226 ELECTRICAL APPARATUS

monocyclic square reaches zero already at 10 amp. output. This
illustrates the monocyclic character of the latter, that is, the limi-
tation of the output of the quadrature voltage.

As the result hereof, the phase converter reaches fairly good
apparent efficiencies, 54 per cent., and reaches these already at
moderate loads.

• The quadrature component, e"2, of the voltage, e0, is much
smaller with the phase converter, and, being in phase with the
supply voltage, e0, can be eliminated, and rigid quadrature relation
of 62 with 60 maintained, by transformation of a voltage — e"2
from the single-phase supply into the secondary. Furthermore, as
#"2 is approximately proportional to io — except at very low loads
— it could be supplied without regulation, by a series transformer,
that is, by connecting the primary of a transformer in series with
the supply circuit, i0j the secondary in series with e2- Thereby
e2 would be maintained in almost perfect quadrature relation
to BQ at all important loads.

Thus the phase converter is an energy-transforming device,
while the monocyclic square, as the name implies, is a device for
producing an essentially wattless quadrature voltage.

133. A very important use of the induction phase converter
is in series with the polyphase induction motor for which it sup-
plies the quadrature phase.

In this case, the phase, e0, io of the phase converter is connected
in series to one phase, eVo, of the induction motor driving the
electric car or polyphase locomotive, into the circuit of the single-
phase supply voltage, e = e0 + e'o, and the second phase of the
phase converter, e2, i^ is connected to the second phase of the
induction motor.

This arrangement still materially improves the polyphase regu-
lation: the induction motor receives the voltages:

e'o = e — 60,
and:

At no-load, e2 is a maximum. With increasing load, e2 = 0'2
drops, and hereby also drops the other phase voltage of the in-
duction motor, e'o. This, however, raises the voltage, 60 = e —
e'0, on the primary phase of the phase converter, and hereby
raises the secondary phase voltage, 62 = e'^ thus maintains the