Improvements in Electrical Mains and in their Manufacture.
Year: 1889

page_text: Date of Application, 15th Oct., 1889
Complete Specification Left, 1st Aug., 1890-Accepted, 15th Oct., 1890
PROVISIONAL SPECIFICATION.
Improvements in Electrical Mains and in their Manufacture.
I, SEBASTIAN ZIANI DE FERRANTI, of 120 Fellows Road, Hampstead, in the County
of Middlesex, Electrician, do hereby declare the nature of this invention to be as
follows:-
My improvements relate to the insulation of electrical conductors which are made
in short lengths of comparatively rigid rods or tubes coupled together end to end by
suitable couplings.
In order to insulate the several lengths of the rods or tubes I wind around each
length a sheet or sheets of paper soaked in an insulating material say for example
melted paraffin and this I do by rotating the rod or tube and causing it to wind the
paper around itself. I use sheets of paper each of a length equal to the length of
the rod or tube to be covered and of any convenient width so that when wound on to
the rod or tube the several layers of paper may be complete in themselves and uniform.
insulation be obtained throughout the length of the rod or tube.
To wind on the paper I preferably place the rod or tube in a V or other con-
veniently shaped groove or trough capable of holding, or of being submerged in, an
insulating material, liquid or liquid when hot and I cause one or more weights such
as rollers to bear upon the tube or rod at or near its top and along the whole or a
portion of its length. A sheet of paper is laid on to a table at one side of the trough
or groove and one edge of it which is of a length equal to the length of the rod or
tube to be covered is led below the rod or tube and between it and the trough or
groove and then upwards and between it and the weights or roller. The liquid
insulation is then made to more or less fill the trough or groove and the rod or tube
is turned in such a direction as to wind on the paper.
in some cases it is desirable to stick or fasten the first sheet of paper to the rod or
tube before placing it in the liquid insulation.
This I do by the use of shellac, shellac varnish or any suitable gum or adhesive
mixture.
When one sheet has so been nearly wound on, the edge of a new sheet may be laid
over the portion of the first sheet which still remains unwound and as the rod or
tube is continued to be rotated be carried onwards by the first sheet into the trough
and around the rod or tube.
In some cases I employ hand pressure, one or more weights, (such as rollers) or
springs, or any such suitable device to press the two sheets of paper closer together,
and thus increase their cohesion.
Another method is to lay the edge of the new sheet of paper over a portion of the
partially wound sheet of paper and cause one or more heavy weights (such as rollers)
of suitable section to run along a portion, or the whole of the entire length of the
overlapping paper, and thus press or corrugate one sheet of paper into the other.
Or I may attach the new sheet of paper to the partially wound one by means of
shellac, shellac varnish, or other suitable gum wax or adhesive mixture, applied along
the whole or a portion of the edge of one or both sheets of paper, or otherwise as may
be most convenient.
Another method is to wind simultaneously onto the rod or tube 2 or more sheets of
paper so arranged that the edge of one sheet is always slightly in advance of the
edge of the other sheet of paper.
The edges of the 2 or more new sheets of paper to be wound on, are entered and
dovetailed between the 2 or more sheets of paper partially wound on, and if
required additional adhesion between the several sheets may be given by any of the
previously enumerated methods.
In place of each sheet of paper being of the same length as the rod or tube two or

page_text: more layers each composed of 2 or more narrower sheets set side by side and with
their edges close together and with the edges of the sheets in one set coming opposite
to the centre of the sheets in the other set, might be used, and be similarly wound
on to the rods or tubes.
'
Or narrow strips might by similar apparatus be wound on spirally and made to
break joint with one another:
After completing the winding of the sheets or strips of paper as above to any
desired thickness,
an additional layer of paper, tape or any suitable material may be
wound on in sections or spirally to prevent the other sheets or strips from unwinding
on removing the covered rod or tube from the trough or groove.
The conductors of concentric mains such as described in my former Patent
No. 15251 in the year 1885 may be insulated in the same way.
Cloth, cotton, hemp, or other fabric might be used instead of paper as a medium
for holding the insulating material.
In place of saturating the paper or other fabric with the insulating material only
at the same time that it is being wound on to the rod or tube the paper or other
fabric might be first saturated with the insulating material and be compressed between
rollers or other suitable gear so as to ensure that each part shall be thoroughly
saturated and to close up any flaws or bubbles that there may be in the insulating
material and be afterwards wound on to the conductors in a similar manner to that
above described, with or without again passing it through the liquid insulation.
