Improvements in or connected with Fusible Electric Cut-outs.
Year: 1896

page_text: Date of Application, 26th Mar., 1896
Complete. Specification Left, 28th, Dec., 1896-Accepted, 20th Feb., 1897
PROVISIONAL, SPECIFICATION.
Improvements in or connected with Fusible Electric Cut-outs.
We ALEXANDER BEWICKE BLACKBURN Manager of The Electric Con-
struction Company Limited of Wolverhampton in the County of Stafford and
WILFRID L. SPENCE Civil Engineer of Dunluce Tettenhall Road Wolverhampton
aforesaid do hereby declare the nature of this invention to be as follows:-
This invention relates to electric cut-outs of the type described in the
Specification of Letters Patent No. 4138 of 1887 and a main feature of this said
invention is the combination with such cut-outs of a bath of oil or the like for
extinguishing the arc which sometimes follows a ruptured fuse, whereby the
arrangement is adapted to circuits of both high and low: tension... According to
this invention each fuse wire which is preferably short and flexible,. is arranged as
a loop over an oil or like bath and is suspended by its extremities, which are
enclosed in or surrounded by tubes sleeves or funnel-shaped. blocks of insulating
and incombustible material, preferably of such diameter that the fuse wire hangs
clear of the sides:
The upper end or ends of the wire is or are secured in fixed terminals, and
tension is put upon them by gravity or spring-loading of the loop..
The fuse wire enclosing tubes, sleeves, or blocks may be independently supported
with their free ends a short distance above, or slightly under, the surface of the
liquid of the bath, or they may form part of the load putting tension on the wire
and so fall with the detached portion into the bath when the fuse ruptures. In all
cases the lower part of the fuse wire is submerged in the oil or liquid, of the, bath
as soon as it is freed by excess.current.
The bridge of the loop is preferably stiffened and increased in cross section to
cause fusion when it occurs to take place within one or both of the insulating tubes,
and also to avoid heating the oil or liquid of the bath.
It is desirable that when a spring is used to load, the fuse, wires it is not itself
either immersed in the liquid of the bath or connected to the circuit, and that it
should throw the freed bridge into the bath like a projectile, as by this means the
arc is instantaneously extinguished.
With regard to the tubes or the like surrounding the fuse wires it is advantageous
to enlarge the lower ends into a funnel or other suitable shape so, that an air blast,
directed into the tube, is formed immediately after the. rupture of the fuse. By
displacement a considerable rise in the level of the liquid. of the bath through the
failing of the disconnected bridge and its weight can be effected, thus reducing the
necessary depth of liquid and economising space.
For convenience of renewal the fuse holder should be readily detachable from
the circuit and for this purpose spring contacts of the chopper or plug types may
be used if the normal current be large, while. gravity-maintained. contacts,
reinforced if necessary by mercury, will be more suitable for the currents. usually
dealt with.
It is preferable that the oil or liquid of the bath be not contained in the removable
portion of the fuse, it is more conveniently. held in a vessel, fixed to the switch-
board; and to facilitate this disposition, the electrical-contacts should be made, or
broken by a vertical movement of the fuse holder.
Dated thie 26th day of March 1906
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.

