor operating under different conditions. The spectral analysis of motor vibration has been carried out using radix-2 decimation in time fast Fourier transform algorithm. The appearance of particular characteristic frequency components in vibration spectrum indicates stator winding inter-turn short circuit faults. The experimental results are found to closely match with the theoretical values, indicating that MEMS accelerometers can be successfully employed for the detection of stator winding inter-turn short circuit fault in induction motors.

Asynchronous motors are frequently used in many industrial applications, especially pumps and fans. Placement, bearing and coupling faults are common faults in these types of engines. Misalignment error is a common type of error that is seen very often among these errors. This error may cause efficiency decrease in a short run and vibration may cause short circuit and wear in moving parts in the stator windings in a long run. Early diagnosis of such faults is important in terms of machine health and productivity. In this study, loose connection and angular imbalance of the asynchronous machine were investigated. In the experimental works, a 1 Phase 0.75 KW power asynchronous motor, Y-0036-024A Electromagnetic Brake and SKF Microlog vibration meter were used during the measurements. The Frequency components of motor caused by the settlement errors were investigated under the different loads. A loose assembly error and angular imbalance were investigated from the misalignment errors. The engine was run idle and without any positioning errors and measurements were taken from different points with the accelerometer and the frequency spectrum examined. Measurements are repeated when the misalignment errors are occurred on purpose and the FFT frequency components were compared under the load of 12.50Nm using magnetic brake. The results show that the FFT frequency components are examined and the placement error can be determined with high success and accuracy. It has been found that harmonic components are formed in the frequency spectrum at 25Hz Coefficients. After the settlement error is generated it is seen that, undesired frequency components that are unloaded are lowered under load when the frequency spectra is examined. In this study, theoretical and experimental comparisons of settlement errors are made. Although many errors in this subject are examined in the same publication in general, only the results of the settlement errors are examined specifically as a contribution to the literature. The results and graphs are presented comparatively to the reader's knowledge.

Problem Asynchronous electric motors (AEs) are the most common among all electric motors. This is due to the simplicity of design, high reliability, relatively low cost, better weight and overall performance, etc. The asynchronous electric drive, which has a vector control based on modern static converters with microprocessor controllers, is especially widespread now. One of the most important characteristics of the engine is its mechanical characteristics. Based on the knowledge of the dependence of the moment on the electric motor shaft on its speed of rotation in various modes of operation, it is possible to implement high-quality and efficient control. Goal. The goal is conducting the analysis of operating modes of the asynchronous motor with the calculation of its mechanical characteristics in the presence of a minimal moment in it. Methodology. Analytical methods of research, methods of the theory of electric machines and electric drives are used, as well as methods of calculating electric circuits. The method of calculating the mechanical characteristics of AE in the presence of a site with a clearly expressed minimum torque is considered. Results. The analysis of the AE is based on its G-shaped replacement scheme. The mechanical characteristics of AE in different modes of operation were considered and analyzed in details. The mechanical characteristics of the AE were calculated in the presence of a minimal moment in it. It is determined that the value of the critical slip depends on the value of the active resistance of the rotor circle. Since the current of the motor is proportional to the voltage in the first stage, and the moment is the supply voltage squared, therefore, the characteristics of the voltage drop change both qualitatively and quantitatively. Originality. The current value of the moment of the AE depends on the square of the supply voltage, the active and inductive resistance of the windings of the rotor and the stator with the given values of slip and synchronous angular velocity. For all values of the voltage, the critical velocity (critical slip) does not change, that is, it does not depend on the voltage value. The magnitude of the moment varies significantly with the change in voltage. Practical value. In real conditions, all industrial networks may be subject to voltage, therefore, it is necessary to continuously monitor how significant it is to reduce the maximum and starting moments of the drives when reducing the voltage and how much they meet the demands of the technological process. If the control of a traction electric drive based on an electric motor is considered, the fact that the voltage from the energy storage will vary with the discharge should also be taken into account. Consequently, there will be a change in both the starting and the maximum moment that this drive can develop.Keywords: asynchronous motor; mechanical characteristic; minimum torque; Clause formula; traction electric drive; electric car; electric drive system.

