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AC Motors 1969 US Air Force Training Film

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Published on Sep 10, 2012

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"AC MOTORS ARE SHOWN IN VARIOUS APPLIANCES AND ELECTRONIC EQUIPMENT TO EMPHASIZE THEIR WIDE USE AND IMPORTANCE. AN ACTUAL MOTOR IS DISASSEMBLED TO POINT OUT EACH PART AND THE SIMPLICITY OF CONSTRUCTION. THE PRINCIPLE OF OPERATION IS DEMONSTRATED, POINTING OUT THE MAGNETIC FIELD AND MAGNETIZATION OF THE ROTOR. A ROTATING MAGNETIC FIELD IS PRODUCED THROUGH A DEMONSTRATION. INDUCTION FROM ROTATING FIELD TO WIRE LOOPS IS DEMONSTRATED, FOLLOWED BY EXPLANATION OF HOW THE ROTOR IS MAGNETIZED. CONCLUDES WITH A DEMONSTRATION OF SLIPPAGE AND ITS RELATIONSHIP TO INTERNAL AND EXTERNAL LOADING, AND AN EXPLANATION OF A TYPICAL TORQUE CURVE."

United States Air Force Training Film TVK 30-704

NEW VERSION with improved video & sound: https://www.youtube.com/watch?v=oegDt...

Public domain film from the National Archives, slightly cropped to remove uneven edges, with the aspect ratio corrected, and mild video noise reduction applied.
The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).

http://en.wikipedia.org/wiki/AC_motor

An AC motor is an electric motor driven by an alternating current.

It commonly consists of two basic parts, an outside stationary stator having coils supplied with alternating current to produce a rotating magnetic field, and an inside rotor attached to the output shaft that is given a torque by the rotating field.

There are two main types of AC motors, depending on the type of rotor used. The first type is the induction motor, which runs slightly slower than the supply frequency. The magnetic field on the rotor of this motor is created by an induced current. The second type is the synchronous motor, which does not rely on induction and as a result, can rotate exactly at the supply frequency or a sub-multiple of the supply frequency. The magnetic field on the rotor is either generated by current delivered through slip rings or by a permanent magnet. Other types of motors include eddy current motors, and also AC/DC mechanically commutated machines in which speed is dependent on voltage and winding connection...

History

With growing demand in the United States and Europe during the late 19th century, alternating current technology was rooted in Michael Faraday's and Joseph Henry's 1830-31 discovery of a changing magnetic field that is capable of inducing an electric current in a circuit. Faraday is usually given credit for this discovery since he published his findings first.

In 1832, French instrument maker Hippolyte Pixii generated a crude form of alternating current when he designed and built the first alternator. It consisted of a revolving horseshoe magnet passing over two wound wire coils.

The first person to conceive of a rotating magnetic field was Walter Baily who gave a workable demonstration of his battery-operated polyphase motor aided by a commutator on June 28, 1879 to the Physical Society of London. Nearly identical to Baily's apparatus, French electrical engineer Marcel Deprez in 1880 published a paper that identified the rotating magnetic field principle and that of a two-phase AC system of currents to produce it. Never practically demonstrated, the design was flawed as one of the two currents was "furnished by the machine itself."

The circumstances surrounding the discoveries and research of Nikola Tesla and Italian physicist Galileo Ferraris are controversial. According to Tesla, he conceived his idea of the rotating magnetic field principle in 1882, a claim neither supported by contemporary publications or witnesses. Ferraris's claim that he discovered the principle in 1885 was not validated until March 1888 when he published his research in a paper to the Royal Academy of Sciences in Turin, Italy— months after Tesla had already filed patents. While Ferraris is generally considered to have built the first single-phase AC comutatorless induction motor, Tesla went on to create the first polyphase induction motor in 1886. On October 12, 1887, Tesla filed U.S. patent #381,968 for an electro-magnetic motor, which in the application, Tesla claimed to have invented a new power distribution system. The patent was issued on May 1, 1888. The rights to this key patent were bought by American entrepreneur George Westinghouse, who demonstrated this system for the first time at the 1893 World's Columbian Exposition in Chicago. Two years later, Tesla's AC motors were installed at the Niagara Falls power project...

Squirrel-cage rotors

Most common AC motors use the squirrel cage rotor, which will be found in virtually all domestic and light industrial alternating current motors...

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