CHAPTER XVII
INDUCTOR 'MACHINES

INDUCTOR ALTERNATORS, ETC.

156. Synchronous machines may be built with stationary
field and revolving armature, as shown cliagrammatically in
Fig. 134, or with revolving field and stationary armature, Fig.
135, or with stationary field and stationary armature, but
revolving magnetic circuit.

The revolving-armature type was the most frequent in the
early days, but has practically gone out of use except for special

FIG. 134.—Revolving armature
alternator

FIG. 135.—Revolving field al-
ternator.

purposes, and for synchronous commutating machines, as the
revolving-armature type of structure is almost exclusively used
for commutating machines. The revolving-field type is now
almost exclusively used, as the standard construction of alter-
nators, synchronous motors, etc. The inductor type had been
used to a considerable extent, and had a high reputation in the
Stanley alternator. It has practically gone out of use fqr
standard frequencies, due to its lower economy in the use of
materials, but has remained a very important type of construc-
tion, as it is especially adapted for high frequencies and other
special conditions, and in this field, its use is rapidly increasing.
A typical inductor alternator is shown in Fig. 136, as eight-
polar quarter-phase machine.