Polyphase Electric Currents and Alternate-current Motors (Google eBook)

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Spon, 1895 - Electric currents, Alternating - 261 pages
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Very nice historical reference, excellent drawings and pictures

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Page 8 - By revolving in a uniform field the electromotive forces set up are proportional to the sine of the angle through which the coil has turned from the position in which it lay across the field. If in this position the flux of magnetic lines through it were N, and the number of spirals in the coil that enclose the N lines be called S, then, as was shown on p.
Page 239 - If this book is not returned on or before the above date a fine of five (5) cents per day will be incurred by the borrower. The charge for this book may be renewed if no one is waiting for it. To renew the charge, the book must be brought to the desk.
Page 265 - Explained, with numerous illustrations and Remarks. By JAMES SWINBURNE, late of JW Swan and Co., Paris, late of Brush-Swan Electric Light Company, USA i8mo, cloth, is. 6d. PhilippReis, Inventor of the Telephone: A Biographical Sketch.
Page 86 - ARAGO'S method of producing rotation in a copper disk consists of suspending it by its centre so as to make it lie horizontally above the poles of a horseshoe magnet, and then rotating the magnet about a vertical axis. The rotation of the disk is due to that of the magnetic field in which it is suspended; and we should expect that if a similar motion of the field could be produced by any other means, the result would be a similar motion of the disk. Possibly the rotation of the magnet may be the...
Page 116 - FIG. 108. downward returning currents are led into some path where they will return across a field of opposite polarity from that across which they flowed up. Then they will doubly tend to produce rotation. As a first stage to this, it will obviously be an improvement to ma,ke in the copper cylinder a number of parallel slits, which extend nearly to the ends of the cylinder as in Fig.
Page 99 - ... that is to say, by producing a progressive movement or rotation of their poles or points of greatest magnetic attraction by the alternating currents until they have reached a...
Page 92 - A rotary electric motor consisting of a field-magnet and armature and pairs of current-leading devices such for instance as contact rings and brushes the respective pairs being independently connected into the armature winding at alternating points of the same, and arranged for connection FIG. 96. with two independent external circuits.
Page 10 - Cardew voltmeters (Art. 430), and electrostatic voltmeters (Art. 290) do not measure the arithmetical average values of the amperes or volts. The readings of these instruments, if first calibrated by the use of continuous currents, are the square roots of the means of the squares of the values. They measure what are called virtual amperes or virtual volts. The mean which they read (if we assume the currents and voltages to follow the sine law of variation) is equal to 0-707 of the maximum values,...
Page 238 - On the Production of Rotary Magnetic Fields by a Single Alternating Current.
Page 86 - The rotation of the disk is due to that of the magnetic field in which it is suspended; and we should expect that if a similar motion of the field could be produced by any other means, the result would be a similar motion of the disk. Possibly the rotation of the magnet may be the only practicable way of producing a uniform rotation of the field ; but it will be shown in this paper that the disk can be made to rotate by an intermittent rotation of the field effected by means of electromagnets.

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