Dynamo-electric Machinery: A Manual for Students of ElectrotechnicsE. & F. N. Spon, 1892 - 876 pages |
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Common terms and phrases
alternate currents alternate-current ampere-turns amperes angle arc-light armature core armature current bars brushes calculated cent centimetre commutator conductors connected constant construction copper core-disks counter electromotive-force curve demagnetizing designed diameter disk eddy-currents effect efficiency electric electrical efficiency Electrician electromagnet electromotive energy Engineers equal equation exciting external circuit field-magnets gap-space given Gramme GRAMME DYNAMO heat Hopkinson horse-power inches increase induction insulated internal resistance iron core Kapp kilowatt lamps lines of force load machine magnetic circuit magnetic field magnetic lines magnetic reluctance magnetizing force maximum mechanical Messrs method Mordey motive-force motor multipolar number of lines number of magnetic ohms output parallel permeability Permeance Plate polar pole-pieces poles potential proportional represents reversed revolutions per minute ring armature rotating round running self-induction separate series coils shaft shown in Fig Siemens sparking Specification of Patent speed square supplied torque turns voltage volts watts whilst winding wire wound
Popular passages
Page 129 - ... currents in the neighbourhood, without the presence of a magnet. Since the peculiarity of the magnetic field consists in the presence of a certain force, we may numerically express the properties of the field by measuring the strength and direction of the force, or, as it may be worded, the intensity of the field and the direction of the lines of force.
Page 8 - A machine for converting energy in the form of mechanical power into energy in the form of electric currents, or vice versa, by the operation of setting conductors (usually in :he form of coils of copper wire) to rotate in a magnetic field, or by varying a magnetic field in the presence of conductors.
Page 465 - ... rotated. As the two coils and commutator are rotated in the direction indicated by the arrows, the two brushes rub against the segments consecutively and always make contact with the two opposite ones. The brushes...
Page 37 - The shorter the length of those parts of the conductor not so employed, the stronger will be the current. (12.) Approach being a finite process, the method of approach and recession (of a coil towards and from a magnet pole) must necessarily yield currents alternating in direction. (13.) By using a suitable commutator, all the currents, direct or inverse, produced during recession or approach, can be turned into the same direction in the wire that goes to supply currents to the external circuits,...
Page 555 - I have already had the honor of delivering, I have treated the dynamo solely in its functions as a generator of electric currents. In this third lecture I come to the converse function of the dynamo, namely, that of converting the energy of electric currents into the energy of mechanical motion. An...
Page 819 - Ampere, which is one-tenth of the unit of current of the CGS system of electromagnetic units and which is represented sufficiently well for practical use by the unvarying current which, when passed through a solution of nitrate of silver in water, in accordance with a certain specification, deposits silver at the rate of 0.001118 of a gramme per second.
Page 13 - Conductors or electric collectors of copper and lead were constructed so as to come in contact with the edge of the copper disc...
Page 560 - While voltaic batteries were the only available sources of electric currents, economical working of electric-motors was hopeless. For a voltaic battery, wherein electric currents are generated by dissolving zinc in sulphuric acid, is a very expensive source of power. To say nothing of the cost of the acid, the zinc — the very fuel of the battery— costs more than twenty times as much as coal, and is a far worse fuel ; for...
Page 815 - ... That it is desirable that new denominations of standards for the measurement of electricity should be made and approved by Her Majesty in Council as Board of Trade standards. 2. That the magnitudes of these standards should be determined on the electro-magnetic system of measurement with reference to the centimetre as unit of length, the gramme as unit of mass, and the second as unit of time, and that by the terms centimetre and gramme are meant the standards of those denominations deposited...
Page 560 - Jacobi enabled him, however, to discern that the observed diminution of current was really due to the fact that the motor, by the act of spinning round, began to work as a dynamo on its own account, and tended to set up a current in the circuit in the opposite direction to that which was driving it. The faster it rotated the greater was the counter-electromotive force (or " electromotive force of reaction ") which was developed.