Improvements in Safety Devices for Use in connection with Electrical Distributing Systems.
Year: 1899

page_text: Date of Application, 19th Apr., 1899
Complete Specification Left, 19th Jan., 1900-Accepted, 24th Mar., 1900
PROVISIONAL DICITIATION
Improvements in Safety Devices for Use in connection with Electrical
Distributing Systems.
We, GERALD WILLIAM PARTRIDGE, Civil Engineer, and THE LONDON ELECTRIC
SUPPLY CORPORATION LIMITED, both of 25A, Cockspur Street, Charing Cross, in
the City of Westminster, do hereby declare the nature of this invention to be as
follows:
In high tension electrical distributing systems it sometimes happens that the
electro-motive force suddenly rises from some accidental cause sufficiently beyond
the normal to cause an electric spark to pass between insulated parts of the system
through which it passes to such an extent as to permit of the formation of a per-
manent are between the said parts and the passage of a large current which causes
considerable damage to the dynamos, transformers, mains or other parts of the
distributing system.
For the purpose of avoiding this danger, various protecting devices have been
used one of which consists of a pair of metal horns connected to parts of the dis-
tributing system and arranged sufficiently near together at their lower parts to
permit of a spark passing from one to the other on the difference of potential
between the two horns exceeding a predetermined amount, the upper parts of the
horns being made to diverge from each other with the object of causing the arc
extending between the two horns to rise and, by becoming lengthened, to
ultimately break itself and so electrically disconnect the two horns and attached
conductors. It has been found in practice however that the arc will not rise and
become lengthened as desired, and although means, such as electro-magnets and
air blasts, have been used for repelling the arc in an upward direction, the arrange-
ments heretofore devised have not been found reliable or satisfactory in practice.
Now this invention has reference to safety. means or apparatus whereby an
arc set up between two conductors under the conditions set forth will be imme-
diately and automatically lengthened to a sufficient extent to break the said
apparatus working automatically and re-adjusting itself to its original position
after the breaking of an arc so that it can be used any number of times in succession
without being re-set by hand.
Apparatus for this purpose comprises two relatively movable pole pieces that
are connected or adapted to be connected through a high resistance to the two
mains or conductors between which an electric discharge is to take place, and
which are normally located at such a distance apart that an arc will be formed
between them when the difference in potential suddenly rises above a pre-
determined amount, and in conjunction with such pole pieces there is provided
an electro-magnetic device that is adapted to be energised upon the formation of
the said arc and to then immediately move the two pole pieces apart to a sufficient
extent to break the arc and so disconnect the two pole pieces and attached con-

page_text: tluctors from each other, whereupon the pole pieces will automatically resume their
normal position ready for re-use.
Apparatus adapted to act in the manner described can be constructed in various
forms.
In one arrangement, one of the pole pieces is in the form of a fixed metal horn,
resembling more or less one of the two horns previously employed, such pole
piece being connected to one of the two mains or conductors through a high
resistance device. The other pole piece is movable upwards about a hort-
zontal axis and comprises a metal disc or block carried by one arm of a horizontal
lever the other arm of which is connected to the movable core of a solenoid which
has one of its ends in electrical connection with the disc or block and the other
with the second main or conductor, the said movable pole piece being so arranged
that when it is in its lower and normal position the distance between it and the
fixed pole piece is such as will permit of the formation of an arc between the two
under the conditions herein before mentioned. This distance may be made adjust-
able, as for example, by adjusting the disc or block towards or from the stationary
pole piece. In proximity to the movable pole piece there is or may be a second
curved stationary metal horn the upper end of which diverges from that of the
first mentioned or fixed pole piece and the lower end of which may be formed with
a slot in which the lever arm carrying the movable pole piece can move up and
down. This second horn is or may be electrically connected to the movable pole
piece. The solenoid is arranged in series between the movable pole piece and
second main or conductor. The arrangement is such that immediately upon the
formation of an arc between the fixed and movable pole pioces, the electro-
magnetic device comprising the solenoid and core will act to turn the movable
pole piece upward and away from the fixed pola piece, and into contact with the
second fixed horn, when this is used, the result being that the arc is rapidly
raised and lengthened to a sufficient extent to break it, or, if the second horn is
used, the arc will leave the end of the movable pole and run up the diverging
horns until it increases in length sufficiently to break itself.
The movable pole piece may be counterbalanced, and the connection between
it and the core of the solenoid may be such that it will exert a practically constant
action upon the core.
A high resistance may also in some cases be placed between the movable pole
piece and the upper part of the second fixed horn so that when the arc leaves
the movable pole piece and runs up the second horn, the intensity of the arc is
further reduced by reason of an additional resistance being thrown into series
with it. For a like purpose, the first fixed pole piece or horn may also be made
in two or more parts arranged lengthwise of each other and electrically connected
together through one or more high resistances.
Dated this 1011. 1
1000
In connection with Plectrical
Distributing Systems.
We, GERALD WILLIAM PARTRIDGE, Civil Engineer, and THE LONDON ELECTRIC
SUPPLY CORPORATION LIMITED, both of 25A, Cockspur Street, Charing Cross, in
the City of Westminster, do hereby declare the nature of this invention and in

