## Electric generators |

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### Common terms and phrases

air gap alternating current ampere turns Amperes per square annealed armature conductors armature core armature lamination armature reaction armature turns C2R loss calculations carbon brushes Cent collector rings commutator segment continuous-current copper core loss cross-section curves of Fig cycles per second demagnetising diameter eddy current electromotive force face conductors field spools full load given hysteresis hysteresis loss increase insulation kilolines length of armature machines magnet core magnetic circuit magnetic flux magnetisation magnetomotive force maximum Mean length mica minimum inductance number of conductors number of poles number of turns ohms output Peripheral speed permeability phase pole arc pole-face Reactance resistance revolutions per minute rheostat rotary converter series winding sets of brushes sheets single winding square inches Length steel Table Terminal voltage tests thickness transformers turns in series Turns per Coil turns per inch turns per pole turns per pole-piece two-circuit windings voltage watt per square

### Popular passages

Page 281 - ... direct-current generator. Another point of difference is in the relative dimensions of the magnetic circuit, including yoke and magnet cores, which are smaller than would be usual or desirable in ordinary direct-current generators. Under the usual condition of running, the armature is driven, as in a simple synchronous motor, by alternating current supplied to the collector rings from an external source. While so revolving direct current can be taken from brushes bearing upon the commutator....

Page 78 - M = the magnetic flux (number of cgs lines) included or excluded by each of the T turns in a magnetic cycle. V, the voltage, is approximately constant during any period considered, and is the integral of all the voltages successively set up in the different armature coils according to their position in the magnetic field ; and since in this case only average voltages are considered, the resultant voltage is independent of any manner in which the magnetic flux may vary through the coils. Therefore...

Page 16 - ... that, beginning with the most impure cast iron, and passing through the several grades of cast iron, steel and wrought iron, the magnetic properties accord principally with the amounts of carbon present, and in a lesser degree with the proportions of...

Page 158 - T turns ; hence the product of flux and turns, ie, the total linkage, the inductance of the coil, is proportional to the square of the number of turns in the coil.

Page 78 - TNM i0-8, in which V = the voltage generated in the armature. T = the number of turns in series between the brushes. N = the number of magnetic cycles per second. M = the magnetic flux (number of cgs lines) included or excluded by each of the T turns in a magnetic cycle.

Page 302 - ... three-phase alternating currents into two-phase alternating currents. For three-phase rotary converters, the transformers should preferably be connected in A, as this permits the system to be operated with only two transformers, in case the third has to be cut out of the circuit temporarily for repairs.

Page 150 - We find, therefore, that while in the first case the armature strength is small, the voltage between segments is excessive. In the second case, while the voltage between segments is small, the armature is altogether too strong. With but two poles, some intermediate value would have to be sought for both quantities ; probably something like 100 turns would give a fairly good result. CONDITIONS ESSENTIAL то SPARKLESS COMMUTATION As a consequence of armature reaction and inductance it becomes not...

Page 302 - six-phase," with six collector rings. This requires in each case subdividing the winding up into just twice as many sections as for the case of three-phase windings. A study of these windings will show that with these connections with six sections (where before there were three), the first and fourth, second and fifth, and third and sixth, taken in pairs, give a distribution of the conductors, suitable for a three-phase winding, each of the above pairs constituting a phase. Furthermore, each portion...

Page 153 - Suppose, for instance, a 10-kw. 100-volt generator, with an armature strength of 2000 * If only two sets of brushes are retained the short-circuited set of conductors no longer consists of the two corresponding to one turn, but now includes as many in series as there are poles. A high reactance voltage is consequently present in this short-circuited set. The presence of the full number of sets of brushes, if correctly adjusted, should reduce this, but cannot in practice be relied upon to do so. Diagrams...