Improvements in Electrical Transformers.
Year: 1892

page_text: Date of Application, 25th Aug., 1892-Accepted, 25th Aug., 1893
COMPLETE SPECIFICATION.
[Communicated from abroad by GUILIO MARIA APOLLONJ, of No. 89, Via
Giubonari, Rome, in the Kingdom of Italy, Engineer.].
Improvements in Electrical Transformers.
1, HENRY HARINGTON LEIGH, Assoc. M. Inst. C.E. Fel. Inst. P.A., practising
as Phillips & Leigh at No. 22, Southampton Buildings, Chancery Lane, in the
Administrative County of London, Engineer and Patent Agent, do hereby declare
the nature of this invention and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement :-
My invention consists in an apparatus that transforms an electric current of any
sort and of any potential into another current of any other sort or potential.
The apparatus is intended to
1. Transform a continuous current into another continuous current.
2. Transform an alternate current into a continuous current, or a continuous
current into an alternate current.
3. Transform a current of three or more phases into a continuous current, or the
latter into the former.
The proportion of the potential of the primary to that of the secondary can be
changed at pleasure by modifying proportionally the number of the turns.
Figure 1 shows the type for transforming a continuous current into a continuous
current of the same, or a different, potential. This apparatus consists principally
in an iron ring A formed by a certain number of iron plates placed one upon the
other.
Between the inner and outer borders of the ring there are a number of
rectangular or circular apertures B, B, symmetrically disposed at equal distances
from each border. By winding two different conductors through the apertures B, B,
two series of bobbins C, C and D, D, are formed, one embracing one side of the
aperture and the inner face of the ring, and the other, the opposite side of the
aperture and the outer face of the ring. By uniting the internal bobbins D, D,
to the section of a commutator E, a Paccinotti armature is obtained; and by
uniting the external bobbins to a similar external commutator H, a second
Paccinotti ring is obtained, forming, with the first, a short magnetic circuit.
Two brushes, F and G, are then put in contact with the internal commutator E,
and two, M and I, with the external one H, H, care being taken that all the
contacts of the brushes with the collectors are on the same diameter of the ring.
If a continuous current is sent through one of the pairs of brushes, say through
the external one, M and I, a pair of magnetic poles will be formed on the ring;
if now a rotating movement be given to the brushes, these two poles will follow
that movement with the same velocity and in the same direction. An induced
current will therefore be developed in the internal winding D, D, D, which will be
carried off through the internal brushes G and F in the form of a continuous
current, provided they move in the same direction and with the same velocity as
those M and I for the external winding. It is sufficient, therefore, to rigidly unite
the two pairs of brushes and put them in motion, in order that the current sent
into two of them may be returned by the other two. It is clear that if the
bobbins of the two armatures have the same number of turns of wire, the difference
of potential at each pair of brushes will be the same. But if this number
varies, the difference of potential will vary in the same proportion. It becomes
possible therefore, to obtain a real transformation of current from a high to a low
potential which remains continuous.

page_text: The second type of apparatus, shown in Figure 2, is intended to transform a
continuous current into an alternating one at a low or high potent al, and is
composed of a laminated iron ring A, identical with the one already described.
In this apparatus, however, it is only the interior winding D, D which constitutes
a Paccinotti armature; the other winding, placed outside, has all the bobbins
(1, 2... 7, 8) disposed in series, and is without commutator or brushes. In this
arrangement, for instance, the internal armature is of four poles and the continuous
external conductor is wound in such a way as to form the four poles corresponding
to those produced internally when the continuous current is introduced. Let it
be supposed that a continuous current is sent into the apparatus through the
brushes F, G, J, K. In the external conductor, which is to be taken as closed
on a resistance, a feeble induced current will be developed, which will last only
for the short time required to establish the regular flow of the current introduced
in the other winding.
If, on the other hand, the brushes F, G, J, K which conduct the current, are
made to revolve in a continuous manner, a magnetic flow will be produced which
will rotate in the iron core of the ring simultaneously. This rotating flow will
produce, in its turn, an alternating current in the external coils 1, 2, 3,.. 8 which
will have 2n alternations per second if the brushes make n revolutions in the same
time. We shall thus obtain the transformation of a continuous current into, an
alternating one at a more or less elevated potential, according to the proportion
that exists between the number of turns of the two windings.
As this apparatus is reversible, it follows that by sending an alternating current
into the external conductor and causing the brushes F, G, J, K of the interior
armature D, D, to move synchronously with the alternations of the current, these
will give a continuous current at the potential which is determined by the propor-
tion referred to above.. There will, therefore, be a true redressing of the current
with an accompanying transformation in its potential.
After examining the mode of action of the preceding types of apparatus, it will.
be easy to understand the third type represented in Figure 3.
In this there is the same laminated iron ring A with two windings C; C, C
and D, D, D of which the interior one forms à Paccinotti armature with two
poles, and the exterior one, which is continuous and closed on itself, has three
wires P, Q, R attached to it at an angular distance of 120 degrees from cach
other. If a continuous current is sent through the revolving brushes N and O,
three alternating currents will be produced in the outside coils C which will be.
displaced in their phases by 120 degrees; and vice versa, if through the three
derivations alternating currents are sent, displaced from each other by 120 degrees,
and the brushes N, O are made to revolve synchronously with the field produced
by the current, a continuous current will be obtained from them.
It may therefore be concluded that, by means of the three types of apparatus
proposed, it is possible to obtain any transformation of current coupled with
redressing; a continuous current, while remaining continuous, can be transformed
into another of different potential, an alternating current can be transformed into
a continuous one at any potential required or vice versú; a continuous current can
be transformed into an alternating one, either simple or polyphase, according as
one type of apparatus or another is used.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The combination of two. Paccinotti armatures the cores of which are
reciprocally closed in short magnetic circuit, as illustrated in Figure 1 and described.
therewith.
2. The combination of a Paccinotti armature with an armature for alternate
currents, the cores of which are arranged as I have described, as illustrated in
Figure 2 and described therewith.

page_text: 3. The combination of a Paccinotti armature with an armature for currents
with three or more periods, the cores of which are arranged as I have described,
as illustrated in Figure 3 and described therewith.
4. The construction of this double core by means of a laminated iron ring,
pierced with holes, through which two coils are wound in the described way, one
primary and the other secondary.
Dated this 25th day of August 1892.
HENRY H. LEIGH,
Chartered Patent Agent.