Electric Motors – Troubleshooting and Repair
An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate by interacting between the motor's magnetic field and electric current in a wire winding 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 power grids, inverters or electrical generators. An electric generator is mechanically identical to an electric motor, but operates with a reversed flow of power, converting mechanical energy into electrical energy.
Electric motors can be classified based on considerations such as type of power source, internal construction, application, and type of output motion. In addition to AC versus DC types, motors can be brushed or brushless, can be multi-phase (see single-phase, two-phase, or three-phase), and can be air- or liquid-cooled. General purpose motors with standard dimensions and features provide mechanical power suitable for industrial use. The largest electric motors are used for ship propulsion, pipeline compression and pumped storage applications with powers reaching 100 megawatts. Electric motors are found in industrial fans, blowers and pumps, machine tools, household appliances, power tools, and disk drives. Small motors can be found in electric watches. In certain applications, such as in regenerative braking with traction motors, electric motors can be used in reverse as generators to recover energy that would otherwise be lost as heat and friction.
Electric motors produce linear or rotational force (torque) intended to drive some external mechanism, such as a fan or an elevator. An electric motor is generally designed for continuous rotation, or for linear motion over a significant distance compared to its size. Magnetic solenoids are also transducers that convert electrical power into mechanical motion, but they 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 ICEs are well below 50%. They are also lightweight, physically smaller, mechanically simpler and cheaper to build, can provide instantaneous and consistent torque at any speed, can run on electricity generated from renewable sources, and do not expel 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 range 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
Rapid increases in energy consumption and emphasis on environmental protection have posed challenges to the motor industry, as well as the design and manufacture of highly efficient, reliable, cost-effective, 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 academic researchers, Mechanical Design of Electric Motors provides in-depth knowledge of state-of-the-art design methods and developments of electric motors. From motor classification, motor component design, model configuration, 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 issues related to the design, 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
Reviews various cooling techniques, including forced air, liquid, and phase change
Discusses the analysis and calculation of motor power losses
Addresses engine vibration and acoustic noise issues
Presents engineering analysis methods and case study results
Emphasizes construction, optimization and applications
Presenting research results from the author's personal experience and the significant contributions of others, Mechanical Design of Electric Motors highlights 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 the various types of electric motors including DC motors, three-phase and single-phase induction motors, synchronous motors, universal motor, AC servo motor, linear induction motor and stepper motors. The book covers all the details of DC motors including torque equation, flyback EMF, characteristics, types of starters, speed control methods and applications.
The book also covers the various testing methods of DC motors such as Swinburne test, brake test, delay test, field test and Hopkinson test. The book also explains three-phase induction motors in detail. It includes the production of rotating magnetic field, construction, operation, slip effect, torque equation, torque relations, torque-slip characteristics, losses, power flow, equivalent circuit, effect of harmonics on performance, circle diagram and applications. This chapter also includes discussion of the induction generator. The book teaches the various starting methods and speed control methods of three-phase induction motors. The book incorporates the explanation of various single-phase induction motors. The chapter on synchronous motor provides the detailed discussion of construction, working principle, behavior under load, phasor diagram analysis, Vee and inverted Vee curves, hunting, synchronous condenser and applications. The book also teaches various special machines such as single-phase commutator motors, universal motors, AC servo motors, linear induction motors and stepper motors. The book uses simple, lucid language to explain each topic. The book provides the logical method of explaining the various complicated topics and step by step methods to make the understanding easy. Each chapter is well supported with 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 who needs to refresh your knowledge of motor starting, a time-poor student new to the subject, or an interested person with an hour to spare, this book is the place to start. Steven McFadyen shares his expert engine starting knowledge in a clear, easily accessible manner without time-consuming verbiage or self-congratulatory discussions. Complete with circuit diagrams and thorough explanations of the most common engine starting methods and their challenges, this book is an invaluable reference. It has something to offer anyone interested in learning new things, while at the same time helping practicing electrical engineers design and implement reliable and functional motor starters.
