Improvements in Electrical Fusible Cutouts.
Year: 1897

page_text: Date of Application, 24th Nov., 1897
Complete Specification Left, 19th Aug., 1898-Accepted, 22nd Oct., 1898
Improvements in Electrical Fusible Cutouts.
I, GUSTAV BYNG, of Nos. 69-71, Queen Victoria Street, in the City and County
of London, Electrical Engineer, do hereby declare the nature of this invention to
be as follows:-
My invention relates to certain improvements in electrical fusible cut outs,
and is especially applicable to the type of cut-out in which the fusible wire or
strip is led or diverted into an enclosed space or chamber formed in or upon the
base or frame of china or other material, for the purpose of enclosing and isolating
a destructive are that may be formed when the fuse is melted. The object of
my invention is to minimise the destructive effect due to the high temperature
developed when such an arc is formed.
I have found in practice that the china, vitrite, or similar material forming
the base and fuse supports, and in proximity thereto, is capable of volatilization,
under the conditions of a high temperature such as that of an electrical arc, thus
contributing towards the maintenance of said arc, until the resulting increase of
temperature causes the interposing walls to crack. In consequence of this, the
terminals are bridged, and the cut-out is destroyed.
In carrying my invention into effect I form the base, frame, or separating parti-
tion or partitions of china, earthenware or vitreous material, or any suitable
insulating and non-inflammable cement, the terminals or connections being fixed
either on the base aforesaid, or on the walls or partitions outside the chamber or
enclosed space in which the fusible wire or strip is suspended. The part of the
aforesaid fuse wire or strip which is intended to melt under an excess of current
is thus suspended in air, within the chamber. Said chamber or enclosed space
is lined or coated with a material which does not volatilize under heat in such a
manner as to maintain an arc after it is started, and is not so liable to be cracked
as china or vitreous material when heated. For this purpose I use preferably
plaster of Paris, or cements of any grade; or I may use wood, vulcanized fibre,
or india rubber, or the like. In addition to coating the inside of the chamber
or enclosed space with such material, I may also coat the exterior thereof, and
the partitions, and sheath the holes through which the fuse wire or strip passes
with the same.
The object is to interpose a film or sheathing of protective material
between the terminals and connections, and the point at which the arc is formed
when the fuse melts. And further, the coating aforesaid prevents the sudden
transmission of heat to the outer walls, frame or base of china. vitreous material
or the like, causing it to crack.
I necessarily vary the manner of applying the aforesaid protective coating,
according to the shape and structure of the cut-out to which it is to be adapted.
1007
FREDK. WALKER.
3, St. Stephen's Road. Upton Park, London, E.,
Agent for the Applicant.

