Improvements in High Tension Electrical Fuses.
Year: 1893

page_text: Date of Application, 7th Feb., 1893
Complete Specification Left, 2nd Nov, 1893-Accepted, 18th Nov., 1893
PROVISIONAL SPECIFICATION.
Improvements in High Tension Electrical Fuses.
I, DARWIN BATES, of 11 Carleton Road, Tufnell Park, London, N., Electrical
Engineer, do hereby declare the nature of this invention to be as follows:-
According to this invention I construct a high tension electrical fuse of a fuse
wire or assemblage of wires led through a comparatively long passage formed
through a block of incombustible non-conducting material such for example as
plaster of Paris or glass or porcelain.
The passage I make of such a diameter relatively to the size of fuse wire or
wires employed that whenever the wire is fused and an arc passes across from one
terminal wire to the other the blast of air or matter which is thereby caused to be
driven from both ends of the passage blows out the arc and stops the passage of all
current. The fuse wire or wires make of slightly smaller diameter at the centre
so as to ensure that the first fusing of the wire shall take place at the centre of the
passage. The wire or wires may be of any suitable metal. The terminals to
which the ends of the fuse wire are secured at the two ends of the block I place
well away from the ends of the passage to keep them out of the line of blast.
Dated this 7th day of February 1893.
CARPMAEL & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in High Tension Electrical Fuses.
I, DARWIN BATES, of 11 Carleton Road, Tufnell Park, London, N., 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 :-
The object of my invention is so to apply a safety fuse in a high tension or extra
high tension electric circuit as to prevent the permanent establishment of an arc
when the fusible wire is called upon to act. For this purpose I locate the fusible
wire in an open and direct passage formed in a block of insulating material and
arranged between the terminals and I have this passage freely open at its ends.
Under such conditions I find that an arc can be established but cannot be
maintained, the arc being at once blown out by the explosive disturbance which
occurs in the passage at the moment in which the arc is established by the fusing
of the wire.
This explosion which is of a comparatively violent nature in consequence of the
fusing wire being enclosed in the passage causes hot air, volatilized metal, gases,
and indeed all matter contained in the passage to be driven violently out at each
end of the passage, and this blast completely stops the passing of any current, by
blowing out the flame of the arc.
This action depends on there being a free, direct and unobstructed passage for
the escape of the products of the explosion.
In order that my invention may be fully understood and readily carried into
effect, I will proceed to describe the drawings annexed.

page_text: DESCRIPTION OF THE DRAWINGS.
Figure 1 is an elevation full size of a high tension electric fuse holder with its
fuse wire arranged in accordance with my invention. The fuse wire which is of
copper or any suitable material is of a size such that it will fuse and stop the flow
of a current exceeding 250 amperes. The arrangement as shown is suitable with a
difference of potential up to 20,000 volts. The figure is partly in section and one
of the terminals is removed.
Figure 2 is an end elevation of this fuse holder.
The
a is a bed of slate and is a metal terminal firmly bolted to the bed a.
terminal has an arm b¹ to which the conducting cable c is clamped in such a
manner as to ensure a good electrical connection. The terminal 6 has four
fingers on the front and these are opposite to four similar fingers on the back.
The distance between these two sets of fingers is such that it requires some force
to insert between them the blade d aud when the blade is so inserted the electrical
contact between the blade and fingers is good. The blade d is formed upon a
socket d' and into this socket there is inserted and fixed by cement one end of a
block of slate or porcelain or hard incombustible insulating material e. This block
which contains the fuse passage from end to end of it is formed as a handle
preferably circular in section so that it may be conveniently grasped; at its other
end it is provided with another blade d making contact with another terminal.
In short the arrangement is symmetrical, the parts at one end being duplicates of
those at the other end. Each socket d' is provided with a screw nozzle d'. fis
the fuse wire it is passed by means of the passage through the block e from end to
end and is passed out through the nozzles d' which are both slit on one side for
this purpose. The wire f is then led around the nozzle d² and it is clamped by
screwing on the nuts g g.
On the fusing of the fuse wire in the passage formed in the block, air and
metallic vapour rush violently from the point where the first fusing takes place
toward the exits at the extremities of the nozzles and it is this outward rush
which prevents the formation of a permanent arc.
In my high tension or extra high tension electric fuse the fusible wire has a
short and direct path within a free and open passage formed through a block of
non-conducting material.
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 1
claim is :-
A high tension electric fuse, in which the fuse wire is led through a free straight
passage open at its ends and formed in a block of insulating material whereby the
maintenance of an arc on the fusing of the fuse wire is prevented.
Dated this 2nd day of October 1802
D. BATES.