Although Westinghouse achieved its first practical induction motor in 1892 and developed a line of polyphase 60 hertz induction motors in 1893, these early Westinghouse motors were two-phase motors with wound rotors until B. Furthermore, he claimed that Tesla's motor was not practical because of two-phase pulsations, which prompted him to persist in his three-phase work. Steadfast in his promotion of three-phase development, Mikhail Dolivo-Dobrovolsky invented the cage-rotor induction motor in 1889 and the three-limb transformer in 1890. Scott was assigned to assist Tesla and later took over development of the induction motor at Westinghouse. Tesla was also employed for one year as a consultant. George Westinghouse, who was developing an alternating current power system at that time, licensed Tesla’s patents in 1888 and purchased a US patent option on Ferraris' induction motor concept. In May 1888 Tesla presented the technical paper A New System for Alternating Current Motors and Transformers to the American Institute of Electrical Engineers (AIEE) describing three four-stator-pole motor types: one with a four-pole rotor forming a non-self-starting reluctance motor, another with a wound rotor forming a self-starting induction motor, and the third a true synchronous motor with separately excited DC supply to rotor winding. In April 1888, the Royal Academy of Science of Turin published Ferraris's research on his AC polyphase motor detailing the foundations of motor operation. Tesla applied for US patents in October and November 1887 and was granted some of these patents in May 1888. The first AC commutator-free three-phase induction motors were independently invented by Galileo Ferraris and Nikola Tesla, a working motor model having been demonstrated by the former in 1885 and by the latter in 1887. The first commutator-free two phase AC induction motor was invented by Hungarian engineer Ottó Bláthy, he used the two phase motor to propel his invention, the Electricity meter By manually turning switches on and off, Walter Baily demonstrated this in 1879, effectively the first primitive induction motor. In 1824, the French physicist François Arago formulated the existence of rotating magnetic fields, termed Arago's rotations. An induction motor's rotor can be either wound type or squirrel-cage type. An induction motor can therefore be made without electrical connections to the rotor. Squirrel cage induction motors are very widely used in both fixed-speed and variable-frequency drive (VFD) applications.Īn induction motor, 3 phase induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. VFDs offer especially important energy savings opportunities for existing and prospective induction motors in variable-torque centrifugal fan, pump and compressor load applications. Although traditionally used in fixed-speed service, induction motors are increasingly being used with variable-frequency drives (VFDs) in variable-speed service. Single-phase induction motors are used extensively for smaller loads, such as household appliances like fans.
Three-phase squirrel-cage induction motors are widely used in industrial drives because they are rugged, reliable and economical. An induction motor, 3 phase induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding.
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