Improvements in Electric Safety Fuses or Cut-outs.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Electric Safety Fuses or Cut-outs.
VERITYS LTD., Electrical Engineers, of Plume Works, Aston, in the County
of Warwick, and LOUIS JOHN STEELE, Electrical Engineer, of 14, Clarendon
Road, Holland Park, London, W., do hereby declare the nature of this invention
to be as follows:-
In electric safety fuses or cutouts specially designed for breaking high tension
currents devices are at present employed whereby one or both terminals (usually
mounted at the ends of springs to which the fuse wire is fixed), are immersed in oil
at the moment of fusion of the wire, thus breaking the arc and preventing a
continued passage of current. One of the principal objections to this method is
that the terminals are immersed under oil, which is somewhat objectionable when
a fuse has to be replaced, and also that the terminals to which the fuse is fixed
are not visible. A further objection is that the use of terminals and springs under
oil renders the design somewhat bulky.
Our invention provides a similar method for preventing an electric arc, but we
dispense with the necessity of immersing the terminals under oil or other suitable
substance.
This we do by means of a fuse or equivalent device fixed to terminals, and
mounted on an insulating frame or to the switchboard itself. The fuse wire is
passed through a vessel containing oil, or some refractory non-conducting
material, or in some cases, the vessel contains only air. When the wire fuses, this
vessel moves by the action of gravity or of a spring, and in so doing causes the
loose end of the fuse to be drawn into the vessel, or under the surface of the oil, and
the arc is thus quickly interrupted, the motion of the fuse being twice the rate at
which the vessel moves. When it is desired that the arc should occur at one
particular point in the fuse, the section is made smaller at this point; or in some
cases we prefer to connect the fuse between one terminal and the end of a flexible
connection passing through the vessel, in which case the fuse wire or the fuse wire
and a portion of the flexible connection, will be drawn into the vessel. The travel
of the vessel is limited either by a stop or by a supporting cord, or may be
arranged to fall against contacts connected to a bell circuit, thus giving a signal
on the "going" of the fuse. When we desire to augment the motion of the vessel,
part of the apparatus is provided with a screw which, when released by the fuse,
provides motion in more than one direction. In order that the force on the wire
should not be carried directly by the terminals, we sometimes prefer to take
a few turns round a porcelain or metal projection or bobbin, or through holes or
slots before connecting to the terminal, this device having the further
advantage of protecting the terminals from the momentary are which
formed on fusion. A portion of the fuse is preferably constructed in the
form of an insulated handle, enabling the whole fuse to be removed from its
base for rewiring. A special form of connecting the fuse to the conductors of an
is

page_text: electric circuit is by means of hooks and pegs or by employing coned connections
or again by means of mercurial contacts.
It is apparent that the above design is equally applicable for mounting on a
vertical switchboard, or for placing in positions where a horizontal space only is
available.
We, VERITYS LTD., Electrical Engineers, of Plume Works, Aston, in the County
of Warwick, and LOUIS JOHN STEELE, Electrical Engineer, of 14, Clarendon
Road, Holland Park, London, W., 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:-
This invention consists in an improved construction of safety fuse or cutout
to be used in connection with electric circuits, the same being designed upon lines
of simplicity and neatness and so that the terminals are always open to view and
available for refitting. The cutout or safety fuse device according to this invention
is characterised by a shifting or movable chamber, tube or trough, containing an
insulating material or fluid, which is held in check or suspension against an auto-
matically moving force by the fuse wire which passes through the said chamber or
tube and whose free ends are connected either directly or indirectly to the terminals
upon the switch board or block within the circuit; the arrangement and fitting
of the said parts being such that on the fuse wire "blowing," by reason of the
passage of an abnormal current, the loose free end of the said fuse wire is instantly
and at a multiple rate drawn within the tube or chamber, as aforesaid, and under
the insulating material contained therein, so that the possibility of any electric arc
being formed is prevented.
One of the characteristics of this invention is the simplicity and quickness with
which a fuse can be refitted, and this is a very important matter, especially when
applied to circuits where loss of time, labour or light would result from the breach
in the supply.
It is important to observe in connection with this invention that the speed
with which the free end of the fuse wire when "blown" is drawn into safety is
considerably multiplied having regard to the displacement of the tube or vessel
containing the insulating material, and that the power to obtain that velocity is
obtained from the actual movement of the said chamber or tube, and this enables a
cutout of small dimensions to be constructed, the mechanical movement being
only small.
It is found in practice that for the majority of electric circuits a cutout, con-
structed according to this invention, in which the free end of the fuse wire is pulled
within the shifting chamber (and under the insulating material) at a ratio of two

page_text: to one of the movement of the said chamber or tube is sufficient for breaking the
arc, and so in connection with such a safety fuse or cutout this invention will be
particularly described.
