The Diagnostics Of Induction Motor Broken Rotor Bars On The Basis Of The Electromotive Force Analysis (energy Science, Engineering And Technology)

Under the conditions of increased energy resources consumption, the researchers around the world face the problem of rational energy use. One of the ways to solve this problem consists of introducing energy saving technologies into the operation of electrotechnical and electromechanical devices. The operation of electric machines (EM) is very often accompanied by the occurrence of various damages. It results in increased energy consumption, untimely failure of electromechanical systems and, consequently, growth of material expenditure. Operation efficiency of electric equipment can be improved due to timely diagnostics of EM damages at early stages of their development. It is for this reason that research in diagnostics of EMs containing induction motors (IM) is of special interest nowadays.Researchers succeeded in searching for efficient methods of IM diagnostics that are mostly suitable for particular conditions and modes of equipment operation. There are different methods for diagnostics of induction motor broken rotor bars. However, the analysis of conventional diagnostics methods revealed that most of them require the removal of the induction motor from the operation process and its disassembling. Presently, such methods of IM broken rotor bars diagnostics in operation modes such as methods of currents spectral analysis, the analysis of zero-phase sequence voltages, and the analysis of external magnetic field parameters are known. Nevertheless, these methods do not provide satisfactory results during diagnostics under a no-load condition and do not take into account that low-quality voltage of the supply network and the fluctuation of load level influence the diagnostic results. Besides, the results of the Fourier transform of current signals does not allow for unambiguous identification of the number and relative position of IM broken rotor bars. Hence, the development of the method for diagnostics of IM broken rotor bars is a topical scientific and applied... Contents Preface List of Abbreviations List of Symbols Chapter 1 The Contemporary State of the Problem of the Diagnostics of Induction Motor Broken Rotor Bars 1.1. The Analysis of Squirrel-Cage Induction Motor Failures 1.2. The Research of the Causes of the Occurrence of Induction Motor Broken Rotor Bars 1.2.1. The Technology of the Manufacture of an IM Rotor Squirrel Cage 1.2.2. Thermal Overloads 1.2.3. Mechanical Overloads 1.3. The Analysis of the Methods for the Diagnostics of Induction Motor Broken Rotor Bars and Their Classification 1.3.1. The Criteria of the Assessment of the Efficiency of Broken Rotor Bars Diagnostics Criterion 1 Criterion 2 Criterion 3 Criterion 4 Criterion 5 Method 1 Method 2 Method 3 Method 4 Method 5 Method 6 Method 7 Method 8 Method 9 Method 10 Method 11 Method 12 Method 13 Method 14 Method 15 1.4. Conclusion Chapter 2 Theoretical Foundation for the Research of Induction Motor Broken Rotor Bars in the Self-Running-Out Condition 2.1. The Substantiation of the Testing Condition and the Determination of Diagnostic Signals for the Assessment of IM Broken Rotor Bars 2.1.1. The Substantiation of the Testing Condition Static Operating Conditions Idle Condition Operation under Load Short-Circuit Condition Dynamic Operating Conditions Start-Up Conditions Self-Running-Out Condition 2.1.2. The Substantiation of Diagnostic Signals 2.2. The Substantiation of the Method for the Calculation of Induction Motor Electromagnetic Field 2.3. The Substantiation of the Use of the Wavelet-Transform for Diagnostic Signals Processing 2.4. The Choice of the Wavelet-Basis Functions for the Diagnostic Signals Wavelet-Transform 2.5. The Research of Factors Influencing the Generation of Electromotive Force in Induction Motor Stator Windings 2.6. The Generalized Methods of the Analysis of Induction Motor Broken Rotor Bars 2.6.1. The Basic Points of the Diagnostics Method 2.7. Conclusion Chapter 3 Mathematical Models for the Research of the Method of Induction Motor Broken Rotor Bars Diagnostics 3.1. The Creation of an Induction Motor Mathematical Model in a Three-Phase Coordinate System for the Determination of Currents in the Rotor Bars at the Moment of Motor Disconnection from the Supply Mains 3.2. Working out a Circuit Model of an Induction Motor Rotor for the Specification of Currents in the Rotor Bars at the Moment of Motor Disconnection from the Supply Mains 3.3. A Mathematical Model with the Use of the Final Element Method for the Calculation of induction motor Electromagnetic Field in the Self-Running-out Mode 3.4. The Analysis of the Process of Generation of Electromotive Force in the Stator Windings under the Influence of Electromagnetic Field in the Air Gap 3.5. Conclusion Chapter 4 The Method of Induction Motor Broken Rotor Bars Diagnostics with the Use of Wavelet-Transform 4.1. The Analysis of Electromotive Force Signals in Induction Motor Stator Windings by Means of Wavelet-Transform 4.2. The Method for Decomposition of the Signal of the Electromotive Force of the Stator Winding Phase 4.2.1. The Method for Decomposition of the Signals of Electromotive Forces in the Stator Windings The Decomposition of the Signal of Winding Phase EMF into the Signals of EMF of the Coil Groups The Decomposition of the Signal of the EMF of the Coil Group into the Signals of Coils EMF The Decomposition of the Coil EMF Signal into the Signals of the EMF of Two Active Sides of the Coil 4.2.2. The Method for the Decomposition of the Coefficients of the Wavelet-Expansion of the Signals of the Electromotive Forces in the Stator Winding 4.3. Conclusion Chapter 5 The Experimental Verification of the Method for the Diagnostics of Induction Motor Broken Rotor Bars 5.1. The Description of the Experiment and Measuring and Diagnostics Equipment 5.2. The Analysis of the Results of the Experimental Research 5.3. The Assessment of Broken Rotor Bars Influence on Induction Motor Operation 5.4. Conclusion Conclusion References Appendices Appendix A Appendix B Appendix C Appendix D Appendix E Authors’ Contact Information Index Blank Page The presented monograph contains theoretical and experimental research that made it possible to solve the topical scientific problem of improving the efficiency of IM broken rotor bars with the use of the signal of electromotive force wavelet analysis in the stator windings under the motor self-running-out condition. (Novinka)