Improvements in the Manufacture of Electrical Circuits and Cables.
Year: 1892

page_text: Date of Application, 6th Sept., 1992-Accepted, 19th Nov., 1892
COMPLETE SPECIFICATION.
[Communicated from abroad by JOHN ARNOLD BARRETT, Electrical Engineer,
of Brooklyn, in the State of New York, United States of America.]
Improvements in the Manufacture of Electrical Circuits and Cables.
I ALFRED VINCENT NEWTON of the Office for Patents 6 Bream's Buildings
Chancery Lane in the County of London Patent Agent 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 the manufacture of insulated electric conductors, and
especially to the construction of electric cables composed of a number of such
conductors, and it is described by my correspondent as follows:-
-
One object of the invention is to provide an improved construction whereby a
greater number of efficient conductors may be enclosed within a given space, and
to provide a simple and cheap method of insulating the conductors.
While certain features of the invention are applicable to all classes of electric
conductors and cables, the improvements have been designed, and are especially
adapted for use in electric cables employed in telephone work, in which the cables
are composed of a number of metallic circuits, the conductors forming each circuit
being insulated from each other and from the conductors of the other circuits.
In the construction of this class of cables, it has been the practice to surround
each conductor with a winding of cotton, tape, or other similar insulating material,
which is generally saturated with paraffine or other suitable insulator, and the
conductors thus insulated grouped together to form the cable.
It is well known that retardation by induction in the metallic circuits forming
the cable is reduced, and the efficiency of the circuits increased, as the distance
and amount of insulation between the conductors is increased, and it is desirable,
therefore, to separate the conductors as widely as possible. In the limited cross
area of a cable, therefore, but a comparatively small number of circuits of high
efficiency can be enclosed, and it has been possible to increase the number of circuits
only by a corresponding loss of efficiency."
It is well known also that the inductive capacity tending to produce retardation,
is greater between conductors forming a circuit than between conductors of
different circuits. It is evident, therefore, that the number of efficient circuits
within a given space may be increased, or a greater efficiency of the same number
of circuits be secured, by increasing the distance and amount of insulating material
between the conductors of each circuit, and decreasing that between conductors of
different circuits, and attain this object in the present case by a simple, convenient,
and cheap method, in which the two conductors forming each circuit are woven in
a single mesh of cord, tape, or other common insulating material, so that a greater
thickness of insulating material lies between the conductors than outside the same.
In the construction now in use, moreover, in which the same thickness of
insulating material is applied on all sides of each conductor, the shorter diameter
of the circuit is necessarily increased correspondingly with the increase of the
longer diameter, as the conductors of the circuits are further separated. As the
insulation between the conductors is increased to a point of high efficiency,
the thickness of the circuit is largely increased, which involves a loss of space
without gain in efficiency. I weave the conductors so as to form a circuit which
is practically a flat band, and so that the insulating material between the conductors
may be increased without increasing that outside the same, thus producing circuits
adapted for close packing in the cable, and securing the highest joint economy of
space and efficiency.
While the cable embodying my invention may be of any other general construction,

page_text: the invention consists in part of improvements on, and will be illustrated and
described as applied to, cables in which the conductor is surrounded by an air
containing "serving," formed preferably by a cord wound about the conductors, 50
as to leave large air spaces between the successive windings, the two conductors
forming a circuit then being enclosed within an envelope of paper or similar
material, preventing or retarding the passage of the sealing material, and a number
of these enveloped circuits grouped together within a protecting sheath of lead,
to form the cable, the spaces between the enveloped circuits and sheath being
filled with suitable sealing material.
A further object of the invention is to provide an improved flexible covering
for a conductor or groups of conductors.
In the manufacture of many classes of insulated electric conductors, it is the
practice to surround a conductor, or group of conductors, with flexible covering,
which consists of a wrapping of paper or of tape, the latter usually being saturated
with some suitable material, and the improvements constituting this part of the
invention are of general application in all classes of electric conductors in the
manufacture of which a flexible covering is used, but it is of special value as
applied to the construction of cable above described, in which scaling material is
applied about the covered conductors, and it has been especially designed for use in
connection therewith.
In the manufacture of this conductor, the paper or other material is preferably
applied by winding in long or short overlapping spirals, and the joints between
the successive windings are closed by some suitable adhesive material.
It is found,
however, that paper is liable to break under the flexure to which the conductor is
subjected, and with cloth or other stronger material, a tight joint between the
windings can be maintained only by a loss of flexibility.
If the covering be applied in any other manner, as by folding or winding a
continuous strip about a conductor or group of conductors lying parallel thereto,
the same danger of breaking in the use of paper and loss of flexibility with stronger
material exists.
