284

ELECTRICAL APPARATUS

two sections, 1 and 3, and 2 and 4, the high-frequency voltages
in the two sections are opposite in phase from each other. Con-
necting, then, as shown in Fig. 143, 1 and 2 in series, and 4 and
3 in series into the two phases of the quarter-phase supply cir-
cuit, no high-frequency induction exists in either phase, but the
high-frequency voltage is generated between the middle points

FIG. 142.—Induction type of high-frequency inductor alternator.

of the two phases, as shown in Fig. 143, and we thus get another
form of a frequency converter, changing from low-frequency
polyphase to high-frequency single-phase.

FIG. 143.—Diagram of connection of induction type of inductor alternator.
163. A type of inductor machine, very extensively used in
small machines—as ignition dynamos for gasoline engines—is
shown in Fig. 144. The field, F, and the shuttle-shaped armature,
A, are stationary, and an inductor, I, revolves between field and
armature, and so alternately sends the magnetic field flux through
the armature, first in one, then in the opposite direction. As
seen, in this type, the magnetic flux in the armature reverses,
by what may be called magnetic commutation. Usually in these