Electric motors – Troubleshooting and repair
An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate by the interaction between the magnetic field of the motor and the electric current in a winding of wire to generate force in the form of torque applied to the motor shaft. Electric motors can be powered by direct current (DC) sources, such as batteries or rectifiers, or by alternating current (AC) sources, such as a power grid, inverters or electric generators. An electric generator is mechanically identical to an electric motor, but operates with reverse power flow, converting mechanical energy into electrical energy.
Electric motors can be classified based on considerations such as power source type, internal construction, application, and output motion type. In addition to AC versus DC types, motors can be brushed or brushless, can be of different phases (see single-phase, two-phase, or three-phase), and can be air- or liquid-cooled. General purpose motors with standard dimensions and features provide practical mechanical power for industrial use. The largest electric motors are used for ship propulsion, pipe compression and pumped storage applications with power ratings up to 100 megawatts. Electric motors are found in industrial fans, blowers and pumps, machine tools, household appliances, power tools and record players. Small motors can be found in electric watches. In some applications, such as regenerative braking with traction motors, electric motors can be used in reverse as generators to recover energy that might otherwise be lost as heat and friction.
Electric motors produce a linear force or rotational torque intended to propel an external mechanism, such as a fan or elevator. An electric motor is generally designed for continuous rotation, or for linear movement over a significant distance relative to its size. Magnetic solenoids are also converters that convert electrical power into mechanical motion, but can only produce motion over a limited distance.
Electric motors are much more efficient than the other main engine used in industry and transportation, the internal combustion engine (ICE); electric motors are typically over 95% efficient while MCIs are well below 50%. They are also lightweight, physically smaller, mechanically simpler and less expensive to build, can provide instantaneous and constant torque at any speed, can run on electricity generated by renewable sources, and do not release carbon into the atmosphere. For these reasons, electric motors are replacing internal combustion in transportation and industry, although their use in vehicles is currently limited by the high cost and weight of batteries that can provide sufficient autonomy between charges.
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Buy books
Electric Motors and Drives: Fundamentals, Types and Applications
Best-selling reference on electric motors and drives for non-specialists, bridging the gap between mathematics and theory.
Mechanical Design of Electric Motors
The rapid increase in energy consumption and the emphasis on environmental protection have posed challenges for the motor industry, as has the design and manufacture of highly efficient, reliable, economical, energy-saving, quiet, precisely controlled and durable electric motors.
Suitable for motor designers, engineers and manufacturers, as well as maintenance personnel, undergraduate and graduate students and university researchers, Mechanical Design of Electric Motors provides in-depth knowledge of cutting-edge design methods and developments in electric motors. From motor classification, motor component design, model setup and material and bearing selection to power losses, motor cooling, design integration, vibration and acoustic noise, this comprehensive text covers the fundamentals, practical design and design issues, modeling and simulation, engineering analysis, manufacturing processes, test procedures and performance characteristics of today's electric motors.
Focusing on the mechanical design of modern electric motors, the book:
Details the design and manufacturing of major components and subsystems, such as rotors, shafts, stators and frames
Examination of various cooling techniques including forced air, liquid, and phase change
Discusses the analysis and calculation of engine power losses
Addresses engine vibration and acoustic noise issues
Presents technical analysis methods and case study results
Focuses on construction, optimization and applications
Integrating research findings from the author's personal experience and significant contributions from others, Mechanical Design of Electric Motors highlights the innovative and advanced electric motors developed over the past decades.
Mechanical Design of Electric Motors
The importance of electric motors is well known in various fields of engineering. The book provides comprehensive coverage of different types of electric motors, including DC motors, three-phase and single-phase asynchronous motors, synchronous motors, universal motor, AC servo motor, linear asynchronous motor, and stepper motors. The book covers all the details of DC motors, including torque equation, counter e.m.f., characteristics, types of starters, speed control methods and applications.
The book also covers the various methods of testing DC motors such as Swinburne test, brake test, retard test, field test and Hopkinson test. The book also explains three-phase asynchronous motors in detail. It includes production of rotating magnetic field, construction, operation, effect of slip, torque equation, torque ratios, torque-slip characteristics, losses, power flow, equivalent circuit, effect of harmonics on performance, pie chart and applications. This chapter also includes the discussion of asynchronous generator. The book teaches various starting methods and speed control methods of three-phase asynchronous motors. The book includes the explanation of different single-phase asynchronous motors. Synchronous motor chapter provides detailed discussion of construction, principle of operation, on-load behavior, phase diagram analysis, V and inverted V curves, timing, synchronous capacitor and applications. The book also teaches the various special machines such as single phase collector motors, universal motor, AC servo motor, linear asynchronous motor and stepper motors. The book uses simple, clear language to explain each topic. The book provides the logical method to explain the various complicated topics and the step-by-step methods to make the understanding easier. Each chapter is well supported by necessary illustrations, self-explanatory diagrams, and a variety of solved problems. The book explains the philosophy of the subject which makes the understanding of the concepts very clear and makes the subject more interesting.
Motor Starting and Control Primer: An introduction to the starting techniques and control of electric motors
Whether you are a busy electrical engineer needing to refresh your knowledge of starting motors, a busy student new to the subject, or an interested individual with an hour to spare, this book is the place to start. Steven McFadyen shares his expert knowledge of engine starting in a clear, easily accessible manner without time-consuming verbiage or self-congratulatory discussions. Complete with circuit diagrams and in-depth explanations of the most common motor starting methods and challenges, this book is an invaluable reference. It has something to offer anyone who is eager to learn new things, while helping practicing electrical engineers design and implement reliable and functional motor starters.
