126

ELECTRICAL APPARATUS

I

the square of this ratio, while the power-factors and the efficien-
cies obviously remain unchanged.

In this manner, in the three cases assumed in the preceding,
the load curves are calculated, and are plotted in Figs. 43, 44,
and 45.

80. It is seen that, even with transformers of good regulation,
Fig. 43, the maximum torque and the maximum power are ap-

Y«0.01-0,ljO Z = 0.1*0,34*

TRANSFORMER IMPEDANCE, Z0 =0.044-0.3 j

CONSTANT PRIMARY POTENTIAL 121 VOLTS

FIG. 44.—Induction-motor load curves corresponding to 110 volts at motor
terminals at 5000 watts load.
preciably reduced. The values corresponding to constant termi-
nal voltage are shown, for the part of the curves near maximum
torque and maximum power, in Figs. 43, 44, and 45.
In Figs. 46, 47, 48, and 49 are given the speed-torque curves
.of the motor, for constant terminal voltage, Z = 0, and the
three cases above discussed; in Fig. 46 for short-circuited
secondaries, or running condition; in Fig. 47 for 0.15 ohm; in
Fig. 48 for 0.5" ohm; and in Fig. 49 for 1.5 ohms additional re-
sistance inserted in the armature. As seen, the line and trans-
former impedance very appreciably lowers the torque, aid