The armature resistance of an 18.65 kW 250 V dc series motor is 0.1 Ω, the brush voltage drop is 3 V and series field resistance is 0.05 Ω. When the motor takes 80 A, its speed is 600 rpm. Calculate the speed when the motor takes a current of 100 A.

The armature resistance of an 18.65 kW 250 V dc series motor is 0.1 Ω

1.	The armature resistance of an 18.65 kW 250 V dc series motor is 0.1 Ω, the brush voltage drop is 3 V and series field resistance is 0.05 Ω. When the motor takes 80 A, its speed is 600 rpm. Calculate the speed when the motor takes a current of 100 A.
A.	556 rpm
B.	315 rpm
C.	474 rpm
D.	653 rpm
Answer» D. 653 rpm