Improvements in Distributing and Controlling Electric Currents in Mines or other Dangerous Places.
Year: 1892

page_text: Date of Application, 23rd Feb., 1892
Complete Specification Left, 23rd Nov., 1892-Accepted, 7th Jan., 1893
PROVISIONAL SPECIFICATION.
Improvements in Distributing and Controlling Electric Currents
in Mines or other Dangerous Places.
We, ROBERT JOHN CHARLETON and HENRY WALKER, both of 131 Pilgrim
Street in the City and County of Newcastle-upon-Tyne, Electrical Engineers,
do hereby declare the nature of this invention to be as follows:-
The invention consists in an improved method of distributing electric currents in
mines, petroleum stores, powder manufactories and other places where sparking or
flashing is likely to be dangerous, as tending to cause an explosion, and where, as
in the case of mines the cables containing the current are liable to injury and
rupture, from various causes, such as a fall in the roof or a truck getting derailed
&c.; and of preventing in case of such injury, "sparking or "arc-ing" between
the two portions of cable, which, without some such protection, would take place at
the point of damage.
"
The cable used for transmitting may be either a concentric cable, having the two
main conductors formed in one, or two separate cables may be used.
In the former case we carry through the centre a single copper wire, which at
the end next the generating dynamo, and throughout its whole length is insulated
from the other strands of the inner conductor (of which it forms part) but at the
other extremity, remote from dynamo, or at any point beyond that part of the mine
or other place, where risk of explosion exists, is joined up to the other strands.
This centre wire, which we will say is the positive, is straight and after insulation
is put round it, the remaining strands of the inner positive conductor are wound in
a right spiral round it and insulated and the outer negative conductor is then wound
in a left hand spiral over the intervening insulation.
In the outer conductor one of the strands is insulated from the other, so as to
form a separate path for the current; or a separate single wire may be carried
alongside and outside the main cable and this separately insulated, or in the latter
case, distinct, wire, is connected to the other strands of the outer conductor at the
end remote from the dynamo, but at the end next the dynamo is kept distinct.
If two separate cables are used each will have a central straight wire, insulated
from the other strands which latter will be put on in a spiral form over the
insulation but we will describe our invention as having the two main conductors in
one cable.
At the end next to the generating dynamo the central and separately insulated
wires will be wound round a solenoid "bobbin," the solenoid being composed of two
separate circuits, the separately insulated positive being wound round so as to cause
the current to flow in one direction and the separate insulated negative wire being
wound so as to cause the current to flow in the opposite direction; the two currents
being equal would therefore neutralise each other, and no attraction would be
exerted on the iron "core" suspended from or supported by a spring or other
means within the central cavity of the bobbin.
The central wire of the cable being straight and the other strands of the
conductors being spirally arranged, the resistance would not be quite the same and
a suitable resistance of platinoid wire, or other means, may be inserted in the centre
wire, near the solenoid, to equalise and render the currents, through the two
conductors and the two circuits round the solenoid, equal.
When a separate single wire is run alongside the main cable instead of specially
insulating one of the strands of the outer conductor, the resistance of this and of
the centre wire will be the same and a platinoid or other resistance may be inserted
in both to make their resistance equal to, or rather more than, the other strands.

page_text: The iron core would be arranged, if attracted by the solenoid, to "short-circuit "
the main positive and negative leads to and from the dynamo, and thus deflagrate
or destroy a fusible "cut-out" or actuate a magnetic "cut-out." In its movement
it also may be caused to actuate a trigger which would release a weight (or other
device) controlling a switch in the main circuit and, by opening this, stop the
current completely.
Either or both these arrangements may be employed as may be deemed necessary
to insure perfect safety.
The method of operation is as follows:-In case of accident to the main cables,
either concentric or separate, causing the insulation to be torn asunder the centre
wire being straight would be broken immediately and before those forming the
remainder of the conductor (being arranged spirally) would be subjected to any
strain.
The result would be that one circuit round the solenoid would be broken, the
balance being therefore destroyed, the current round the other circuit would at
once exert a pull on the iron core, and this, bringing the contact maker into action,
would short circuit the main leads, and at the same time would release the trigger
and cut off by the switch the main circuit and to stop the flow of current, without
any spark at the point of damage.
If the negative current separate wire should break the result would be the same,
one circuit round the solenoid being broken.
