Thury's dynamo-electric machine, which presents some peculiarities,
has never to our knowledge been employed outside of Sweden and a few
neighboring regions; but this is doubtless due to some personal motive
or other of its constructors, since it has, it would seem, given
excellent results in every application that has been made of it. It is
represented in perspective in Fig. 1, and in longitudinal section and
elevation in Figs. 2 and 3.
As may be seen, it is a multipolar (6-pole) machine in which an attempt
has been made to utilize magnetically, as far as possible, all the iron
used in the frame. For this reason the system has been given the form of
a hexagonal prism, whose faces are formed of flat electro-magnets, A, A,
xxx, constituting the inductors.
The internal angles of this prism are filled by polar expansions, P, P,
xxx, alternately north and south, that thus form in the interior of the
apparatus an inscribed cylinder designed to receive the armature. This
latter belongs to the kinds that are wound upon a cylinder in which the
wire is external thereto.
The conductors are placed upon the iron drum longitudinally and parallel
with its axis. But instead of being connected with each other at the
posterier end of the armature, as in the Siemens system, they are
connected according to chords that correspond to a fourth, a sixth,
or any equal fraction whatever of the circumference. Fig. 4 gives a
perspective view of the cylinder, upon which the conductors 1, 2, 3,
4, and so on, are placed according to generatrices. The armature is
supposed to be divided into six parts, each conductor passing over the
bases of the drum through a chord equal to the radius, that is to say,
corresponding to a sixth of the circumference.
Three conductors are all connected together in such a way as to form
but a single circuit closed upon itself. Conductor 1, for example, is
connected with No. 6 in such a way that the end issuing from 1 becomes
the end that enters No. 6. Conductor No. 3 is connected in the same way
with No. 8, and so on, up to the last conductor, which is connected in
its turn with the end that enters the first.
As the figure shows, the conductor before passing from 3 to 8, for
example, returns several times upon itself in following 6 and 3, and the
same is the case with all the rest of the winding.
[Illustration: FIG. 1. PERSPECTIVE VIEW OF THE THURY MACHINE.]
In this way the cylinder becomes inclosed within nine rectangular wire
frames, each of which is connected with the following one by a conductor
that is at the same time connected with one of the nine plates of
the collector. The number of the rubbers corresponds to that of the
inducting poles. They may be coupled in different ways, but they are in
most cases united for quantity.
It will be seen that the Thury armature resembles, in the system of
winding, those of the Siemens machines and their derivatives. But it
differs from these, however, in the details connected with the coupling
of the wires, from the very fact that the features of a two-pole machine
are not found exactly in a multipolar one.
[Illustration: FIGS. 2 AND 3.]
This latter kind of machine is considered advantageous by its inventors,
in that there is no need of revolving it with much velocity. It must not
be forgotten, however, that although we reduce the velocity by this mode
of construction, we are, on another hand, obliged to increase the size
of the machine, so that, according to the circumstances under which we
chanced to be placed, the advantage may now be on the one side and now
on the other.
[Illustration: FIGS. 4 AND 5.]
It goes without saying that Fig. 4 is essentially diagrammatic, and is
designed to give a clearer idea of the mode of winding the armature. In
practice the number of the frames, and consequently that of the plates
of the conductor, is much greater, and the arrangement that we have
described is repeated a certain number of times, the conducter always
forming a circuit that is closed upon itself.
The Thury machines are constructed in different styles. No. 1 is a
100-lamp (16 candles and 100 volts) machine, and Nos. 2 and 3 are
nominally 250-lamp ones, but may be more. Their weight is 1,100
kilogrammes, and their velocity, for 100 volts, is from 400 to 500
revolutions, according to the mode of coupling.
A later type, now in course of construction, is to furnish from 750 to
2,000 lamps, with 250 revolutions, for 100 volts, and is not to weigh
more than 2,000 kilogrammes. Let us add that Messrs. Meuron and Cuenod,
the manufacturers, have likewise applied their mode of winding to
conductors arranged radially upon the surface of a circle. Fig. 5 shows
this arrangement.
In this case the inductors will, it is unnecessary to say, be arranged
laterally as in all flat ring machines. The arrangement will recall, for
example, that of the Victoria machines (Brush-Mordey).
We do not think that the inventors have applied this radial arrangement
practically, for it does not appear to be advantageous. The parts of
conductors which are perpendicular to the radius, and which can be only
inert (even if they do not become the seat of disadvantageous currents),
have, in fact, too great an importance with respect to the radial
parts.--_A. Guerout, in La Lumiere Electrique_.
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