. Electrical world. ycles. A number of railway motors of this type were Thegreat difficulty, however, was that during these early days 125 to133 cycles was the standard frequency in this country, 60 cycleshardly considered, and 25 cycles not yet proposed. The efficiency of this alternating-current series motor is slightlylower than that of the same motor on direct-current circuit, due:(,1) To the hysteresis loss in the field. (2) The hysteresis loss inthe armature core, which is of full frequency up to synchronousand of still higher frequency, the frequency of rotation, beyond syn-c
. Electrical world. ycles. A number of railway motors of this type were Thegreat difficulty, however, was that during these early days 125 to133 cycles was the standard frequency in this country, 60 cycleshardly considered, and 25 cycles not yet proposed. The efficiency of this alternating-current series motor is slightlylower than that of the same motor on direct-current circuit, due:(,1) To the hysteresis loss in the field. (2) The hysteresis loss inthe armature core, which is of full frequency up to synchronousand of still higher frequency, the frequency of rotation, beyond syn-chronism. (3) The I-R loss in the short-circuited secondary con-ductors surrounding the armature. As will be seen, to make the alternating-current series motor prac-ticable, the transformer feature must be introduced, by having itsarmature as primary circuit closely surrounded by a short-circuitedsecondary circuit, as shown diagrammatically in Fig. 2. Instead of closing the stationary circuit upon itself as secondary. FIGS. 2 .\XD 3.âDIAGRAMS OF ALTERNATING-CURRENT SERIES MOTOR. â sircuit and feeding the main current into the rotating armature asprimary circuit, mechanically the same results would obviously beobtained by using the stationary circuit as primary energized by themain current and closing the armature upon itself as secondary byshort circuiting the brushes and thereby keeping the main currentand the line potential away from the armature, as shown diagram-matically in Fig. 3. This introduces the great advantage of revers-ing the sign of the uncompensated part of the armature self-induction,so that it is subtractive, which results in an essential improvementof the power-factor, especially at low speed. This is shown in Fig. 4, where with the speed as abscissas, in percent, of synchronism, are plotted the power factor of the Eicke- - â 1 1 , i â 1 . 1 1 1 *-00 1 â ! : 1 1 1 â â ^ â â â â , - - 90 ! .âJ ^ 80 : :.-^f^\ 1 [1-i. ^ â . â n i / ^^ / ^X ⢠CO /
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectri, bookyear1883
