Q. A 100 hp, 250 V, 350 A shunt dc motor with an armature resistance of 0.05 ohms. To limit maximum starting current to twice the rated of its value, what will be the number of stages of starting resistances?
✅ Correct Answer: (A)
3
Explanation: n = log(ra/rt)/log(imin/imax); rt = vt/imax = 250/700 = 0.357 ohms