Year: 1886

page_text: Date of Application, 28th Sep., 1886.
Complete Left, 27th Nov., 1886.
Complete Accepted, 7th Jan., 1887.
I, ALEXANDER BERNSTEIN, of 9A, Commercial Road, Pimlico, in the County of
Middlesex, Electrician, do hereby declare the nature of this invention to be as
follows:-
This invention relates to a suitable and simple apparatus to provide against
accidental interruption of a circuit, in which a number of electric lamps or other
devices are placed in series.
Hitherto it has been the practice to use electro-magnetic devices for this purpose,
but all such devices are expensive, cumbersome and complicated, and not as certain in
their action as the device which forms the subject of my present invention, which I
shall now describe.
I shall suppose that a number of glow lamps of low resistance, for example, such
as are known under the name of Bernstein lamps, are placed in series one after
the other. I now arrange around each lamp a shunt of high resistance, produced by
a metallic compound which is of high specific resistance at ordinary temperature. If
the lamp is in proper condition, then only a small part of the total current in the
line will pass through the compound which is thereby not affected. This part of the
total current I shall designate as the normal current. But if the carbon in the lamp
should break and the resistance of the lamp be increased through the formation of
an arc, then the large amount of current (which I call the abnormal current) which
is passing through the compound in the shunt, will effect such local heat in the
same, that a reduction of the metallic compound takes place and a pure metal is
produced, which offers a very low resistance to the passage of the total current,
thereby preserving the continuity of the line.
Almost all metallic compounds are decomposed by heat if the temperature be
sufficiently high, but it is quite evident that those compounds which are decomposed
at a comparatively low temperature and then yield a pure metal of high conductivity
are best suited for the purpose. Such compounds are, for example, oxyde of mercury,
oxyde of silver or of copper, copper nitride, &c.
As some of the metallic compounds are of rather high resistance, they can be
mixed with pulverised Carbon or metal, in order to reduce their specific resistance.
In the same way it is possible to increase the resistance of the mixture by the addition
of a non-conducting substance; several compounds may be mixed together.

page_text: In order to better illustrate the nature of my invention, I will describe the same
by reference to the annexed drawing.
Figure 1 shows the general arrangement of a series circuit in which S. S. represent
switches.; C. C. my improved cut-outs; L. L. lamps and M. a motor. A. A. the line
conveying the current.
The switch is made in such a manner that it either produces a short circuit
in the line and thereby extinguishes the lamp, or, by turning the handle the other
way, allows the whole or total current to pass through the lamp and cut-ont. These
two being in parallel the current divides itself according to the respective resistances.
The switches, the lamps, and the motor are too well known to require further
description and I shall therefore now describe the peculiar construction of my auto-
matic cut-out, which is shewn in figure 2.
The cut-out consists of an insulating shell D, preferably made of glass, which
carries the metallic stoppers E and I, on each end respectively. The conducting
wires are attached to these stoppers which therefore form the electrodes. The
stopper E, has a recess which contains the metallic compound G, in the form of a
button, shown black in the drawing.
The stud F. which presses on the compound G, passes in the form of a screw
through the stopper I.
The button is advantageously made in the following manner; the metallic
compound, for example, oxyde of silver is mixed with a very slight addition of
carbon powder and brought into a pasty state by the addition of a small amount of a
concentrated solution of sugar or gluo or any other similar material which gives the
desired consistency. This mixture is then dried, pressed in forms and is then ready
for use.
It may be noted that Carbon alone has the peculiarity of a reduction in resistance
when hot, but this reduction is by no means sufficient for the purpose.
I have further tried to produce a mere contact of high resistance between the
pieces E. and I, with the view of decreasing the resistance of contact by fusion of
the metal in case the current through the shunt is increased. But this method has
proved unsatisfactory and unreliable.
Although I have described the metal compound G as being a separate piece it will
be obvious that it can be formed by chemical action directly on the end of either of
the electrodes E or I, or on both.
The action of my improved cut-out is as follows; If the switch $ (figure 1) is
turned so as to divert the current into the lamp, and this in proper condition, then
only a very small part of the current will pass through the cut-out, which is thereby
not affected. The cut-out now receives what I have called its normal current. But if
the carbon in the lamp should give out, then a current of abnormal strength passes
through the cut-out and immediately decomposition of the compound commences.
In practice I find that if the E M F between the lamp terminals is increased three
times the normal amount, then the resistance of the cut-out, which was 40 ohms is
reduced to what may be considered practically nothing in about ten seconds.
In replacing a lamp a new cut-out is put in the place of the old one.
The cut-outs
are generally located inside the switch S.
G. F. REDFERN,
4, South Street, Finsbury, London,
Agent for the Applicant.

