Science Abstracts Volume 11

Science Abstracts Volume 11

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908 edition. Excerpt: ...coefficient, 1: the number of poles, 21 the number of stator slots per pole per phase, d the diam. of rotor in cm., A the air-gap depth, and 1 denotes the length of iron axially (core length). Tabulated values of the coefficicnts K1 and K, are given for various conditions. 778. Graphical Treatment of the Rotating Field. R. E. Hellrnund. (Amer. Inst. Elect. Engin., Proc. 27. pp. 927-948, une, 1908.)---The author first describes Gorges' diagram for the flux in the teeth of the rotor. The space values of the magnetic flux density for the case of a two-phase winding with four slots per pole per phase are shown graphically. The time values of the quantities are then developed, and a comparison is made with the results obtained on the ordinary theory. The diagrams show that the max. values of the flux in individual teeth vary in magnitude, and that the time values are different from those obtained by merely considering the distances between the teeth. They also show that the total field rotates with varying speed. The author develops a method of taking the reactive effect of the secondary circuit into account, and for this purpose he finds it convenient to define the ratio of the magnetising current of a motor with short-circuited and synchronously rcvolving rotor to the current when the rotor windings are on open circuit, as the reactance factor of the motor. Field diagrams for a threephase motor with three slots per pole per phase, and for a two-phase motor with four slots per pole per phase, are given and compared. The diagrams show that the three-phase field approaches the ideal condition much more closely than the two-phase field. This explains why the two-phase field requires more magnetising " volt-amps." than more

Product details

  • Paperback | 328 pages
  • 189 x 246 x 18mm | 585g
  • United States
  • English
  • black & white illustrations
  • 1236956192
  • 9781236956194