Improvements in Electric Cables.
Year: 1893

page_text: Date of Application, 17th Apr., 1893
Complete Specification Left, 17th Jan., 1894-Accepted, 24th Feb., 1894
Improvements in Electric Cables.
I, GEORGE GATTON MELHUISH HARDINGHAM, of 191, Fleet Street, in the
City of London, Civil Engineer and Chartered Patent Agent, do hereby declare
the nature of this invention (a communication to me from the Firm of Felten &
Guilleaume, of Mülheim on the Rhine, in the German Empire, Cable Manu-
facturers,) to be as follows:-
This invention relates to electric cables or conductors embodying one of the
principal features of an invention communicated to me by my present correspondents,
and forming the subject of my application for Letters Patent filed 12th April, 1892,
No. 7029.
The cables particularly described with reference to the drawings appended to the
Complete Specification filed in pursuance of that application are principally intended
for telephonic and telegraphic transmission.
The object of the present invention is to produce cables or conductors to some
extent similar in character, but specially adapted for electric light service or
transmission of power; the formation of air-spaces being for such duties of no
practical importance.
In carrying out this invention, several conductors and a body of insulating
material, which may be merely a flat strip or may be cross-shaped or star-shaped
in transverse section, are twisted together, the several conductors lying in the
respective grooves of the insulating material, and being thus separated from one
another. Each conductor may be a strand comprising any suitable number of
wires of any appropriate transverse section or sections. A convenient form of
insulating body is one which is star-shaped in transverse section, and has three
arms. The insulating strip or body and the conductors twisted therewith are
surrounded by exterior insulation, which may be protected by lead sheathing, hoop
iron or other material.
This method of construction is particularly appropriate for use where the
conductors are of unequal sectional area; as, for instance, in the so-called "three-
wire" and "five-wire" systems.
In the three-wire system, the two chief conductors may respectively consist of
single wires or of strands. of wire and the third conductor may be a single wire, a
pair of wires or a small strand of wire. Or it may consist of a series of separate
wires arranged equidistantly around the exterior of the insulating envelope.
In the five-wire system, the two principal and the two secondary conductors may
consist of strands of wire; whilst the fifth conductor may be formed of single wires
placed equidistantly around the exterior of the insulating envelope. The fifth
conductor may however consist of a single wire arranged in the centre of the cable;
or, in cases where economy in first cost is of importance, the protective sheathing
itself may be utilised as the fifth conductor.
According to the above-described methods of construction, several conductors of
unequal sectional area may be readily united to form a compact cylindrical cable,
whereas the manufacture of cables of this class has hitherto presented considerable
difficulty.
Dated the 7th day of Anvil 1002

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Cables.
1, GEORGE GATTON MELHUISH HARDINGHAM, of 191, Fleet Street, in the
City of London, Civil Engineer and Chartered Patent Agent, do hereby declare
the nature of this invention (a communication to me from the Firm of Felten &
Guilleaume, of Mülheim on the Rhine, in the German Empire, Cable Manu-
facturers,) 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 electric cables or conductors embodying one of the
principal features of an invention communicated to me by my present corre-
spondents, and in respect whereof Letters Patent dated 12th April, 1892,
No. 7029, were granted to me.
The cables particularly described with reference to the drawings appended to
the Complete Specification pertaining to those Letters Patent are mainly intended
for telephonic and telegraphic transmission.
The object of the present invention is to produce cables or conductors to some
extent similar in character, but specially adapted for electric light service or
transmission of power; the formation of air-spaces being for such duties of no
practical importance.
In the accompanying drawings,
Fig. 1 is a transverse section and Fig 2 a fragmentary elevation of a cable built
up in accordance with the present invention.
Fig. 3 is a transverse section of a cable containing flat-sided wires adapted for
ause in the "three-wire" system.
Fig. 4 is a similar view of a cable for that system; the strands, however, being
of the kind shewn in Fig. 1.
Fig. 5 is a transverse section of a cable adapted for employment in the "five-
wire" system; the protective sheathing being utilized as the fifth conductor.
Fig. 6 is a similar view of a cable for the same system; the fifth conductor
being a group of wires arranged equidistantly round the main conductors.
In Fig. 7, the fifth conductor is a single wire in the centre of the cable.
Fig. 8 illustrates a cable for the three-wire system wherein the chief conductors
are twisted about a flat strip of insulating material; the third conductor being a
group of wires arranged equidistantly round the main conductors.
In Fig. 9, the third conductor consists of two half-round wires.
In carrying out this invention, several conductors, and a body of insulating
material, which may be merely a flat strip or may be cross-shaped or star-shaped
in transverse section, are twisted together, the several conductors lying in the
respective grooves of the insulating material, and being thus separated from one
another. Each of the conductors e e' e² may be a strand comprising any suitable
number of wires of any appropriate transverse section or sections. 6³ is a convenient
form of insulating body, star-shaped in transverse section, and having three equal
arms. The insulating strip or body and the conductors twisted therewith are
surrounded by exterior insulation f, which may be protected by lead sheathing,
hoop iron or other material gh.
.
This method of construction is particularly appropriate for use where the
conductors are of unequal sectional area; as, for instance, in the so-called "three-
wire" and "five-wire" systems.
In the three-wire system, the two chief conductors may respectively consist of
single wires a a' (Figs. 8 and 9) separated by a strip 6 of insulating material, or of
strands of wire ese (Figs. 3 and 4) separated by a body of insulating material,
and the third conductor may be a single wire, a pair of wires kk (Fig. 9)
between the insulating material f and f, or a small strand of wire (Figs. 3
and 4). Or the third conductor may consist of a series of separate wires k k¹ k², etc.,

