220

ELECTRICAL APPARATUS

e, at all loads, while for non-inductive load the monocyclic voltage,
e0, not only shrinks with increasing load, but also shifts in phase,
from quadrature position, and the diagram is in the latter case
shown for 4 amp. load by the dotted lines in Fig. 67.
In Fig. 68 the drawn lines correspond to non-inductive load.
The regulation for 45° lagging load is shown by dotted lines in
Fig. 68.
e'o shows the quadrature component of the monocyclic voltage,
e0, at non-inductive load. That is, the component of e0, which is
in phase with e, and therefore could be neutralized by inserting
into e0 a part of the voltage, e, by transformation.
As seen in Fig. 68, the supply current is a maximum of 20 amp.
at no-load, and decreases with increasing load, to 10 amp. at
short-circuit load.
The apparent efficiency of the device, that is, the ratio of the
volt-ampere output:
QQ = eQiQ
to the volt-ampere input:
Q = ei
is given by the curve, 7, in Fig. 68.
As seen, the apparent efficiency is very low, reaching a maxi-
mum of 14 per cent. only.
If the monocyclic square is produced by capacity and induc-
tance, the extreme case of dropping of voltage, eo} with increase of
current, i0, is reached in that the circuit of the voltage, e0, becomes
a constant-current circuit, and this case is more fully discussed
in Chapter XIV of " Theory and Calculation of Electric Circuits "
as a constant-potential constant-current transforming device.
Induction Phase Converter
130. The magnetic field of a single-phase induction motor at
or near synchronism is a uniform rotating field, or nearly HO,
deviating from uniform intensity and uniform rotation only by
the impedance drop of the primary winding. Thus, in any coil
displaced in position from the single-phase primary coil of the
induction machine, a voltage is induced which is displaced in
phase from the supply voltage by the same angle as the coil is
displaced in position from the coil energized by the supply vol-
tage. An induction machine running at or near synchronism
thus can be used as phase converter, receiving single-phase sup-