Moreover, it is well known that in applying a strip of any material, by winding
it spirally about the article to be wrapped, a slackness and consequent buckling
in the wrapping is caused at the advance edge, this resulting from the overlapping
of the rear and front edges of the successive windings, so that the wrapping is
more rapidly taken up by the rear than the front edge. This is objectionable in
all cases in which such a wrapping is used, but is especially so, as applied to
electric conductors, on account of the irregularities in the form and size of the
conductors and core, caused by the bending over of the buckling portion, and in
conductors in which a tight joint is required, there is the further objection, that
the openings thus formed afford passage for the material which the covering is
intended to exclude.
I avoid these difficulties by the use of a wrapping formed and applied as will
be hereinafter described in detail.
:-
In the accompanying drawings, forming a part of this Specification:
Fig. 1 shows an uncovered electric circuit partially woven in accordance with
the first part of my invention.
Fig. 2 is a central longitudinal section of the same.
Fig. 3 is a cross section on the line - of Fig. 1.
Figs. 4 and 5 show modifications.
Fig. 6 is a cross section of my improved cable.
Figs. 7 to 15 show, in detail, the wrapping forming the second part of my
invention.
Fig. 7 is a detail of a partially wound circuit, showing the application of the
second part of my invention in its preferred form.
Fig. 8 is a central longitudinal section of the same.
Fig. 9 is a plan view of the wrapping strip of Figures 7 and 8, before folding,
the lines of fold being indicated in dotted lines.

page_text: 15 perspectiv view of the wrapping folded ready
Fig. 11 shows another method of applying the wrapping.
Fig. 12 shows a slightly modified form of wrapping.
Fig. 13 shows a long spiral wrapping.
Fig. 14 shows a straight wound single conductor; and
TOT WIBATg.
Fig. 15 is a perspective view of the wrapping of Figs. 13 and 14.
Referring to said drawing, a a are the electric conductors forming the circuit.
These conductors, in the construction shown in Figs. 1 to 3, are woven in a single
mesh by three strands, 1, 2, 3,-the strands 2, 3, lying between the conductors, and
the strand being wound about the conductors, and intermediate strands crossing
the latter alternately on opposite sides, the conductors, therefore, remaining
straight, and the weaving being entirely by the strands of insulating material.
The method of weaving is clearly shown in Figs. 1, 2, and 3, the strands 2, 3
being alternately raised and lowered as the strand 1 is wound, so that the latter
passes across upon one side of the strands 2, 3, and returns upon the opposite
side of the conductors and of the strands 2, 3.
In this construction, it is evident that the thickness of the insulating material
between the conductors a, will be double that outside the same, the circuits in the
cable falling naturally into such position that the conductors of the different
circuits are separated only by the single outside strands of insulating material.
The number of strands, however, is not an essential feature, but any convenient
number may be used.
Thus, the same result may evidently be obtained by using but two strands, as
shown in Fig. 4, the intermediate strand 2 being of greater diameter than the
outside strand 1. The construction shown in Figs. 1 to 3 is preferable, however,
as the same distance between the conductors is secured, while the thickness of the
circuit in one direction is little greater than that of a single-wound conductor.
Two outsides strands may be employed, as shown in Fig. 5, these strands lying
side by side, so that the thickness of insulating material outside the circuit is still
only that of a single strand. The single outside strand is preferred, however, for
convenience in winding, and because it affords greater air spaces.
It will be seen that the woven circuit has substantially the form of a flat band,
and in grouping the circuits to form a cable, and twisting them, as usual, in cable
construction, these bands will adjust themselves so as to occupy substantially all
the space within the sheath. This is shown clearly in Fig. 6, in which each pair
of conductors a a, forming a circuit, and wound as described, is enclosed within an
envelope c, as above described, and the enveloped circuits enclosed within a
protecting sheath d, the spaces between the envelopes and sheath being filled with
sealing material e.
In cables of this general construction, it is evident that the thickness of the
envelope is added to that of the insulating material outside of, but not between,
the conductors of the circuit. The envelope, therefore, occupies space in the
cable without increasing the distance between the conductors forming the respective
circuits, and consequently without increasing their efficiency.
By the first part of my invention, I not only provide a means for applying the
air-containing "serving" to the two conductors of a circuit at a single operation,
and with large air spaces, but am enabled to adjust the amount of insulating
material between and outside the conductors, so that the use of the envelope shall
involve no waste of space, but, with the "serving," shall form just the amount of
insulation between the conductors of different circuits required for the highest
economy of combined efficiency and number of circuits.
