Improvements in the Construction of Electrical Transformers with Ventilating Passages.
Year: 1898

page_text: Date of Application, 12th Dec., 1898-Accepted, 18th Feb., 1899
COMPLETE SPECIFICATION.
Improvements in the Construction of Electrical Transformers with
Ventilating Passages.
I, OTRO TITUS BLÁTHY, of II Nagy Rókus-utcza, Budapest, Hungary, Engineer,
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:-
-
This invention relates to a construction of transformer windings, with ventilating
channels, whereby in particular with transformers for high pressures, firstly, a
considerable reduction of the insulating material and consequently of the weight
of the transformer is enabled to be effected, secondly the windings are protected
against detrimental heating, and thirdly, the arrangement of the several coil sec-
tions and the securing of the same in position is greatly facilitated.
These advantages are obtained by separating the said sections from each other
by radial arms lying in planes at right angles to the primary and secondary wind-
ings, which arms are either smooth or otherwise formed, such as grooved, ribbed,
or perforated, and are so arranged that between the coil sections there are produced
radially arranged free spaces, constituting channels at right angles to the direction
of the coils, through which the air has a free passage, and thus has a cooling effect
upon the windings.
By this means the insulating material hitherto employed for enclosing the coil
sections is in great measure superfluous and on the other hand these sections are
much more effectually secured in position notwithstanding the considerable reduc-
tion of the material used.
The formation of ventilating channels in transformer-windings for high pressures
for the purpose of cooling and insulating is not new in itself, but the insulating
and cooling action of the air could not be fully utilised with the arrangements
hitherto employed, as the channels were comparatively long, so that the air remained
some considerable time therein and thus itself became heated to such an extent that
no cooling action could be produced thereby.
According to some of the arrangements of transformer windings proposed for this
purpose the primary and secondary coils were arranged in parallel windings, or
were inserted one within the other in the form of concentric cylinders, between
which an annular channel was left, extending the whole length of the coil, as
shewn in the section at Fig. 1 of the accompanying drawing, and the air passing
through this long channel often became considerably heated.
This arrangement cannot be employed when the primary and secondary windings
are made in sections and so arranged that the sections of the one winding are placed
alternately with those of the other winding, as shewn at Figure 2; with such an
arrangement a ventilation was heretofore hardly possible.
The arrangements that have been more recently proposed are partly very com-
plicated, and partly possess the above mentioned disadvantage that the air between
the coil sections has to traverse a long distance and consequently becomes heated.

page_text: One of these more recently proposed arrangements consisted in providing the
coil sections on their narrow sides with annular trough shaped covering strips
formed of insulating material, and then enclosing the entire section in an envelope
of insulating material in such manner that between this envelope and the coil
section were formed spaces corresponding in height to the thickness of the said
strips. These spaces are however entirely closed and have the same circular
direction as the windings, so that they are necessarily much too long, and the air
in the same becomes correspondingly heated.
This arrangement is shewn at Fig. 3.
The arrangement which forms the subject of my present invention is distinguished
from all those above referred to in that the ventilating channels are formed at
right angles to the windings, this being effected as above stated by arranging
between the alternately placed primary and secondary coil-sections separating and
insulating arms in such manner that they have a radial direction, in planes at
right angles to the windings, thus forming between them and the coil sections
broad open radial channels which, in working, produce an energetic ventilation.
This method of construction can be carried out in practice in a great variety of
ways.
By way of example I will describe some of the constructions with reference to
the drawing.
The simplest mode of construction is that shewn at Fig. 4, in which there are
placed upon the opposite flat sides of a coil section (which is, for instance of a rect-
angular cross section) radial strips I of a suitable insulating material; these strips
may be formed with longitudinal grooves on their outer sides in which is then laid
a thread of insulating material that extends across from the one side to the other
so as to tie the strips together.
The coil section which may be the primary P, thus prepared is then laid against
a secondary coil section S of the same or different section, so that between the two
is formed a space equal in width to the thickness of the strips 1. The number of
such strips employed will depend upon the diameter of the coil section. Fig. 5
shews an end view of the coil section P having for instance six radial strips I on
each side, so that the side surface of these armis form with the flat surfaces of the
coils six radial channels through which the air can flow freely in a direction at
right angles to the windings, a circular space being left between the inner surfaces
of the coil sections and the core, for the entrance of the air.
In the construction at Fig. 6, the arms I are provided at their ends with exten-
sions, of which the outer ones i serve to prevent the lateral shifting of the
windings, situated between the arms I, while the inner ones ¹ serve to maintain the
inner circular surface of the coil a certain distance away from the core thus forming
between the two a cooling air passage.
This arrangement can be modified by dividing each of the strips I into two parts
as shewn at Fig. 7 and connecting the two corresponding outer parts by a transverse
piece, while the two corresponding inner parts are also connected by a transverse
piece 22.
As shewn at Figs. 8 and 9 the insulating arms I, are not only provided with
extensions i extending over the outer and inner circular surfaces of the coil I',
but also farther extensions extending over the inner circular surface of the secon-
dary coil, or, as at Fig. 9, they may also have other extensions 23 extending over
the outer circular surface of the secondary coil. In the arrangement shewn in side
view and section at Fig. 10, two opposite arms I can be rigidly connected together
at their inner ends by means of a piece so as to constitute a frame which is open
at the outer circular surfaces of the coil. In this case, as also in the preceding
ones the arms I can be provided with longitudinal ribs between which other
radial air channels are formed.
Lastly, as shewn at Fig. 11 the arms I can also be connected together both at the
inner and the outer ends by transverse pieces, thus forming closed frames, which
entirely surround the coils at intervals.

page_text: In this case the arms I as also the connecting pieces may be formed with
openings as shewn, so that by this means the two radial air channels separated
by the arms communicate with each other through these openings. These framed
arms may be built up of any desired number of separate parts if necessary.
It is sufficient if only the coil-sections, for instance of the primary winding P
are provided with the said insulating arms, as by this means the contiguous
secondary coil sections are also secured in position in an insulated manner as above
described.
The coil sections of each winding may however all be provided with such arms,
in which case the arms of the one coil section may either be opposite to and in
contact with the arms of the contiguous coil sections, or the arms of the one
section may be arranged in intermediate positions between those of the contiguous
sections.
The said arms can be made of any suitable insulating material, such as wood,
stabilite, leatheroid, ambrion, or the like, but they must possess sufficient rigidity
to maintain their configuration, and to maintain the requisite distance between the
coil sections.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
-
1. A construction of transformer windings wherein there are arranged between
the alternately placed coil sections of the primary and secondary windings radial
arms such as I of insulating material placed at right angles to the windings so as
to produce between the flat surfaces of the contiguous coil sections radial spaces
through which the air can circulate freely.
2. In the construction of transformer windings referred to in the first claim, the
use of insulating arms I having at their outer or their inner ends or both at their
outer ends extensions such as i arranged and operating substantially as and
for the purpose herein described with reference to Figs. 6 to 9 of the drawings.
3. In the construction of transformer windings referred to in the first claim the
use of opposite arms I connected together by transverse pieces such as either at
one end or at both ends so as to constitute open or closed frames that may be either
solid or perforated, substantially as described with reference to Figs. 10 and 11 of
the drawings.
4. Constructing the radial insulating arms I referred to in the first claim with
longitudinal grooves a or ribs b for forming ventilating passages, substantially as
described.
5. Transformers having windings formed with ventilating channels arranged
and operating as herein described with reference to the drawings.
100
1001
HONY SU cr
day
of December 1890.
ABEL & IMRAY,
Agents for the Applicant.