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Electromagnetic rotation experiment of Faraday, ca. 1821 [2] Working principle of a homopolar motor: due to movement of negative charges from center towards rim of the disk, a Lorentz force F L is created which brings the entire disk into rotation. The homopolar motor was the first electrical motor to be built.
Electric motors have efficiencies ranging from around 15%-20% for shaded pole motors, up to 98% for permanent magnet motors, [101] [102] [103] with efficiency also dependent on load. Peak efficiency is usually at 75% of the rated load. So (as an example) a 10 HP motor is most efficient when driving a load that requires 7.5 HP. [104]
An electrostatic motor or capacitor motor is a type of electric motor based on the attraction and repulsion of electric charge. An alternative type of electrostatic motor is the spacecraft electrostatic ion drive thruster where forces and motion are created by electrostatically accelerating ions.
The rotating magnetic field is the key principle in the operation of induction machines.The induction motor consists of a stator and rotor.In the stator a group of fixed windings are so arranged that a two phase current, for example, produces a magnetic field which rotates at an angular velocity determined by the frequency of the alternating current.
An AC motor is an electric motor driven by an alternating current (AC). The AC motor commonly consists of two basic parts, an outside stator having coils supplied with alternating current to produce a rotating magnetic field, and an inside rotor attached to the output shaft producing a second rotating magnetic field. The rotor magnetic field ...
Fleming's left-hand rule. Fleming's left-hand rule for electric motors is one of a pair of visual mnemonics, the other being Fleming's right-hand rule for generators. [1] [2] [3] They were originated by John Ambrose Fleming, in the late 19th century, as a simple way of working out the direction of motion in an electric motor, or the direction of electric current in an electric generator.
The switched reluctance motor (SRM) is a type of reluctance motor. Unlike brushed DC motors , power is delivered to windings in the stator (case) rather than the rotor . This simplifies mechanical design because power does not have to be delivered to the moving rotor, which eliminates the need for a commutator .
Bipolar toy motor of 1948. Note the three-pole rotor with a bipolar field. A bipolar electric motor is an electric motor with only two (hence bi-) poles to its stationary field. [1] They are an example of the simple brushed DC motor, with a commutator. This field may be generated by either a permanent magnet or a field coil.