Improvements in Electrical Cut-outs.
Year: 1897

page_text: Improvements in Electrical Cut-outs.
We CHARLES MARK DORMAN of Ordsal Electrical Works, Salford in the County
of Lancaster, Electrical Engineer and REGINALD ARTHUR SMITH of Ordsal Electrical
Works Salford in the County of Lancaster, 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 :-
Our invention relates to that class of Electrical Cut-outs known as fusible Cut-outs
in which a length of fusible wire or strip hereinafter called the fuse is introduced
into an electrical circuit which wire or strip melts or volatilizes if the current in the
circuit becomes excessive and so breaks the circuit and prevents any further flow of
current.
In cut-outs of this description it frequently happens that when the fuse melts
an electrical arc is formed between the terminals of the cut-out and it consequently
fails to perform its proper function of stopping the flow of current in the circuit
effectually; this is more especially the case if the Electro-motive force in the circuit
is high.
The object of our invention is to prevent the formation of an arc between the
terminals of the cut-out and to make it more quick and certain in its action.
fuse.
It is a common practice when fusible cut-outs are covered in or enclosed in air
tight or approximately air tight chambers to provide holes or vents in the covers or
chambers for the escape of the gases generated by the sudden volatilization of the
Our improvements consist in placing these holes or vents in such a position
in close proximity to the fuse that the sudden rush of gas from the chamber in
which the cut-out is enclosed which takes place when the fuse acts, either prevents
the formation of an arc between the terminals of the cut-out or instantly blows it
out if it should be formed.
Some forms of fusible cut-outs are in common use in which one or more baffle-
plates or bridges of insulating material are placed between or partly between the
terminals of the fuse in order to impede the formation of an arc.
Our invention is
applicable to cut-outs either with or without these baffle-plates or bridges. Our
invention is not applicable to cut-outs which are not enclosed in chambers or boxes.
The drawings accompanying this specification show the application of our
invention to several forms of Cut-outs.
Fig. 1 is a plan of an oblong cut-out, without baffle-plates or bridges with our
improved vent with cover removed. Fig. 2 is a sectional elevation of same on the
line X X with cover. Fig. 3 is the plan of a circular cut-out with cover removed
with two baffle-plates or bridges and our improved vent. Fig. 4 is a sectional elevation
of same on the line X X with cover and Fig. 5 a sectional elevation of same on the
line Y Y with cover. Fig. 6 is the plan of an oblong cut-out with cover removed
with three baffle-plates or bridges and our improved vents. Fig. 7 is a sectional
elevation of same on the line X X with cover and Fig. 8 is a sectional elevation of
same on the line Y Y with cover.
In all the drawings A is the fuse, B₁ B, are the terminals to which the fuse is
attached. C, C are the terminals for attachment of the circuit wires. D is the

page_text: insulating base of the cut-out. E is the cover. The base D and cover E forming
together the box or chamber in which the cut-out is enclosed. F, F, are holes or
vents which are in close proximity to the fuse A for the escape of gases from the
cut out. G, G, G, are baffle-plates or bridges of insulating material between the
terminals. In all the different forms of cut-out the fuses are held closely in front
of the inner opening of the holes or vents either directly by means of the terminals
or by the baffle-plates or bridges, consequently when the fuse melts or volatilizes it is
directly in the path of the rush of gas from the fuse chamber and if an are should
be formed it is instantly blown out. In some cases we prefer to use a shield made
of porcelain or metal placed in front of the outer opening of the holes or vents in
order to prevent the hot gases which issue from them blowing directly on surrounding
objects. Such a shield of a circular form is shown at H, Figs. 3. 4. 5.
The drawings show single pole cut-outs but our invention is also applicable to
enclosed double-pole or multiple cut-outs. In the case of these cut-outs we provide
a vent or vents as shown in the drawings for each separate fuse.
Having now particularly described and ascertained the nature of our said invention
and in what manner the same is to be performed we declare that what we claim is
(1) An enclosed fusible cut-out either with or without baffle-plates or bridges
having a vent or vents in close proximity to the fuse arranged in such a manner
that the rush of gas through the vent or vents when the fuse acts either prevents
the formation of an arc or instantly blows it out if formed, substantially as
described.
Dated th: zl.
1007
CHARLES MARK DORMAN.
REGINALD ARTHUR SMITH.