page_text: Improvements in or connected with Fusible Electric Cut-outs.
We, ALEXANDER BEWICKE BLACKBURN Manager of The Electric Con-
struction Company Limited of Wolverhampton in the County of Stafford and
WILFRID L. SPENCE, Civil Engineer, of Dunluce, Tettenhall Road, Wolver-
hampton aforesaid, 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:-
This invention relates to electric cut-outs of the type described in the
Specification of Letters Patent No. 4138 of 1887 and a main feature of this said
invention is the combination with such cut-outs of a bath of oil or the like for
extinguishing the arc which sometimes follows a ruptured fuse, whereby the
arrangement is adapted to circuits of both high and low tension. The liquid of
the bath may be of any appropriate kind such for instance as oil of a high flashing
point, resin-oil or the like. Water or oil of a low flashing point should of course
not be used.
According to this invention the fuse wire or conductor, the fusible part of
which is preferably short and flexible, is arranged as a loop it being suspended by
its extremities over an oil or like bath preferably so that the lower part is
submerged in the liquid. The extremities or fusible parts are enclosed in or
surrounded by tubes, sleeves or funnel-shaped blocks of insulating and incom-
bustible material preferably of such diameter that the fuse wire hangs clear of
the sides and the upper end or ends is or are secured in fixed terminals and
tension is put upon them by gravity or spring loading of the loop. The said
enclosing tubes, sleeves or blocks may be independently supported with their
lower or free ends a short distance above, or slightly under, the surface of the
liquid of the bath or they may form part of the load, putting tension on the wire,
and so fall with the detached portion into the liquid of the bath when the fuse
ruptures. In all cases the lower part of the fuse descends in the oil or liquid of
the bath as soon as it is freed by excess current.
The bridge of the loop is preferably stiffened and increased in cross section to
cause fusion, when it occurs, to take place within one, or both, of the insulating
tubes or the like, and also to avoid heating of the oil or liquid of the bath.
It is desirable that when a spring is used to load the fuse it is not itself either
immersed in the liquid of the bath or connected to the circuit and that it should
throw the freed bridge into the bath like a projectile, as by this means the arc is
instantaneously extinguished.
With regard to the tubes or the like surrounding the fuse wires they may be
plain or enlarged at their lower ends into a funnel or other suitable shape.
Immediately after the rupture of the fuse an air blast is formed in the tubes or
the like or in the enlargement and directed into the tubes. By displacement a
considerable rise in the level of the liquid of the bath through the falling of the
disconnected bridge and its weight can be effected thus reducing the necessary
depth of liquid and economising space.
For convenience of renewal the fuse holder should be readily detachable from
the circuit and for this purpose spring contacts of the chopper or plug types are
preferably used especially if the normal current be large, but gravity maintained
contacts, reinforced if necessary by mercury can be used for the currents usually
dealt with.
It is preferable that the oil or liquid of the bath be not contained in the
removeable portion of the fuse, it is more conveniently held in a vessel fixed to
the switchboard, and to facilitate this disposition the electrical contacts should be
máde or broken by a vertical movement of the fuse holder.

page_text: In order that the invention may be clearly understood we will describe with
reference to the accompanying drawings an arrangement according thereto.
Figure 1 is a front view of the fuse, part being in section and part in elevation,
and Figure 2 is a plan of the same. The fuse wires F fixed to the terminals T,
are suspended in the asbestos lined glass tubes G. The lower part of the fuse is
greatly increased in section, and stiffened so as to act as a bridge piece F and to
prevent any appreciable heating in the oil bath B. The fuse wires are weighted
by this bridge piece F, and further loaded by the spring S, whose function it is
to rapidly detach and project the bridge piece F2 downwards in the liquid of the
bath or the fusion of either of the fuse wires. The terminals T are fixed to the
porcelain or other insulating holder H, and carry the contacts C, preferably at
the back for connection to the circuit by inserting them into the spring tongues as
shewn in Figure 2. The spring S bears at one end on the underside of the holder
and at the other end is connected to a rod P and both rod and spring pass through
a hole in the holder H and the end of the rod bears on an insulating saddle I
resting on the bridge piece F2. The spring S being in tension tends to pull the
rod 1 downwards. A milled head M at the top and the insulating saddle I at the
bottom enable the rod P to be safely lifted from contact with the bridge piece F.
A handle or lever L may be provided for convenience in detaching and replacing
the fuse holder.
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. A fusible electric cut-out constructed substantially as hereinbefore described
and illustrated in the accompanying drawings.
2. In fusible electric cut-outs the combination with the loaded fuse of the tube
sleeve or the like of insulating and incombustible material surrounding the fuse
wire and a bath in which when the current becomes excessive the detached portion
of the fuse falls or is projected substantially as described and illustrated.
3. In fusible electric cut-outs the combination of a removable loaded fuse carried
in a holder and a bath separate from the said holder and into which the lower
loaded part of the fuse dips substantially as and for the purposes set forth.
4. In fusible electric cut-outs arranged as claimed under the first claiming clause
an auxiliary spring outside the bath and exerting pressure on the detachable
portion of the fuse so as to project it away from the fixed terminals when the
fuse is ruptured substantially as herein before described and illustrated in the
accompanying drawings.
Dated this 28th day of December 1896.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.