236 POWER DISTRIBUTION FOR ELECTRIC RAILROADS. 
service makes it necessary to take, say, 14 as the track 
constant. 
Now turning to Plate II (p. 81) we can find the feeder 
area. It is 700,000 c. m. per one hundred amperes for fifty 
volts drop. In our case then the feeder area is 
789‘7079&X;5 =T, 106" 0006: 
5 
This feeder should supply the terminal sections of track, 
say, sooo ft. long. For convenience we may divide the 
line into 5000 ft. sections lettered on Fig. 121. Sections a 
(and 7) being thus disposed of, we may turn to sections & 
and ¢, treating them together. The average distance of 
_transmission is 15,000 tt. and the maximum load may be 
taken as one train under full headway and one starting, 
say, 650 amperes. From Plate II the copper is 
p*_—-——_oo’ooz K05 == 866,000 C. M. 
Similarly, for sections & and ¢ we have approximately 
140,000, X 6.5 i 303,000, 
3 
Now for the working conductors and then to fine down the 
feeders. 
Using trolley wire such as is used on the Nantasket 
Beach road, we should have about 660,000 c. m. available 
at once in the two trolley wires. Much smaller trolley wire 
would be inadvisable on account of lack of contact surface 
and carrying power. Sections & and ¢ will obviously take 
care of themselves and generally have large capacity to 
spare. Along & and c¢the trolley wire is available, and even 
if the maximum load were at the further end of 4 a 750,000 
c. m. feeder extended from calong these sections would give 
sufficient conductivity. Now for the terminal sections. 
Throughout @ the 660,000 c. m. of the trolley wires is 
available. Hence up to the beginning of the section 
1,000,000 c. m. is sufficient without allowance for help 
from the other feeder. Just how much this help would be 
is hard to estimate. It should certainly not be less than 
100,000 ¢. m. If then the long feeders are of yoo,000 c. m., 
      
  
  
  
  
  
   
  
  
  
  
  
  
  
  
   
  
   
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
   
   
    
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Wil i AR