In case neither the separate external wire or the centre wire should be broken,
but the remainder of the strands forming either the positive or negative conductor
should be damaged and reduced in numbers, there would be an increase in the
strength of one circuit round the solenoid over the other, which would destroy the
balance between the two and so cause the core to be attracted and operate as before
to break the circuit when the spring suspending or supporting it would restore it
to its normal position ready to act again.
The solenoid, trigger &c. may be contained in a lock up case, open only to the
person in charge as no attention under ordinary circumstances would be required.
For purposes of testing by an inspector at any time to see if all was in working
order, small switches may be fitted on each of the two wires, forming the two
circuits round the solenoid, by opening either of which when the generating dynamo
was working, the core could be attracted and operated at will.
By forming a loop in either of the separately insulated wires which pass round
the solenoid, at the end fremote from the dynamo, as for instance in a mine, and
fixing therein a small switch, in case of necessity, the current could be stopped
instantly, at will, by turning the switch which would break one of the circuits
round the solenoid and so break the circuit and cut off the main current. There
would be no "sparking" whatever at this switch as it deals with only a small part
of the main current.
In the case of concentric cables if they should be crushed between two hard
substances without being torn asunder the arrangement of the inner and outer
conductors of right and left hand spirals would bring the two into contact and so
"short circuit" the main leads and cause the fusible or the magnetic "cut-out
" to
operate but in the case of the separate single wire (forming one of the solenoid
circuits and carried externally alongside the main conductor) it would certainly be
broken before the large cable, in case of the fall of the roof in a mine.
Dated this 22nd dow of Fahmi 1900

page_text: COMPLETE SPECIFICATION.
Improvements in Distributing and Controlling Electric Currents in
Mines or other Dangerous Places.
We ROBERT JOHN CHARLETON and HENRY WALKER, both of 131 Pilgrim
Street, in the City and County of Newcastle upon Tyne, Electrical Engineers, 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:-
The invention consists in an improved method of distributing electric currents
in mines, petroleum stores, powder manufactories and other places where sparking
or flashing is likely to be dangerous, as tending to cause an explosion, and where,
as in the case of mines the cables conveying the current are liable to injury and
rupture, from various causes, such as a fall in the roof or a truck getting derailed &c.
and of preventing, in case of such injury, "sparking" or "arc-ing" between the
two portions of cable, which without some such protection, would take place at the
point of damage.
The cable used for transmitting may be either a concentric cable, having the
two main conductors formed in one, or two separate cables may be used.
In the former case we carry through the centre a single copper wire, which at
the end next the generating dynamo, and throughout its whole length is insulated
from the other strands of the inner conductor (of which it forms part) but at the
other extremity, remote from dynamo, or at any point beyond that part of the
mine or other place, where risk of explosion exists, is joined up to the other
strands.
This centre wire, which we will say is the positive, is straight and after insulation
is put round it, the remaining strands of the inner positive conductor are wound in
a right spiral round it and insulated and the outer negative conductor is then wound
in a left hand spiral over the intervening insulation.
In the outer conductor one of the strands is insulated from the other, so as to
form a separate path for the current; or a separate single wire may be carried
alongside and outside the main cable and this separately insulated, or in the latter
distinct wire is connected to the other strands of the outer conductor at the
end remote from the dynamo, but at the end next the dynamo is kept distinct.
case,
If two separate cables are used each will have a central straight wire, insulated
from the other strands which latter will be put on in a spiral form over the insula-
tion but we will describe our invention as having the two main conductors in one
cable.
At the end next to the generating dynamo the central and separately insulated
wires will be wound round a solenoid "bobbin," the solenoid being composed of two
separate circuits, the separately insulated positive being wound round so as to cause
the current to flow in one direction and the separate insulated negative wire being
wound so as to cause the current to flow in the opposite direction; the two currents
being equal would therefore neutralise each other, and no attraction would be
exerted on the iron "core" suspended from or supported by a spring or other means
within the central cavity of the bobbin.
The central wire of the cable being straight and the other strands of the con-
ductors being spirally arranged, the resistance would not be quite the same and a
suitable resistance of platinoid wire, or other means, may be inserted in the centre
wire, near the solenoid to equalise and render the currents, through the two
conductors and the two circuits round the solenoid, equal.
