222

ELECTRICAL APPARATUS

or second phase, #2/2, as secondary circuit. It thus can be repre-
sented diagrammatically by the double transformer Fig. 695.
The only difference between Fig. 69A and GQB is, that in Fig.
69A the synchronous rotation of the circuit, EJi, carries the cur-
rent, Zi, 90° in space to the second transformer, and thereby pro-
duces a 90° time displacement. That is, primary current and
voltage of the second transformer of Fig. 695 are identical in
intensity with the secondary currents and voltage of the first
transformer, but lag behind them by a quarter period in space
and thus also in time. The momentum of the rotor takes care
of the energy storage during this quarter period.
As the double transformer, Fig. 695, can be represented by
the double divided circuit, Fig. 69C,1 Fig. 69C thus represents
the induction phase converter, Fig. 69A, in everything except
that it does not show the quarter-period lag.
As the equations derived from Fig. 69(7 are rather complicated,
the induction converter can, with sufficient approximation for
most purposes, be represented either by the diagram Fig. 69D,
or by the diagram Fig. 69E. Fig. 69D gives the exciting current
of the first transformer too large, but that of the second trans-
former to.o small, so that the two errors largely compensate.
The reverse is the case in Fig. 69J5/, and the correct value, cor-
responding to Fig. 69C, thus lies between the limits 69D and 69$.
The error made by either assumption, 69D or 69JSJ, thus must be
smaller than the difference between these two assumptions.
131. Let:
YQ = 0o — jfro = primary exciting admittance of the induc-
tion machine,
ZQ = r0 + fa* — primary, and thus also tertiary self-induc-
tive inl|>edance,
Zi = TI + jxi = secondary self-inductive impedance,
all at full frequency, and reduced to the same number of turns.
Let:
Y% = #2 — j&2 = admittance of the load on the second phase;
denoting further:
Z = ZQ + Zij
1" Theory and Calculation of Alternating-current Phenomena/' 5th
edition, page 204, *