Q. A 7.5-hp, 250-V, 1800-r/min shuntmotor, having a full-load line current of 26 A, is started with a four-point starter. The resistance of the armature circuit, including the interpole winding, is 0.48 ; and the resistance of the shunt-field circuit, including the field rheostat, is 350 . The resistances of the steps in the starting resistor are 2.24, 1.47, 0.95, 0.62, 0.40, and 0.26 , in the order in which they are successively cut out.When the armature current is dropped to its rated value, the starting box is switched to the next point, thus eliminating a step in the starting resistance.

Neglecting field-current changes, armature reaction, and armature inductance, find the initial and final values of the armature current and speed corresponding to each step.