Theory and Calculations of Electrical Apparatus, Volume 6

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McGraw-Hill book Company, Incorporated, 1917 - Electric machinery - 480 pages
 

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Page 307 - III. (1) Polyphase Induction Motor. In the polyphase induction motor a number of primary circuits, displaced in position from each other, are excited by polyphase emf's. displaced in phase from each other by a phase angle equal to the position angle of the coils. A number of secondary circuits are...
Page 438 - ... or subnormal direct voltage, the armature reaction is positive; that is, the same as in a direct-current generator, but less in intensity, and the magnetic flux of armature reaction tends to impair commutation. In a direct-current generator, by shifting the brushes to the edge of the field poles, the field flux is used as reversing flux to give commutation. In this converter, however, decrease of direct voltage is produced by lowering the outside sections of the field poles. The...
Page 299 - A sufficiently large term, pPo. (1) refers to the design of the synchronous machine and the system on which it operates. (2) leads to the use of electromagnetic anti-surging devices, as an induction motor winding in the field poles, short-circuits between the poles, or around the poles, and (3) leads to flexible connection to a load or a momentum, as flexible connection with a flywheel, or belt drive of the load. The conditions of steadiness are...
Page 330 - As instance as shown in Fig. 9. with the speed as abscissae, and values from standstill to over double synchronous speed, the characteristic curves of a polyphase series motor of the constants: e=640 volts Z — 1 — 10 j ohms Za = Z, = .1 — .3 ; ohms e=I •= 37 (sin <a = .6 ; cos w — .8) hence: , 640 1 = aniDS.
Page 294 - P\ = 0*8, where c is a function of the conductivity of the eddy-current circuit and the intensity of the magnetic field of the machine, c2 is the power which would be required to drive the magnetic field of the motor through the circuits of the anti-surging device at full frequency, if the same relative proportions could be retained at full frequency as at the frequency of slip, s. That is...
Page 429 - F', to maintain constant flux. Such a converter requires compounding, as by a series field, to take care of the demagnetizing armature reaction. If the alternating current is not in phase with the field, but lags or leads, the armature reaction of the lagging or leading component of current superimposes upon the resultant armature reaction, F', and increases it, with lagging current in Fig.
Page ii - Uforld v Engineering News-Record Railway Age Gazette <* American Machinist Electrical Merchandising ^ The Contractor Engineering 3 Mining Journal •=• Power Metallurgical 6 Chemical Engineering THEORY AND CALCULATIONS OF ELECTRICAL APPARATUS BY CHARLES PROTEUS STEINMETZ, AM, PH.
Page 310 - IJ vhere the brackets [] denote the absolute value of the term included by it, and the small letters e0 , z, etc., the absolute values of the vectors E o, Z, etc. Since the imaginary term of power seems to have no physical meaning, it is: Mechanical power output : 8 ' ~ This is the power output at the armature conductors, hence includes friction and windage.
Page 453 - ... circuit depends on the electromotive force which excites the current, and on the resistance of the circuit through which the current is made to flow. In the case of induction of currents the electromotive force is directly due to, and is measured in terms of, the rate of change of the number of lines of magnetic force embraced by the circuit ; and this rate of change depends on the geometrical form of the circuit and on its space relations to the magnetic field surrounding it. Thus the induced...
Page 301 - ... construction) — reaction motors. (4) One member excited by alternating current, the other by alternating current of different frequency or different direction of rotation — general alternating-current transformer or frequency converter. No. 1 is the synchronous motor of the electrical industry. Nos. 2 and 3 are used occasionally to produce synchronous rotation without direct-current excitation, and of very great steadiness of the rate of rotation, where weight — efficiency and power factor...

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