Improved Safety Cut-out Apparatus for a Network of Multiple Electrical Conductors.
Year: 1889

page_text: Date of Application, 16th Nov., 1889
Complete Specfication Left, 22nd July, 1890-Accepted, 6th Sept., 1890
PROVISIONAL SPECIFICATION.
[Communicated from abroad by the firm of SIEMENS & HALSKE, of 94, Markgrafen-
strasse, Berlin, in the Empire of Germany, Electrical Engineers.]
Improved Safety Cut-out Apparatus for a Network of Multiple
Electrical Conductors.
We, SIEMENS BROS. & Co. LIMITED of 12 Queen Anne's Gate, Westminster in the
County of London do hereby declare the nature of this invention to be as follows:-
When two electrical conductors between which a dynamo machine is inserted come
in contact, thereby establishing a short circuit, the current produced by the machine
becomes of undue strength, and may produce combustion through overheating of the
conductors. In order to prevent this, safety fuses are introduced which melt or burn as
soon as the current exceeds a certain strength, and thus interrupt the circuit before
overheating has taken place.
This does not, however, hold good with a network of multiple conductors, and in
particular with the system described in the application for Letters Patent No. 3674
of 1889 in which the current passes in series through several groups of lamps arranged
in parallel.
With this system there is no dynamo machine between two conductors, the terminals
If in this case
of the machine being only connected to the two outermost conductors.
two conductors come in contact the resistance produced by the lamp &c. between
these conductors is reduced to zero, while that of the lamps in the other groups
remains the same.
In this case an increase of the strength of the current will also take place, but as
the resistance of the other groups is maintained, it will not necessarily rise to such a
degree as to be dangerous. The lamps in the other series will however have a much
stronger current passing through them than is requisite for their proper action, and
they are therefore liable to destruction.
This disadvantage can be obviated by the arrangement described in the said
application No. 3674 of 1889 wherein accumulator batteries are introduced into the
circuits; but if with such an arrangement a short circuiting occurs between two
contiguous conductors, the external resistance for the section in question becomes zero,
and in consequence hereof a discharge of the accumulators through the short circuit
will take place with very considerable strength of current, whereby the safety fuses
situated between the accumulators and the short circuit will be burnt or melted.
This arrangement is quite sufficient for the points of junction between the multiple
conductor system and the two conductor system, that is to say, at the honse service
mains, but if a short circuiting takes place between two conductors of a multiple
system, the corresponding safety fuse will no doubt be burnt, but the current supply to
the lamps of the other groups of the system will not be interrupted and the lamps may
consequently be damaged by the increased strength of current.
The present invention relates to constructions of safety apparatus whereby when, in
the above mentioned case, the current in one of the conductors becomes too strong, an
interruption is effected in all the conductors.
For this purpose according to one arrangement all the safety fuses of the multiple
conductor system are embedded in a non conducting combustible mass, so that on the
burning of one fuse this mass will be ignited and will thereby effect the burning or
melting of all the other fuses.
According to another arrangement, there is introduced into each conductor of the
system the coil of an electromagnet through which the current consequently passes;
these clectromagnets are all arranged in close proximity to each other and facing an
armature lever retained by a spring and having a catch holding a contact slide that

