66 SELLERS — TRANSMISSION OF ENERGY BY ELECTRICITY. [Feb. 3, 



current is distributed at from 2200 to 2000 volts (depending on dis- 

 tance) to points outside of the power-house within a radius of two 

 miles. By means of step-up. transformers 10,000 electric horse 

 power of induced current of 11,000 volts can be carried to Buf- 

 falo by six cables, each 5/^" in diameter, and capable of trans- 

 mitting 10,000 electric horse power at the said voltage, or double 

 that amount, at 22,000 volts, with a loss, based on Lord Kelvin's 

 law of economy as to size of conductors.^ You can better realize the 

 idea of the size of the conductors when I tell you that from each tur- 

 bine exerting over 5000 horse power a steel shaft ii'^ in diameter is 

 needed to drive each dynamo delivering 5000 electrical horse 

 power, from which are carried the conductors of the sizes named. 

 Four bus bars receive the current from five dynamos, the heaviest 

 part of each bus bar being 3'' in diameter; /. e., one 11" steel shaft 

 transmits kinetic energy of 5500 horse power; four 1^4^'' cables 

 transmit 5000 electric horse power energy of 2200 volts; three ^" 

 cables transmit 5000 electric horse power to Buffalo. 



Besides the development of power at Niagara Falls, to which I 

 have called your attention, numerous successful installations in 

 various parts of our country could be referred to, and even in Europe 

 we find the transmission of power by alternating current in exist- 

 ence, and, in fact, in some instances preceding in actual operation 

 the starting of the plant at Niagara Falls ; such installations being 

 on a smaller scale required less time to construct them. 



^ Lord Kelvin proposed, in determining the size of conductors tor electricity, 

 that the most economical area of conductor is that for which the annual cost of 

 energy wasted is equal to the interest on that portion of the capital outlay which 

 can be considered to be proportionate to the weight of the metal used ; that is to 

 say, the amount of copper and other details of the transmission line, the interest 

 of which should equal that amount of energy at its cost of production that may 

 be wasted. The lower the cost of the power generated the more energy may be 

 wasted to advantage. If too large a conductor is installed for the purpose of 

 decreasing the loss, the capital outlay will be needlessly great. If too small a 

 conductor is adopted the waste of energy will be too great, hence the importance 

 of a law that indicates what the economical loss should be. In applying this law 

 there is more or less divergence of opinion as to what part of the capital outlay 

 should be taken into consideration in determining the amount to be wasted. As, 

 for instance, an underground conduit system may be built to accommodate a 

 great increase of the number of conductors installed, or when a pole line is 

 erected for a given amount of power, additional conductors may be supported on 

 the same poles without any great increase of the cost due to enlarging the ca- 

 pacity of the transmitting line. The law, therefore, bears with most force on the 

 metal if naked or the cable if the conductor is insulated. 



