3. A factory's separately excited DC generator has an armature resistance of 0.250. The at 1000 revolutions per minute giving the following data: E= [V] 5 28 75 112 132 If [A] 0 0.1 0.3 0.5 0.7 a) Plot the open circuit characteristic when the machine is driven at 1000 and at 1; b) If the machine is drive at 1500 rev/min and its field current is adjusted to 0.2 voltage (in the same axis with (a)) as the load current is varied from 0 to 40 current of 40A, what is the voltage regulation