INDUCTION -MOTOR 85

of the current wave lower the power-factor, so that ill extreme
cases the shunted condenser may actually lower the power-
factor. However, with the usual commercial, voltage wave
shapes, this is rarely to be expected.

In single-phase induction motors, the condenser may be used
in a tertiary circuit, that is, a circuit located on the same member
(usually the stator) as the primary circuit, but displaced in posi-

LOW SPEED INDUCTION MOTOR
WITH SHUNTED CONDENSER
Z0 = .

10 20 80 40 SO CO ?p 80 90 100 110 120 KW.

FIG. 32.—Load curves of high-excitation induction motor with shunted
condenser.
tion therefrom, and energized by induction from the secondary.
By locating the tertiary circuit in mutual induction also with the
primary, it can be used for starting the single-phase motor, and
is more fully discussed in Chapter V.
A condenser may also be used in the secondary of the induction
motor. That is, the secondary- circuit is closed through a con-
denser in each phase. As the current consumed by a condenser is
proportional to the frequency, and the frequency in the secondary
circuit varies, decreasing toward zero at synchronism, the cur-
rent consumed by the condenser, and thus the secondary current
of the motor tends toward zero when approaching synchronism,