Improvements in Means for Controlling Electric Circuits which will allow a Circuit to be Broken and Completed from another Circuit.
Year: 1899

page_text: Improvements in Means for Controlling Electric Circuits which will
allow a Circuit to be Broken and Completed from another Circuit.
I, HENRY EDMUNDS, of 2, Queen Anne's Gate, in the City of Westminster,
Electrical Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention has for its object to provide means for controlling electric circuits
whereby an electric circuit can be broken and completed by means of a current
sent through another circuit. It is more especially intended for use in cases
where incandescent lamps are required to be lighted when arc lights are extin-
guished, but its application is not limited to this purpose. For convenience of
description I will however presume that the invention is applied to such a case,
and from this description the general application of the invention will also be
understood.
In the arc-light circuit I provide an armature and a field therefor, and in
connection with the armature I provide a switch by which the incandescent-light
circuit is completed and broken, the said switch being provided with a permanent
magnet whose poles, when the incandescent-light circuit is broken, are moved
into proximity with a material, such as nickel, or an alloy of nickel, (such as
nickel-steel), whose magnetic properties are neutralized, or lessened, by heat.
The said material is arranged so that it becomes heated by the current passing
through the arc-light circuit. When the arc-light circuit is completed the
armature aforesaid is caused to take up a position in which the incandescent-light
switch breaks the incandescent-light circuit, and the poles of the permanent
magnet of the said switch are in such proximity to the nickel-steel, or the like,
that it is within the range of attraction of the said magnet; but the heating
effect of the are light current on the said nickel-steel, or the like is such that
the magnetic properties of the nickel-steel, or the like, are neutralized, or lessened
to below the degree necessary to hold the switch in its off position, the armature
in the arc light circuit keeping the said switch in the off position. When the
arc light circuit is broken therefore the armature, being no longer controlled by
the current which before maintained it in position, allows the incandescent-light.
switch to move so as to complete the incandescent light circuit. When the incan-
descent-light circuit is to be broken a current is momentarily sent through the
arc-light circuit, so that the armature moves and brings the switch of the incan-
descent light circuit into a position to break the said incandescent-light circuit
and, at the same time, the permanent magnet in connection with the said switch
is brought into proximity with the nickel-steel, or the like, and, as the said
nickel-steel, or the like, is not heated, owing to the arc-light current being put
on but momentarily, the attraction between the said nickel-steel, or the like.
and the magnet is such as to hold the incandescent-light circuit switch in its off
position and thus both the arc and incandescent light circuits are interrupted.
It will be seen that by this invention one circuit only need be led to a central

page_text: In place of the field and armature aforesaid a solenoid and core may be used.
I will describe with reference to the accompanying drawing an apparatus
constructed in accordance with this invention. Fig. 1 being a front elevation &
Fig. 2, a transverse section.
The switch in the lower half of the case A fulfils the same function as does the
switch in the Specification of Letters Patent No. 11181 of 1895 & may be con-
structed as there described.
The apparatus in the upper half of the case is that according to this invention
and cosists of an iron ring R, provided with internal poles P, P, & constituting
a magnetic circuit; which will be laminated when the switch is used for alter-
nating, or rectified, currents.
The armature B has rotary movement through a limited angle within the said
magnetic circuit, the said armature being set at such an angle that the magnetism
excited by the winding C (which is in series with the arc circuit), tends to rotate
the armature B to the position of least magnetic reluctance.
On the armature spindle is fixed a bell-crank lever (two separate levers may of
course be used instead) the arm L of which carries a bridging piece K insulated..
from it and electrically connecting the terminals t, t, so as to switch on the
incandescent lamp.
The arrangement is such that gravity tends to keep the bell-crank lever in
the position in which the incandescent lamp is switched on.
When the arc circuit is switched on, the bell-crank lever is rotated to such a
position that the incandescent lamp is switched off.
Another lover E (which is free to swing on the centre F) carries a stop, or
catch S. When the lever E is in the position shewn in the drawing, and the
arc-circuit is switched off, the bell-crank falls but its movement is arrested by
the hook of the arm engaging the stop S, thus preventing the closing of the
incandescent lamp circuit.
The normal position of the lever E is, however, such that the stop S swings
clear of the hook on the arm l.
The position of the swinging lever E is controlled in the following manner : —
When the arc-circuit is switched on, the arm of the bell-crank lever, or a
projection on the said arm, presses against a projection e on the swinging lever E,
which is thereby moved into the position where the permanent magnet P, M.
carried by its lower end, is brought against, and attracted to, the keeper, or
armature N, of a material whose magnetic properties are affected by heat such as
nickel, or nickel-steel for example. The attraction is sufficient to retain the
swinging lever E in that position.
The keeper or armature, N, is however in series with, or otherwise heated by
the arc-circuit current, so that, when the arc-circuit is switched on, the current
by gradually heating the keeper or armature N, causes it to lose its permeability
to magnetism and thus neutralizes the magnetic attraction, and allows the lever E.
with its stop S, to swing clear of the bell-crank lever which thus falls clear and
switches on the incandescent lamp when the arc-circuit is switched off and the
armature B is released from the attraction of the pole-pieces P, P.
When it is desired to extinguish the incandescent lamp the arc-circuit is
switched on momentarily, the result being that the armature B and lever L 1, are
moved so as to break the incandescent light circuit and move the swinging
lever E, so as to bring the permanent magnet P, M, in proximity to the arma-
ture N, so that the said lever E, is retained in such a position that the stop S,
receives the hook of the arm 7, of the bell-crank lever as it falls on the arc-
circuit being switched off again, and thus the incandescent lamp is prevented from
being switched on again.
In place of a permanent magnet (P,M) on the lever E an electro-magnet may
be used consisting of a core of nickel, or nickel-steel, (or other material which
gradually loses its permeability to magnetism by heat) and a coil, and excited by
the current of the arc-circuit, the swinging lever E, being provided with an