While it is preferable that the conductors, when forming a circuit, should be
separated by a greater thickness of insulating material than that surrounding
the conductors as above pointed out, and I have shown the conductors thus wound,
my improved method of weaving is not to be limited to this feature, as it is evident
that this method of weaving a pair of conductors into a single mesh is applicable
independently of this special construction, and whether the conductors form a

page_text: - circuit or not, and the same amount of insulating material may be used between, as
about, the conductors, if desired.
Although the flat band construction is preferred, it will be readily understood
that my improved method of weaving may be employed without the formation of
the band, as an intermediate circular strand may be used of such size that a circuit
of substantially circular cross section is produced. A circuit forming a flat band,
or oblong in cross section, is not claimed broadly in the present case, but forms the
subject matter of another application (No. 15,998) of even date herewith.
Referring to Figs. 7 to 10, a a are the conductors of the circuit; b is an air-
containing serving," consisting of the cord or tape woven as previously described
and the wrapping embodying the present invention in its preferred form. I
prepare this wrapping by taking a strip of paper or other material, and forming in
it a tuck 4, preferably approximately upon the central line thereof, as shown in
Figs. 9 and 10. By this tuck the strip is divided longitudinally into two sections 5
and 6, lying in different planes, the section 5 being raised above the section 6, by
two thicknesses of the material which form the tuck 4. A fold 7 is then preferably
formed near the outer edge of the section 6, parallel to the tuck 4, and
strip or section 8 folded over upon the upper side of the section 6, thus forming two
thickesses of material at the outer edge of the lower section.
narrow
The wrapping may be used without adhesive material, but usual adhesive
material will be applied either to the whole lower side of the strip before folding,
or to the section 8, either before or after folding, so that the joint is closed by
uniting the outer edge of section 5 and section 8, as will presently be described.
In applying this wrapping to my conductor, I prefer to coat the wrapping on
one side, and to use, as the adhesive material, a sizing of mucilaginous, gelatinous,
or albuminous material, which is adhesive when moist and flexible when dry, but
so far as the present invention is concerned, other materials may be used.
37
The wrapping thus prepared is applied to the article to be wrapped, in this case
the "served conductors a, by winding the wrapping about the article in short
spirals, preferably with the adhesive section 8 outside, and in advance, and with
the section 5 of each winding overlapping the adhesive section 8 of the previous
winding, the over lapping being preferably just sufficient to bring the edges of
the sections 5 and 8 together. The application of the wrapping is fully shown
in Fig. 8.
With the wrapping thus formed and applied, it is found that great flexibility is
secured, while preserving a tight joint, and that paper may used without danger
of breakage, the opening and closing of the tucks enabling the wrapping to bend
freely in any direction, without strain upon the material.
It will be seen, also, that the sections 5, 6 of the wrapping lic at equal distance
from the centre throughout, so that the material of no part of one of these sections
is taken up more rapidly than that of any other part of the same, and it is found,
in practice, that all slackness or buckling is taken up in the central part of the
wrapping, where no joint is formed, and that the objectionable tendency to buckle
at the edges and break the joint is entirely obviated.
Many modifications may be made in the construction and method of applying my
wrapping, without departing from my invention.
For instance, while I prefer to wind the wrapping with section 6 inside, as
shown in Fig. 7, as there is less tendency to buckling, the wrapping may, with
approximately as good results, be wound with sections 5 and 8 inside, as shown in
Figure 11. The fold 7 and section 8 may be omitted, and a wrapping used
employing only the feature of the tucks 4, which will still operate to secure
flexibility, this construction being shown in Fig. 12.
The tucks are applicable also to other than the preferred short spiral wrapping
thus far described.
If a long spiral wrapping be desired, the strip shown in Figure 15 will be used.
the tucks 4 being formed transversely of the strip, instead of longitudinally, and
lying as shown in Figure 13 when the wrapping is applied.

page_text: The strip shown in Figure 15 may also be applied by winding it about the
conductor or circuit in the manner shown in Figure 14, with a single conductor,
the strip and conductor extending parallel with each other.
It will be seen that the essential feature of this branch of my invention consists
in the flexible covering having tucks extending transversely to the line of flexure,
and this feature forms a part of my invention, whether the covering be applied by
winding a strip of material about the article covered, or in any other manner.
It will be understood that my cover is applicable to other classes of conductors
than that shown, and that this cover may be applied directly to one or more
conductors, or outside an inner covering or coverings of any desired form.
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. An electric circuit consisting of a pair of naked conductors, and a single mesh
of cord, tape, or similar insulating material, woven between and about said con-
ductors, with a greater thickness of the woven insulating material between the
conductors than about the same, substantially as described.
