Improvements in Electrical Transformers.
Year: 1897

page_text: Date of Application, 13th Apr., 1897
Complete Specification Left, 14th Feb., 1898-Accepted, 13th May, 1898
+
Improvements in Electrical Transformers.
I, ARTHUR FRANCIS BERRY, of Manor House, Ashley, Market Harborough, in
the County of Leicester, Electrical Engineer, do hereby declare the nature of this
invention to be as follows:-
This invention has reference to a construction of electrical transformer built up
of laminated metal plates arranged radially round a centre to form a cylindrical
or other suitably shaped core or casing having within it an endless space, passage
or way of annular polygonal form or equivalent shape wherein the primary and
secondary windings are placed.
In one construction of such a transformer according to this invention, each
radially arranged metal plate is built up of a number of straight strips or stampings
of thin sheet iron arranged at right angles to one another so as to form a hollow
rectangular built up plate or frame, the metal strips composing each side of which
being so arranged that the alternate plates overlap one another at the ends
thus
and the projecting ends of each of two adjacent series of strips
entering the spaces between the projecting ends of the opposite series of strips so
as to become bonded or jointed therewith. A number of such built up plates are
arranged radially round a centre so as to form, as seen in plan or end view, a star
shaped core or body. Within the diverging or angular spaces between the radial
plates are or may be arranged other or additional similarly constructed plates the
radial width of which may be approximately equal to but is preferably less than
the main plates between which they are placed so as to leave ventilating spaces
extending lengthwise of the core. The spaces between these two series of plates
may, according to the size of the transformer, be fitted with other similarly con-
structed plates or by metal strips. The width of the sides of the hollow frame-like
plates may be equal or unequal, as may be desired in any particular case, but the
rectangular openings in the several plates are made equal or approximately equal
in width radially and arranged to correspond with one another so as to form an.
annular space or way for the windings which may be left partly exposed between
the plates.
if
As will be obvious the arrangement of the laminated iron plates can be variously
modified. Thus four plates may touch each other at their adjacent edges so as
to form, as seen in plan or end view, a cross with a hollow passage between them of
square section. Between these four plates, four smaller plates may be arranged,
and between the two sets of plates a still smaller set of plates and so on,
necessary, longitudinal ventilating spaces being left between the several plates.
In building up my improved transformer, the inner series of metal strips and.
those constituting one of the end series, are placed in position, and the primary
and secondary windings are placed around the inner series and adjacent to the end
series, after which the outer series of metal strips and the other end series are bonded
with each other and with the two other series of strips and the whole suitably secured
together so as to enclose or surround the windings. The various plates are or may
conveniently be clamped or held between two end plates provided with hollow

page_text: projections that take into the hollow centre and the angular spaces formed by and
between the several built up plates.
By my invention electrical transformers possessing a high efficiency can be
easily, cheaply and conveniently made with plenty of ventilating spaces into which
may be dissipated in the best possible manner, the energy wasted in the copper
and iron of the transformer. The ventilating spaces might be partially or wholly
filled with tubes of thin non-magnetic material such as copper, having a blackened
surface, such tubes being filled or traversed by a suitable substance for example
water to carry off the heat, the arrangement resembling a water tube boiler in
which the heating is effected by electrically produced heat. When water is caused
to flow through the tubes, the ends of the transformer would be provided with water
chambers.
Improvements in Electrical Transformers.
I, ARTHUR FRANCIS BERRY, of Manor House, Ashley, Market Harborough, in
the County of Leicester, Electrical 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 has reference to improvements in the construction of electrical
transformer of the kind built up of laminated metal plates arranged radially round
a centre to form a cylindrical or other suitably shaped magnetic core or casing
having within it an endless space, passage or way of annular, polygonal or equiva-
lent shape wherein the primary and secondary windings are placed, as described
in the Specification of another application for Letters Patent filed by me No. 2801
of 1897.
In such a transformer according to this invention, each radially arranged metal
plate is built up of a number of straight strips or stampings of thin sheet iron
arranged at right angles to one another so as to form a hollow rectangular built
up plate or frame (hereinafter called a plate) the metal strips composing each side
of which are so arranged that the alternate strips overlap one another at the ends
thus
and the projecting ends of each of two adjacent series of plates
enter the spaces between the projecting ends of the opposite series of strips so as
to become bonded or jointed therewith.
In the accompanying drawings,
Fig. 1 shows in elevation and Fig. 1 in plan, a laminated iron plate of the kind
referred to the four sides 1ª, 1b, 1, 1d of which are composed of groups of straight
strips of sheet iron the adjacent ends of which are bonded or jointed with each
other as hereinbefore described.
Fig. 2 shows partly in vertical section and partly in side elevation, and Fig. 3
partly in plan and partly in horizontal section, à transformer the iron core of which
is composed of a number of such built up laminated plates 1 arranged radially
round a centre so as to form, as seen in plan or end view, a star shaped core or
body. Within the diverging or angular spaces between the radial plates 1 are or
may be arranged other or additional similarly constructed plates 1* so as to leave
ventilating spaces extending lengthwise of the core. The radial width of the
plates 1 may be approximately equal to, but, as shown, preferably less than that

