CH. IX CONTROL 201 



The vertical ordinates of the acceleration curves give 

 the speed of the car in feet per second . The base of both 

 acceleration and current curves gives the time in seconds, 

 measured from the moment of starting. 



The curves of induction factor and torque for the G. E. 

 800 motor have been given in Fig. 21, and may be taken 

 as representing very nearly the action of the motors used 

 on the Buffalo and Niagara Falls line. 



Fig. 51 gives the record of a test arranged to effect a 

 continuous start. The point at which the motors are 

 thrown over into parallel can only be detected from the 

 current curve, the acceleration curve being unbroken by 

 any sudden change of curvature. This means that the 

 start was effected without shock. The dip in the current 

 curve at six seconds from the start shows that the motors 

 were allowed to speed up in series for a short time, but 

 not long enough to cause a shock in the transition to 

 parallel. In other words, the change over was made when 

 the acceleration in series had diminished to the value of 

 the acceleration on the parallel connection. 



The current per motor at the start was 60 amperes, 

 but the full current was not thrown on at once, a period 

 of about two seconds elapsing before the maximum current 

 per motor is reached. If we take the initial friction to be 

 twice as great as the running friction, the current must 

 rise to 72 amperes before the car will begin to move. The 

 friction decreases to the running value directly motion 

 commences. 



When the motors are thrown into parallel connection 

 the current from the line rises from 120 to 200 amperes, 

 while the current per motor decreases from 60 to 50 

 amperes. The form of the current curve as the motors 