page_text: I ALEXANDER BERNSTEIN, of 9A, Commercial Road, Pimlico, 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 :-
This invention relates to a suitable and simple apparatus to provide against
accidental interruption of a circuit in which a number of electric lamps or other
devices are placed in series.
Hitherto it has been the practice to use electro magnetic devices for this purpose
but all such devices are expensive, cumbersome and complicated and not as certain in
their action as the device which forms the subject of iny present invention which I
shall now describe.
I shall suppose that a number of glow lamps of low resistance, for example, such as
are known under the name of Bernstein lamps are placed in series one after the other.
I now arrange around each lamp a shunt of high resistance, produced by a metallic
compound which is of high specific resistance at ordinary temperature. If the
lamp is in proper condition, then only a small part of the total current in the line will
pass through the compound which is thereby not affected. This part of the total
current I shall designate as the normal current. But if the carbon in the lamp
should break and the resistance of the lamp be increased through the formation of
an are, then the large amount of current (which I call the abnormal current) which
is passing through the compound in the shunt, will effect such local heat in tho
same, that a reduction of the metallic compound takes place and a pure metal is
produced, which offers a very low resistance to the passage of the total current,
therefore preserving the continuity of the line.
Almost all metallic compounds are decomposed by heat if the temperature bo
sufficiently high, but it is quite evident that those compounds which are decomposed at
a comparatively low temperature and then yield a pure metal of high conductivity are
best suited for the purpose. Such compounds are, for example, oxyde of mercury,
oxyde of silver or of copper, copper nitride, &c.
As some of the metallic compounds are of rather high resistance, they can be
mixed with pulverised carbon or metal in order to reduce their specific resistance.
In the same way it is possible to increase the resistance of the mixture by the
addition of a non-conducting substance. Several compounds may be mixed together.
In order to better illustrate the nature of my invention I will describe the same by
reference to the drawing filed with my Provisional Specification.
Figure 1 shows the general arrangement of a series circuit in which S, S,
represent switches, C,C, my improved cuts-out, L, L, lamps and M a motor, A, A, the
line conveying the current.
The switch is made in such a manner that it either produces a short circuit in the
line and thereby extinguishes the lamp, or by turning the handle the other way,
allows the whole or total current to pass through the lamp and cut-out. These two
being in parallel the current divides itself according to the respective resistances.

page_text: The switches, the lamps and the motor are too well known to require further
description and I shall therefore now describe the peculiar construction of my
automatic cut-out, which is shown in figure 2.
The cut-out consists of an insulating shell such as D, made of any suitable
insulating material (or of strips of insulating material) which shell or which strips
carries or carry the metallic stoppers E and I on each end respectively. The
conducting wires are attached to these stoppers which therefore form the electrodes.
The stopper E may have a recess for containing the metallic compound G, in the
form of a button, shewn black in the drawing or the metallic compound may be
placed directly on the surface of the stopper.
The stud F, which presses on the compound G, passes in the form of a screw
through the stopper I.
The metallic compound is advantageously made in the following manner; the
metallic compound, for example, oxyde of silver is mixed with a very slight addition
of carbon powder and brought into a pasty state by the addition of a small amount
of a concentrated solution of sugar or glue or any other similar material, which gives
the desired consistency. This mixture is then dried, and is then ready for use.
It may be noted that carbon alone has the peculiarity of a reduction in resistance
when hot, but this reduction is by no means sufficient for the purpose of my invention.
I have further tried to produce a mere contact of high resistance between the pieces
E and I with the view of decreasing the resistance of contact by fusion of the metal
in case the current through the shunt is increased. But this method has proved
unsatisfactory and unreliable.
Although I have described the metal compound G as being a separate piece it will
be obvious that it can be formed by chemical action directly on the end of either of
the electrodes E or I or on both.
The action of my improved cut-out is as follows:- If the switch S (figure 1) is
turned so as to divert the current into the lamp and this is in proper condition, then
only a very small part of the current will pass through the cut-out, which is thereby
not affected. The cut-out now receives what I have called its normal current.
But if the bon in the lamp should give out, then a current of abnormal strength
passes thr the cut-out and immediately decomposition of the compound commences.
In practice I find that if the E. M. F. between the lamp terminals is increased
three times the normal amount, then the resistance of the cut-out, which was 40
ohms is reduced to what may be considered practically nothing in about ten seconds.
In replacing a lamp a new cut-out is put in the place of the old one. The cut-
outs are generally located inside the switch S but it will be obvious that a cut-out
based on my principle of construction may be placed inside the lamp.
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-
1. An automatic electric cut-out consisting of two electrodes between which is
placed a metallic compound which offers a comparatively high resistance to the
passage of the current of normal strength but is decomposed by a current of
abnormal strength and then becomes of low resistance.
2. In an electric circuit, in which electric devices are placed in series, the use of a
cut-out containing a metallic compound, which is reduced to a metallic state by
reason of an abnormal current passing through it.
3. The manufacture and use of the improved automatic electric cut-outs herein-
before described.