Improvements in the Manufacture of Insulated Cables.
Year: 1895

page_text: Date of Application, 8th Aug., 1895
Complete Specification Left, 18th Feb., 1896-Accepted, 8th Aug., 1896
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Insulated Cables.
I, GEORGE HINDE NISBETT, Prescot, Lancs. Electrical Engineer do hereby
declare the nature of this invention to be as follows:-
The object of my invention is to improve and cheapen the manufacture of
insulated cables (more especially such as are for electric lighting), in which paper
is used in coating the wire.
Paper is a strong hydroscopic material and its suitability for insulating
conducting wires is prejudicially affected by its power of absorbing moisture to
such an extent that it is necessary in manufacturing cables with paper insulation
to thoroughly dry the paper, and after it is applied to the wire the whole is soaked
in oil or composition to prevent its again acquiring moisture. This is a wasteful
and objectionable process.
Attempts have been made to render the paper waterproof before applying it to
the wire, but they have not succeeded. The requisite for such a treatment have
not been attained inasmuch as the inventors have sought to protect the cables by
this treatment alone and have therefore chosen waterproofing substances and
processes which exposed them to the difficulties due to the inelasticity of the paper
which makes it impossible to bend such cables without injuring the insulation
unless the coatings of paper are put on in a spiral form, and there is considerable
freedom of motion of the layers of paper upon each other. These conditions have
not been attained hitherto partly because it has been sought to manufacture a
cable in itself waterproof and permanent by reason of the treatment of the
paper and this has led to the adoption of unsuitable substances and processes.
My invention has for its object the manufacture of a cable which shall be capable
of being bent without injuring the insulation and which shall also be permanent in
its qualities. For this purpose I use a paper previously waterproofed with a
composition which either remains sufficiently fluid to permit the requisite amount
of motion in the coats of the wire, or which dries so as to give a surface sufficiently
smooth to allow such movement. I cover the wire with this paper spirally, and I
then enclose the whole in a lead covering. By these means I obtain a cable that
can readily be bent and which at the same time is permanent in its characteristics
and which can be manufactured more conveniently and without the objectionable
and wasteful processes otherwise required.
Dated this 8th day of August 1895.
W. P. THOMPSON & Co.,
31, High Holborn, W.C., Patent Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Insulated Cables.
I, GEORGE HINDE NISBETT, of Prescot, Lancs., Electrical Engineer, do
hereby declare the nature of this invention and in what manner the same is to
O be performed, to be particularly described and ascertained in and by the following
statement:—
The object of my invention is to improve and cheapen the manufacture of insulated

page_text: cables (more especially such as are for electric lighting), in which paper is used in
coating the wire; and also, amongst other things, to manufacture a cable which
shall be capable of being bent without injuring the insulation, and which shall also
be permanent in its qualities. To this end I use a paper previously waterproofed
with a composition, and I cover the wire or conductor with this paper spirally, and
then enclose the whole in a lead covering; and I carry out the manufacture of this
cable in the manner following, and with the effects hereafter specified.
From the above description, it will be seen that the type of electric insulated
cables to which this invention has reference, is that which is adaptel for use, more
particularly, in subterranean and submarine work, for electric lighting and power
transmission (but also for telephonic and telegraphic purposes), and in which the
insulating material used in connection with the conductor or conductors is paper
(the electrical qualities of which are well known), and also in which the conductor
or conductors is or are flexible, or of such a nature that they can be readily turned
or bent at more or less severe curvatures or radii.
"
In the term "paper as herein used, is included such materials as obviously
come within the meaning of the term, and besides these, such materials as partake
more or less of the nature of paper as regards the form of the manufactured article
and its constituents, or which are as regards electrical qualities-insulating
qualities--analogous to it.
Cables of the type or nature above referred to exist, or have been proposed, in
great variety, as to their form of construction or build, and methods of manufacture,
but in all of these there have been drawbacks, which drawbacks have, in most
cases, existed, either as defects in their electrical principle of construction and
consequent electrical efficiency, by which they are practically precluded from being
considered or employed as useful articles, or in the case of those which have been
used, or are capable of being used, with more or less success as defects in their
practical and commercial characteristics. Of those cables under the latter head,
in some, the drawbacks have been that their form or method of manufacture has
been costly; in others their method of manufacture has been objectionable
in itself, and sometimes wasteful. For instance, paper is a strong hydroscopic
material, and its suitability for insulating conducting wires is prejudicially
affected by its power of absorbing moisture to such an extent that it has
generally been deemed necessary in manufacturing cables with paper insulation
to thoroughly dry the paper, and after it is applied to the wire, the whole is soaked
in oil or composition to prevent its again acquiring moisture. This is a wasteful
and objectionable process. Again in other cases, the cable has contained the
drawback that it could not be bent within reasonable degree, i.e. such degrees as
cables are subject to in practice, without damage or having their electrical
qualities impaired, while in some cases, the cables described and proposed would,
if used for the purposes intended, or those herein specified, not be durable, that is,
some portions of them would perish in a relatively short time, or become so
affected as to be very defective; and some, moreover, have possessed two or more
of these drawbacks. Besides these, there have been some cables which, while they
may have been more or less practical or useful when applied under certain conditions
would, by reason of their form of construction, not be useful for, or suited to, the
conditions and requirements of general application.
Now, in a cable according to the present invention, the nature of which is above
described and which is hereafter fully set forth-none of the drawbacks above
specified exist, or in the manufacture of it, the objections and drawbacks referred
to are obviated. That is to say, the cable, while it is electrically efficient, and
capable of being bent at reasonably sharp or short curves or radii without
impairment of its electrical qualities or becoming damaged, is less costly than the
more or less effective or successful cables hitherto made or proposed; is not
objectionable in the mode of manufacture, nor wasteful of material used in it; and
is not detrimentally affected by the conditions of its use and place; that is, it is
durable, and so, in one form, possesses such electrical qualities in respect of

