Benjamin Berling Peter A. Karahalios AC Motors Benjamin Berling Peter A. Karahalios

History of AC Motors Inventor: Nikola Tesla 1982: Tesla envisions rotating fields 1883: Tesla develops polyphase AC induction motor 1887: Tesla develops brushless AC motor and files patent 1888: Westinghouse controls AC motors and transformers Tesla sees the rotating fields in a vision, meticulously detailing the construction of both single and polyphase motors it in his notebook. He later designs his motor just "as seen" and it works just as he envisioned. Tesla begins working for Continental Edison in Paris, France, helping them to resolve problems with their DC dynamos. While on assignment to Strasburg, France, Tesla constructs a working brushless polyphase AC induction motor. It is demonstrated before the former Mayor of the town and to wealthy potential investors. Unfortunately, Tesla is unable to secure financing. In 1884 Tesla arrives in New York. Tesla is hired to improve Edison's DC dynamos in the U.S. In 1885, Edison reneges on a promise to pay Tesla $50,000 for improvements to his dynamos, saying he was just joking - Tesla resigns in disgust and his financial backers, Robert Lane and B. A. Vail, refuse to fund Tesla's AC Motor, and they fire Tesla! He is forced to work as a manual laborer. In 1887, Tesla develops the world's first brushless AC motor. Tesla files key worldwide patents, locking the rights to the invention. During this time, direct current (DC) was king. At that time there were 121 Edison power stations scattered across the United States delivering DC electricity to its customers. But DC had a great limitation -- namely, that power plants could only send DC electricity about a mile before the electricity began to lose power. After obtaining the patent rights to Tesla’s AC motor, George Westinghouse introduced a system based on high-voltage alternating current (AC), which could carry electricity hundreds of miles with little loss of power, people naturally took notice. A "battle of the currents" ensued. In the end, Westinghouse's AC prevailed. Introduction of Tesla's motor from 1888 onwards initiated what is known as the Second Industrial Revolution, making possible the efficient generation and long distance distribution of electrical energy using the alternating current transmission system, also of Tesla's invention (1888) http://205.243.100.155/frames/tesla.html http://en.wikipedia.org/wiki/Nikola_tesla http://www.pbs.org/wgbh/amex/edison/sfeature/acdc.html http://en.wikipedia.org/wiki/George_Westinghouse

Alternating Current vs. Direct Current AC is an electrical current whose magnitude and direction vary cyclically DC is an electrical current whose direction remains constant An alternating current (AC) is an electrical current whose magnitude and direction vary cyclically, as opposed to direct current, whose direction remains constant. The usual waveform of an AC power circuit is a sine wave, as this results in the most efficient transmission of energy. Used generically, AC refers to the form in which electricity is delivered to businesses and residences. However, audio and radio signals carried on electrical wire are also examples of alternating current. In these applications, an important goal is often the recovery of information encoded (or modulated) onto the AC signal. Direct current (DC or "continuous current") is the constant flow of electrons from low to high potential. This is typically in a conductor such as a wire, but can also be through semiconductors, insulators, or even through a vacuum as in electron or ion beams. In direct current, the electric charges flow in the same direction, distinguishing it from alternating current (AC). http://en.wikipedia.org/wiki/Alternating_current

Applications of AC Motors CD/DVD players Toys Household appliances Locomotives Pipeline compressors Wind-tunnel drives http://en.wikipedia.org/wiki/Electric_motor#AC_motors

Electric Motors An electric motor converts electrical energy into kinetic energy. (The reverse task of a generator) Most (not all) electric motors work off of electromagnatism where a mechanical force is placed on any current-carrying wire contained within a magnetic field. This force is known as the Lorentz force law and acts perpendicular to both the wire and the magnetic field

Cross Section of DC Motor Cross Section of AC Motor AC Motors vs. DC Motors The classic DC motor has a rotating armature in the form of an electromagnet. A rotary switch called a commutator reverses the direction of the electric current twice every cycle, to flow through the armature so that the poles of the electromagnet push and pull against the permanent magnets on the outside of the motor. As the poles of the armature electromagnet pass the poles of the permanent magnets, the commutator reverses the polarity of the armature electromagnet. During that instant of switching polarity, inertia keeps the classical motor going in the proper direction. the commutators from a machine could be removed and the device could operate on a rotary field of force. This classic alternating current electro-magnetic motor was an induction motor. In the induction motor, the field and armature were ideally of equal field strengths and the field and armature cores were of equal sizes. The total energy supplied to operate the device equaled the sum of the energy expended in the armature and field coils.[3] The power developed in operation of the device equaled the product of the energy expended in the armature and field coils. [4] Cross Section of DC Motor Cross Section of AC Motor

A/C Motor Construction An outside stationary stator having coils supplied with AC current to produce a rotating magnetic field An inside rotor which is attached to the output shaft.

Types of A/C Motors Synchronous/Induction motors Single/Multiphase The synchronous motor rotates at the supply frequency The induction motor, turns slightly slower. (Typically in the form of a squirrel cage motor.) Single/Multiphase Single-phase motors run on only one of the three phases of current operate on the domestic electricity supply.  Multi (Commonly three phase) motors run three of the phases of current produced by power stations. Mainly used for high power applications

Squirrel Cage Motors Name is derived by it’s shape Typically low voltage/high current Very common in light industrial applications

A/C Motor anatomy (EG Squirrel Cage) Armature/Rotor Conduction bars End rings Shaft/Spindle Laminated iron core Stator Stationary frame

Sources: http://webs.mn.catholic.edu/~physics/emery/hsc_motors.htm#AC%motor www.ent.ohiou.edu/~manhire/basic ee/chapter16/sld003.htm www.phys.vusw.edu.au/~jw/SCmotors.html#ACmotors/~jw/AChtml