Page 254 - Solutions Manual to accompany Electric Machinery Fundamentals

E 120 V
n  A n   1000 r/min  949 r/min
E Ao o 126.4 V

8-22. The magnetization curve for a separately excited dc generator is shown in Figure P8-7. The generator is
rated at 6 kW, 120 V, 50 A, and 1800 r/min and is shown in Figure P8-8. Its field circuit is rated at 5A.
The following data are known about the machine:
R A  18  V  120 V
.
0
F
R  adj 0 to 40  R  20 
F
N  1000 turns per pole
F
Answer the following questions about this generator, assuming no armature reaction.
(a) If this generator is operating at no load, what is the range of voltage adjustments that can be
achieved by changing R adj ?

(b) If the field rheostat is allowed to vary from 0 to 30  and the generator’s speed is allowed to vary
from 1500 to 2000 r/min, what are the maximum and minimum no-load voltages in the generator?

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