page_text: efficiency as meet the requirements of an ordinary useful standard, while in another
form, it attains a still higher standard of electrical excellence.
The carrying out of the manufacture of the cable is as follows:-The complete
cable comprises, firstly a. flexible conductor, or a plurality of flexible conductors
secondly, an insulating spiral covering round the conductor or conductors, consisting
of paper which has been rendered as far as possible, or to a considerable degree,
non-hydroscopic previou-ly to use in the cable, or, of paper which has been coated
with insulating material, rendering it also waterproof by reason of such coating, if
not already waterproof in itself, which material either remains sufficiently fluid or
elastic to permit the requisite amount of motion in the coats of the wire, or which
dries so as to give a surface sufficiently smooth to allow such movement; or of
paper of a non-hydroscopic or waterproof nature, and the convolutions of which
will not and do not rigidly adhere in the completed cable, but have some freedom
of movement upon and in relation to one another; these said paper coverings being
applied spirally (ie. as the thread of a screw) to the conductor or conductors in
the manufacture of the cable, in a previously prepared condition, that is, they are
not waterproofed or coated after or during the manufacture of the cable
thirdly, an outer metallic covering by which the entrance of water or moisture into
the cable is prevented, and the insulating covering or coverings of the several
wires is or are preserved, and shielded against the action of the substances or
matters in which the cable is laid, or which it may be exposed to or subjected to
the action of such metal being also flexible or capable of being readily bent.
The metal I use for this covering is lead, or equivalent metal.
and
The advantages rendered by the two coverings mentioned, and applied in the
manner, and having the characteristics just specified, are, first, that as regards the
insulating material, by the use of paper possessing before its application in
the manufacture of the cable, a non-hydroscopic nature, or which has been
rendered waterproof, the manufacturing of the cable, and the material and
apparatus used, are simplified and cheapened, and also there are no objectionable
or dirty operations to be performed or handling to be done; and further, the waste
of material, such as exists in the common present mode or method of manufacturing
this type of paper covered cable, is obviated. And secondly, as regards the
characteristics of the cable so made, by the spiral winding and non-rigid adhesion
of the convolutions of the insulating paper ribbons one upon the other, it (the
cable) may be bent even at severe angles—that is, at angles such as cables are
commouly subjected to at present-without damage by the cracking of the paper,
or impairment of the insulating material electrically in any way, as the construction
always allows of sufficient movement between the paper convolutions, not-
withstanding, that in some cases, according to the kind of paper, or the nature of
the surface of the prepared paper, there may be more or less adhesion of such
convolutions-but not rigid adhesion. And as regards the lead or equivalent
metallic outer covering, this, as already stated, affords to the cable water-tightness,
and protection against the action of its surrounding substances which may come
in contact with it and act upon it, and also against ordinary mechanical actions.
In one form of cable constructed according to this invention, the insulating
material, that is the paper, will consist of simple waterproof paper ribbons which
have been waterproofed-
-as for instance, Willesden water-proof paper, Christia
paper, and the like- and which are in such a state of dryness, as to provide when
wound upon the conductor, a sufficiently high degree of insulation, and produce
cables of a good commercial or practical standard of insulation; this degree of
dryness being provided either by the inherent quality or nature of the paper as
manufactured, or by drying it just prior to the operation of rendering it non-
hydroscopic, or at other suitable stage. These paper ribbons are spirally coiled
upon the conductor or conductors to sufficient thickness or extent and over this or
these insulated conductors the metallic covering of lead or equivalent metal
is formed; and it may be conveniently provided or formed in the ordinary way by
squirting.

