Proceedings of the Institution of Electrical Engineers Volume 28

Proceedings of the Institution of Electrical Engineers Volume 28

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1899 edition. Excerpt: ...for three values of pl = p2 = p3, the external resistance in the armature of this motor, namely 1-03, o'i5, and 0-012 ohm, and found to be about 1, 7, and 2 lbs. respectively at a radius of 3-5 feet. Tables VI., VII. and VIII. give the results of the experiments in each case, and Table IX. shows the collected results, from which we see that the calculated values are 15, 672, and 2-2 lbs. at a radius of 3'5 feet. The agreement is as good as one could expect from the rough way in which the torque was measured, owing to the friction of brushes and bearings rendering an exact measurement difficult. It is interesting to examine the effect of waste field upon the distribution of power in this motor over a half period in time. The sum of in, f Xjdt and m2x2-dt over half a period divided by 2/ is the energy delivered to the motor by the primary circuit irrespective of x R, and x R2 losses, since the potential differences EI( E2, have been corrected for x, R, and x2 R2. Similarly y, dt + j e2y2di+ Jf3 y3 dt divided by 2 / is the energy received by the secondary or armature circuits. The difference gives the dissipation of energy due to magnetic hysteresis and induced currents in the iron (and copper if there be any) Vol. Xxviii. 22 and that due to waste field. When the machine has opencircuited armature, the average rate of dissipation of energy in watts is 176 (see Table V.). Take Table VI., in which the external resistances pt = p2 = p3 = 1.03 ohms. The average watts due to waste field and iron losses =1301. Assuming that 176 watts represents the rate of dissipation of energy in the iron, we have 1125 watts due to waste field. Take Table VII., in which the external resistances p!--p2 = p3 = 015 ohm. The average rate of dissipation of energy more

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  • Paperback | 224 pages
  • 189 x 246 x 12mm | 408g
  • United States
  • English
  • black & white illustrations
  • 1236795245
  • 9781236795243