page_text: of the main plates between which they are placed. The spaces between the two
series of plates 1, 1 may, in the case of transformers of large size, be fitted with
other similarly constructed plates, or by metal strips. The width of the sides of
the hollow frame-like plates may be equal or unequal, as may be desired in any
particular case, but the rectangular openings 2 in the several plates are made equal
or approximately equal in width radially, and arranged to correspond with one
another so as to form an annular space or way in which are arranged the insulated
primary and secondary windings 3 and 4 respectively which are left partly exposed
between the plates as shown.
In building up my improved transformer, the groups of overlapping strips of
iron to form the inner sides 1ª of the several plates 1, 1, and also those to con-
stitute one of the ends, say 1b, of the plates, are held around a cylindrical former
or mandrel A (Figs. 4 and 4^) and in radial grooves B in two end plates C into
which they are slidden and temporarily held by split spring metal bands D which
are arranged around the two ends of the radially arranged groups, the said end
plates C being suitably held together as by a central bolt E. The outer edges of
the strips in all the groups are arranged to be at the same radial distance from the
centre of the former or mandrel A, and the ends of the adjacent groups are bonded
or interlocked with each other in the manner herein before described. When the
strips are thus arranged they will be firmly held together around the former or
inandrel and the bands D are removed. A ring 5 (see Fig. 2) of the insulating
material, such as paste-board saturated in ozokerite, is placed against the radial
end strips 1b, and around the longitudinal strips 1", the whole being placed in
a machine such as a lathe, the strips 1ª are covered with a layer or layers 6 (Fig. 2)
of insulating material such as woven cotton tape, or canvas saturated with a suitable
insulating varnish or gum, a ring 6 of such insulating material being formed
adjacent to the ring 5 preferably by winding tape upon itself. A secondary wind-
ing 4, preferably in the form of an insulated copper strip, is then wound over the
layer 6 of insulating material, the several layers of the secondary winding
being well insulated from each other and the outer one covered with a layer 7 of
insulating material. The primary winding 3, preferably in the form, as shown,
of a number of separately wound sections with intervening washers 3ª of insulating
material, is then slipped endways over the secondary winding 4. The primary coil
is then covered with a layer 7" of insulating material, and another secondary
winding 4 wound on over the primary winding 3 and covered with a layer of
insulating material 6b. A layer 6° of insulating material like 6 and a washer 5ª
of insulating material like 5 is then placed at the opposite end of the windings.
The core A and end plates are then removed from the partly finished transformer
and the groups of iron strips with alternately overlapping ends to form the side and
end 1° and 1d, respectively of the several plates 1 and 1 are then placed in position
and so that the projecting ends of each two adjacent series or groups of strips enter
the spaces between the projecting ends of the opposite series or group of strips so as
to become effectually bonded or jointed therewith. Blocks 8 of suitable material
such as wood are then placed between the outer ends of the plates 1 and so as to
fit the outer ends of the plates 1, and are held in place by a wrapping of fine wire 9
wound on tightly. After the former or mandrel A is removed from the hollow
centre 10 of the core, spring metal rings 11 are placed therein to keep the plates 1
in position. The transformer thus made has a star-shaped core or body with
outwardly diverging ventilating spaces 12 extending longitudinally through it
and with a hollow tubular centre 10 so that the transformer will be efficiently
ventilated. It is clamped between two perforated or slotted plates 13 and 14 by
an eye bolt 15 by means of which it can be readily supported when desired, the
perforations or slots 13, 14 in the two plates being opposite the tubular centre 10
and wedge shaped spaces 12 in the star-shaped core or body. A sheet of fine wire
gauze 16 is preferably placed between each end of the core or body and the adjacent
end plate 13 or 14 to exclude foreign matter. The lower plate 14 is provided on its
underside with two ribs 17 which serve to support the plate above the floor and

