Improvements in Insulating Electrical Conductors.
Year: 1891

page_text: Date of Application, 2nd Apr., 1891
Complete Specification Left, 1st Jan., 1892-Accepted, 6th Feb.,
1892
PROVISIONAL SPECIFICATION.
Improvements in Insulating Electrical Conductors.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, (a communi-
cation to me from abroad by Edward Crawford Davidson, of 109 West 12th Street,
in the City of New York, State of New York, United States of America, Solicitor,)
do hereby declare the nature of this invention to be as follows :-
This invention relates to the insulation of electrical conductors by means of
ribbons of paper or other material wound spirally thereon. To increase the tensile
strength of the ribbons and to provide a ribbon having multiple layers of paper,
I fold a ribbon of paper longitudinally one two or more times. This ribbon is
then wound spirally around the conductor to be insulated. The tensile strength of
the ribbon is such that the covering machine may be run at a high rate of speed
without liability of breaking the ribbon, and consequently there is little loss of
time in repairing ribbons and starting and stopping the machine. In some cases
it is desired to wind the paper ribbons around relatively small conductors for
telephonic use in such manner as to leave an open spiral space between the adjacent
spiral edges of the ribbon. A flat paper ribbon sufficiently narrow to permit of
this being done would have so little tensile strength that it would be impossible to
apply it to the conductor in any practical way. With a folded ribbon, however,
the width is reduced by the longitudinal folds and the tensile strength is increased.
One or more longitudinally folded ribbons may be wound around a conductor and
over them I may wind a flat ribbon any insulating or sealing compound may be
used and the individual wires so insulated may be each covered with an exterior
sheath of lead or other material, or the wires may be made up into a cable to be
enclosed as usual in a lead sheath. The paper ribbons may be folded longitudinally
in any suitable manner, either at the time of their application to the wire, or
previously. An important feature incident to this method of insulation is the
presence of air spaces between the layers of the paper, these spaces tending to
reduce the static capacity of the conductor.
:
Dated this 2nd day of April 1891.
CARPMAEL & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Insulating Electrical Conductors.
I SYDNEY PITT, of Sutton in the County of Surrey, Gentleman, (a communi-
cation to me from abroad by Edward Crawford Davidson, of 109 West 12th Street,
in the City of New York, State of New York, United States of America, Solicitor)
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 that class of insulated conductors in which ribbons of
paper are wound spirally thereon.
The object of the invention is twofold. When plain flat ribbons of paper are
wound spirally around the electrical conductors, it is necessary that a comparatively
high speed of operation should be attained, and although the machinery may be of
the most approved' pattern and constructed in the best manner the ribbons of paper
are so deficient in tensile strength that they frequently break and the time spent in
[ Ꭰ Ꮧ

page_text: repairing the ribbons, stopping and starting the machine materially reduces the
output and correspondingly increases the cost of manufacture. This is one of the
difficulties which this invention is designed to obviate.
In some cases it is desired to wind the paper ribbons around relatively small
conductors such as are used for telephone purposes-in such manner as to leave
an open spiral space between the adjacent spiral edges of the ribbon. A flat paper
ribbon sufficiently narrow to permit of this being done would have so little tensile
strength that it would be impossible to apply it to the conductor by means of any
machinery of which I am aware.
Another object of the invention is to permit the application of paper ribbons to
a small conductor in the manner just described.
To accomplish the objects of the invention, the paper ribbons are folded longi-
tudinally, either two or more times, so as to give two, three, four or more thicknesses
of paper. This materially increases the tensile strength, since there are then no
exposed edges liable to rupture. The paper ribbon may be folded a sufficient
number of times to reduce it to the desired width.
In the accompanying drawings,
Figure 1 indicates a flat and folded ribbon.
Figure 2 shows the application of a folded ribbon to an electrical conductor,
and
Figures 3 and 4 are similar views.
Figure 5 is a cross-section of a cable of such insulated conductors, and
Figure 6 a perspective view of the end of a conductor insulated according to the
invention.
A. indicates a flat ribbon of paper of any suitable width. At A this ribbon is
shown folded inwardly from each edge, and at A the ribbon is again folded on the
line of the edges of the ribbon, as seen at A. The paper may be folded in any
other manner and any desired number of times, this depending upon the width of
the ribbon and the narrowness to which the folded ribbon is to be reduced. Thus,
if the ribbon A is of sufficient width, it may be folded two or more times and yet
be of such width when folded as to permit of its application to electrical con-
ductors in the manner now commonly practiced-namely, by winding the ribbon
around the conductor in overlapping spirals. Obviously the tensile strength of
such a multiple layer ribbon is far in excess of the ribbon when unfolded. It may
therefore be wound around the conductor more firmly and rapidly and with less
liability of rupture and consequent stoppage of machinery.
B indicates an electrical conductor. In Figure 2 a folded ribbon A' is shown as
wound thereon in such manner as to leave an open spiral space between its adjacent
edges, as indicated at a. As shown in Figure 3, such a ribbon may be wound upon
the conductor with its adjacent edges abutting, as indicated at a'. In Figure 4 are
shown three folded ribbons A, of successively greater width, wound one over the
other, so as to break joints. If these ribbons are of the character shown at A'
when three ribbons are applied, as in Figure 4, six thicknesses of paper will have
been placed around the wire; or, if each ribbon be composed of four thicknesses
of paper, as shown at A³, Figure 1, twelve layers of paper will have been wound
around the conductor. The number of layers of paper and the thickness of the
insulation depends, of course, upon the size of the conductor and the purpose for
which it is intended.
Outside of the insulation thus far described a flat ribbon C of a single thickness
of paper may be wound in overlapping spirals, and, if desired, this winding may be
coated with a waterproofing, sealing and insulating compound as indicated by D.
Where the insulated conductors are laid up into a cable they may be enveloped by
an exterior lead sheath E as usual, or a single conductor may be insulated in the
manner described and covered with a lead sheath E, as shown in Figure 6.
The paper ribbons may be folded in the manner described by being passed
through suitable folding-dies as the ribbons are drawn from their bobbins and
passed to the conductor around which they are being wound; or they may be

page_text: previously folded and wound upon bobbins in the same manner that the ordinary
flat ribbon is.
A very important feature incident to this method of insulation is that between
the layers of paper there necessarily exists air-spaces. As is well known, the
presence of such spaces materially improves telephone-conductors in that their
static capacity is reduced.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I.
claim is :-
1. The combination of an electrical conductor and an insulating-ribbon of paper
folded longitudinally and having therefore multiple layers applied thereto.
2. An electrical conductor having wound thereon an insulating-ribbon of paper
folded longitudinally, substantially as described.
3. An electrical conductor having wound thereon in an open spiral an insulating-
ribbon of paper folded longitudinally, substantially as set forth.
4. The combination of an electrical conductor having wound spirally thereon
two or more insulating-ribbons composed of paper folded longitudinally, successive
windings of the ribbons breaking joint with the preceding winding.
5. The combination of an electrical conductor, one or more insulating-ribbons
composed of longitudinally-folded paper and having therefore multiple layers, and
a lead sheath enveloping such insulation.
Dated this 23rd day of November 1891.
CARPMAEL & Co.,
Agents for the Applicant.