Original Papers on Dynamo Machinery and Allied SubjectsW.J. Johnston, 1893 - 249 стор. |
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Загальні терміни та фрази
abscissæ alternate current machines Amperes angle armature armature coil brushes calorimeter carbons cent centimetre Chance Brothers characteristic curve coefficient column commutator conductor connected convolutions copper core current passing Deflection determined diagram diameter difference of potential dynamo machine dynamo-electric machine dynamometer effect efficiency electric arc electric current electric light electromotive force energy engine equation experiments external circuit galvanometer given gives Gramme machine Hence horizon horse power incandescent induction integral of magnetic iron lamp lens lighthouse line integral loss magnet coils magnet limb magnetic circuit magnetic field magnetizing force maximum mean measured motor observed obtained open circuit ordinates pole pieces potential difference produce pulley represents resistance revolutions per minute short circuited Siemens speed square temperature Thick Coil Tino tion transformer velocity volts waste field watts wire
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Сторінка 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...
Сторінка 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...
Сторінка 103 - The currents in the moving coils of the armature have also their effect upon the resultant field. In well-constructed machines the effect of the latter is reduced to a minimum, but it can be by no means neglected. This introduces a second independent variable, viz., C, the current in the armature. The effect of the current in the armature depends upon the lead given to...
Сторінка 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...
Сторінка 80 - Such empirical formulae possess no advantage over the graphical method aided by algebraic processes, and tend to mask much that is of importance. One purpose of the present investigation is to give an approximately complete construction of the characteristic curve of a dynamo of given form from the ordinary laws of electro-magnetism and the known properties of iron, and to compare the result of such construction with the actual characteristic of the machine. The laws of electro-magnetism needed are...