Improvements in Electrical Transformers.
Year: 1889

page_text: Date of Application, 10th May, 1889
Complete Specification Left, 10th Feb., 1890-Accepted, 15th Mar., 1890
PROVISIONAL SPECIFICATION.
Improvements in Electrical Transformers.
We, WALTER CLAUDE JOHNSON and SAMUEL EDMUND PHILLIPS, both of 14 Union
Court, Oid Broad Street, in the City of London, Telegraph Engineers, do hereby
declare the nature of this invention to be as follows:-
Our invention has for its object to reduce the number of breaks in the magnetic
circuit of an electrical transformer so as thereby to reduce its resistance. For this
purpose, according to one arrangement, we construct the core of thin soft iron plates
or laminae separated from each other either by being coated with a varnish containing
French chalk, or by the interposition of paper, such plates being so formed as to afford
angular or chamfered faces at the ends of the core. This may be effected either by
cutting, or stamping the plates all of the same configuration with the angular or
chamfered end faces formed thereon, or they may be made of varying lengths so that
when placed upon each other they form the angular faces by their varying length, such
faces being if necessary planed true afterwards.
After winding upon the core so formed the primary and secondary coils, we surround
them with bars similarly built up of thin plates having a curved or angular or U shape
at the ends formed either by bending or stamping and which have angular or
chamfered faces so formed as to fit accurately against the chamfered faces of the core,
the whole being thus made to present the shape of a closed loop or chain link, with a
bar, constituting the core with its coils, passing across its middle, the separate plates
forming the loop and core lying either parallel to the plane of the loop or at right
angles thereto.
By this construction it will be seen that there occur only four breaks in the magnetic
circuit, and these, presenting a large area of contact, will offer comparatively little
resistance.
Instead of forming the surrounding plates with bent or stamped angular or rounded
ends, they may be composed of three separate straight parts, one running parallel
with the core, and the other two connecting the ends of these plates with the ends of
the core the meeting surfaces of the several parts being chamfered and accurately
fitted together as before.
In the above described constructions, the side bars of the loop may constitute the
core round which the coils are wound, instead of the central bar.
According to another modification the one side bar may be dispensed with, thus
forming a loop consisting of the one side bar and the core; in this case the coils
may be wound either on the one or the other side of the loop, or on the two end
parts.
According to another construction we employ two separate closed loops or links for
forming the magnetic circuit, and place them close together, so that a central core is
formed by the two contiguous sides of the loops, and for enabling the coils to be
wound thereon the two loops are cut through at one point, and are bent open to allow
of the coiling after which they are closed up again, the meeting surface being
accurately fitted together. In like manner a single closed loop may be employed cut
through at one point to allow of the coils being wound on one of the sides of the loop.
Such single or double loops may be formed of a continuous band wound round a
rounded or rectangular former, the loop when completed being cut through at one
point as described.
Instead of forming the above described magnetic circuits of thin plates, they may
be formed wholly or partially of wire, preferably varnished; thus the core may be
formed of a bundle of wires of cylindrical, rectangular or other shaped section, and
the side pieces or side pieces completing the magnetic circuit of plates suitably shaped

page_text: by bending or stamping for embracing the cylindrical or other shaped surface of
the ends of the core; or the side pieces may also be formed of wire, having either a
cylindrical. rectangular, or other suitable cross section.
The bundles of wires forming the core and side pieces may be held together by any
suitable means, such as by binding with tapes or by enclosing in covers of vulcanite,
paper, &c. The layers of plates may be secured, together by rivets or screws passing
through holes bushed with insulating material:
--
The close contact of the chamfered or other meeting surfaces of the separate parts
forming the inagnetic circuits may be insured by pressing them together by screws,
wedges or other incans, the magnetic circuit being if necessary surrounded by a frame
for this purpose.
In the first described construction, instead of forming chamfered contact surfaces
for the core and side pieces, the core may present a square butt joint at each end to
corresponding butt joints formed on the side pieces which are suitably bent or stamped
so as to bring their meeting faces round to the end faces of the core.