دو
In the sheets of drawings annexed herewith, Fig. 1 is a front elevation, Fig. 2
a section, Fig. 3 an end elevation and Fig. 4 a top side plan of a two-to-one-ratio
safety fuse or cutout applied to a terminal wall block or switch board and adapted
to work vertically. The position of the fuse or cutout in Figs. 1 and 3 is normal
or making circuit, whilst its position in Fig. 2 is "blown or broken and the
electric are extinguished or drowned out in the insulating material. Figs. 5 and 6
show the terminal block or switch board and the safety fuse or cutout separated, an
insulating carrier, which will be hereinafter more particularly described, forming
the medium of connection between the parts. Fig. 7 is a like view as Fig. 3, but
the carrier, as before referred to, is fashioned with a handle projecting therefrom.
Figs. 8 and 9 are slight modifications of the mounting and carrying means to the
fuse, whilst Fig. 10 sets forth a combination traversing and part rotating move-
ment of the shifting or movable chamber or tube carrying the insulating fluid. A
part-rotating movement only of the shifting tube is a very essential element if the
said chamber or tube has no straight line displacement.
In Figs. 1 to 7 of the sheets of drawings, a is à terminal block or switch board
which is adapted to be fitted vertically upon a wall or the like, and a², a³, are the
terminals of the electric circuit, the said terminals being respectively provided
with screw-up clamping nuts a¹, a³. The fuse wire is indirectly connected
to the terminals, a², a³, through the medium of conducting catch plates c², having,
respectively, hooked ends 4, co which are attached to opposite terminations
of the head d² of a non-conducting carrier d, the said catch plates engaging
the terminals a², a³, through their hooked ends and supporting the said carrier
vertically upon the said terminals. The non-conducting carrier d has a hollow
waist part which depends from the head d2 and constitutes a hand grip to the
fuse and a guide to the movable chamber, and a foot part d³ is formed at its one
end to constitute a stand to the said carrier and also to cover up parts of the fuse
and render them neat. The free ends c, c, of the fuse wire c are connected to
the conducting catch plates, 2, 3, by being wound upon outstanding pins or pegs,
and being gripped by screw pins ; the said free ends of the wire being guided
through the opposite terminations 3, of the carrier by passing through slotted
parts formed therein. Thus is the fuse wire made endless between the terminals
and connected up thereto indirectly.
Fitted to the lower part of the carrier d is a U-shaped chamber or tube e
filled or partly filled with a non-conducting material, such as a heavy non-inflammable
oil, or a refractory material, such as sand, the said U-shaped tube having flared
open ends e², e³, and being attached to and carried by a stem or hollow leg g so as
to freely move vertically up and down and to and from the circuit terminals or
parts connecting therewith, the movement of the said U-shaped tube being
limited in a downward direction by a check cord 2, and in an upward direction
by the top part g³ of the foot of the carrier. The U-shaped tube or chamber e
which is preferably of glass is connected to the stem or legg by a split spring
clip h, a soft material liner h² interposing between the said tube and clip. A
portion of the fuse wire c passes into and through the hollow interior of the
U-shaped tube and through the insulating material contained therein, and the
said wire forms the means for stringing up or suspending the said tube in the
position as shown in Fig. 1, viz. against its own gravitation, the said tube
tending to keep the fuse wire taut between the pegs and pins, c, of the catch
plates 2, 3, to which its free ends are connected. Thus is the movable or shift-
ing U-shaped tube strung up, held in suspension, or held in check by the con-
tinuity and tying-in of the fuse wire, and liberated when the same has blown";
the said liberation causing the U-shaped tube to shift or be displaced and the loose
end of the fuse wire to be drawn into the said tube at double the rate at which the
said tube travels.
*

page_text: The foot d of the carrier d is bifurcated or formed with a clearance, so that
the middle portion of the U-shaped tube, and the lower part of the stem or leg
carrying it, is embraced or covered in. The check cord g² pays out from a plug
end i fixed in the centre of the head of the carrier.
In Fig. 7 the parts are the same as in Figs. 1 to 6 other than the carrier d
is provided with an accessory in the form of a handle or fingers grip m. In Figs. 8
and 9 are shown slight modifications of the forms of U-shaped tubes or chambers
and their carrier means; the tube in the first named fig. having a vertical stem n
upon its underside which works in a socket n², the terminals of the circuit being
much the same as the former, but the free ends of the fuse wire are connected
directly thereto. In Fig. 9 the U-shaped tube is guided from the switch board,
an eye n² being formed therethrough for the tube's stem n to work in, but the
action of the fuse is identical with the one first described.
In Fig. 10 is shown a movement of the U-shaped tube which combines a straight
line movement with a vertical one, so as to increase the speed at which the arc
is drowned out or extinguished. In this view the stem or leg g is formed with
an helical slot 92, with which latter a pin or peg o, extending within the bore of
the waist d of the carrier d, engages, so that as the stem g falls down the hollow
waist it is partly revolved, which causes the mouth of the U-shaped tube, upon
the side which the fuse wire blows, to have a compound movement and the wire's
end to be more quickly drawn under the oil.
The part rotation of the U-shaped tube can of itself form sufficient movement of
the tube to extinguish the electric arc, this being specially important if the fuse
is horizontally disposed and the switch board in the way of a straight line move-
ment. In this case of rotation only, a spring would be used to effect the movement,
but the said movement would be held in check by the fuse wire, until burnt, in the
same manner as the forms before described.
If the speed of pulling within the tube the loose end of the fuse wire is required
to be increased, a number of U-shaped tubes or a number of small pullies can be
used, and these would be arranged in the same way as a system of pulley blocks
acting in concert, the fuse wire being threaded and doubled around them so that its
one end shall be pulled into the non-conducting liquid within the U-shaped tube
at an extremely rapid rate, and entirely by the said tube's displacement.
In order to guarantee the blowing of the fuse wire at a predetermined part in
its length, such as that markeds in Fig. 1, the said wire at that particular part is
of a smaller section or gauge than the body part of the said wire, so that it is
positively the first part in the fuse that would "go."
It will be obvious from Figs. 1 to 6 of the drawings that the fuse can be simply
hooked on and off the switch board of the circuit to be protected at any moment,
and this is of great importance when a fuse wire or a fuse has to be replaced.
If necessary a flexible conductor having a fuse wire fixed at one end may pass
through the U-shaped tube, or the moving chamber, instead of the fuse wire itself;
but its arrangement is such as to allow of the fused end of the wire being pulled
within the tube in the manner previously described without a flexible connection.
This arrangement is particularly applicable to fuses applied to circuits of extreme
high tension currents, as in some cases it would be necessary to have a fuse wire
of such a gauge that a free running movement within the U-shaped tube, when
the latter is displaced, could not be insured.
Instead of a single fuse wire several wires may be used, and the stem of the
U-shaped tube may be of glass or other suitable non-conducting material and
formed in one piece with the said tube; further the U-shaped tube may be dis-
placed on the fuse "going" by the action of a spring.
Having now particularly described; and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:-
First. An electric safety fuse or cutout distinguished by an automatically shift-

page_text: ing or movable chamber, tube or trough containing an insulating fluid or material,
and a fuse wire whose ends are connected either directly or indirectly (or by a
flexible conductor) to the terminals of the electric circuit, and which passes into
and is threaded through the said chamber, tube or trough so as to hold it in check
or suspension against a moving force, the motion of which latter multiplies the
movement of the loose end of the fuse wire when blown in relation to itself,
substantially as described and set forth.
Second. An electric safety fuse or cutout comprising a U-shaped tube or chamber
containing an insulating fluid or material, a fuse wire whose ends are connected
to the terminals of the circuit to the protected and which passes though the said
tube and supports it and holds it in check or suspension against a moving force,
and a T-shaped non-conducting carrier to which the said U-shaped tube and fuse
wire is fitted, and which forms a portable basis to the fuse so that it can be simply
and easily placed into and out of contact with the terminals of the circuit to be
protected, substantially as described and set forth.
Third. In combination in an electric safety fuse or cutout, a movable or shifting
U-shaped tube or chamber containing an insulating material, a T-shaped non-
conducting carrier to which the said tube or chamber is connected and which has
hook shaped conducting catch plates upon it for the said carrier's connection
to the terminals proper of the circuit to be protected, and a fuse wires whose ends
are connected to the catch plates, as aforesaid, and which passes into and is
threaded through the U-shaped tube or chamber, and by which the said tube or
chamber is held in check or suspension against its own gravitation or the action
of a spring, the said threading of the wire within the tube being such as to ensure
the loose end of the fuse wire being drawn into the tube at an increased rate to the
said tubes movement, substantially as set forth.
Fourth. In combination in an electric use or cutout, a vertically moving
U-shaped tube e filled with insulating material and having a leg g, a carrier d of a
T-form, whose waist part is hollow and which carries the aforesaid U-shaped tube,
and which has conducting catch plates c², c³, upon it, terminals a² a³ of the circuit
to be protected with which the catch plates, as aforesaid, engage, and a fuse wire
whose ends are connected to the catch plates and which passes into, and is threaded
through, the U-shaped tube or chamber and drawn up so as to hold the said tube or
chamber in check, or in suspension, against its own gravitation or the action of
a spring and so as to multiply the speed of its loose end being drawn into the
said U-shaped tube on the fuse "going" substantially as set forth in Figs. 1 to 7.
Fifth. In an electric safety fuse or cutout, the combination of the fuse wire
having a part of a reduced section or gauge to that of its body, so as to guarantee
the fuse blowing at one end only, and a U-shaped automatically moving or shifting
tube or trough containing oil which is suspended or held in check by the fuse
wire so long as the electric circuit is closed, but is liberated on the fuse "blowing,"
substantially as described and set forth.
Sixth. In an electric safety fuse or cutout of the kind as claimed in the preceding
claims, the combination of a straight-line and a part-rotating movement of the
U-shaped tube, the stationary catch plates or terminals of the carrier, and the fuse
wire, substantially as described in connection with Fig. 10.
1000
Dated
2435
day of
1000
W. P. THOMPSON & Co.,
11, Burlington Chambers, New Street, Birmingham,
Also of Liverpool, London & Manchester,
Patent Agents for the Applicants.