2. An electric circuit consisting of a pair of naked conductors, and a single mesh
of cord, tape, or similar insulating material, woven between and about the con-
ductors and constructed to form an oblong circuit with a great thickness of the
woven insulating material between than about the conductors, substantially as
described.
3. An electric circuit consisting of a pair of naked conductors, one or more
strands of cord, tape, or similar insulating material lying between the conductors,
and one or more strands wound about the conductors and intermediate strand or
strands, and crossing the latter alternately on opposite sides, substantially as
described.
4. An electric circuit consisting of a pair of naked conductors, one or more
strands of cord, tape, or similar insulating material lying between the conductors,
and one or more strands of similar material wound about the conductors and
intermediate strand or strands, and crossing the latter alternately on opposite sides,
said strands being constructed and arranged to form a greater thickness of insulating
material between than outside the conductors, substantially as described.
5. An electric circuit consisting of a pair of naked conductors, two strands of
cord, tape, or similar insulating material lying between the conductors, and a single
strand wound about the conductors and intermediate strands, and crossing the latter
alternately on opposite sides, substantially as described.
6. In an electric cable, the combination of a plurality of independent circuits,
each circuit consisting of a pair of conductors woven in a single mesh of cord, tape,
or other insulating material, with a greater thickness between the conductors than
outside the same, substantially as described.
7. In an electric cable, the combination of a plurality of independent circuits,
each circuit consisting of a pair of conductors woven in a single mesh of cord, tape,
or other insulating material, with two strands between the conductors and one strand
outside the same, substantially as described.
S. An electric cable consisting of a plurality of independent circuits, each circuit
consisting of a pair of conductors woven into a flat band, with a greater thickness
of insulating material between the conductors of the same circuit than between
those of different circuits, substantially as described.
9. In an electric cable, the combination of a plurality of electric circuits, each
circuit consisting of a pair of naked conductors, insulated by being woven in a
single mesh of cord, tape, or other insulating material forming an air-containing
serving, an envelope about each circuit preventing or retarding the passage of the
scaling material, a protecting sheath enclosing the enveloped circuits, and sealing
material filling the space between the envelopes and sheath, substantially as
described.

page_text: 10. In an electric cable, the combination of a plurality of electric circuits, each
circuit consisting of a pair of conductors woven in a single mesh of cord, tape, or
other insulating material forming an air-containing serving, with a greater thickness
of insulating material between than outside the conductors, an envelope about each
circuit preventing or retarding the passage of the sealing material, a protecting
sheath enclosing the enveloped circuits. and sealing material filling the space
between the envelopes and sheath, substantially as described.
11. In an electric cable, the combination of a plurality of electric circuits, each
circuit consisting of a pair of conductors insulated by an air-containing serving,
with a greater thickness of insulation between them than outside the conductors,
and an envelope about each circuit, substantially as described.
12. An electric conductor, or group of conductors, having a covering consisting
of paper, cloth, or other flexible material, provided with tucks extending transversely
to the lines of flexure, substantially as described.
13. An electric conductor, or group of conductors, having a covering consisting
of a strip of paper, cloth, or other flexible material, wound about the conductor or
group of conductors, and provided with tucks extending transversely to the lines of
flexure, substantially as described.
14. An electric conductor, or group of conductors, having a covering consisting
of a strip of paper, cloth, or other flexible material, wound spirally about the
conductor, or group of conductors, and provided with tucks extending transversely
to the lines of flexure, substantially as described.
15. An electric conductor, or group of conductors, having a covering consisting
of a strip of paper, cloth, or other flexible material, wound spirally about the
conductor, or group of conductors, and provided with tucks extending transversely
to the lines of flexure, the overlapping edges of the successive windings being
gummed together, substantially as described.
16. An electric conductor, or group of conductors, surrounded by a spiral
wrapping formed of the flexible strip c, having the longitudinal tuck 4, substantially
as described.
17. An electric conductor or group of conductors surrounded by a spiral
wrapping formed of the flexible strip e, having the longitudinal tuck 4, and the
fold 7, parallel thereto, the sections formed by the tuck and fold overlapping,
substantially as described.
18. A wrapping consisting of a strip of paper e, or other flexible material,
provided with tucks extending transversely to the lines of flexure of the applied
wrapping, substantially as described.
19. A spiral wrapping consisting of the flexible strip e, having a longitudinal
tuck 4, substantially as described.
20. A spiral wrapping consisting of the flexible strip c, having the longitudinal
tuck 4, and fold 7 parallel thereto, substantially as described.
Dated this 5th day of September 1892.
NEWTON & SON,
Agents for the Applicant.