voltage E, is therefore fixed. illaChime op- erates at no-load, terminal voltage E12 is equal to the induced voltage E, because the voltage drop in...
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# 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 when under a load of 24 kW. 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.

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.

voltage E, is therefore fixed.
illaChime op-
erates at no-load, terminal voltage E12 is equal to the
induced voltage E, because the voltage drop in the
armature resistance is zero. However, if we connect
a load across the armature (Fig. 4.23), the resulting
load current / produces a voltage drop across resist-
ance Ro. Terminal voltage E12 is now less than the
induced voltage E.. As we increase the load, the ter-
minal voltage diminishes progressively, as shown
in Fig. 4.24. The graph of terminal voltage as a
the generator.
Hang esuit
blud ovi
Ro
F1
o
+
Eo
R
10
F2
guna
NO
Figure 4.23

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