When a separate single wire is run alongside the main cable instead of specially
insulating one of the strands of the outer conductor, the resistance of this and of
the centre wire will the same and a platinoid or other resistance may be inserted
in both to make their resistance equal to, or rather more than, the other strands.

page_text: The iron core would be arranged, if attracted by the solenoid, to "short-circuit'
the main positive and negative leads to and from the dynamo, and thus deflagrate
or destroy a fusible "cut-out" or actuate a magnetic "cut-out." In its movement
it also may be caused to actuate a trigger which would release a weight (or other
device) controlling a switch in the main circuit and, by opening this, stop the
current completely.
Either or both these arrangements may be employed as may be deemed necessary
to ensure perfect safety.
The method of operation is as follows:-
:-
In case of accident to the main cables, either concentric or separate, causing the
insulation to be torn asunder the centre wire being straight would be broken imme-
diately and before those forming the remainder of the conductor (being arranged
spirally) would be subjected to any strain.
The result would be that one circuit round the solenoid would be broken, the
balance being therefore destroyed, the current round the other circuit would at
once exert a pull on the iron core, and this, bringing the contact maker into action,
would short circuit the main leads, and at the same time would release the trigger
and cut off by the switch the main circuit and to stop the flow of current, without
any spark at the point of damage.
If the negative current separate wire should break the result would be the same,
one circuit round the solenoid being broken.
In case neither the separate external wire or the centre wire should be broken,
but the remainder of the strands forming either the positive or negative conductor
should be damaged and reduced in numbers, there would be an increase in the
strength of one circuit round the solenoid over the other which would destroy the
balance between the two and so cause the core to be attracted and operate as before
to break the circuit when the spring suspending or supporting it would restore it to
its normal position to act again.
The solenoid, trigger &c. may be contained in a lock up case, open only to the
person in charge as no attention under ordinary circumstances would be required.
For purpose of testing by an inspector at any time to see if all was in working
order small switches may be fitted on each of the two wires, forming the two circuits
round the solenoid, by opening either of which when the generating dynamo was
working, the core could be attracted and operated at will.
By forming a loop in either of the separately insulated wires which pass round
the solenoid, at the end remote from the dynamo, as for instance in a mine and
fixing therein a small switch in case of necessity, the current could be stopped
instantly, at will, by turning the switch which would break one of the circuits
round the solenoid and so break the circuit and cut off the main current. There
would be no "sparking" whatever at this switch as it deals with only a small part
of the main current.
"
In the case of concentric cables if they should be crushed between two hard
substances without being torn asunder the arrangement of the inner and outer
conductors of right and left hand spirals would bring the two into contact and so
"short-circuit "the main leads and cause the fusible or the magnetic "cut-out to
operate but in the case of the separate single wire (forming one of the solenoid
circuits and carried externally alongside the main conductor) it would certainly be
broken before the large cable, in case of the fall of the roof in a mine.
DESCRIPTIONS OF DRAWINGS.
On the accompanying sheet we illustrate our invention as it may be practically
applied Fig. 2 shewing sections of the main transmitting cable in the concentric form
having a centre core wire and two main conductors in. one cable and of the single
separate insulated wire forming part of the outer conductor carried alongside.the
main cable. The alternative arrangement in which two separate cables may be
used each with a straight core wire with the main conducting strands wound around
it is not shewn as we consider the other form preferable.

page_text: Fig. 1 shews in plan the general arrangement of the dynamo, the solenoid, the
terminals, fuses (or "cut-outs") the switch and its controlling armature as they may
be conveniently disposed but not necessarily in their relative positions.
66
"
Referring to Fig. 2 the cable A used in transmitting is shewn as having the two
main conductors formed in one cable concentric to each other in the usual way, with
the exception that a core wire carefully insulated from the rest of the strands of
the inner conductor (of which it is intended to form part) is carried in the centre.
At the end next the generating dynamo this core wire is carried round a solenoid,
as described later herein but at the other extremity remote from the dynamo, or at
any point beyond that part of the mine, or other place, where risk of explosion exists,
it is joined up to the other strands.
This centre core wire which we will say is the positive is straight and after
insulation is put round it, the remaining strands of the inner conductor, shewn by
the inner circle of wires, and after intervening insulation those of the outer
conductor, shewn by the outer circle of wires, are wound on it in the usual way.
