Electric motors – Troubleshooting and repair
An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electrical 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 the electrical grid, inverters or electrical generators. An electric generator is mechanically identical to an electric motor, but works with a reversed flow of energy, converting mechanical energy into electrical energy.
Electric motors can be classified by considerations such as type of power source, internal construction, application and type of motion output. In addition to AC versus DC types, motors can be brushed or brushless, can be multiphase (see single-phase, two-phase, or three-phase), and can be air-cooled or liquid-cooled. General purpose motors with standard dimensions and features provide convenient mechanical power for industrial use. The largest electric motors are used for ship propulsion, gas 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 clocks. In certain applications, such as 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 rotary force (torque) designed to propel some external mechanism, such as a fan or 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 energy into mechanical motion, but they can produce motion only over a limited distance.
Electric motors are much more efficient than the other prime mover used in industry and transport, the internal combustion engine (MCI); Electric motors are typically more than 95% efficient while MCIs 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 spew 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 Electrical Motors and Drives for non-experts, bridging the gap between mathematics and theory.
Mechanical Design of Electric Motors
Rapid increases in energy consumption and emphasis on environmental protection have created 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.
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Examines various cooling techniques, including forced air, liquid, and phase change
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With research findings from the author's own personal experience and the significant contributions of others, Mechanical Design of Electric Motors highlights innovative and advanced electric motors developed over the past few decades.
Mechanical Design of Electric Motors
The importance of electric motors is well known in various engineering fields. 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, back electromotive force, characteristics, starting types, speed control methods and applications.
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Motor Starting and Control Primer: An introduction to the starting techniques and control of electric motors
Whether you're a busy electrical engineer needing a refresher on motor starting, a time-strapped student new to the subject, or an interested layman 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 way, without time-consuming verbiage or self-centered discussions. Complete with circuit diagrams and thorough explanations of the most common motor starting methods – and challenges – this book is an invaluable reference. It has something to offer anyone interested in learning new things, while helping practicing electrical engineers design and implement reliable and functional motor starters.
