Need the detailed answer, thanks! A 15 kW, 72 V, 6000 rpm seperately excited DC machine has the field current adjusted to 3. create rated flux. The machine has an armature resistance Ra 20.5 m2...

Need the detailed answer, thanks!

A 15 kW, 72 V, 6000 rpm seperately excited DC machine has the field current adjusted to 3. create rated flux. The machine has an armature resistance Ra 20.5 m2 (miliohms). At no-load, the armature consumes 6 A. Assuming the rotational and iron losses are unchanged from no-load to rated conditions. The motor is being supplied at the rated voltage. a) Calculate the rated efficiency, ignore the field winding losses. (10 pts) b) Calculate the half-load speed (half-load is the condition in which the armature consumes half the rated current). (10 pts) c) If the armature voltage can now be adjusted, calculate its value to obtain a speed of 3000 rpm, at full-load torque. (10 pts)