Improvements in Electrical Transformers.
Year: 1897

page_text: Date of Application, 2nd Feb., 1897
Complete Specification Left, 2nd Dec., 1897-Accepted, 8th Jan, 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:-
My invention has reference to a construction of electrical transformer which,
whilst possessing a high efficiency, is capable of being easily cheaply and conveniently
made. To this end my improved transformer is composed of hollow or perforated
thin metal plates arranged radially around a centre or support so as to form a
cylindrical aud usually hollow core or casing having within it an annular space or
chamber wherein the primary and secondary windings are enclosed. The radial
plates are preferably of hollow rectangular shape made up of L shaped stampings of
sheet iron, one set of these stamping being arranged to form the inner side and one
end of the said annular space or chamber and the other set to form the outer side and
other end of the space or chamber. The two L shaped plates comprising each plate
are preferably arranged in the reverse manner to those in adjacent plates so as to
break joint therewith. As the radial plates will diverge from each other, the spaces
between them may advantageously be fitted with additional hollow rectangular plates
composed of L-shaped stampings like the main plates but having their long sides
narrower than those of the said main plates.
The stampings may advantageously be formed out of rectangular sheets of iron from
each of which there can be cut four L shaped stampings two of which are adapted to
be placed thus L1 and two thus [], leaving a rectangular shaped piece of metal
suitable for other purposes, so that all waste of material will be obviated.
In building up my improved transformer, the inner series of ✓ shaped stamping
are placed in position and the primary and secondary windings placed around them
after which the outer series of L shaped stampings are suitably secured in position
around the inner series so as to enclose the windings.
In one construction the stampings are arranged in radially arranged groups so as
to form as seen in plan or end view, a star shaped core or body with outwardly
diverging ventilating spaces between the groups and with a hollow tubular centre so
that the transformer will be efficiently ventilated. At the inner periphery of the
core or body, where the stampings preferably bear against each other, there may be
a tubular or ring-light support or supports.

page_text: I, ARTHUR FRANCIS BERRY, of Manor House, Ashley, Market Harborough, in the
County of Leicester, Electricial 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 :-
My invention has reference to a construction of electrical transformer which, whilst,
possessing a high officiency, is capable of being easily, cheaply, and conveniently
inade. To this end my improved transformer is constructed as I will proceed to
explain with the aid of the accompanying drawings of which Fig. I shows partly in
vertical section and partly in side elevation, and Fig. 2 partly in plan and partly in
horizontal section, a transforiner according to my invention.
The transformer is composed of hollow or perforated laminated metal plates 1
arranged radially around a centre so as to form a cylindrical and usually (as shown)
hollow core or casing having within it an annular space or chamber 2 wherein the
primary and secondary windings 3 and 4 are enclosed. The radial plates are of
hollow rectangular shape (see Fig. 1) made up of L-shaped stampings 1, 1, 1º, 1ª
of sheet iron, formed as hereinafter described, one set of these stampings viz. 1*
and 1b being arranged to form the inuer side and one end of the said annular space or
chamber and the other set viz. 1° and 1d to form the outer side and other end of the
space or chamber 2 as hereinafter described. As the radial plates 1 diverge from
each other, the spaces between them are fitted with additional hollow rectangular
laminated plates 1* composed of L-shaped stampings like the main plates 1 but
having their vertical or long inner sides, and also it may be their long outer sides,
as in the arrangement shown, narrower than those of the said main plates. The
upper and lower ends of the additional stampings may be of the same depth as that
of the stampings composing the main plates.
The stampings are formed out of rectangular sheets of iron one of which is shown
in Fig. 3 and from each of which there can be cut four L-shaped stampings
viz. 1, 1, 1 and 1d, two of which viz. 1 and 1° are alike in dimensions and are
adapted to be placed thus [], and as shown at the left hand side of Fig. 4, the other
two, vis. 1 and 1d, differing in dimensions from the others but agreeing with each
other, being adapted to be placed thus, L1, and as shown at the right hand side of
Fig. 4 so that the rectangular spaces enclosed between the several pairs of stampings
when arranged as shown, will be of similar width and length. When the sheet of
inetal is cut as described there is left a rectangular shaped piece of metal 1° suitable
for other purposes, so that all waste of material is obviated."
In building up iny improved transformer a number of the stampings 1 and 1b are
arranged alternately with their long sides against one another and their short sides at
the same end to form a number of similar groups 1 (Fig. 2) which are held around a
cylindrical core and in radial grooves in two end plates by metal bands arranged
around the two ends of the radially arranged groups, the end plates being suitably
held together as by a central bolt. A number of similar groups 1 (Fig. 2) of
similarly shaped stampings to 1 and 1b but having their long sides of less radial width
than those of the stampings 12 and 1b are arranged in the diverging spaces between
the groups which touch each other at their inner edges, the outer edges of the
stampings in all the groups being at the same distance from the centre of the core.
When the stampings are thus arranged a ring 5 of insulating material such as paste.
board saturated in ozokerite, is placed against the short ends of the stampings 1* 1b.
The whole is then placed in a machine such as a lathe, and the long sides of the
stampings covered with a layer or layers 6 of insulating material such as woven

page_text: 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 winding 4, preferably in the form of un insulated
copper strip, is then wound over the layer G 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 3 of insulating material, is then slipped endways over the secondary winding 4,
one of the aforesaid end plates being removed for the purpose, after which the end
plate is replaced. 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 5* of insulating material like 5 is then placed at the opposite
end of the windings.
A number of groups of alternately arranged stampings like 1° and 1d are then
placed into juxtaposition with the stampings 1 1 in the manner shown in Fig. 4 so
ns to complete the formation of the laminated plates 1 and 1°, the adjacent stamp-
ings in each plate being reversely arranged (see dotted lines in Fig. 1) so as to break
joint with one another. Blooks 8 of suitable material such as wood, are then placed
between the outer ends of the plates 1 and fitting the outer ends of the plates 1* aud
are held in place by wire 9 wound on tightly. After the former or mandrel is
removed from the hollow centre 10, of the core, spring metal rings 11a are placed in
the hollow centre 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 the transformer can be readily
supported, the perforations or slots in the two plates being opposite the tubular
centre and wedge shaped spaces 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 foreigu unatter. The lower plate 14 is provided
on its underside with two ribs 17 which serve to support the plate above the Hoor and
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 protecting
casing 18 of thin sheet steel and with a cap or cover 19 to enclose the terminals.
The casing at points above the top plate 14 is formed with holes covered with gauze
for outlet of air.
As will be obvious each secondary winding may consist of one or more sections, and
the several sections of the two windings may be variously connected up. Also
instead of using two secondary windings, arranged one on each side of the primary
winding as shown, a single secondary winding inay be used if desired but I consider
the arrangement shown the best one.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what I
claim is :-
1. The manufacture of electrical transformers substantially as hereinbefore
described with reference to and illustrated in the accompanying drawings.
2. The improved electrical transformer shown in and described with reference to
the drawings annexed.