50 ELEMENTS OF ELECTRICAL ENGINEERING

current, before the magnetism.- It is called the angle of hysteretic

lead. _

In this case the exciting current 01 =^can be resolved in two
components: the magnetizing current 0/2 = Ii, in phase with
the magnetism 0¥ = $, that is, in quadrature with the e.m.f.
OE" = Eff, and thus wattless, and the magnetic power component
of the current or the hysteresis current OIi = /i, in phase with the
e.m.f. OE" = E", or in quadrature with the magnetism Ojp = &-

Magnetizing current and hysteresis current are the two com-
ponents of the exciting current.

FIG. 22.—Angle of hysteretic
lead.

PIG. 23.--Effect of resistance
on phase relation of impressed
e.m.f. in a hysteresisless circuit.

If the circuit contains besides thfe reactance x = 2 TrfL, a re-
sistance r, the e.m.f. OE" = E" in the preceding Figs. 21 and 22
is not the impressed e.m.f., but the e.m.f. consumed by self-
inductance or reactance, and has to be combined^ Figs. 23 and
24, with the e.m.f. consumed by the resistance, OlB' = W = Ir,
to get the impressed e.m.f. OE = E.

Due to the hysteretic lead a, the lag of the current is less in
Figs. 22 and 24, a circuit expending energy in molecular mag-
netic friction, than in Figs. 21 and 23, a hysteresisless circuit.

As seen in Fig. 24, in a circuit whose ohmic resistance is not
negligible, the hysteresis current and the magnetizing current
are not in phase and in quadrature respectively with the im-
pressed e.m.f., but with the counter e.m.f. of inductance or e.m.f.
consumed by inductance.

Obviously the magnetizing current is not quite wattless, since

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