page_text: improvements in Electrical Fusible Cutouts.
I, GUSTAV BYNG, of Nos. 69-71 and SS, Queen Victoria Street, in the City
and County of London, Electrical Engineer, 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 improvements in electrical cut-outs, fuse boxes and the
like, and has for its objects the prevention of damage by the creation and main-
tenance of a destructive arc when a fuse is ruptured by excess of current, and
also to confine the are within a space protected by an insulating and refractory
medium. I effect this by carrying the fuse wire or strip through the partitions
or walls forming part of the base, so that the central part is freely suspended in
the air within the lined chamber hereinafter to be described. Thus the point
of fusion is fixed in the air space, the ends resting upon the china or like base
and the isolating lining, which absorbs part of the heat generated, and causes
it to be concentrated at or near the centre.
I have found in practice that china or like substances become volatilized under
the excessive temperature of an are formed by the rupture of a fuse in an enclosed
space, and that such volatilization tends to maintain a destructive arc, which
eventually cracks the base and cover and is a source of danger to inflammable
objects in proximity thereto.
In order to obviate there disadvantages, I prefer to construct the bases of cut-
outs, fuse boxes, distribution boards and the like, of china, slate, Or
any like substance or material, providing dividing ribs, diaphragmns or
walls of the same substance, which may separate the contacts. T'he
fusible strip, wire or the like is carried through there partitions in
such a manner that rupture may take place at or near the centre, within
a recess or chamber formed by the junction of, or extension of said partition
or partitions. Said recess or chamber is lined with an insulating and refractory
material, such as plaster of Paris, cement, anhydrous fire clay, or any amalgama-
tion of mica, tale or asbestos to form a refractory and isolating medium that will
not, by molecular disintegration, feed the arc, but protect the outer structure.
I may also use a wood, vulcanized, fibre or any like material or substance in
constructing the base without detriment, so that the recess or chamber is lined
as aforesaid, and the arrangement and path of the fuse is set out so that the rupture
shall occur within said recess or chamber, and the air space therein provided.
I have illustrated my invention by the accompanying sheet of drawings in
which Figure 1 is a plan and Figure 2 a sectional elevation of a cut out with
a lined chamber.
Figure 3 shows a plan of a cut out board with spring clips, and Figure 4 is
an elevation of a hollow china fuse holder therefor, and Figure 5 is a cross section
thereof, Figure 6 being a plan of the same. Figure 7 is a cross section of a
cut out board with lined chambers, and Figure 8 is a plan view thereof.
Similar letters of reference indicate corresponding parts throughout the several
views.
These drawings are hereto appended as examples of application, and do not in
any way confine the invention within the limits of the structure therein shown.
In Figures 1 and 2, a base A carries a central boss forming an interior
chamber B which has a sheath or lining C, of refractory material or substance.
Two terminal plates E E' are screwed or otherwise attached to the exterior surface

page_text: of the boss, and are divided by a partition D extending therefrom on either side.
and a cover F closes the whole. The fuse is led from E to E' through the
chamber B; and when the current exceeds the normal to which it is adjusted,
the rupture takes place therein, and if an arc is formed it dies away by reason
of its enclosure within a surrounding refractory medium.
In Figure 3 I show a plan of a cut out board upon a base A with spring
clips EE to receive a fuse holder shown by Figures 4, 5 and 6. Said fuse
holder is preferably constructed of china or the like with a hollow bridge G with
contacts a fitted upon opposite sides thereof.
The section Figure shows the hollow structure, with a lining C of refractory
material as herein before described, which encloses the fuse at each end where
indicated by the dotted lines. leaving the centre clear for fusion. The fuse, being
therein enclosed, behaves when ruptured exactly as in the former example, and
the arc formed is confined within said enclosed space. The projecting contacts a a¹
fit the spring clips E E upon the board A.
In another adaptation of my invention I may construct a cut out board as shown
by the sectional elevation Figure 7, and the plan view Figure 8. in which the
two terminals E E' of each section are divided by a boss or wall H upon the base A,
in which a chamber or chambers B are formed, with a refractory lining C through
which the fuse is led through the orifices bb between the terminals E E. In
this case, as in those hereinbefore described, the rupture of the fuse upon access
of current, and a consequent arc is confined to a protected space beyond which
said arc cannot reach, and is quickly extinguished by reason of the refractory
nature of the sheathing.
In the drawings I have shown a circular chamber, and radial walls or divisions,
but I do not confine my invention to this particular shape or conformation, I
may use a square or polygonal chamber, and arrange the divisions or walls so
as to stagger the direction of the fuse between its terminals, always however,
providing for its rupture within the sheathed or protected chamber, and within an
air space.
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. In cut outs and fuse boxes the arrangement of parts and general con-
struction for the purposes set forth, substantially as herein described.
Second. The construction of china cut outs, fuse boxes and boards with divi-
sions forming a fuse chamber or chambers lined with an insulating and refractory
substance or material, and arranged so that the centre of the fuse wires or strips
is surrounded by air and is ruptured or broken within said chamber or chambers,
and the arc formed is therein retained.
Third. The method of and means for isolating the destructive are in cut-outs
and fuse boxes substantially as described.
Dated this 18th Joy of Aunct 1808
FREDK. WALKER.
73, St. Stephen's Road, Upton l'ark, London, E.,
Agent for the Applicant.