The comparatively rigid rod or tube, covered by any of the aforesaid methods, is
then inserted bodily into the interior of another tube, the sectional area of which is
preferably equal to that of the former rod or tube, and the internal diameter of which
is slightly greater than the external diameter of the covered rod or tube, and in order to
compress this outer tube firmly on to the insulation of the inner tube, I cause the
entire length of the main so formed, to pass through a die, or equivalent thereof, of
diameter. smaller than the outer diameter of the outer tube. This I do by means of
an ordinary draw bench, rolling mill; or by compression by hydraulics, steam or
compressed air &c., or other known method.
The concentric electric main so formed can then be again covered on the outside
with insulation by any of the methods aforesaid and when covered be again bodily
inserted into another tube preferably of iron, which iatter tube can be compressed on
to the inner tube as aforesaid.
The outer iron tube is then coated with any anti-corrosive mixture, to prevent
oxidation &c. as this is usually laid into the ground without other external protection.
In addition to the above methods of insulating the rod or tube I arrange in some
instances to fill the interior of the inner tubes when jointed and laid with a heavy oil,
wax, or other suitable insulating material which may be kept under a heavy head or
pressure for the purpose of filling up any flaws in the insulating, material.
Or I may apply such a head or pressure to the insulation portion of the cable only,
with or without suitable insulation containers or receivers.
Or. I may keep the entire cable under a head or pressure as above described.
D
CARPMAEL & Co.,
Agents.
COMPLETE SPECIFICATION.
Improvements in Electrical Mains and in their Manufacture.
I, SEBASTIAN ZIANI DE FERRANTI of 120, Fellows Road, Hampstead in the County
of Middlesex, Electrician, do hereby declare. the nature of this invention and in what 5
manner the same is to be performed to be particularly. described and ascertained in
and by the following statement:
My improvements relate to the insulation of electrical conductors which are made.
in short lengths of comparatively, rigid rods or tubes coupled together. end to end by :
suitable couplings.
5

page_text: In order, to insulate the several lengths of the rods or tubes I wind around each
length a sheet or sheets of paper soaked in an insulating material say for example
melted paraffin and this I do by rotating the rod or tube and causing it to wind
the paper around itself. I use sheets of paper each of a length equal to the length
of the rod or tube to be covered and of any convenient width so that when wound
on to the rod or tube the several layers of paper may be complete in themselves and
uniform insulation be obtained throughout the length of the rod or tube.
To wind on the paper I preferably place the rod or tube in a V or other
conveniently shaped groove or trough capable of holding, or of being subinerged in,
an insulating material, liquid or liquid when hot and I cause one or more weights
such as rollers to bear upon the tube or rod at or near its top and along the whole
or a portion of its length. A sheet of paper is laid on to a table at one side of the
trough or groove and one edge of it which is of a length equal to the length of
the rod or tube to be covered is led below the rod or tube and between it and the
trough or groove and then upwards and between it and the weights or roller. The
liquid insulation is then made to more or less fill the trough or groove and the rod
or tube is turned in such a direction as to wind on the paper.
Figure 1 of the drawings hereunto annexed is a side elevation,
Figure 2 a vertical cross section and
Figure 3 a plan of apparatus constructed as I prefer for covering electric conductor
in the above manner.
The machine is composed of 4 box castings A which are bolted together to form
one continuous length rather longer than the length of the main to be covered.
These are closed on the top and two sides, but are open at the bottom, the top
forming a trough in which the paraffin or other material used for insulation can be
heated if desired and retained. Standing up from the bottom of this trough is, a
projection B having a V shaped recess B' formed along it at the top. In this
V recess is placed the conductor C which is to be covered. E is a table supported
ou arms or brackets D which are fixed to the front of the castings A. The table is
free to be racked in or out by the shaft F carrying a pinion that gears into a
rack G. On the table is placed the sheet of paper that is to be wound on to the
conductor.
At the back of the machine are also brackets H which support a shaft K which
gives the necessary turning motion to the conductor when the latter is being covered.
The shaft K is driven from a pulley Y which is loose upon it and which is itself
driven at a constant speed. The pulley can by a fork entering a groove formed
around its hollow axis be moved endwise on the shaft K and pressed against a disc Z
which is fixed to the shaft and so drive the shaft by friction.
