A shunt-connected 75 𝑘𝑊, 250 𝑉 DC motor has an armature
resistance of 45 𝑚Ω and a field resistance of 185 Ω. When operated
at 250 𝑉 its no-load speed is 1850 𝑟𝑝𝑚.
The motor is operating under load at a terminal voltage of 250 𝑉 and
a terminal current of 290 𝐴. Calculate:
a) motor speed, load power, load torque.
b) Assuming the load torque remains constant as a function of
speed, calculate the motor speed if the terminal voltage is
reduced to 200 𝑉.