This paper presents a new technique for detecting and diagnosing various disturbances occurring in three-phase induction motors. The proposed technique is based on a wavelet-based multiresolution analysis (MRA), where samples of three-phase stator current are analyzed using wavelet-based MRA. Different disturbances have been created in both stator and rotor windings of a wound rotor induction motor. Stator currents data have been collected for processing using a wavelet-based MRA. The application of the wavelet packet transform has shown that all fault conditions have non-zero second level high frequency subband coefficients, while normal and starting currents have zero values for the same coefficients. This property can be used as a main diagnosis tool for induction machine protection.

single phase asynchronous motor is a kind of motor which is widely used in household and power industrial fields. It has the advantages of simple structure, low cost and convenient maintenance, which is suitable for various complex situations. With the development of science and technology and the improvement of people's living standards, although single-phase asynchronous motor speed regulation methods are various, but the traditional control methods are inefficient and limited in speed range, which can not meet the needs of production and life. At present, the technology of speed regulation is mainly concerned with three-phase asynchronous motors, and there are few researches on single-phase asynchronous motors. Therefore, referring to the methods of three phase motor can improve the speed governing performance of single phase asynchronous motor and achieve the goal of energy conservation. This is the hot spot of the research on SPM nowadays. This paper mainly focuses on the research of variable frequency speed regulation of SPM. According to the motor principle and coordinate transformation theory, the mathematical model of SPM with asymmetric winding in two-phase static coordinate system is built; then the topology structure and modulation technology of power supply inverter are studied, and the main circuit structure adopted in this project is determined; finally, the simulation model is built in MATLAB by using vector control technology.

Considering the problem of energy saving at industrial enterprises, attention should be paid to the fact that about 70 ... 80% of all electric motors are asynchronous, and most of them are installed in unregulated drives. Most of these electric drives are equipped with asynchronous electric motors with a squirrel-cage rotor (AM SC). Energy saving problem in such cases can be solved by using a frequency converter (FC), however, all FC models are intended for AM SCs, while until the mid-90s the most common variable AC drives were electric drives equipped by an asynchronous motor with a phase rotor (AD PR) as they provided easy speed regulation through the rotor circuit. Such drives are usually used in hoisting and transport machines (conveyors, cranes, etc.). Direct transfer of the abovementioned drives to frequency-controlled mode is quite complicated due to the fact that standard inverters are designed to work with AM SCs having no phase rotor winding, and whose short-circuiting leads to additional electromagnetic losses in comparison with AM SC. An upcoming engineering trend is the development and research of synchronized AM control systems.

The three-phase induction motor is the most popular electric motor used in industry. It has a simple and robust construction as well as a higher power density. It is a self-starting motor, therefore easier to start as compared to other types of electric motor. As the other benefit, a three-phase induction motor requires fewer maintenance measures. In order to maintain proper and continued operation, many parameters of a three-phase induction motor are constantly monitored. Among them is motor vibration. This is an important operation parameter frequently used to determine repair and maintenance needs to be taken on the motor. The vibration of a three-phase induction motor might be caused by mechanical as well as electrical problems. In this paper, the effect of magnitude unbalance of a three-phase voltage supply on the vibration of a three-phase induction motor is carefully investigated. To achieve this objective, two different laboratory experiments have been conducted. The first one is a three-phase induction motor supplied from a balance three-phase voltage supply. The second one is a three-phase induction motor supplied from an unbalance three-phase voltage supply. The unbalanced three-phase voltage supply condition is achieved by making the magnitude of one phase-voltage is 3%, 4%, and 5% lower than the magnitude of the other two phase-voltages. The vibration measurement is then taken in three different directions of the motor non-drive end (MNDE), i.e., horizontal (MNDEH), vertical (MNDEV), and axial (MNDEA). The experiment data show higher vibration in all directions, MNDEH, MNDEV, and MNDEA, as a load of the three-phase induction motor increases. Further, experiment data also show that higher vibration in all directions, MNDEH, MNDEV and MNDEA, is produced when unbalanced in magnitude voltage supply is higher

Magnetic field in the air gap is obtained from electrical currents in stator and rotor windings. Another source of the air gap field can be permanent magnets that may be placed within magnetic circuits of either stator or rotor. The stator and rotor fields in the air gap are calculated in the previous chapter. Interaction of the two fields incites the process of electromechanical conversion.