Year: 1888

page_text: I, SEBASTIAN ZIANI DE FERRANTI of 120 Fellowes Road, Hampstead in the County
of Middlesex Electrician do hereby declare the nature of this invention to be as
follows:-
Ordinarily electrical safety fuses are formed of a fine wire which is introduced into
the electrical circuit and which fuses if too much current is passed through it.
When used in circuits of high tension such fuses are inefficient as even when a fuse
wire of considerable length is used the current does not cease to pass even when the
wire has been fuzed-the current continues to pass from one terminal to the other as the
metallic particles or vapour left in the casing by which the fuse is surrounded serves to
convey it. I remedy this by making the casing by which the fuse wire is surrounded
to fit to the wire at one or more points of its length whilst open spaces are left
between the wire and the sides of the cases at the remaining parts of its length. Or
discs of asbestos or like insulating material may be placed at intervals across the
interior of the casing and the wire inade to pass through them or a single disc might
be used.
Or in place of the wire being surrounded in places by refractory material in the
above manner the wire may be made thin so that when overheated, the thin parts may
fuse and the remainder drop away without fusing.
D
1511 1
.1
1000

page_text: I, SEBASTIAN ZIANI DE FERRANTI, of 120 Fellowes Road, Hampstead, in the
County of Middlesex, Electrician, 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 :-
Ordinarily electrical safety fuses are formed of a fine wire which is introduced into
the electrical circuit and which fuses if too much current is passed through it.
When used in circuits of high tension such fuses are inefficient as even when a fuse
wire of considerable length is used the current does not cease to pass even when the
wire has been fused-the current continues to pass from one terminal to the other as
the metallic particles or vapour left in the casing by which the fuse is surrounded
serves to convey it. I remedy this by making the casing by which the fuse wire is
surrounded to fit to the wire at one or more points of its length whilst open spaces
are left between the wire and the sides of the cases at the remaining parts of its
length. Or discs of asbestos or like insulating material may be placed at intervals
across the interior of the casing and the wire made to. pass through them or a single
disc might be used.
Or in place of the wire being surrounded in places by refractory material in the
above manner the wire may be made thin so that when overheated, the thin parts may
fuse and the remainder drop away without fusing.
The drawing annexed shews an electrical safety fuse constructed in the manner I
prefer for carrying out my invention.
Figure 1 is an elevation Figure 2 a longitudinal section of the safety fuse and
Figure 3 a plan and Figure 4 a cross section with the cover removed. It consists of
an oblong block of earthenware having in it near each end a cavity A and a narrow
slit B passing from one cavity to the other and having at intervals on opposite sides
of the slit semi circular recesses B¹.
Into each of the cavities A is cemented a metallic terminal block C. Each block C
has a hole through it into which the end of a wire conductor can be inserted and
clamped by the screw D and also has formed through it another hole into which can
be inserted a metallic peg F which has one end of a fuse wire G secured to it.
HH are blocks of vulcanite or other insulating material into which the upper ends
of the pegs are secured and which serve as handles by which the pegs may be held
safely whilst being inserted into or withdrawn from the socket holes. I is a cover of
earthenware by which the slit in which the fuse wire lies is covered over-it can be
slidden endwise and removed whenever desired.
At Figure 5 I have shewn a fuse wire made thin in places and made of a length to
ensure that when the wire is fused at any point the wire shall drop away. The wire
might if desired be weighted near to the portion where it is made thin so as to ensure
the wire quickly dropping away when the thin portion has been fused.

page_text: Having now particularly described and ascertained the nature of my said inven
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. An electrical safety fuse in which the fusible wire conductor is passed through
narrow holes or slits in partitions of insulating material substantially as described.
2. An electrical safety fuse constructed substantially as herein before described and
illustrated at Figures 1 to 4.
3. An electrical safety fuse in which the fusible conductor is made thin at one point
of its length whilst the remainder of the wire is unsupported for a sufficient length
for it to drop whenever the thin portion fuses.