SUBSTATIONS. 127% 
transmission of all the power from some one point with sub- 
stations at one or more of the others? . 
Of the plans with two generating stations, that with 
stations at A and Bis undoubtedly the better since the ter- 
minal loads are so considerable. ’The single station at D 
requires a little consideration, because the difference in 
cost of power between a 500 k.w. station and two 250 k.w. 
stations is very material. Of the possible transmission 
plants, that comprising a generating plant at one end of 
the line and a substation at or near the other is at first 
glance the most promising. For the total amount of power 
to be transmitted is very moderate and the subdivision of 
even this by using two or more substations would only 
involve useless expense. 
We may now compare more closely the plan calling 
for stations at A and B with that for the installation of a 
single plant at the point D. On the one hand we have the 
economy of the larger station—on the other the cost of 
distributing 200 k.w. at a point ten miles from home. 
A ' i : B 
C D E 
  
BTG /L 
Assuming the yearly differences in cost of power be- 
tween a 500 k. w. station and two 250 k. w. stations to be 
about $o0.4 per kilowatt hour in favor of the former, the 
yearly differenceis $14,600. Now for the approximate cost 
of feeder copper. If a simple station at D be used we must 
practically allow for 400 k. w. delivered at a distance of ten 
miles. Using the formula employed in the previous cases 
L 42CE m 
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W 
  
  
and assuming ten per cent drop we have a call for 940 tons 
of feeder copper costing about $263,000. Even at twenty 
per cent loss the feeder copper would amount to more than 
$130,000, exclusive of the nearer distribution. ‘This settles 
the matter off hand, for with two stations the average dis- 
tance of transmission would be hardly more than three to