Movement may be given to the fork from a treadle at the end of the machine or
in other suitable ways. At each end of the shaft is fixed a small sprocket wheel A¹
on either side of each sprocket wheel is an arm or strap B' which is free to turn
around the shaft. At the upper end of the straps which are on either side of each
sprocket wheel is carried a sprocket wheel D' of larger diameter and this is driven
by an endless chain from the sprocket wheel A'.
The lower ends of the arms carry
a weight to balance the weight of the parts which are carried by the upper ends
A shaft E' which is provided with a continuous key way passes
through the centre of the sprocket wheel D. At one end it carries a hand wheel Fi
which is free to turn on the shaft but is held from moving endwise of the shaft by
the shoulder Ġand lock nut H'-at the other end it carries a gear wheel K and
also two straps L' loose upon it and one on either side of the gear wheel-these straps
at their lower end carry another wheel M' into which the wheel K' gears.
of the arms.
The spindle of the wheel M' is at one end bored out to form a socket to receive
and hold a stem projecting from a plug that is driven into the end of the tubular
conductor that is to be coated. The plug may have sharp edged ratchet like teeth
formed along its sides so that when driven into the end of a tubular conductor it
shall not be able to revolve therein.
When a conductor with a plug secured in each of its ends is placed into the

page_text: V groove B the sockets in the spindles of the wheels M' are made to pass on to
the stems of the plugs by moving the shafts E' end wise by the hand wheels F' which
are upon them and when the shaft K is rotated the conductor which is to be coated
will also be rotated. Other means than that above described might be adopted for
connecting the ends of the conductor which is to be covered with the pulleys by
which the conductor is to be rotated.
O are rollers covered with india rubber these rest upon the top of the paper
nich is on the table E and keep it from creasing-they also serve to put a certain
amount of tension on the paper.
L L are arms on standards rising up from the bottom of the trough. Q is a bar
of Hiron held to the vertical front face of the standard by straps T which allow of
the bar being raised or lowered. The bar Q has bolted to it brackets U to which
are hinged arms V which at their ends embrace the axes of the rollers O. The
standards L at the top also carry a shaft M on which are three arms N from which
chains W descend to links X for raising the rollers O. Other chains from the
shaft M also raise or lower the bar Q.
S is a roller resting upon the top of the conductor which is to be coated. This
roller may be in three or more sections to give flexibilty, it is embraced and kept
in place by a number of two pronged forks R which descend from the bar Q. The
extremities of the two prongs of the forks extend to a short distance below the
central axis of the roller S and below the central axis they are bent inwards towards
one another so that the space between them is less than the diameter of the roller.
Consequently when the forks are raised they carry up with them the roller S.
The axis M. has an arm or hand wheel upon it by which it can be turned whenever
the rollers O and S are to be raised. When the axis is free the rollers descend
until the roller S rests upon the conductor.
Rare weights carried by chains from a shaft N¹ so that they can be raised or
lowered. When they are lowered and immersed in the melted paraffin the surface
level of the paraffin rises until the paraffin flows over the top of the projection B
into the ✓ recess B₁. When the weights are raised up the surface level of the
paraffin is lowered until it is below the bottom of this recess. When the level is
so lowered a coated conductor can readily be raised up out of the V groove and
taken away and another conductor to be coated put into its place.
The shaft N can be turned to raise or lower the weights R' by a worm wheel
upon it into which gears a worm P¹ on a shaft which can be turned by a hand
wheel Q The operation of the machine is as follows:-A sheet of paper of the
same length as the conductor which is to be coated is laid upon the table E.
conductor is also laid along the table and the edge of the paper is secured to it
preferably by shellac solution.
The
The conductor is then laid into the V groove B₁ and its ends coupled to the
pinions M as above explained. The rollers and S are then lowered and the
pinions M¹ made to revolve to cause the paper to be wound up on to the conductor.
As the paper is being wound up another sheet of paper is laid on to the table and
made to overlap and adhere to the first sheet and so the winding goes on until the
requisite thickness of coating is attained.
When working with sheets of paper that have already been coated with paraffin
the pressure of the rollers O upon the overlapping sheets is sufficient to cause them
to adhere to one another-in other cases I may attach the new sheet of paper to
the partially wound one by means of shellac, shellac varnish, or other suitable gum,
wax, or adhesive mixture, applied along the whole or a portion of the edge of one
or both sheets of paper, or cause them to adhere in other suitable ways.
