A dc series motor has an armature resistance of 0.06 Ω and series field resistance of 0.08 Ω. The motor is connected to a 400 V supply

Q. A dc series motor has an armature resistance of 0.06 Ω and series field resistance of 0.08 Ω. The motor is connected to a 400 V supply. The line current is 20 A when the speed of the machine is 1100 rpm. When the line current is 50 A and the excitation is increased to 30%, the speed of the machine in rpm is

A.            1100 RPM

B.            1003 RPM

C.            837 RPM

D.            938 RPM

Answer: 837 RPM