K.W. Output 
a1 
  
178 POWER DISTRIBUTION FOR ELECTRIC RAILROADS. 
variation characteristics of a fifteen horse power induction 
motor with a rheostat in the armature circuit. Starting at 
full output and speed, the speed was gradually lowered 
from 1400 r. p. m. to 150 1. p. m. The torque remained 
uniform, so that the output was almost exactly proportion- 
ate to the speed. 'The relation between them is shown in 
curve A. The input meanwhile remained nearly con- 
~ 
1 
  
Speed in 100 p.p.m. 
FIG. 97. 
stant. B gives the variation of the power factor and C 
shows the slight and gradual diminution of the input. 
Altogether this motor behaved almost exactly like an 
ordinary railway motor with rheostatic control, regulating 
quite as well and with closely similar inefficiency. 
At full load this motor had about the efficiency of a 
fifteen horse power motor of the ordinary kind, but sub- 
stantially all the reduction in output by lowering the 
speed represented loss of efficiency as is the case with a 
series wound, continuous current railway motor with rheo- 
  
     
  
   
   
   
    
   
   
  
  
  
   
  
  
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