page_text: what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement:-
1
In high tension electrical distributing systems it sometimes happens that the
electro-motive force suddenly rises from some accidental cause sufficiently beyond
the normal to cause an electric spark to pass between insulated parts of the system
through which it passes to such an extent as to permit of the formation of a per-
manent are between the said parts and the passage of a large current which causes
considerable damage to the dynamos, transformers, mains or other parts of the
distributing system.
For the purpose of avoiding this danger, various protecting devices have been
used one of which consists of a pair of metal horns connected to parts of the dis-
tributing system and arranged sufficiently near together at their lower ends to
pernit of a spark passing from one to the other on the difference of potential
between the two horns exceeding a predetermined amount, the upper parts of the
horns being made to diverge from each other with the object of causing the arc
extending between the two horns to rise and, by becoming lengthened, to
ultimately break itself and so electrically disconnect the two horns and attached
conductors. It has been found in practice however that the arc will not rise and
become lengthened as desired, and although means, such as electro-magnets and
air blasts, have been used for repelling the arc in an upward direction, the arrange-
ments heretofore devised have not been found reliable or satisfactory in practice.
Now this invention has reference to safety means or apparatus whereby an
arc set up between two conductors under the conditions set forth will be imme-
diately and automatically lengthened to a sufficient extent to break the said
apparatus working automatically and re-adjusting itself to its original position
after the breaking of an arc so that it can be used any number of times in succession
without being re-set by hand.
Apparatus for this purpose comprises two relatively movable pole pieces that
are connected or adapted to be connected through a high resistance to the two
mains or conductors between which an electric discharge is to take place, and
which are normally located at such a distance apart that an arc will be formed
between them when the difference in potential suddenly rises above a pre-
determined amount, and in conjunction with such pole pieces there is provided
an electro-magnetic device that is adapted to be energised upon the formation of
the said are and to then immediately move the two pole pieces apart to a sufficient
extent to break the arc and so disconnect the two pole pieces and attached con-
ductors from each other, whereupon the pole pieces will automatically resume their
normal position ready for re-use.
Apparatus adapted to act in the manner described can be constructed in various
forms.
In the accompanying drawings, Fig. 1 shows partly in vertical section and
partly in side elevation, Fig. 2 in plan, and Fig. 3 in end elevation, one arrange-
ment of apparatus according to this invention.
In this arrangement, a is one of the pole pieces made in the form of a fixed
metal horn, resembling more or less one of the two horns previously employed,
such pole piece being connected through conductors 6, 61 to one, viz. c, of the
two electric mains or conductors c, c¹ through a high resistance device d, as for
example a water resistance, or a high resistance wire immersed in oil. Satisfactory
results have been attained with a non-inductive wire resistance of about
10000 ohms., in connection with conductors having a difference of potential of
about 10,000 volts, the wire being immersed in resin oil to give high insulation.
The other pole piece is movable upwards about a horizontal axis and comprises
a metal block 9 carried by one arm of a horizontal lever h, the other arm of which
is connected to the movable core i of a solenoid k which has one of its ends in
electrical connection with the block and the other with the second main or con-
ductor c¹, the said movable pole piece being so arranged that when it is in its
lower and normal position, the distance, between it and the fixed pole piece

