DIRECT FEEDING*S,YSTEMS. 17 
compelling the motors to slow down and work inefficiently, 
while if the drop reaches 125 volts or more the motors are 
nearly inoperative under heavy loads, although they will 
still work if tco great demands are not put upon them. It 
is highly undesirable to deal with more than 100 volts loss 
under maximum load in a 50ovolt system. By overcom- 
pounding the generators these conditions can be much re- 
lieved. With the maximum drop limited to twenty per 
cent, it is clear that the average drop, with the ordinary 
ratios between average and maximum load would have to 
be limited to five or at the utmost ten per cent. 
  
T'1c. 48. 
If the dynamo be overcompounded, as it should be for 
at least the average drop, then the maximum drop will gen- 
erally fall within safe limits. It isa common practice to 
overcompound ten per cent, i. e., fifty volts, so that even 
a total drop of twenty-five per cent will still leave the sys- 
tem in fair operative condition. 
Coming back now to Fig. 48, we have found that the 
system is operative at average load by means of the trolley 
wire alone, but should be well re-enforced by feeders to 
meet the conditions of heavy load. Since we have found 
that feeding at the middle point of A B would give too 
much drop even if the loss in the feeder were as small as 
five per cent at average load, the next step is to feed at two 
points. ‘These should be so chosen, if the load is uniform 
along the section, as to be one-half the length of the sec-