Improvements in Connection with Electric Fuses.
Year: 1889

page_text: Date of Application. 13th Apr., 1889
Complete Specification Left, 19th Sept., 1889-Accepted, 26th Oct., 1889
PROVISIONAL SPECIFICATION.
Improvements in Connection with Electric Fuses.
We WILLIAM HARDING SCOTT Electrical Engineer, of Gothic Works King Street
Norwich & LAURENCE PARIS & SCOTT Ltd. Electrical Engineers Gothic Works King
Street Norwich do hereby declare the nature of this invention to be as follows:-
Electric fuses are generally made of more or less fusible metal which is usually a
had conductor of Electricity & when in the form of wire it has to have considerable
mass, in order that it may carry the current & also that it may be readily handled in
putting in the fuse boxes. These fuses on account of their comparatively large mass,
take a very much larger current before they fuse, on a short circuit than when as in
testing them a gradually increasing current is employed; the consequence is that
when magnetic cutiouts are employed in the mains with small fuses in the single
lamp leads, the cut outs invariably go at the same time as or without the small fuse
when there is a short circuit in the single lamp leads.
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In this invention we propose to use for the fuse wire metal of high conductivity
such as copper, silver or silver gilt, enclosing it in little tubes of glass or earthenware
with metal caps at each end to which the fuse wire is soldered. In the fuse boxes are
little clips which when the fuse is inserted make good contact with each of the little
metal caps on the fuse. The clips may be of thin sheet brass or steel and may make
spring contact with each cap of the fuse in three places, one on each side of the cap
and one at the end. When the clips are of steel we prefer to line them with thin
sheet copper, the
copper being best bent over the upright sides of the clip and on one
side it may be left longer so that the leading in wires may be soldered to it or they
may be bent round the screw which holds the clips down.
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WILLIAM HARDING SCOTT.
Reginald Laurence,
William Harding Scott.} Directors.
Arthur F Armstrong. Secretary.
COMPLETE SPECIFICATION.
Improvements in Connection with Electric Fuses.
We, WILLIAM HARDING SCOTT Electrical Engineer of Gothic. Works, King Street,
Norwich and LAURENCE PARIS & SCOTT, Electrical Engineers, Gothic Works, King
Street, Norwich, 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 :-
Electric fuses are generally made of more or less fusible metal which is usually a
bad conductor of electricity and when in the form of wire it has to have considerable
mass in order that it may carry the current and also that it may be readily handled.
Such fuses on account of their comparatively large mass, take a very much larger
current before they fuse, on a short circuit than when as in testing them a gradually..
increasing current is employed, and the consequence is that when magnetic cut outs
are employed in the mains with small fuses in the single lamp leads the cut, outs
invariably, go at the same time as or without the small fuse when there is a short
circuit in the single lamp leads or if magnetic cut outs are not employed an unpleasant
blink is produced in the other lamps on the same circuit.
According to this invention we employ for the fusible device metai of high con-
ductivity such as for instance fine copper silver or silver gilt wire or foil by which
we get the same current carrying power as with ordinary fusible, metal fuses with
only a fraction of the sectional area or mass, and although the fusing temperature:

page_text: may be higher yet the mass to be heated is so much smaller that the current, multi-
plied by the time of flowing which gives the quantity of heat is enormously
reduced.
This high conductivity fuse wire or foil for comparatively small currents is too small
and delicate to be used in the same way as ordinary tin or lead fuse wire therefore
we enclose it in or protect it by tubes containers or supports of a non-conducting
and non-combustible character such for instance as glass or eathenware. At each
end of this tube container or support are caps or the like to which the fusible device
is soldered or otherwise brought into electric contact.
In the accompanying drawing Figure 1 is a section and Figure 2 a plan of a fuse
and holder made in accordance with this invention. Figure 3 shows the removeable
fuse and its container separately. A is the aforesaid fusible wire protected by the
non-conducting and incombustible tube B provided with metal caps b at the ends to
which the respective ends of the wire A are soldered.
In the fuse box or holders C are clips c which when the fuse (A B b) is inserted'
make good contact with each of the metal caps b and thus complete the circuit. The
clips c may be of any suitable conducting material such as sheet brass or steel and
they may make spring contact with each cap b in any suitable way preferably in
three places viz. :-one on each side of the cap and one at the end.
When the clips care of steel we prefer to line them with thin sheet copper, the
copper being bent over the upright sides of the clip and on one side it may be left
longer so that the leading in wires may be soldered to it; or it may bent round
the screws c² which hold the clips c down.
Figure 4 shews the device as applied between the main lead and a branch line. It
is substantially the same as in the foregoing arrangement and the corresponding parts
are marked with the same letters of reference. The clips c are secured to the lead
and branch lines D and E by soldering or in any suitable way and to reduce the
effective length of the fine wire fusible device A we may cover some considerable
portion of it with one or both of the metal caps b which is or are in contact with the
said fine wire. This is shewn on the drawing as being the case with the lower
cap b.
.
Figure 5 shows a modification wherein the fine wire A is brought into contact
with the lead D and branch line E by means of a screw 62 on the lower cap or
plug to which the wire A is soldered the said screw screwing into the lead D and
by wrapping the said wire A over the end of the branch E as at b³. B is the
protecting tube of non-conducting and incombustible material.
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
1. In fuses for electric circuits a wire or the like of high conductivity and very
small sectional area and made of copper, silver, silver-gilt; or the like substantially
as herein before described:
2. In fusible devices for electric circuits a high conductivity fusible wire or
portion of very small sectional area A enclosed in a protecting tube container or
support of a non-conducting and incombustible material the said high conductivity
fusible wire or portion being provided with caps and when in use being seated or
bearing against clips or other contact makers with which the lead wires are in con-
nection substantially as herein before described.
3. The several constructions or arrangements of parts constituting the fusible
devices herein before described and illustrated in the several Figures of the accom-
panying drawings.
Dated this 19th day of September 1889.
Dated this 19th day of September 1889.
W. H. SCOTT.
Laurence, Paris & Scott, Ltd.
Arthur F. Armstrong,
Secretary.