page_text: In
1s such as will permit of the formation of an arc between the two under the con-
ditions herein before mentioned. This distance may be made adjustable, as for
example by adjusting the block 9 towards or from the stationary pole piece a,
as for example by screwing it on the arm of the lever that carries it.
proximity to the movable pole piece there is, or may be, a second curved stationary
metal horn the upper end of which diverges from that of the fixed pole piece a
and the lower end of which may be formed with a slot, or, as shown, a recess 1,
in which the lever arm can move up and down. This second horn is or may
be electrically connected to the movable pole piece g-h. The solenoid kis
arranged in series between the movable pole piece and second main or con-
ductor c¹.
In the arrangement shown, the pole piece a is supported by a tube n of insu-
lating material secured to the top of a box o that is provided with a removable
door and wherein is secured an insulator p carrying a binding screw q to which
is connected one end of the conductor b connected to the pole piece and also
one end of the conductor 61 which is led through an insulating bush r and con-
nected to the main conductor c. The block g and lever h may be normally sup
ported in the horizontal position shown, by a stop a¹.
The lever h is mounted
to oscillate upon a pin s fixed to a standard t¹ on a plate t that is supported upon
an insulator u fixed to the top of the box, the said plate t also serving to carry
the solenoid k and the metal horn 1.
The arrangement is such that immediately upon the formation of an arc between
the fixed and movable pole pieces a and gh, the electro-magnetic device com-
prising the solenoid and core i will act to turn the movable pole piece g-h
upward and away from the fixed pole piece a and into contact with the second
fixed horn, when this is used, the result being that the arc is rapidly raised
and lengthened to a sufficient extent to break it, or, when the second horn is used,
the arc may leave the end g of the movable pole piece and run up the diverging
horns a and until it increases in length sufficiently to break itself.
The movable pole piece g-h may be counter-balanced, as shown, and the con-
nection between it and the core of the solenoid k may be effected by a flexible
connector i¹.
で
Figs. 4, 5 and 6 are similar views to Figs. 1, 2 and 3 respectively, showing a
modified construction wherein the movable pole piece g- normally rests in
electrical connection with the fixed pole piece a, for which purpose it may rest on
a stop a of conducting material fixed to the said pole piece a, and the are is
initially set up between two adjacent metal balls and that are enclosed in
the box and one of which, viz. r, is connected to the conductor b. and the other v
is connected to the pole piece a by an adjusting screw w by which it can be
adjusted relatively to the other ball. With this arrangement, immediately upon
the formation of an arc between the balls and el, the electro-magnetic device i
will act, as hereinbefore described, to turn the movable pole piece upward and
away from the fixed pole so as to form between them an are that is rapidly
raised and lengthened to a sufficient extent to cause it to become broken, as with
the arrangement shown in Figs. 1, 2 and 3, whereupon the movable pole piece
will fall back into its normal position in readiness for re-use. By enclosing the
spark gap formed between the balls ¹ within a box, there is no liability of dust
or other matter getting between the pole pieces and causing the device to act
without undue increase of electro-motive force. The ball and terminal or bind-
ing post are the only parts of the apparatus connected to the conductor c, the
other parts of the apparatus being connected to the conductor c¹ which will usually
be earthed.
A. high resistance may in some cases be placed between the movable pole
piece and the upper part of the second fixed horn so that when the arc leaves
the movable pole piece and runs up the second horn, the intensity of the arc
is further reduced by reason of an additional resistance being thrown into series
with it. For a like purpose, the first fixed pole piece or horn a may also be made

page_text: in two or more parts arranged lengthwise of each other and electrically connected
together through one or more high resistances. Usually however such resistances
are unnecessary, the apparatus when constructed and arranged as hereinbefore
described and shown in the drawing annexed, working satisfactory without them.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed we declare that what
we claim is:-
1. A safety device for electrical distributing systems, arranged and operating
substantially as hereinbefore described for the purpose specified.
2. A safety device for electrical distributing systems wherein two pole pieces
are so arranged and controlled that, in conjunction with a high resistance, upon
an electrical discharge taking place between the parts of the electrical distributing
system between which the device is connected, due to sudden increase of electro-
motive force, the passage of a large current through the device will be prevented
and the pole pieces will be automatically moved apart to a sufficient extent to
break the are formed between them, substantially as described.
3. A safety device for electrical distributing systems comprising two relatively
movable pole pieces adapted to be connected through a high resistance to the
two parts of a distributing system between which an electrical discharge is liable
to take place, and an electro-magnetic device that is adapted upon an electrical
discharge taking place to move the pole pieces apart to a sufficient extent to break
the are formed between them and to afterwards permit the pole pieces to auto-
matically resume their normal relative positions ready for re-use, substantially
as described.
4. In safety apparatus for electrical distributing systems, the combination of
two fixed diverging horns one of which is connected or adapted to be connected
to one of the two parts of a distributing system between which an electrical dis-
charge is liable to take place, a pivoted pole piece, an electromagnetic device
connected to the movable pole piece and to the other of the said two parts of the
distributing system, and a high resistance in circuit with such electromagnetic
device, the arrangement being such that upon an electrical discharge taking place
between the two parts of the distributing system through the said apparatus, the
electro-magnetic device will turn the pivoted pole piece away from the first men-
tioned horn and into contact with the second one so as to break the are formed
between the movable pole piece and first mentioned horn, whereupon the pivoted
pole piece will automatically resume its original position ready for re-use, sub-
stantially as described.
5. Safety apparatus for electrical distributing systems constructed, arranged
and operating, substantially as herein before described with reference to Figs. 1,
2 and 3 of the drawings annexed.