Dated this 10th day of May 1889.
ABEL & IMRAY,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Electrical Transformers.
We, WALTER CLAUDE JOHNSON, and SAMUEL EDMUND PHILLIPS, both of 14 Union
Court, Old Broad Street, in the City of London, Telegraph 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
Our invention has for its object to reduce the number of breaks in the magnetic
circuit of an electrical transformer, so as thereby to reduce its resistance, and also to
increase the contact surface of the junctions. For this purpose, according to one
arrangement, we construct the core of thin soft iron plates or laminae separated from
each other either by being coated with a varnish containing French chalk, or by the
interposition of paper or other suitable material, such plates being so formed as to afford
angular or chamfered faces at the ends of the core. This may be effected either by
cutting or stamping the plates all of the same configuration with the angular or
chamfered end faces formed thereon, or they may be made of varying lengths so that
'when placed upon each other they form the angular faces by their varying length,
such faces being if necessary planed or machined true afterwards.
After winding upon the core so formed, the primary and secondary coils, we surround
them with a shell consisting of bars similarly built up of thin plates having a curved
or angular or U shape at the ends formed either by bending or stamping and which
have angular or chamfered faces so formed as to fit accurately against the chamfered
faces of the core, the whole being thus made to present the shape of a closed loop or
chain link, with a bar constituting the core with its coils, passing across its middle,
the separate plates forming the loop and core lying at right angles to the plane of the
'loop.
By this construction it will be seen that there occur only four breaks in the magnetic
circuit, and these, presenting a large area of contact, will offer comparatively little
⚫ resistance.
Instead of forming the surrounding plates with bent or stamped angular or
rounded ends, they may each be composed of three separate straight parts, one
running parallel with the core, and the other two connecting the ends of these
plates with the ends of the core the meeting surfaces of the several parts being
chamfered and accurately fitted together as before.
In the above described constructions, the side bars of the loop may constitute the
core round which the coils are wound, instead of the central bar:

page_text: According to another modification the one side bar may be dispensed with, thus
forming a loop consisting of the one side bar and the core; in. this case the coils
may be wound either on the one or the other side of the loop, or on the two
end parts.
According to another construction we employ two separate closed loops or links
for forming the magnetic circuit, and place them close together, so that a central
core is formed by the two contiguous sides of the loops, and for enabling the coils to
be wound thereon the two loops are cut through at one point, and are bent open to
allow of the coiling after which they are closed up again, the meeting surface being
accurately fitted together; or the loops may be cut through at two opposite joints
so as to enable the one part to be removed for coiling.
In like manner a single closed loop may be employed cut through at one point to
allow of the coils being wound on one of the sides of the loop. Such single or double
loops may be formed of a continuous band wound round a rounded or rectangular
former, the loop when completed being cut through at one or more points as described.
Or the loop may be left entire and merely have circular or other shaped holes formed
at opposite sides through which is fitted a correspondingly shaped core built up of
wire or of thin plates, a close contact between the core and the holes being insured by
expanding the core by means of wedges.
Instead of forming the above described magnetic circuits of thin plates, they
may be formed wholly or partially of wire, preferably varnished; thus the core
may be formed of a bundle of wires of cylindrical, rectangular or other shaped
section, and the side piece or side pieces completing the magnetic circuit of plates
suitably shaped by bending or stamping for embracing the cylindrical or other shaped
surface of the ends of the core; or the sido pieces or complete loop constituting the
shell may also be formed of wire, having either a cylindrical, rectangular, or other
suitable cross section.
The bundles of wires forming the core and side pieces may be held together by any
suitable means, such as by binding with tapes or by enclosing in covers of vulcanite,
paper &c. The layers of plates may be secured together by rivets or screws passing
through holes bushed with insulating material.
The close contact of the chamfered or other meeting surfaces of the separate
parts forming the magnetic circuits may be insured by pressing them together by
screws wedges or other means, the magnetic circuit being if necessary surrounded by
a frame for this purpose.
