76 POCWER DISTRIBUTION FOR ELECTRIC RAILROADS. 
Step 6. Approximate data are now at hand for laying 
cut the feeding system proper. We may start with a 
duplicate of Fig. 46, as Fig. 48, showing now only the actual 
linesand H, the location of the station. From A to D there 
are two No. oo trolley wires, one for each track. From Cto 
E thereis one such trolley wire. We may now find more 
exactly the proper distance between feeders. Beginning 
with section 1, we find that in regular traffic each trolley 
wire will supply five cars at various points. Now going 
back toequation 2, substituting our new constant and 
transposing we have 
e X, 
v R0 
Heree. m, =— 133,000, E=—25; and 13 C = 19:. F there- 
fore equals for a single car very nearly 17,000 ft., for two 
cars 8500 ft., for three cars 5666, for four cars 4250, and for 
five cars 3400 ft. Hence a single feeder at the middle point of 
A B would be sufficient to handle the average load uniformly 
distributed, very nicely. ‘The same is obviously true of 
sections BD and CE. Just here appears the peculiar 
characteristic of railway systems—the unpleasantly large 
maximum loads. If the load at the end of A B should be 
300 amperes as we have supposed, i. e., 150 amperes to be 
supplied by each trolley wire, the corresponding drop in 
volts would be by equation 3 
  
E—=18CL_ . 
c M. 
Which in addition to the loss in the feeder would produce a 
total drop which would be decidedly troublesome, although 
hardly enough to cause serious difficulty. ‘The cars would 
run, but the motors would heat badly and it would be diffi- 
cult to make time. On B D the conditions weuld be better, 
but with the maximum load at E the drop would be enough 
to stall the cars completely and they would have to be slowly 
worked away one at a time. 
As to the effect of drop, with the usual 500 volt 
motors, a drop of 75 to 100 volts is decidedly annoying