250

ELECTRICAL APPARATUS

143. To reduce the sparking at the rectifying commutator,
the gap between the segments may be divided into a number of
gaps, by small auxiliary segments, as shown in Fig. 104, and
these then connected to intermediate points of the shunting re-

FIG. 104.—Rectifier with intermediate segments.

sistance, r, which takes the differential current, iQ — i, or the
auxiliary segments may be connected to intermediate points of
the winding of the transformer, Ty which feeds the rectifier,
through resistances, /, and the supply voltage thus successively

FIG. 105.—Three-phase ^-connected rectifier.
rectified. Or both arrangements may be combined, that is, the
intermediate segments connected to intermediate points of the
resistance, r, and intermediate points of the transformer wind-
ing, T.
Polyphase rectification can yield somewhat larger power than