page_text: A cable so made will possess an efficiency as regards insulation to a degree which
will meet the requirements of certain standards of test, but these though high, are
not so high as some special standards which cables in certain cases are required to
pass. To meet such cases, the construction of the cable is modified in certain
respects. The modification consists in the insulating covering, namely, in these
cases, I employ paper ribbons which are provided with a coating of, or impregnated
with, insulating compound or substance, and, preferably, but not necessarily,
waterproof, the latter quality being provided by the nature, or waterproofing
treatment, of the paper, or by virtue of such coating or impregnation. The coating
or impregnation of insulating material should in any case be such as will not cause
the superposed spiral convolutions of the paper to rigidly adhere to one another
when the cable is made up. Any well known insulating compounds or materials,
such for instance as india-rubber, gutta-percha, vegetable pitch, resin, bitumen,
insulating wax of any sort, or such materials or substances mixed with other
materials, as vaseline, or glycerine, where required, to give suitable flexibility,
will do. Or, again the material or materials used may, in some cases, be vulcanized
where desired; or, other suitable ingredients, so long as they give the required
nature of coating, may be employed.
In manufacturing cables of a high insulation efficiency according to the latter
mode, in one mode of making up the cable, I employ as a suitable paper, ordinary
close fibred manilla paper, which after being dried, is waterproofed in any known
suitable way; or, I use water-proof paper of this kind; in either case, the paper,
while in an electrically dry state, is coated or impregnated with the insulating
compound or material. The paper so coated is used in the form of ribbons in the
manufacture of the cable as insulating material, it being spirally wound upon the
conductor or conductors as specified, whilst dry. The conductor or conductors
thus made is or are enclosed in the lead or like metallic covering as described.
It may be stated, that while the spiral convolutions of non-hydroscopic or
waterproof paper serve to insulate the conductors, and at the same time preclude
the insulating medium taking up or absorbing into itself any moisture, yet they do
not in themselves necessarily constitute a water tight covering to the conductor or
conductors.
In the operation of providing over the paper insulations the lead or equivalent
metallic covering, it should be so applied that in the finished cable such covering
will not press upon the paper insulation too severely, i.e. to such a degree as will
interfere with the conditions of the superposed convolutions of paper ribbons, or
their action in relation to and upon each other, as specified.
In the case of the application or use of the invention to or in connection with
electric light and power cables, in most cases the conductor or conductors, when a
plurality of wires are used, would be grouped together in the centre of the cable,
and the spirally wound paper ribbon insulation would be concentrical to the wires:
outside of which the outer lead or metallic covering comes; so that the cable in
this case would be concentric as to the three portions of which it is composed, and
practically solid.
In the case of a multiple conductor telephonic or telegraphic cable, the
conductors would be each covered with the spiral paper insulating covering, and
generally the covered conductors would be twisted together, in pairs say, and then
grouped together; and outside this group the metallic covering would be provided,
however the invention is not restricted to these exact relative arrangements of
conductors in the cable.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The herein described improvement in the manufacture of electric cables,
namely, a cable consisting of one or more flexible conductors, or a group or groups
of flexible conductors; insulating covering or coverings to said conductor or

page_text: conductors of spirally wound ribbons of non-hydroscopic or waterproof paper; and
an outer metallic covering, as lead or equivalent metal; he said paper insulating
spiral coverings being applied to the conductor or conductors in the manufacture
of the cable, as described, in a prepared or manufactured state; for the purposes
described.
2. The herein described improvement in the manufacture of electric cables,
namely, a cable consisting of one or more flexible conductors, or a group or groups
of flexible conductors; insulating covering or coverings to such conductor or
conductors of spirally wound ribbons of paper coated or impregnated with
insulating compound or substance, or of spirally wound ribbons of paper coated or
impregnated with insulating compound or substances, and such paper being in
itself waterproof, or rendered waterproof by such coating or impregnation; the
said coated or impregnated paper insulating spiral coverings being applied in the
manufacture of the said cable, as described, in a prepared or manufactured state :.
for the purposes described.
Dated the 14th day of February 1896.