9-2. A 50-hp, 250-V, 1200 r/min de shunt motor without compensating windings has an armature resistance (including the brushes and interpoles) of 0.06 0. Its field circuit has a total resistance RF + Radj of 50 O. which produces a no-load speed of
1200 r/min. There are 1200 turns per pole on the shunt field winding. and the armature re action produces a demagnetizing magnetomotive force of 840 A • turns at a load current of 200 A. The magnetization curve of this machine is shown in Figure 9-9.
(a) Find the speed of this motor when its input current is 200 A.
(b) This motor is essentially identical to the one in Example 9-1 except for the ab sence of compensating windings. How does its speed compare to that of the pre vious motor at a load current of 200 A?
(c) Calculate and plot the torque-speed characteristic for this motor.