Page 233 - Solutions Manual to accompany Electric Machinery Fundamentals

The resulting plot is shown below:

Compare this torque-speed curve to that of the shunt motor in Problem 8-7 and the cumulatively-
compounded motor in Problem 8-10.

8-13. A 7.5-hp 120-V series dc motor has an armature resistance of 0.1  and a series field resistance of 0.08
. At full load, the current input is 56 A, and the rated speed is 1050 r/min. Its magnetization curve is
shown in Figure P8-5. The core losses are 220 W, and the mechanical losses are 230 W at full load.
Assume that the mechanical losses vary as the cube of the speed of the motor and that the core losses are
constant.

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