Original Papers on Dynamo Machinery and Allied Subjects

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W.J. Johnston, 1893 - Electric engineering - 249 pages
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Page 254 - The Electric Motor and Its Applications. By TC Martin and Jos. Wetzler. With an appendix on the Development of the Electric Motor since 1888, by Dr, Louis Bell.
Page 103 - The currents in the fixed coils around the magnets are not the only magnetising forces applied in a dynamo machine; the currents in the moving coils of the armature have also their effect on the resultant field. There are in general two independent variables in a dynamo machine, the current around the magnets and the current in the armature, and the relation of EMF to currents is fully represented by a surface. In well-constructed machines the effect of the latter is reduced to a minimum, but it...
Page 62 - All but the first two arrangements named depend on residual magnetism to initiate the current, and below a certain speed of rotation give no practically useful electromotive force. A dynamo machine is, of course, not a perfect instrument for converting mechanical energy into the energy of electric current. Certain losses inevitably occur. There is, of course, the loss due to friction of bearings, and of the collecting brushes upon the commutator; there is also the loss due to the production of electric...
Page 149 - ... machines, independently driven, it is not quite obvious what the result will be, for the polarity of each machine is constantly changing. Will two machines, coupled together, run independently of each other, or will one control the movement of the other in such wise that they settle down to conspire to produce the same effect, or will it be into mutual opposition ? It is obvious that a great deal turns upon the answer to this question, for in the general distribution of electric light, it will...
Page 255 - Universal Wiring Computer, for Determining the Sizes of Wires for Incandescent Electric Lamp Leads, and for Distribution in General Without Calculation, with Some Notes on Wiring and a Set of Auxiliary Tables. By Carl Hering.
Page 37 - A represents the current which will pass if the lamp be prevented from operating. Let ON represent the current to which the lamp is adjusted; then if the abscissa of A be greater than ON, the carbons will part. Through N draw the ordinate BN, meeting the curve in the point B ; and parallel to OA draw a tangent CD, touching the curve at D. If the point B is to the right of D, or...
Page 256 - THE ELECTRICAL WORLD Is the largest, most handsomely Illustrated, and UIO-.1 widely circulated electrical journal iu the world. It should be read not only by every ambitious electrician anxious to rise in his profession, but by every intelligent American. The paper is ably edited and noted for explaining electrical principles and describing new inventions and discoveries in simple and easy language, devoid of technicalities. It also gives promptly the most complete news from all parts of the world,...
Page 186 - Fio. 3. induction be deduced on the assumption that the induction is a simple harmonic function of the time, results may readily be obtained vastly in excess of the truth.
Page 252 - Railways," or of any other Electrical book or books published, will be promptly mailed to any address in the world, POSTAGE PREPAID, on receipt of the price.
Page 77 - ... gas engine driving a dynamo, and using the electricity in the ordinary way in incandescent lamps, we can obtain more than 5 candles per cubic foot of gas, a result you would be puzzled to obtain in 16-candle gas burners. With arc lights instead of incandescent lamps many times as much light could be obtained. At the present time, lighting by electricity in London must cost something more than lighting by gas. Let us see what are the prospects of reduction of this cost ? Beginning with the engine...

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