An Improved Method of and Means for Distributing Electric Currents.
Year: 1891

page_text: Date of Application, 2nd Feb., 1891
Complete Specification Left, 4th Sent., 1891-Accepted, 31st Oct., 1891
PROVISIONAL SPECIFICATION.
An Improved Method of and Means for Distributing Electric
Currents.
1, LLEWELYN BIRCHALL ATKINSON, of Woodfield Works, Harrow Road, W.
in the County of Middlesex, Civil Engineer, do hereby declare the nature of my
invention to be as follows :—
My invention relates to an improved method of, and means for distributing
electric currents in order to obviate the occurrence of accident or fire, resulting
from fracture or damage to electric conductors, giving rise to sparking or arcing
at the point of damage.
My invention consists in the combination with the main-conductor, which may or
may not be protected by fuses or cut-outs in the usual manner, of a subsidiary
circuit insulated except at its extremities, from the main-conductor, the subsidiary
circuit being protected by a fuse or cut-out operating with less than the normal
current carried by the main-conductor.
It is important where electric-conductors are carried in close proximity to
inflammable material, or where they are used for underground electrical operations,
where they may be surrounded by an inflammable atmosphere; or where, being
carried overhead there is danger to life or property, to prevent the violent sparking
or arcing of such an electric-conductor carrying an electric-current, should the
electric-conductor be broken by any accident.
I effect this prevention by laying a subsidiary electric-conductor, either in con-
junction with the main-conductor but insulated from it, or quite independent and
separate from the main-conductor, which is normally intended to carry only a
fractional part of the main-current, and which is provided with a safety fuse or
cut-out which readily operates or deflagrates, when loaded with a current such as
that which is normally conveyed by the main-conductor.
The protective action of this subsidiary-conductor is as follows:-
Should the main-conductor be suddenly broken, the current finds, for the moment,
a closed circuit through the subsidiary-conductor, which prevents the sparking or
arcing of the main-conductor across a moderate interval, whilst the broken ends of
the main-cable are in close proximity to one another.
The subsidiary-conductor then carries the whole normal current, and the fuse
or cut-out will be opened and completely break the circuit.
The only spark or arc which occurs under these circumstances, is that which
takes place at the aforesaid safety fuse or cut-out, which may easily be covered
and protected against the possibility of firing any inflammable substance or gas.
In cases where, as with conductors carrying high E. M. forces, especially in the
case of overhead conductors, where it is desirable to totally disconnect the main-
conductors from the source of electric current, an automatic cut-out is provided,
such that when the subsidiary cut-out is operated, the main cut-out also operates,
thus totally disconnecting the circuit.
A convenient form of construction for these main and subsidiary-conductors to
effect my purpose may be :-
First. A perfectly independent laying of the two cables apart from one another,
or, Second. The insertion within, or application without the ordinary stranded or
solid portion of the main-conducting cable, of a spirally twisted elastic subsidiary-
conductor, insulated from the said main-conductor. Should the main-conductor
break, in this case the elastic character of the internal or external spirally twisted
subsidiary-conductor will allow the broken ends of the main-cable to spring
apart to a considerable distance, while the subsidiary conductor remains intact

page_text: Third. The insertion within, or application without a double concentric lead and
return cable, of a spirally twisted subsidiary conductor or conductors insulated from
the main-conductors. Should one or both of the lead and return conductors of this
combined cable break, the spirally twisted subsidiary-conductor will allow the
broken ends to spring apart, whilst remaining intact itself.
Further, in this latter arrangement should the wires of the lead or return con-
ductors be laid bare by fracture or cutting, there is further every probability that
the bare wires of the lead and return main-cables would come into contact and be
short-circuited, preventing sparking or arcing at the fracture, and causing only the
discontinuity of the circuit at the safety fuses or cut-outs situated on the main
conductors, which may be externally protected, as before described for the safety
fuses or cut-outs of the subsidiary-conductor or conductors.
Dated this 2nd day of February 1891.
FELL & WILDING,
1, Queen Victoria Street, E.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
An Improved Method of and Means for Distributing Electric
Currents.
I, LLEWELYN BIRCHALL ATKINSON of Woodfield Works, Harrow Road, W.
in the County of Middlesex, Civil 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 :-
My invention relates to an improved method of and means for distributing
electric currents in order to obviate the occurrence of accidents or fire resulting
from fracture or damage to electric conductors, giving rise to sparking or arcing
at the point of damage.
My invention consists in the combination with the main conductor, which may or
may not be protected by fuses or cut-outs in the usual manner of a subsidiary
circuit insulated except at its extremities from the main conductor, the subsidiary
circuit being protected by a fuse or cut-out, operating with less than the normal
current carried by the main conductor.
It is important where electric conductors are carried in close proximity to
inflammable material, or where they are used for underground electrical operations
where they may be surrounded by an inflammable atmosphere or where being
carried overhead there is danger to life or property to prevent the violent sparking
or arcing of such an electric conductor carrying an electric current, should the
electric conductor be broken by any accident.
I effect this prevention by laying a subsidiary electric conductor, either in con-
junction with the main conductor but insulated from it or quite independent and
separate from the main conductor which is normally intended to carry only a
fractional part of the main current and which is provided with a safety fuse or cut-
out which readily operates when loaded with a current such as that which is
normally conveyed by the main conductor.
The protective action of this subsidiary conductor is as follows :-
Should the main conductor be suddenly broken, the current finds for the moment
a closed circuit through the subsidiary conductor which prevents the sparking or
arcing of the main conductor across a moderate interval whilst the broken ends of
the main cable are in close proximity to one another. The subsidiary conductor
then carries the whole normal current, and the fuse or cut out will be operated and
completely break the circuit.
The only spark or are which occurs under the circumstances is that which takes
place at the aforesaid safety fuse or cut-out which may easily be covered and
protected against the possibility of firing any inflammable substance or gas.
In cases where as with conductors carrying high E. M. forces, especially in the