In place of each sheet of paper being of the same length as the rod or tube two
or more layers each composed of two or more narrower sheets set side by side and
with their edges close together and with the edges of the sheets in one set coming
opposite to the centre of the sheets in the other set, might be used and be similarly
wound on to the rods or tubes.
Or narrow strips might by similar apparatus be wound on spirally. To do this

page_text: the strips might be carried by bobbins and the bobbins be caused to traverse slightly
in a direction endwise of the conductor at the same time that the conductor was
rotated to wind the strips around itself. In this way the ends of the section
of the covering formed by each strip would be coned one end convex and
the other concave and the convex end of one section would enter the concave end
of the next section as shewn in the diagram Figure 4.
Similarly the ends of the whole covering on each conductor would be coned one
end convex the other concave and when coupling together two lengths of conductor
the convex end of the insulation on one length would enter the concave end of the
insulation on the next length so that the joint between them would be inclined to
the conductors in place of at right angles to them.
When the insulating covering is about an inch in thickness the coned ends may
conveniently be about 6 inches in length. Each joint therefore in the insulating
covering is a long sloping joint instead of a short one at right angles to the conductors
so that in case of any defect in the union of the end of one length of the insulation
to the end of the next-the distance a spark would have to travel to pass through
the insulation would be of considerable length and so perfect insulation is ensured.
If two or more layers of strips are wound on to the conductors at the same time
then the coned junctions in one layer may be intermediate of the coned junctions of
the next layer as shewn in the diagram Figure 5.
Or strips of paper or fabric of the same length as the conductor might be used in
which case the ends of the covering of insulation would be coned in the manner
above described.
It is not necessary that the strips should be wound on spirally to obtain these
coned ends to the covering of insulation the same result may be obtained in other
ways as for example the conductors may first be covered with a uniform cylindrical
covering and the ends be afterwards turned down in a lathe. In this way the edge
of the paper would be made to wind in a slow spiral around the conductor just as
though the strip had been wound on spirally.
Similar coned ends might also be obtained by using a knife to cut each edge of
the paper as it is being wound on to the conductor, a slow traversing movement
being given to the knives in a direction endwise of the conductor as the winding goes
In this way the edges of the strips would similarly be made to wind in slow
spirals around the conductor.
on.
Other ways of forming the cones might also be adopted so long as when the
paper is unwound from the conductor its edge is inclined to the main and not at
right angles to it.
After completing the winding of the sheets or strips of paper as above to any
desired thickness, an additional layer of paper, tape or any suitable material may be
wound on spirally to prevent the other sheets or strips from unwinding or removing
the covered rod or tube from the trough or groove.
Cloth, cotton, hemp, or other fabric might be used instead of or in combination
with paper as a medium for holding the insulating material.
In place of saturating the paper or other fabric with the insulating material only
at the same time that it is being wound on to the rod or tube the paper or other
fabric might be first saturated with the insulating material and it might be compressed
between rollers or other suitable gear so as to ensure that each part shall be
thoroughly saturated and to close up any flaws or bubbles that there may be in the
insulating material and be afterwards wound on to the conductors in a similar manner
to that above described, with or without again passing it through the liquid
insulation.
In practice I find it preferable to use paper so treated, passing it again through
the liquid insulation when winding it.
To first saturate the paper with paraffin or like material I first cause it to travel
over heated cylinders or plates so as to dry it and then cause it to pass down into a
trough containing the melted insulating material and around a roller immersed in

page_text: this material and then lead the paper up out of the bath and over rollers until it is
sufficiently cool to allow of its being wound into rolls.
It must be understood that the paper, cloth, cotton or other fabric employed is of
pure of comparatively pure material and contains no substance or chemical that will
conduct electricity, further the paper or other fabric must be entirely free from
moisture, and this I achieve by passing the inaterial slowly over revolving steam
heated cylinders, over heated iron plates, or by other well known methods as above
described.
The comparatively rigid rod or tube, covered by any of the aforesaid matho is, is
then inserted bodily into the interior of another tube, the sectional area of which is
preferably equal to that of the former rod or tube, and the internal diameter of which
is slightly greater than the external diameter of the covered rod or tube, and in
order to compress this outer tube firmly on to the insulation of the inner tube to
prevent the inner covered rod or tube from separating or slipping away from the
ofiter tube I cause the entire length of the main so formed, to pass through a die,
or equivalent thereof, of diameter smaller than the outer diameter of the outer
tube. This I do by means of an ordinary draw bench or rolling mill or other known
method.
