Improvements in Electric Cut-outs.
Year: 1892

page_text: Date of Application, 21st Jan., 1892
Complete Specification Left, 21st Oct., 1892-Accepted, 26th Nov., 1892
Improvements in Electric Cut-outs.
1, HUGO KORTEN of 4 Stephen Street, Tottenham Court Road, in the County
of Middlesex, Electrician, do hereby declare the nature of this invention to be as
follows:-
This invention relates to improvements in electric cut-outs and is based upon the
fact that when iron is heated beyond a certain temperature it ceases to be attracted
by a magnet.
According to this invention I provide a permanent steel or an electro-magnet
before the poles of which is suspended an iron armature insulated therefrom, and
which, when not attracted by the magnet is lifted away from it by the action of a
weight or spring. The current is made to pass through this armature, and on its
strength exceeding a certain limit the armature becomes heated and ceases to be
attracted by the magnet.
The weight or spring then acts to withdraw the armature and in so doing breaks
the circuit. This principle may be applied in several ways, according to one of
which, two depending copper rods are attached one to each end of the armature,
each rod being arranged to dip into a different mercury contact cup. From these
two cups the current passes through the armature while the same is attracted by
the magnet.
It will be readily understood that on the weight or spring acting to
withdraw the armature from the magnet the copper rods are removed from the
contact cups and the circuit broken.
+
In a modified arrangement the armature acts as a bridge or connecting piece to
convey the current between two terminals up to and against which it is supported
by the attractive force of the magnet. On becoming heated the armature drops
away from the magnet and so breaks the circuit.
It has been found that cut-outs constructed as hereinbefore described may be
employed with continuous or alternating currents with equal success.
Dated this 21st day of Tanu 190
CASTLE SMITH,
Invention" Office, 54, Fleet Street, London, E.C.,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Electric Cut-outs.
I, HUGO KORTEN of 4 Stephen Street, Tottenham Court Road 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 an appliance for cutting out an electrical circuit when
the strength of the current exceeds a certain limit.
In Fig. 1. N S is a permanent magnet whose poles are furnished with two soft
iron pole pieces, preferably shaped as shown in Fig. II. which shows a section of
the said permanent magnet.
A A is a wire made of magnetic material, preferably of iron.
This wire A A. is held by two bent copper contact pieces B₁ and B₁ and is
fastened thereto by the screws S₁ and S₁.
One end of B, dips into a mercury contact cup Q, and its other end is fastened to
the insulating arm 1.

page_text: One end of B dips into another mercury contact cup Qn and its other end is
fastened to the insulating arm I as shown in sketch.
This insulating arm I is fixed to a lever L, which is pivotted at R and carried
by a frame F in such a manner that it can move freely like a see-saw....
The lever L is furnished with an, adjustable counterweight W which is furnished
with a set screw X as shown in sketch.
The iron wire A A is held suspended in the magnetic field N S by this said
magnetic field and consequently the contact pieces B₁ and B₁₁ are held down and
dip into the mercury contact cups Q and Qui respectively.
In order to prevent the iron wire A A from accidently coming into contact with
either of the pole pieces, these latter are covered with thin mica or other suitable
insulating material.
The action of the apparatus is as follows:
The current comes in say at Q₁, from there it passes through the mercury and B1,
thence through the iron wire A A and passes out through. B₁ and Qu
As soon as the current becomes strong enough to heat the iron wire to a high
temperature, this iron wire will lose its permeability, that is a magnet will no
longer attract it, the counterweight W then begins to act and lifts the contact
pieces B₁ and B₁ out of the contact cups and the circuit is broken thereby.
In dealing with large currents it may be deemed advisable to allow only part of
the total current to pass through the iron wire A A and for this purpose I have
provided two additional screws G₁and G, tapped into B, and B₁ respectively, as
shown in sketch. Now these screws can be conveniently used to connect B₁ and B
by means of a wire of copper or other suitable conducting material, thus forming a
shunt to A A.
It has been found that with alternate current the break occurs, sooner than with
continuous current. This is no doubt due to the magnetic disturbance which an
alternating current creates in a wire of magnetic material.
To prevent the iron wire from oxydising it is given a coating of silver or other
suitable material.
It is not essential that the apparatus should have the form as that given in sketch.
Instead of a lever and a weight a spring may, be utilised for pulling the contact
pieces out of the mercury cups and instead of a permanent steel magnet an electro-
magnet may be employed.
I
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 :-
I. An electric cut-out depending for its action on the fact that iron (or steel)
loses its magnetic properties at a high temperature.
11. An apparatus for cutting out an electrical circuit when the current rises
beyond a certain limit, wherein an iron conductor; suspended in a magnetic field,
and forming part of the electrical circuit when held in a certain position by this
field, is pulled out of this field by a weight or spring and thereby breaks the circuit
through the increased current destroying its permeability; substantially as described.
Dated this 20th day of October 1892.
"