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An Introduction to Motors. Objectives. Describe how an electric motor operates. Describe the basic construction of an electric motor. Define work, horsepower, torque, RPM, and motor efficiency. Explain how an electric motor performs under load conditions. Explain why a motor can overheat.
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Objectives Describe how an electric motor operates. Describe the basic construction of an electric motor. Define work, horsepower, torque, RPM, and motor efficiency. Explain how an electric motor performs under load conditions. Explain why a motor can overheat.
Electric motors have two main parts • Stator • Rotor • Both produce magnetic fields that interact, resulting in in a force that turns the motor shaft
Main Parts The stator is stationary. It does not turn. Other stationary components include the frame, end bells (housings, or covers), and bearings
Stator The rotor is mounted on, and turns with, the motor shaft.Other rotating parts may include a commutator or a set of slip rings on the shaft. Many motors also have a fan.
Magnetic Field • A magnetic field can be visualized as lines of force, or flux • The lines form continuous loops between the North and South poles • When two fields approach each other, the lines of force interact • Like magnetic poles (north-north or south-south) repel each other • Unlike poles (north-south) attract each other
Magnet • Rotating magnet between two stationary magnets • N-N repel, and N-S attract • Middle magnet will rotate until poles are aligned • N-S, N-S
What if the poles on the stationary magnets get reversed JUST as they line up? Now the unlike poles become like poles, and repel each other as they pass By reversing polarity back and forth with the right timing, the rotating element will continue to rotate