page_text: permit air to pass upward through the ventilating spaces in the core or body and
out at the top. The transformer is preferably provided with a surrounding pro-
tecting casing 18 of thin sheet steel and with a cap or cover 19 to enclose the
insulated terminals 20. The casing at points above the top plate 14 is formed with
holes covered with gauze for outlet of air.
As will be obvious the arrangement of the laminated iron plates 1 can be
variously modified. Thus four plates may touch each other at their adjacent edges
so as to form, as seen in plan or end view, and as shown diagrammatically in
Fig. 5, a cross with a hollow passage 10ª between them of square section. Between
these four plates, four smaller plates 1* may be arranged, and if necessary, between
the two sets of plates a still smaller set of plates and so on, longitudinal ventilating
spaces 12 being left between the several plates. The sheet metal strips forming
the laminated metal plates hereinbefore described are, as usual insulated from each
other. For this purpose they may be each coated on one side with an insulating
varnish, the insulated side of one strip being placed next the uninsulated side of
the next strip in the way commonly adopted.
Also
As will be obvious each secondary winding 4 may consist of one or more sections,
and the several sections of the two windings may be variously connected up.
instead of using two secondary windings, arranged one on each side of the primary
winding as shown, a single secondary winding may be used if desired but I
consider the arrangement shown the best one.
By my invention electrical transformers possessing a high efficiency can be
easily, cheaply and conveniently made with plenty of ventilating spaces into which
may be dissipated, in the best possible manner, the energy necessarily wasted in
the copper and iron of the transformer. The ventilating spaces 12 may, especially
in the case of large transformers, be partially or wholly filled with tubes of thin
non-magnetic material such as copper, having a blackened or dead outer surface
capable of readily absorbing radiant heat, such tubes being filled or traversed by
a suitable substance, for example water or oil, to carry off the heat, the arrange-
ment resembling a water tube boiler in which the heating is effected by
electrically produced heat. When water or oil is caused to flow through the tubes,
the ends of the transformer would be provided with chambers. Fig. 6 shows in
vertical section, an arrangement of this kind wherein 21 are copper tubes coated
for example with a mixture of lamp-black and an oil or a varnish and arranged in
the angular spaces 12 between the plates 1, 1*, the said tubes being connected at
their ends to chambers 13b, 14b formed in the end plates 13 and 14, through which
and the tubes water or oil is caused to flow. For this purpose, two chambers may
be connected by an external pipe 22 (or pipes) which may be coiled, or by an
annular chamber 22" which may have corrugated surfaces, to increase the cooling
surface, the said pipe or pipes or chamber being arranged to pass through the air
or other cooling medium external to the transformer core; or the lower chamber
may be connected to a water main and the upper one with an exhaust pipe. Fig. 7
shows partly in section and partly in elevation, a modified arrangement in which
the vertical tubes 21 are connected at the top to a flat coiled pipe 13° and at the
bottom to a wheel shaped casting 14°, the pipe 13° and casting being connected by
an external coiled cooling pipe 22°. The chambers 13, 14b, or casting 14°, as the
case may be, can be formed with removable plates or screw plugs, to enable ready
access to be obtained to their interiors to admit of the tube ends being readily
secured in place by expanding or otherwise.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. In the construction of transformers of the type described in the Specification
of the Letters Patent No. 2801 of 1897 the employment of straight strips of soft
iron shaped and arranged as hereinbefore described and shewn in the accompanying
drawings.

page_text: 2. My improved electrical transformer constructed as hereinbefore described and
shown in Figs. 1 to 4*, inclusive, or modified according to Fig. 5, or according to
Fig. 6, or according to Fig. 7 of the accompanying drawings.
Dated this 14th day of February 1898.
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.