In the first described construction instead of forming chamfered contact surfaces for
the core and side pieces, the core may present a square butt joint at each end to
corresponding hutt joints formed on the side pieces which are suitably bent or
stamped so as to bring their meeting faces round to the end faces of the core.
Fig. 1 of the accompanying drawings shews a perspective view of one form. of our
before described transformer formed of thin plates or laminae of iron lying in a direc-
tion at right angles to the plane of the transformer.
The core A has four chamfered surfaces a, a, a, a, against which fit the corre
spondingly chamfered surfaces of the parts B B of the shell; these may either be
formed by bending the several plates at right angles at the ends as shewn in this
figure or by curving the ends as shewn at Fig. 2, or the shell B B might be formed
by coiling up a continuous iron band into the form of a loop, and then cutting this
through at opposite ends in the manner indicated, to receive the core A.
In order to increase the extent of surface of metal in contact at the joints, we
prefer to interpose extra thicknesses of paper between the ends at of the plates
of B. so, as to widen the surface at those points, and thus by enabling the
chamfers a a to be made at a sharper angle to increase the surface of metal in
contact.
Fig. 3 shews an arrangement in which the transformer shell is-formned of two
separate loops CC, each formed by coiling up a continuous iron band, placed
side by side, so that the two sides c c' together form the core while the other
parts forin the shell.

page_text: To enable the coils to be wound on the core, the side c and c of each coil is
separated by cuts at the angle thus forming angular joints the surface of which may
be increased by the insertion of extra thicknesses of paper &c. between the plates
at cc', as in the previous case.
Or instead of making two complete coils as described, the parts c c¹ and c² c³ may be
built up as separate pieces as in the first instance.
Fig. 4 shews a similar construction to the foregoing, the loops CC being made
with rounded ends instead of angular.
In this case the loops are cut through at a, close to the parts c c¹ forming the core,
in order, in the first place to enable the wire coils to be slid on to the core from the
end, and in the second place to obtain thereby an extended joint surface, this being
increased as before by the insertion of extra thicknesses of paper.
In the construction shewn at Fig. 5 the shell D is formed by coiling up a con-
tinuous iron band and then cutting holes in the same at d d for the reception of the
core A, the holes and the core being either rectangular as shewn, with the strips
arranged either parallel to the strip of D, or at right angles thereto; or the holes and
core may be cylindrical or of other configuration and the latter may be formed either
of plates or of wires. In order to obtain a close contact between the surface of the
ends of the core and that of the holes, wedges E, or tapered pins are driven into the
core as shewn.
.
For placing the coils upon the core, the former are introduced into the space of the
shell D' before the core is inserted this being then passed through the shell and coils,
and secured as described.
In all the above described constructions, either the shell or the coil, or both may be
built up of wire instead of thin plates or bands as described.
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. Constructing electrical transformers with shells formed of plates or bands
coiled or laid with their flat surfaces at right angles to the plane of the shell,
and arranged substantially as herein described with reference to the drawings.
2. In the construction of the shells of transformers of thin plates or laminae with
angular joints, the introduction of paper or other equivalent material between the
plates at the joints, so as to increase the metal surfaces in contact, substantially as
herein described.
3. Constructing electrical transformers of two separate loops formed of coiled iron
bands placed close together so that the contiguous sides of the loops form the core,
the loops being cut through at each end in a direction parallel with the core, and at a
point close to the latter in order to allow of the wire coils being slid upon the core,
substantially as described with reference to Fig. 4 of the drawings.
4. Constructing electrical transformers with a shell formed of a continuous band
wound upon itself and having holes formed at two opposite sides, for the insertion of
a core, close contact between the core and the shell being insured by expanding the
core by wedges or other suitable means, substantially as described with reference to
Figure 5 of the drawings.
5. In transformers such as are herein described and shewn on the drawings con-
structing either the core or the shell, or both parts, of wire instead of plates or bands,
substantially as described.
Dated this 10th day of Fahmu 1800
ABEL & IMRAY,
Agents for the Applicants.