Engineers and Engineering Volume 24

Engineers and Engineering Volume 24

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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. 1907 edition. Excerpt: ...that there may be a greater actual volts drop at high voltage. The resultant tendency of these two relations is to reduce the amount of material in the supply circuit and to decrease the number of feeding points on a system where high voltage is used. In single phase systems this tendency is partially counteracted by the fact that an electric circuit offers a greater impedance to alternating current than the amount of its ohmic resistance to direct current, and the drop with alternating current is dependent upon the impedance of the circuit, just as the drop with direct current is dependent on the circuit's ohmic resistance. The practical result of this feature of the single phase system is to first cut down the amount of overhead material to a definite quantity, and then space the feeding points to suit the drop permissible with this standard overhead construction at the voltage which seems best adapted to the problem in hand. The desirability of having a standard type of overhead construction is due to the fact that this reduces the cost of production, and consequently the cost to the customer, and also facilitates delivery from the factory. Where transformer stations are used, the drop in the low tension distribution system should be limited to 10 percent maximum, because of the cumulative effect of the drops in transformers and high tension line. Where a line is fed entirely from the generators direct, the maximum trolley and track drop may be so high as 20 percent. By observing these limits of maximum drop the loss in the trolley and track system may be kept as low as 5 percent in the first case, and 10 percent in the second case, which is a decided improvement in efficiency over the 15 or 20 percent line loss often found in direct...
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Product details

  • Paperback | 134 pages
  • 189 x 246 x 7mm | 254g
  • United States
  • English
  • black & white illustrations
  • 123683321X
  • 9781236833211