A separate insulated wire B, having the same sectional area as the centre wire
above described and intended to form part of the outer conductor, is intended to be
carried alongside and parallel with the main concentric cable and, as described for
the centre wire of the inner conductor, is connected to the other strands of the outer
conductor at the end remote from dynamo, but at the end next the dynamo is also
kept distinct.
Referring to Fig. 1, near the generating dynamo the insulated central and
separate wires are wound round a solenoid "bobbin " C, the solenoid being composed
of two separate circuits, the separately insulated positive wire being wound on so as
to cause the current to flow in one direction and the separately insulated negative
wire being wound so as to cause the current to flow in the opposite direction, the
two currents, being equal therefore neutralise each other and no attraction is exerted
on the iron core Ď suspended from or supported by a spring or other means within
the central cavity of the bobbin.
The iron core D is arranged, if attracted by the solenoid, to make magnetic
contact between the disc E and the terminals & and thus to "short-circuit" the
main positive and negative leads to and from the dynamo by opening a path for the
current round the small solenoid F and across the terminals G G and thus to destroy
or deflagrate the fusible "cut-outs" H H whilst the core of the smaller solenoid F
attracts the armature J, which holds the switch K in place, and the latter being
released by this movement is instantly opened by the spring L and thus stops the
flow of the current independently of the fusible cut outs H H.
Either or both these arrangements for breaking the circuit may be employed as
may be deemed necessary to insure perfect safety.
The method of operation is as follows:-
The large concentric cable A and the small separate wire B forming part of the
outer conductor are disposed close together the latter one being rigidly and firmly
fixed whilst the main cable A is so fixed that in case of accident such as a fall from
the roof of a mine it would be carried away from its supports without breaking and
would fall to the ground whilst the small one being firmly fixed would be instantly
broken.
The result would be that one circuit round the solenoid C would be broken and
the balance being therefore destroyed the current round the other circuit would at
once exert a pull on the iron core D and this bringing the contact maker E into
action would "short-circuit" the main leads and at the same time would release the
trigger and cut off by the switch the main circuit and so stop the flow of current
without any spark at the point of damage.
If from any cause the central separately insulated wire of the main cable
should break the result would be the same, one circuit round the solenoid being
broken.
In case neither the separate single wire B or the centre wire of the main cable
should be broken, but from some cause the remainder of the conductors, forming

page_text: either the positive or negative conductor should be damaged and reduced in
numbers, there would be an increase in the strength of one circuit round the
solenoid over the other, which would destroy the balance between the two and so
cause the core to be attracted and operate as above described to break the circuit
when the spring suspending or supporting it would restore it to its normal position
ready to act again.
The solenoid, trigger &c. may be contained in a lock up case open only to the
person in charge, as no attention under ordinary circumstances would be required.
For testing purposes by an inspector, at any time to see if all is in working order,
small switches M M may be fitted on each of the two wires, forming the circuits
round the solenoid, by opening either of which when the generating dynamo was
working, the core D could be attracted and operated at will."
For convenience of illustration the positive and negative conductors are shewn
separately on Fig. 1 but they would immediately be joined into one in the concentric
main cable.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is
First. The improvements in distributing and controlling electric currents in
mines or other dangerous places consisting of the combination of a differentially
wound solenoid with a concentric cable having a straight core wire insulated from
the remaining strands; this central wire and a similar wire carried separately
external to the concentric cable forming the two circuits of the solenoid substantially
as described and shewn.
Second. The modified form of the invention in which two separate cables may be
adopted each containing a straight. core wire insulated from the remaining strands
of the cable and forming the two circuits around the differentially wound solenoid
substantially as described.
Third. The combination of such concentric cable or cables having straight core
wires insulated from the remaining strands and forming the two circuits around a
differentially wound solenoid, having an iron core suspended by a spring and
arranged by contacts, in mercury cups or otherwise, to short circuit the positive and
negative leads from and to a dynamo such short circuits forming a path around a
second solenoid which by the action of its core upon an armature releases a trigger
retaining a spring switch in the main circuit of the dynamo arranged and operating
substantially as described and illustrated by the drawings.
001 Nanamban 1800
T. J. DANSON, F. Inst. P.A.,
Chartered Patent Agent,
Newcastle-upon-Tyne, Agent for Applicants.
T. J. DANSON, F. Inst. P.A.,
Chartered Patent Agent,
Newcastle-upon-Tyne, Agent for Applicants.