REVIEW 465
phases, fed by polyphase transformer increasing the number of
phases, and driven by a synchronous motor having as many cir-
cuits as the rectifier has phases, each synchronous motor circuit
being connected in shunt to the corresponding rectifier phase to
byepass the differential current and thereby reduce inductive
sparking. Can rectify materially more power than the standard
rectifier, but is inferior to the converter.
Magneto Commutation.—163. Apparatus in which the induc-
tion' is varied, with stationary inducing (exciting) and induced
coils, by shifting or reversing the magnetic flux path by means
of a movable part of the magnetic circuit,, the inductor. Applied
to stationary induction apparatus, as voltage regulators, and to
sync.hronous machines, as inductor alternator.
Monocyclic.—127. A system of polyphase voltages with essen-
tially single-phase flow of power. A system of polyphase vol-
tages, in which one phase regulates for constant voltage, that is,
a voltage which does not materially drop within the range of
power considered, while the voltage in quadrature phase thereto
is of limited power, that is, rapidly drops with increase of load.
Monocyclic systems, as the square or the triangle, are derived
from single-phase supply by limited energy storage in inductance
or capacity, and used in those cases, as single-phase induction
motor starting, where the use of a phase converter would be
uneconomical.
Motor Converter.—112. An induction machine concatenated
with a synchronous commutating machine. (See'' Concatenation
(3).") The latter thus receives part of the power mechanically,
part electrically, at lower frequency, and thereby offers the ad-
vantages incident to a lower frequency in a commutating machine.
It permits phase control by the internal reactance of the induc-
tion machine. Smaller than a motor-generator set, but larger
than a synchronous converter, and the latter therefore preferable
where it can be used.
Multiple Squirrel-cage Induction. Motor.—(See "Double
Squirrel-cage Induction Motor.")
Multispeed Induction Motor.—14. Polyphase Induction
Motor with the primary windings arranged so that by the opera-
tion of a switch, the number of poles of the motor, and thereby
its speed can be changed. It is the most convenient method of
producing several economical speeds in an induction motor, and
therefore is extensively used. At the lower speed, the power-
factor necessarily is lower.