A 240 V DC shunt motor draws 40 A while driving a constanttorque load. The armature resistance is Ra = 0.2 Ω, the fieldresistance is Rf = 240 Ω and machine constant is Ka = 120. The partof magnetization characteristic (field flux versus field current)related to the question is:
If (A) : Â Â Â Â Â 0.70 0.80 0.86 0.90 1.001.10 1.20 1.30 1.40
Ï• (mWb) : 5.80 6.30 6.59 6.70 7.20 7.60 7.96 8.20 8.45
The constant rotational loss is 240 W and the armature reactionis neglected. Find
a. the internal torque developed by the motor
b. speed   Â
c. efficiency   Â
