Improvements in Electrical Transformers and in Boxes or Casings therefor.
Year: 1893

page_text: Date of Application, 14th Feb., 1893
Complete Specification Left, 28th Oct., 1893-Accepted, 2nd Dec., 1893
PROVISIONAL SPECIFICATION.
Improvements in Electrical Transformers and in Boxes or Casings
therefor.
We, WALTER CLAUDE JOHNSON, and SAMUEL EDMUND PHILLIPS, both of
14, Union Court, Old Broad Street, London, E.C. Electrical Engineers, do hereby
declare the nature of this invention to be as follows:-
--
According to our invention we construct electrical transformers as follows.
We construct a core of rectangular looped shape built up of thin plates in such
manner that the two side parts of the core on which the primary and secondary
coils are placed are separate from the two end parts. At the ends of each part of
the core, every alternate plate is made shorter than the others, so as to form a
series of alternate narrow tongues and mortices, the tongues of each part being
made to fit closely into the mortices of the contiguous ends of the other parts, thus
forming closely interlaced connections between the side parts and the end parts of
the core. Such interlaced ends are secured together by means of insulated screw
bolts passing through holes formed transversely through the joints, and provided
with a suitable non conducting lining.
The primary and secondary windings are separately wound upon sleeves of
insulating material that are slipped over each other and upon the longer side
pieces of the core before these are connected to the end pieces as above
described.
The casing or box of the transformer is constructed as follows.
A cast iron box having an internal configuration approximating to that of the
external configuration of the transformer, but of such a size as to leave inter-
vening spaces all round, is arranged to receive the transformer in an upright
position, that is to say, with the sides carrying the windings placed vertically.
From the bottom of the box narrow ribs project up to a certain height, between
which the lower end of the transformer rests so as to leave a clear space below for
the insulating liquid with which the box is filled, and similar ribs project down
from the cover, so as to hold the transformer securely between the two sets of ribs.
In the sides of the box there are formed hollow vertical passages partly projecting
outside the box and partly inside the same, which passages are open at the upper
and lower ends to the interior of the box. By this arrangement an effective
circulation and cooling of the insulating liquid is effected, as the sides of the said
vertical passages being more or less exposed to the cooling influence of the
atmosphere, they will effect the cooling of the liquid contained therein and
cause a downward flow thereof while the liquid in the central part of the case
in becoming heated by contact with the transforiner will circulate in an upward
direction.
The cooling effect of the casing may be further increased by forming externally
projecting ribs thereon.
On the one side of the box at the upper end is formed an enlargement for
containing the necessary connections of the primary and secondary windings of the
transformer with the external leads which pass in through suitable stuffing boxes.
Above such enlargement an opening is provided in the cover of the box closed by
a small supplemental cover by means of which access can be gained to the
connections without opening the main cover.
Dated this 14th day of February 1893.
ABEL & IMRAY,
Agents for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements in Electrical Transformers and in Boxes or Casings
therefor.
We, WALTER CLAUDE JOHNSON, and SAMUEL EDMUND PHILLIPS, both
of 14 Union Court, Old Broad Street, London, Electrical Engineers, 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: —
According to our invention we construct an electrical transformer as we shall
describe referring to the accompanying drawings.
Fig. 1 is an elevation and Fig. 2 is a plan of the core.
Fig. 3 is a perspective shewing to an enlarged scale one of the angles of the
core with its bolt, and Fig. 4 is a part vertical section through the angle.
Fig. 5 is a vertical section on X X of Fig. 9 of the box for holding the
transformer.
Fig. 6 is a vertical section and Fig. 7 is a longitudinal section shewing the
transformer in place in the box.
Fig. 8 is a plan of the upper part of the box and Fig. 9 is a sectional plan of the
box.
The core is of rectangular shape built up of thin iron plates, the two side
parts AA which receive the primary and secondary coils being connected to the
end parts B B by making each alternate plate shorter than those on each side of it
so that the end of A presents a series of narrow tongues and mortices, and the end
of B presents a series of corresponding mortices and tongues and the tongues of
each part fit into the mortices of the other. At each angle where the plates
thus interlace there an insulated bolt C by which the plates are clamped
together, and there may also be an insulated bolt D at the middle of each end
part B.
The primary and secondary coils are separately wound on sleeves E and F of
insulating material, the sleeve F is slipped over the coils on E, and both sleeves
with their coils are slipped over the sides A A of the core before these are connected
to both the end pieces B.
The cast iron box G for containing the transformer has free space around the
transformer for insulating fluid. At the bottom and also at the cover there are
projecting ribs between which the end parts B B are held steadily. In the sides
and ends of the box are formed vertical passages H open at the upper and lower
ends to the interior. As the external surfaces of these passages are more or less
exposed to the cooling influence of the atmosphere, the insulating liquid, which is
heated by the transformner, ascends within the box and descends by the passage H
becoming cooled, a continual circulation being thus maintained while the transformer
is in action, preventing it from being overheated.
The cooling effect is increased by making the box with externally projecting
ribs I. In the upper part of the box there is at one side an enlargement K
containing the connections for the coils to the external leads which pass through
stuffing boxes L. Above the space K there is an opening provided with a separate
cover M by which access can be had to the connections without having to remove
the main cover of the box.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we declare that what we
claim is
1. For an alternating current transformer with closed magnetic circuit, a core of
rectangular shape consisting of thin iron plates alternately long and short so that

page_text: the plates interlace at each angle where they are clamped by insulated bolts,
substantially as described.
2. In a transformer such as is above referred to winding the primary and secondary
coils separately on sleeves of insulating material, slipping the larger sleeve over the
coil on the smaller and slipping the whole over one or each of the long limbs of the
core, substantially as described.
3. For holding a transformer such as is above referred, a box and cover having
ribs between which the short limbs of the core are steadied and having vertical
channels for circulation of insulating liquid with which the box is charged,
substantially as and for the purpose set forth.
4. A transformer and box substantially as described with reference to the
accompanying drawings.
Dated this 28th day of October 1893.
ABEL & IMRAY,
Agents for the Applicants.