Thus an outer tube say of 2
inch external diameter, is reduced by this treatment
to approximately 118 inch external diameter.
The concentric electric main so formed can then be again covered on the outside
with insulation by any of the methods aforesaid or combination thereof and when
covered he again bodily inserted into another tube preferably of iron, which latter
tube can be compressed on to the inner tube as aforesaid.
The outer iron tube is then or previously coated with any anti-corrosive mixture,
to prevent oxidation.
In addition to the above methods of insulating the rod or tube I arrange in some
instances to fill the intérior of the inner tubes when jointed and laid with a heavy
oil, wax, or other suitable insulating material which may be kept under a heavy bead
or pressure for the purpose of filling up any flaws in the insulating material and
for this purpose holes may be provided in the tubes at convenient distances apart
preferably at the junctions where the lengths are connected one with another.
Or I may apply such a head or pressure to the insulation portion of the cable
only, with or without suitable insulation containers or receivers.
Or I may keep the entire cable under a head or pressure as above described.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed 1 declare that what I
claim is
1. In the manufacture of electric mains composed of comparatively rigid insulated
conductors in short lengths coupled one to another covering each length of conductor
with several layers of paper, cloth or other fabric by winding on to it sheets of
paper &c. of the same length as the rod or tube to be covered or with narrower sheets
side by side similarly wound on at right angles to the rod or tube.
2. In the manufacture of electric mains composed of comparatively rigid insulated
conductors in short lengths coupled one to another covering each length of conductor
by rotating the conductor and causing it to wind on to itself a covering of paper or
fabric whilst it is lying in a V trough or similarly supported and pressed upon by a
roller or otherwise.
3. In the manufacture of electric mains composed of comparatively rigid insulated
conductors in short lengths coupled one to another covering each length of conductor
with insulating material by simultaneously winding on to it spirally two or more
narrow parallel strips set side by side substantially as described.
4. In the manufacture of electric mains composed of comparatively rigid insulated
conductors in short lengths coupled one to another covering each length of the
conductor with insulating material by simultaneously winding on to it two or

page_text: more layers of narrow strips of paper or fabric with the edges of the several strips
in one layer breaking joint with or intermediate of the edges of the strips in the next
laver.
5. In the manufacture of electric mains composed of comparatively rigid insulated
conductors in short lengths coupled one to another covering each length of conductor
with paper or fabric wound around it and with the edges of the fabric at the two
ends of the insulating covering winding around the conductor in a slow spiral
substantially as described.
6. An electric main composed of comparatively rigid insulated conductors in short
lengths coupled one to another with the insulation on each length coned at each end
so as to overlap at the joints substantially as described.
7. In the manufacture of electric mains consisting of comparatively rigid
concentric tubular conductors in short lengths coupled one to another first covering
a length of the inner conductor with paper a fabric saturated with insulating material
by rotating the conductor and causing it to wind the paper or fabric on to itself→
then placing the coated conductor within a length of the outer tubular conductor
and causing this outer tube to be closed tightly on to the insulating material which
surrounds the inner conductor and afterwards covering the outer conductor by rotating
it and causing it to wind paper or fabric saturated with insulating material on to
itself substantially as described.
8. The combination of machinery substantially as described
comparatively rigid conductors.
for covering
9. Covering comparatively rigid conductors by winding around them paper or
fabric previously saturated with paraffin or like insulation.
10. Covering comparatively rigid conductors by winding around them paper or
fabric previously saturated with paraffin or like insulation and causing the previously
saturated paper or fabric to again pass through liquid insulation as it is being wound
on to the conductor.
11. In the manufacture of electric mains composed of short lengths connected end
to end of insulated concentric tubular conductors filling the inner conductor with oil
or liquid insulating material under heavy pressure and providing holes at intervals
through this conductor to allow insulating liquid to pass into the space between the
inner and outer conductors and fill up any flaws in the insulating material by which
this space is occupied.
12. In the manufacture of electric mains composed of short lengths connected
end to end of insulated concentric tubular conductors feeding insulating material to
the joints from the inside through the inner conductor substantially as described.
Dated this 31st day of July 1890.
CARPMAEL & Co.,
Agents for the Applicant.