page_text: establishes the contacts of all the conductors of the system. On the current in any
one of the conductors becoming too strong, the corresponding electromagnet will
attract the armature lever, causing this to release the contact slide, which will then be
moved by a spring or weight, so as to break the contacts of all the conductors.
According to another arrangement, the conductors have each a mercury contact
introduced in them, consisting of two cups into each of which the one end of the
conductor dips, while the two cups are connected by a fork dipping into them.
The one end of each conductor that dips into one of the cups is formed as a separate
piece, which is connected to the main body of the conductor by a fuse, and such
separate piece acts as a support for the pivotted frame carrying the forked contact
pieces, and it is also connected to a spring tending to draw it up and out of the
mercury.
Thus on the current in any conductor becoming too strong and burning the fuse
connecting it to its separate piece, this will be drawn up by its spring, and in thereby
raising the frame, will draw all the contact forks out of the mercury cups, and thus
break all the circuits.
This tel
1000
COMPLETE SPECIFICATION.
Improved Safety Cut-out Apparatus for a Network of Multiple
Electrical Conductors.
We, SIEMENS BROS. & Co. LIMITED of 12 Queen Anne's Gate, Westminster in the
County of London do hereby declare the nature of our invention and in what manner the
same is to be performed to be particularly described and ascertained in and by
the following statement :-
When two electrical conductors between which a dynamo machine is inserted come
in contact, thereby establishing a short circuit, the current produced by means of the
machine becomes of undue strength, and may produce combustion through overheating
of the conductors. In order to prevent this, safety fuses are introduced which melt or
burn as soon as the current exceeds a certain strength, and thus interrupt the circuit
before overheating has taken place.
This does not however hold good with a network of multiple conductors and in
particular with the system described in the application for Letters Patent No. 3674
of 1889 in which the current passes in series through several groups of lamps arranged
in parallel.
With this system there is no dynamo machine between two conductors, the terminals
of the machine being only connected to the two outermost conductors. If in this case
two conductors come in contact, the resistance produced by the lamps &c. between
these conductors is reduced to zero, while that of the lamps in the other groups remains
the same.
In this case an increase of the strength of the current will also take place, but as
the resistance of the other groups is maintained, it will not necessarily rise to such a
degree as to be dangerous. The lamps in the other series will however have a much
stronger current passing through them than is requisite for their proper action, and
they are therefore liable to destruction.
This disadvantage can be obviated by the arrangement described in the said
application No. 367480 wherein accumulator batteries are introduced into the circuits;
but if with such an arrangement a short circuiting occurs between two contiguous
conductors, the external resistance for the section in question becomes zero, and in
consequence hereof a discharge of the accumulators through the short circuit will take
place with very considerable strength of current, whereby the safety fuses situated
between the accumulators and the short circuit will be burnt or melted.
This arrangement is quite sufficient for the points of junction between the multiple
conductor system and the two conductor system, that is to say at the house service

page_text: mains, but if a short circuiting takes place between two conductors of a multiple
system, the corresponding safety fuse will no doubt be burnt, but the current supply
to the lamps of the other groups of the system will not be interrupted, and the lamps
may consequently be damaged by the increased strength of current.
The present invention relates to constructions of safety apparatus whereby when in
the above mentioned case, the current in one of the conductors becomes too strong, an
interruption is effected in all the conductors.
For this purpose according to one arrangement shewn in vertical section and
sectional plan at Figs. 1 and 1 of the accompanying drawings all the safety fuses a be
&c. of the multiple conductor system are embedded in a nonconducting combustible
mass A so that on the burning of one fuse this mass will be ignited and will thereby
effect the burning or melting of all the other fuses.
According to another arrangement shewn at Fig. 2 there is introduced into each
conductor abcd &c. of the system the coil of an electro magnet a b' c' d' &c. through
which the current consequently passes; these electro magnets are all arranged in close
proximity to each other and facing an armature lever D retained by a spring Gand
having a catch E holding a contact slide F that establishes the contacts of all the
conductors of the system. On the current in any one of the conductors becoming too
strong, the corresponding electro magnet will attract the armature lever D causing
this to release the contact slide F which will then be moved by a spring or weight, so
as as to break the contacts of all the conductors. According to another arrangement
shewn in vertical section and plan at Figs. and 3* the conductors have each a
mercury contact introduced in them, consisting of two cups A. A into each of which
the one end of the conductor dips, while the two cups are connected by a fork C dipping
into them.
The one end of each conductor that dips into one of the cups is formed as a separate
pivotted piece X which is connected to the main body of the conductor by a fuse B
and such separate piece acts as a support for the pivotted frame R carrying the forked
contact pieces C and it is also connected to a spring F tending to draw it up out of
the mercury.
Thus on the current in any conductor becoming too strong and burning the fuse B
connecting it to its separate piece X this will be drawn up by its spring, and in thereby
raising the frame R, will draw all the contact forks C out of the mercury cups, and
thus break all the circuits.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed we declare that what we
claim is:
In a network of multiple electrical conductors, the use of safety cut-out apparatus
connected with all the conductors and so constructed and arranged that when the
current in one of the conductors becomes too strong it effects automatically the
interruption of all the conductors, such apparatus consisting either of an inflammable
mass in which the safety fuses of all the conductors are imbedded, or of an electro
magnet included in the circuit of each conductor the armature of which controls a cut-
out switch for all the conductors, or of any equivalent device for carrying out the
above named object substantially as described.
Dated this 22nd day of July 1890.
ABEL & IMRAY,
Agents for the Applicants.