With a separately excited 2-kW DC machine, which has the following parameters, draw the capability curve in the first quadrant and the second quadrant of the torque-speed plane. Also in the plane, simultaneously plot the electric power to (from) the machine, along with the armature voltage, and the field current according to the torque. Because of the commutation problem, the field flux can be reduced down to one-third of the rated value. It is assumed that the field flux is proportional to the field current.
