380

ELECTRICAL APPARATUS

fully abroad in the so-called "compensated repulsion motor" of
Winter-Eichberg. This motor differs from the ordinary repul-
sion motor merely by the field coil, F, in Fig. 183 being replaced
by a set of exciting brushes, G, in Fig. 184, at right angles to the
main brushes of the armature, that is, located so that the m.m.f.
of the current between the brushes, G, magnetizes in the same

FIG. 183.—Plain repulsion motor.

direction as the field coils, F, in Fig. 183. Usually the exciting
brushes are supplied by a transformer or autotransformer, so an
to vary the excitation and thereby the speed.

This arrangement then lowers the e.m.f. of self-inductance of
field excitation of the motor from that corresponding to full fre-

FIG. 184.—Winter-Eichberg motor.
quency in the ordinary repulsion motor to that of the frequency
of slip, hence to a negative value above synchronism; so that
hereby a compensation for lagging current can be produced
above synchronism, and unity power-factor or even leading
currents produced.