Conductors for Electrical Distribution; Their Materials and Manufacture, the Calculation of Circuits, Pole-Line Construction, Underground Working, and Other Uses

Conductors for Electrical Distribution; Their Materials and Manufacture, the Calculation of Circuits, Pole-Line Construction, Underground Working, and Other Uses

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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. 1903 edition. Excerpt: ...is about 30 Fahr., while the temperature elevation allowed for weatherproof wires approaches 70 Fahr., though it is stated that temperature elevations of only twenty-five degrees were observed in the experiments made by the underwriters. From the formulas given we see that the current-carrying capacity of a wire varies as the 3/2 power of the diameter, while we know that the area varies simply as the square of the diameter, and in consequence it is plain that any rule for the carrying capacity of a wire which refers simply to its area or its diameter will give different temperature elevations for different sizes of wire. As, for instance, a rule has been often used allowing 1,000 amperes per square inch for the carrying capacity of a wire, which determines a wire 713 mils in diameter for a current of 400 amperes; while, according to Kennelly's formula, a wire of 800 mils should be used for this current. One thousand amperes per square inch requires a wire 225 mils in diameter to carry 40 amperes; whereas a smaller wire of 172 mils is seen to be sufficient according to Kennelly's rule, the two methods of calculation giving the same size only for 196 amperes, requiring a wire 500 mils in diameter; the rule allowing 1,000 amperes per square inch entailing a less temperature elevation than 190 Fahr. for smaller currents, and a higher temperature elevation for larger currents. Furthermore, we see from Kennelly's investigations that many small wires will carry more current than a single large wire of equivalent area with the same temperature rise; the difference between one wire for carrying a definite current and two wires for transmitting the same current amounting to a reduction of 20 per cent in the total area, and, in consequence, where...show more

Product details

  • Paperback | 82 pages
  • 189 x 246 x 4mm | 163g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236917316
  • 9781236917317