Improvements in Apparatus for Opening Electric Circuits to Prevent Damage, Applicable Especially to the Derived Circuits in which Incandescent Lamps are Placed.
Year: 1885

page_text: Improvements in Apparatus for Opening Electric Circuits to
Prevent Damage, Applicable Especially to the Derived
Circuits in which Incandescent Lamps are Placed.
I THORSTEN NORDENFELT of 53 Parliament Street in the City of Westminster
Civil Engineer do hereby declare the nature of any invention for "IMPROVEMENTS
IN APPARATUS FOR OPENING ELECTRIC CIRCUITS TO PREVENT DAMAGE APPLICABLE
ESPECIALLY TO THE DERIVED CIRCUITS IN WHICH INCANDESCENT LAMPS ARE
"
PLACED (a communication to me from abroad by Oscar Fredrik Jönsson of
Stockholm Sweden Engineer) to be as follows:-
To open a derived circuit in which are incandescent lamps in order to protect this
circuit from destruction in the event of short circuiting an apparatus is employed
consisting of attachments each having a clamping screw and each being fixed to an
insulating board they receive the wires of the main circuit. The current passes
from one attachment to a spring and on the end of the spring is a hook which
engages with another similar hook on another spring. Through this spring the
current passes to an electro magnet from which a circuit wire is led to one or more
incandescent lamps whence it passes to and is connected with an attachment clip
on the main lead. On one of the springs an iron piece is attached serving as an
armature to the electro magnet but it is kept remote therefrom.by the elasticity of
the spring. The electro magnet is adjustable and may be moved nearer to or
farther from its armature to regulate the safety apparatus and set it to be operated
by a larger or smaller current as may be required, due consideration being had to
the maximum current which the derived circuit can pass without danger to the
circuit or the lamps. If this maximum is exceeded owing to short circuiting or
other cause the electro magnet by its attraction moves its armature whereby the
springs became detached from one another, an interruption thus occurs and
destruction is obviated. The springs may readily be re-connected.
This automatic current opener is destined to supersede the so called fusible
apparatus hitherto used or the leaden wires introduced in the circuit. It has. the

page_text: following advantages, viz, that it works instantaneously that in consequence of its
great conductive capacity it does not uselessly consume electricity as do the leaden
wires which in order to be able to work must first be heated to fusion and finally
the apparatus may also be adjusted to break contact with different amounts of
current.
Improvements in Apparatus for Opening Electric Circuits to
Prevent Damage, Applicable Especially to the Derived
Circuits in which Incandescent Lamps are Placed.
I THORSTEN NORDENFELT of 53 Parliament Street in the City of Westminster
Civil Engineer do hereby declare the nature of this invention (a communication
from abroad by Oscar Fredrik Jönsson of Stockholm Sweden Engineer) 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 this invention is a safety apparatus which apparatus is inserted
into a derived circuit in which are incandescent lamps in order to protect this
circuit from destruction in the event of short circuiting.
In the Drawings hereunto annexed Figure 1 is a side view and Figure 2 an end
view of the apparatus.
•
This apparatus consists of attachments a. and beach having a clamping screw
and each being fixed to an insulating board, they receive the wires c, and d of the
main circuit. The current passes from the attachment a through the piece e to the
spring f. On the end of the spring fis a hook which engages with another similar
hook on the spring g. Through this spring the current passes to the rail h the
electro magnet i, and the piece k. From k a circuit wire is led to one or more
incandescent lamps whence it passes to and is connected with the attachment clip b
on the main lead d. On the spring g an iron piece 7. is attached serving as an
armature to the electro magnet i but it is kept remote therefrom by the elasticity
of the spring. The electro magnet is adjustable and may be moved nearer to or
farther from its armature to regulate the safety apparatus and set it to be operated
by a larger or smaller current as may be required due consideration being had to
the maximum current which the derived circuit can pass without danger to the
circuit or the lamps. If this maximum is exceeded owing to short circuiting or
other cause the electro magnet i, by its attraction moves its armature 2, whereby

page_text: the springs fand g, became detached from one another (see the dotted lines in
Figure 1) an interruption thus occurs and destruction is obviated. The springs
may readily be reconnected.
This automatic current opener is destined to supercede the so called fusible
apparatus hitherto used or the leaden wires introduced in the circuit. It has the
following advantages viz. that it works instantaneously that in consequence of its
great conductive capacity it does not uselessly consume electricity as do the leaden
wires which in order to be able to work must first be heated to fusion; and finally
the apparatus may also be adjusted to break contact with different amounts of
current.
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
An automatic safety apparatus or circuit opener consisting of an electro magnet
in a derived circuit, and acting upon an armature attached to a spring and retained
in a determined position by the locking of the first spring with another spring
until separated by the attraction of the electro-magnet which thereby causes the
circuit to be opened, all substantially as described.