page_text: case of overhead conductors, when it is desirable to totally disconnect the main
conductors from the source of electric current, an automatic cut-out is provided
such that when the subsidiary cut-out is operated the main cut-out also operates
thus totally disconnecting the circuit.
Convenient forms of construction for these main and subsidiary conductors to
effect. my purpose may be,
First. A perfectly independent laying of two cables apart from one another, or
Second. The insertion within, or application without the ordinary stranded or
solid portion of the main conducting cable of a spirally twisted elastic subsidiary
conductor insulated from the said main conductor. Should the main conductor
break, in this case the elastic character of the internal or external twisted subsidiary
conductor will allow the broken ends of the main cable to spring apart to a
considerable distance while the subsidiary conductor remains intact.
Third. The insertion within, or application without, a double concentric lead
and return cable, of spirally twisted subsidiary conductor or conductors insulated
from the main conductors. Should one or both of the lead and return conductors
of this combined cable break, the spirally twisted subsidiary conductor will allow
the broken ends to spring apart whilst remaining intact itself.
Further in this latter arrangement should the wires of the lead or return con-
ductors be laid bare by fracture or cutting, there is further every probability that
the bare wires of the lead and return main cables would come into contact and be
short circuited preventing sparking or arcing at the fracture and causing only the
discontinuity of the circuit at the safety fuses or cut-outs situated on the main
conductors which may be externally protected, as before described, for the safety
fuses or cut-outs of the subsidiary conductor or conductors.
Where it is necessary to prevent the possibility of a spark even should the
cable be cut by a sharp instrument this may be effected as follows:-In the circuit
of the subsidiary elastic conductor at the end remote from the generator is a
resistance, the result of this is that instead of the fall of potential along the sub-
sidiary conductor being the same as that in the main conductor per-unit of length
it is less. When therefore by cutting the cable through the subsidiary and main
conductors are put in contact, the fall of potential in each cable becomes the same,
the result being an increase of current, which fuses the fuse of the subsidiary
circuit as before.
In order that my invention may be the better understood, I now proceed to
describe the same in relation to the drawings hereunto annexed, reference being
made to the figures and letters marked thereon.
Figure 1 shows the general arrangement of circuits in this invention. A A' are
the terminals of the source of supply. B, B', the terminals of the recipient device..
1, Lare the two subsidiary conductors.
C, Care the main fuses.
S, S¹ are the fuses in the subsidiary circuit M M'.
Figure 2 shows an arrangement for totally disconnecting the circuits on the
occurrence of a break.
A weight W is held up on a sliding bar, by means of a fusible wire S. At the
lower part of the bar is a slider carrying a switch tongue which connect two
plates PP thus completing the main circuit L.
The fusible wire S is in circuit with the subsidiary wire M and when fused as
described by the breaking of the outer conductor L, the weight W drops and
breaks the circuit at P.
Figure 3 shows one form of the cable as constructed with a spiral flexible core,
having an outer insulating layer, a conductor of stranded wire then a light
insulating layer, and finally the inner concentric spiral conductor which may be
made of one wire, but which is preferably composed of several wires laid parallel.
Figure 4 shows such a cable broken with the inner conductor intact and
expanding.
Figure 5 shows the arrangement of circuits where it is desired to allow for the

page_text: cutting of the cable by means of a sharp instrument which is provided for as
explained by the insertion of resistances R'R' in each subsidiary conductor M M.
Having now particularly described and ascertained the nature of my inven
tion and in what manner the same is to be performed, I declare that what I
claim is:
-
1st. The combination in electric supply or distributing circuits of main and
subsidiary conductors with independent fuses or cut-outs, substantially as described.
2nd. The combination in electric supply or distributing circuits with main and
subsidiary conductors as claimed in Claim 1, of a switch in the main circuit controlled
by the fuse or cut-out in the subsidiary circuit.
3rd. In electric conductors, the combination of a main conductor with a spiral
elastic subsidiary conductor surrounding or surrounded by and insulated from the
said main conductor to form a safe cable.
4th. In such a safety cable the in the spiral conductor, of two or more wires laid
together side by side and connected electrically in parallel.
5th. The combination with such a cable and connections of resistances in the
subsidiary conductor, substantially as and for the purposes described.
6th. The construction of concentric cables having one or more spiral flexible
subsidiary conductors connected as described.
Dated this 4th day of September 1ș91.
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicant.