Year: 1887

page_text: Date of Application, 19th Mar.. 1887
Complete Left, 15th Dec., 1887
Complete Accepted, 20th Jan., 1888
ARTHUR CECIL COCKBURN of 26 Petherton Road, Canonbury, London, N. in the
County of Middlesex, Demonstrator of Physics, in the City and Guilds of London
Technical College, Leonard Street, London E.C. do hereby declare the nature of this
invention to be as follows:-
My Invention relates to safety Devices or fusible cut-outs in electric circuits.
In the well known, usual form of fusible cut-out or safety-catch, the fuse consists of
a wire or strip of lead, tin, copper, or other metal or alloy, which ruptures under the
heating effect of the current when the strength of the current becomes excessive.
Now I have found by experience that where strips or wires of lead, tin or other
similar material are used, if the current is increased beyond its normal value in a
gradual manner rupture does not occur for a long time after the wire or strip is in
a molten condition, its surface becoming coated with a semi-rigid layer of oxide.
Hence such cut outs are unreliable. It is impossible to state what percentage of
excess of current will cause them to act. My invention removes this unreliability
and enables me to make cut outs or safety devices which are more reliable in action.
I employ a wire or strip of metal or alloy, in one or more pieces and capable of
being fused by the passage through it of a current exceeding the normal strength;
the wire or strip being weighted at its middle or other point or points, by one or
more weights fixed to it, or movable along it, in such a manner as to exert a stress
upon it, which on the wire or strip becoming plastic or molten by heat assists its
rupture. I use as a weight either a mere thickening of the strip or wire near its
middle or other point, or a fixed or suspended piece of lead or other suitable heavy
material attached or slung upon the strip or wire. The effect of my device is to
ensure with certainty a break of the wire or strip at the first moment when it is
softened by heat. The fuse is adapted for use either against wall, or ceiling, or upon
or under the floor; being attached to a suitable frame to meet the varying require-
ments. It may be used in every kind of electric circuit, whether for lighting, for
transmission of power, or heat, for electrodeposition, or any other service for which
electric currents whether direct or alternating can be employed; the diameters and
cross sections of the wires or strips, and the sizes of the weights being proportioned
suitably according to the conditions of the electric circuit in which they are to
be used.

page_text: Improvements in Safety Devices in Electric Circuits.
I, ARTHUR CECIL COCKBURN of 26 Petherton Road, Canonbury, London, N. in the
County of Middlesex, Demonstrator of Physics in the City and Guilds of London
Technical College, Leonard Street, London E.C. 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 safety devices or fusible cut-outs for use in electric
circuits.
In the well known usual form of fusible cut-out or safety catch the fuse consists of
a wire or strip of lead, tin, copper, or other metal or alloy, which ruptures under the
heating effect of the current, when the strength of the current becomes excessive.
Now I have found by experience that when these strips or wires of lead, tin, or other
similar material are used, if the current is increased beyond its normal value in a
gradual manner, rupture does not occur for a long time after the wire is in a molten
condition, its surface becoming coated with a semi-rigid layer of oxide. Hence such
cut outs are unreliable, and it is impossible to state with certainty, what percentage
of excess of current will cause them to act. My invention removes this unreliability,
and enables me to make cut-outs or safety devices which are more certain in action.
1 employ a wire or strips of metal or alloy in one or more pieces, and capable of
being fused by the passage through it of a current exceeding the normal strength;
the wire or strip being weighted at its middle or other point or points, by one or more
weights fixed to it, or movable along it, in such a manner as to exert a stress upon it,
which upon the wire or strip becoming plastic or molten by heat, assists its rupture.
I use as a weight, either a mere thickening of the strip or wire near its middle or
other point, or a fixed or suspended piece of lead or other suitable heavy material
attached or slung upon the strip or wire. The effect of my device is to ensure with
certainty a break of the wire or strip at the first moment when it is softend by heat.
The fuse is adapted for use either against a wall, or ceiling, or upon or under the
floor, being attached in a suitable manner, for example by hooks or eyelets to a
suitable frame to meet the varying requirements.
It may be used in every kind of electric circuit, whether for lighting, for trans-
mission of power or heat, for electro deposition or any other service for which electric
currents, whether direct or alternating can be employed. The diameters and cross
sections of the wires or strips, and the sizes of the weights being proportioned suitably
according to the conditions of the electric circuit in which it is to be used.
In order that my said invention may be most fully understood, and readily carried
into effect I will proceed to describe the drawings hereto annexed.
Fig. 1. shows one of the forms of fuse I prefer.
F. F. represents a fusible wire; W. a weight, preferably a small leaden bead,
perforated or split to enable it to be placed upon the wire. If desired it may be
fixed by giving it a squeeze, or it may be fixed in any other suitable manner, or may

page_text: be left free to slide; E. E. eyelets or loops. The employment of an eyelet with the
wire turned into a loop round it, serves to protect the softer metal from injury by the
binding screws or line wire, but I may use the fuse without such loop or eyelet.
Fig. 2. shows the fuse bent with a weight slung or fixed upon it at W.
Fig. 3. represents a method of arranging the fuse and holder, so that it can be
easily attached to the leads. A, B are two pieces of metal so shaped, that the current
on entering say at I, is conducted by metal A, to the point of junction with the fuse
at G, passing along fuse F to H, and out at C. By this means unnecessary crossing
of local lead wires is prevented.
Fig. 4. represents the arrangement of double-pole cut-outs on the same system.
In conclusion, I would remark that I do not claim any arrangement in which the
fusible wire is loaded only on either or both sides beyond the points of connection
with the circuit; as in my invention I employ a load or loads placed upon that part
of the fusible conductor which carries the current.
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:-
1. The system of loaded fusible safety devices substantially as described.
2. The method of connecting a loaded fusible safety device, such as described by
protecting it with metallic eyelets adapted to fix upon clamping pins or screws
substantially in the manner set forth.
3. The method of arranging the loaded fusible safety device, substantially as
described with reference to Figs. III. & IV.
Dated this 15th day of December 1887.