REVIEW

471

connected constant-current alternator with .rectifying commu-
tator.
Thomson Repulsion Motor.—193. Single-phase compensated,
commutating machine with armature energized by secondary
current, and field coil and compensating coil combined in one coil.
Unipolar Machines.—Unipolar or acyclic machine, XXII, 247.
Machine in which a continuous voltage is induced by the rotation
of a conductor through a constant and uniform magnetic field.
Such machines must have as many pairs of collector rings as there
are conductors, and the main magnetic flux of the machine must
pass through the collector rings, hence current collection occurs
from high-speed collector rings. Coil windings are impossible
in unipolar machines. Such machines either are of low voltage,
or of large size and high speed, thus had no application before
the development of the high-speed steam turbine, and now three-
phase generation with conversion by synchronous converter has
eliminated the demand for very large direct-current generating
units. The foremost disadvantage is the high-speed current
collection, which is still unsolved, and the liability to excessive
losses by eddy currents due to any asymmetry of the magnetic
field.
Winter-Eichbery-Latour Motor.—194. Single-phase compen-
sated series-type motor with armature excitation, that is, the
exciting current, instead of through the field, passes through the
armature by a set of auxiliary brushes in quadrature with the
main brushes. Its advantage is the higher power-factor, due to
the elimination of the field inductance, but its disadvantage the
complication of an additional set of alternating-current commu-
tator brushes.