74 Till'. MI;K<T-ITI;I;KNT M<TOI; en. iv 



taking for any given speed. \Yhen the speed is nothing, 

 the currents are 100 and 1 i'o amperes. When the speed is 

 1,200 r.p.m. the current in A is nothing, and that in II is 

 3(v7 amperes. When the speed is 1,800 r.p.m. the cur- 

 rent in II is nothing, and A is now generating a current 

 of 50 amperes. If the speed is above 1,800 both dynamos 

 are acting as generators-, if it is below 1,200 both are 

 acting as motors, between these speeds A is acting as a 

 generator and tt as a motor. 



If horizontal lines are drawn through fj and /to cut 

 the two speed curves in /r and //, and if a line is drawn 

 through the points h and /., this line is the com- 

 bined speed curve, and will give the speed for any 

 current from the line. The horizontal ordinates of this 

 curve represent the current from or into the line. 

 Where the combined speed curve cuts the axis of speed, 

 the current from the line is nothing, and the current 

 from A is the same as that into II. 



Now let by represent the torque in A for a current of 

 ab amperes, and let bp represent the torque in 7? for the 

 same current ; these distances will be related to one another 

 in the ratio of the two induction factors. Join aq and ap, 

 and produce in both directions. These lines will then be the 

 torque curves for the two dynamos, on a base of amperes. 



From A- draw a vertical line to cut the torque curve of 

 A. in the point r. Then since at the speed uy there is no 

 current in B, the ordinate of the torque curve of A at r 

 represents the combined torque of the two dynamos, and 

 hence r is a point on the curve of combined torque, 

 the horizontal ordinates of which would give the current 

 from or into the line. A second point 011 this curve may 

 be found bv drawing a vertical line from li to cut the 



