SYNCHRONOUS RECTIFIER

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—the other half wave—it does not conduct. A large induc-
tance is used in the rectified circuit, to reduce the pulsation of
current, and inductances in the two alternating supply circuits
—either separate inductances, or the internal reactance of the
transformer—to prolong and thereby overlap the two half waves,
and maintain the rectifying mercury arc in the vacuum tube. A
diagram of a mercury-arc rectifier with its reactances, xi, z2, %Q,

FIG. 103.—Voltage and current waves of mercury-arc rectifier.

is shown in Fig. 102. The "A.C. reactances" %i and #2 often
are a part of the supply transformer; the "D.C. reactance" x$
is the one which limits the pulsation of the rectified current. The
waves of currents, ii, it and iQ, as overlapped by the inductances,
Xi, x% and XQ, are shown in Fig. 103.
Full description and discussion of the mercury-arc rectifier is
contained in "Theory and Calculation of Transient Phenomena,"
Section II, and in "Radiation, Light and Illumination."