Improvements in Electric Cables.
Year: 1897

page_text: Date of Application, 23rd Nov., 1897
Complete Specification Left, 23rd Aug., 1398-Accepted', 19th Nov., 1898
Improvements in Electric Cables.
We, GEORGE HINDE NISBETT, of Ashfield, Huyton, in the County of Lancaster,
Electrical Engineer, and DARWIN BATES, of Stanley Crescent, Prescot, in the
County of Lancaster, Electrical Engineer, do hereby declare the nature of this
invention to be as follows:-
This invention has reference to electric cables of the type in which the twin
or pairs of conductors are contained within tubes or coverings of paper, or the
like, and have an air space, more or less, about them, the conductors with their
air space tubes, being twisted spirally about each other.
In cables of the kind referred to, by the natural consequence of the method of
manufacture, the conductors will not be wholly and evenly surrounded with air,
but will, practically, have an air space between them, and the paper
of the tubes or coverings, all along the adjacent surfaces of the tubes;
thus, the adjacent or inner portions of the cable tubes or covering merely forms a
paper septum between the two conductors; and, consequently, in twin conductors
of this kind, the mutual capacity is not as high, as if the conductors were solidly
wound.
Now our invention has chiefly for its object, not only the production of a cable
having a low capacity, and low total capacity (that is, the capacity between any
one wire and all the others and the sheath); but, also, low mutual capacity; i.e.
low capacity between one wire and the other of the same pair. And, according
to our invention, we construct a twin cable of the kind referred to, wherein the
wires are drawn together on the opposite sides of the septum, or septa, with a
special formation of septum, or septa, or a special construction of tubes, by which
not only does the insulation at this part consist of paper, but a combination of
paper (or like material), and an air space.
In one case, between the folds, or lamina, or laminae, of the paper septum of
the tubes containing the conductors, there is provided a strip or strips of paper
with the central portion cut away, the openings being in the form of elongated
slots or circles, or the like. By this, the two conductors will lie on the opposite
sides of the tube septa, with the air spaces between them.
According to a modification, between the tubes, a special septum of waved
string, or the like, stiffened by starch or the like, is employed; or, string made up
in the form of a ladder.
Again, in another modification, the special insulating strip or septum is made
of corrugated paper; or twisted paper, more or less flattened; or paper with
bulbous or enlarged edges; or paper with ribs on it, produced by pressure or
adhered pieces.
According to another modification, the air space forming strip or septum may
consist of a strip of paper, with inturned edges, or two strips of paper with
inturned edges, the edges being adjacent and touching each other. Or, according
to another modification, the edges of the tubes, in which the conductors lie, are
carried in between, and turned over at the two meeting portions or lamina of

page_text: the tubes, so as to form a central air space between the two wires. In some cases,
these overlapping parts may be carried right over from one side to the other,
between the wires, and then turned up or folded at the edges, so producing the
air space between the wires, as well as providing an extra thickness or laminae
of paper between the wires.
Dated this 20th day of Novambar 1907
We, GEORGE HINDE NISBETT, of Ashfield, Huyton, in the County of Lancaster,
Electrical Engineer, and DARWIN BATES, of Stanley Crescent, Prescot, in the
County of Lancaster, 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 electric cables of the type in which the twin
or pairs of conductors are contained within tubes or coverings of paper, or the
like, and have an air space, more or less, about them, the conductors, with their
air_space tubes, being twisted spirally about each other.
In cables of the kind referred to, by the natural consequence of the method of
manufacture, the conductors will not be wholly and evenly surrounded with air,
but will practically, have no air space between them, and the paper of the tubes
or coverings, all along the adjacent surfaces of the tubes; thus, the adjacent or
inner portions of the cable tubes or covering merely form a paper septum between
the two conductors; and, consequently, in twin conductors of this kind, the mutual
capacity is the same as if the conductors were solidly wound.
Now our invention has chiefly for its object, not only the production of a cable
having a low capacity, and low total capacity (that is, the capacity between any
one wire and all the others and the sheath); but, also, low mutual capacity; i.e.
low capacity between one wire and the other of the same pair. And, according
to our invention, we construct a twin cable of the kind referred to, wherein the
wires are drawn together on the opposite sides of the septum, or septa, with a
special formation of septum, or septa, or a special construction of tubes, by which
not only does the insulation at this part consist of paper, but a combination of
paper (or like material), and an air space.
In one case, between the folds, or lamina, or laminae, of the paper septum of
the tubes containing the conductors, there is provided a strip or strips of paper
with the central portion cut away, the openings being in the form of elongated
slots or circles, or the like. By this, the two conductors will lie on the opposite
sides of the tube septa, with the air spaces between them.
According to a modification, between the tubes, a special septum of waved
string, or the like, stiffened by starch or the like, is employed; or, string made up
in the form of a ladder.
Again, in another modification, the special insulating strip or septum is made
of corrugated paper: or twisted paper, more or less flattened;
or paper with
bulbous or enlarged edges; or paper with ribs on it, produced by pressure or
adhered pieces.
According to another modification, the air space forming strip or septum may
consist of a strip of paper, with inturned edges, or two strips of paper with
inturned edges, the edges being adjacent and touching each other. Or, according