page_text: (Fig. 8,) arranged equidistantly around the exterior of the insulating envelope ƒ
and within the insulating material f¹.
In the five-wire system, the two principal conductors and the two secondary
conductors 1213 may consist of strauds of wire; whilst the fifth conductor may be
formed of single wires m m² m², etc., (Fig. 6,) placed equidistantly around the
exterior of the insulating envelope f. The fifth conductor may, however, consist
of a single wire n (Fig. 7) arranged in the centre of the cable; or, in cases where
economy in first cost is of importance, the protective sheathing g (Fig. 5) may
itself be utilized as the fifth conductor.
According to the methods of construction described above with reference to
Figs. 3 to 7, several conductors of unequal sectional area may be readily united to
form a compact cylindrical cable, whereas the manufacture of cables of this class
has hither presented considerable difficulty.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I claim :-
1. Cables or conductors for electric light service or transmission of power built
up substantially as described with reference to the accompanying drawings.
2. For electric light service or transmission of power, a cable circular in
transverse section and comprising a body of grooved insulating material and
several conductors twisted together with the insulating material, each groove in
the insulating material being just large enough to hold the conductor lying within
same, substantially as described with reference to Figs. 1 and 2 of the accompanying
drawings.
3. For electric light service or transmission of power, a cable circular in
transverse section but comprising a body of grooved insulating material irregular
in transverse section, and several conductors of unequal transverse section twisted
together with the insulating material, each groove in the insulating material being
just large enough to hold the conductor lying within same, substantially as herein
described.
4. For electric light service or transmission of power, a cable circular in
transverse section but comprising a body of grooved insulating material, main and
secondary conductors of unequal transverse section twisted together with the
insulating material, each groove in the insulating material being just large enough
to hold the conductor lying within same, and a fifth conductor separated from the
other conductors by insulating material, substantially as herein described.
5. For electric light service or transmission of power, a cable for the "five-wire"
system in which the protective sheathing is utilized as the fifth conductor, substan-
tially as described with reference to Fig. 5 of the accompanying drawings.
6. For electric light service or transmission of power, a cable for the "five-wire"
system in which the fifth conductor consists of a series of single wires placed
equidistantly around the exterior insulating envelope and twisted with the other
conductors and the insulating material, substantially as described with reference to
Fig. 6 of the acccompanying drawings.
7. For electric light service or transmission of power, a cable for the "five-wire"
system in which the fifth conductor is a single wire in the centre of the cable,
substantially as described with reference to Fig. 7 of the accompanying drawings.
8. For electric light service or transmission of power, a cable for the "three-
wire" system, substantially as described with reference to Fig. 8 of the accom-
panying drawings.
9. For electric light service or transmission of power, a cable for the "three-
wire" system, substantially as described with reference to Fig. 9 of the accom-
panying drawings.
Dated the 17th day of January 1891
G. G. M. HARDINGHAM.