A series connected DC motor has R_A = 3 ohm and R_F = 13 ohm. When driving an unknown load at 1100 rpm, the current is I_A = 10 A from a voltage source of VT = 300 V with a rotational loss of 100 W.
a) Find the output power and the developed torque
b) What fraction of the input power makes it to the output
c) Find the maximum allowed developed torque and corresponding motor speed that will ensure that no more than 25% of the power is lost in conductive losses in the armature and field windings