page_text: to another modification, the edges of the tubes, in which the conductors lie, are
carried in between, and turned over at the two meeting portions or lamina of
the tubes, so as to form a central air space between the two wires. In some cases,
these overlapping parts may be carried right over from one side to the other,
between the wires, and then turned up or folded at the edges, so producing the
air space between the wires, as well as providing an extra thickness or laminae
between the wires.
The improvements hereinabove specified are illustrated in the accompanying
drawings, which we will now describe in the order of the figures.
In Figure 1, the type of air space electric cables to which the invention refers
is illustrated; namely, a cable comprising a pair of conductors a, contained within
tubes or coverings 6 of paper or the like, the two conductors within their tubes
being wound spirally upon each other. As will be seen in the drawings, the con-
ductors a lie, practically, on the inner parts 61 of the tubes (which in the case
shewn consists of the overlapping edges of the paper covering), the wires or
conductors being caused to take this position by the act of twisting them around
each other. Normally, therefore, in a cable of this kind, it will be seen, that
between the two conductors, while there is insulation due to the portion b¹ of the
covering tubes, yet there will be no air space directly between the conductors.
In the cable shewn, an air space, according to this invention, between these two
tubes and conductors is provided by the strip c, which represents a ribbon or strip
(or strips) of paper, or other suitable material, with oblong apertures in it, which
say are cut out of a solid strip of the material. These oblong apertures will
therefore provide air spaces between the two tubes, and, consequently, between the
two conductors a, with the effects and advantages above specified.
A surface view of this air space perforated strip c is shewn in Figure 2.
Figure 3 shews a modified form of strip for providing the air space septum. It
merely consists of a strip in which the apertures are circular, instead of oblong.
In the modification shewn in Figure 4, the air space septum provided between
the two conductors, consists of string, or the like, waved as shewn; and it is
preferably stiffened up by starch or the like into the form shewn, so that it shall
retain the form.
It con-
Figure 5 shews a modification of the septum air space last described.
sists of string, or the like, made up in the form of a ladder, as shewn; and it may
be stiffened up with starch, or the like, as in the preceding case.
Figures 6 and 7 shew two modifications of means or devices for producing an
air space septum, consisting, respectively, of a strip of corrugated paper or like
material, and a ribbed strip of such material. In the latter, the ribs or projecting
parts may be formed or produced by pressing the papers into this form, or
otherwise.
In the cable shewn in Figure 8, a third modification of means of forming the
air space septum is illustrated. This consists of two strips of paper c with their
edges folded in a short distance laterally, the inward foldings of the two strips
being placed one on the other, so providing a longitudinal air chamber or space
within these two strips of a depth equal to the two thicknesses of the paper. This
arrangement or construction not only provides the air space, but, also an extra
thickness of paper or like insulation between the conductors.
without
or cover-
or means.
In the modification shewn in Figures 9 and 10, a continuous air
space,
the employment of any
as in Figure 8, is provided,
to that which forms the tubes
material septum, extraneous
ings of the conductors; that is, without any separate device
It is provided by a special arrangement and formation of the paper
or material of which the tubes bare formed, namely, a special arrangement and
formation of the edges of the paper forming the inner portions b₁ of the tubes,
between the conductors. One of the edges of each tube has a longitudinal short
fold (or it may be a double fold) 6, by which, when the two tubes are placed
or one another, the air space, or air septum, is provided between the conductors.

page_text: In Figure 9, this edge fold 62 is on the outer flap of the paper, or other material,
and is an outward fold. In this case, therefore, there is a single layer of paper
under each conductor, with the air space or septum between them. In the other
modification in Figure 10, the outer edge of each tube is folded outwardly, but is
carried across the part 6 of the tube, so that there are two thicknesses of paper
under the conductor. When these conductors are placed together, the two longi-
tudinal folds 62 present an inward fold in relation to each other, with the air space
or septum between them. Therefore, between the two conductors, there is the
central air space, and two thicknesses of paper on each side of it.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:
1. The herein described improvement in air space electric cables in which the
conductors are enclosed within tubes or coverings of paper, or the like, and are
twisted about each other; namely, a cable of this kind, wherein an air space is
provided by means of formations substantially as described, between the tubes or
coverings and conductors at the meeting or adjacent parts of the said tubes or
coverings; for the purposes set forth.
2. An air space electric cable comprising conductors; tubes or coverings of
paper or other suitable material enclosing the said conductors; and a septum
between said tubes or coverings, producing an air space between them, and the
conductors, at the meeting or adjacent sides or parts; substantially as set forth
with reference to and shewn in Figures 1 to 7 of the drawings.
3. An air space electric cable comprising conductors; tubes or coverings of
paper or other suitable material enclosing the said conductors; and a septum
between said tubes or coverings, producing an air space between them, and the
conductors, at the meeting or adjacent sides or parts; substantially as set forth
with reference to and shewn in Figure 8 of the drawings.
4. An air space electric cable comprising conductors; tubes or coverings of
paper or other suitable material enclosing the said conductors; an air space between
said tubes or coverings and their conductors at the meeting or adjacent sides or
parts, provided by the formation of the edges of the tubes or coverings; substan-
tially as set forth with reference to and shewn in Figures 9 and 10 of the
drawings.
5. The improved cables of the type herein specified, with an air space between
the conductors at the meeting or adjacent sides or parts, particularly as shewn in
and set forth with reference to the different figures of the drawings, respectively.
Dated this 22nd day of August 1898.
CHEESBROUGH & ROYSTON,
Applicants' Patent Agents, 15, Water Street Liverpool.