Question

# Can i get some help with these question?

1. A separately excited DC

generator with an equivalent circuit similar to Figure 4.23 in textbook would produce a terminal voltage of 125 V at a speed of 3000 rpm * at no load*. The generator is observed to be operating with a terminal voltage of 124 V

*. The armature resistance is 0.02 Ω. Calculate the actual operating speed of the generator, assuming armature voltage is linearly proportional to the generator speed.*

__when under a load of 24 kW__2. The equivalent circuit of a shunt DC motor is shown. If the input voltage = 120 V, input current = 10 A, shunt field resistance = 80 Ω, and armature resistance = 0.3 Ω, calculate:

(a) Field current

(b) Counter emf

(c) Total mechanical power developed by the motor (that is: total input power minus the loss in the motor).

3. A 25-hp, 240-V shunt motor (with the same equivalent circuit as in problem 2) operating at 850 rpm draws a total current of 91 A when operating at rated conditions. A 2.14-Ω resistor inserted in series with the armature causes the speed to drop to 634 rpm. The respective armature resistance and shunt field resistance are 0.221 Ω and 120 Ω. Determine the new armature current, assuming output speed is linearly proportional to the armature voltage.