provements in Alternating Current Arc Lamps.
Year: 1895

page_text: Date of Application, 27th Nov., 1895-Accepted, 28th Dec., 1895
provements in Alternating Current Arc Lamps..
A communication by WILHELM MATHIESEN, of 4 Bahnhofstrasse, Leutzsch, near
Leipzig, in the Empire of Germany, Manufacturer.
I, WILLIAM PHILLIPS THOMPSON F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool and 6, Bank Street,
Manchester, both in the County of Lancaster, 118 New Street, Birmingham in
the County of Warwick and 31 High Holborn in the County of Middlesex, Civil
Engineer, 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 has for its object to utilize the inductive repulsion of rings, coils
or discs, placed in front of the poles of alternating current magnets, for striking and
regulating the arc of light in alternating current are lamps. For this object as
shown in Figures 1 and 2 of the accompanying drawings, two rings c c formed in
one piece with lever d are arranged before the two poles of an electro-magnet
consisting of the coils a a¹, which, two rings c c', with the lever d are caused to
oscillate.
When the magnets are void of current the rings rest on the upper ends of the
coils, by their own weight, which may be further increased by an adjustable
weight; as soon however as the magnet is excited, the lines of force by their
change of direction induce a secondary current in the rings. As this secondary
current, in consequence of the periodic change of phase, practically coincides with
the maximum of density of the lines of force, a strong repulsion takes place
between the lines of force and the secondary current in the direction of the
magnetic axis, or between the magnet poles and the induction rings, whereby
the latter are raised. The lever d, which is formed as an elbow lever, then
oscillates on its pivot e, and its movement is transmitted by means of a draw bar or
link to the running gear which swings on i. This wheel-work or running gear
swings until the fly k is released from a catch g, when the carbon pencils, which
previously stood apart, will run together impelled by the weight of the upper
carbon holder. As soon however as the carbons come in contact, the magnet,
which is considered as being in shunt, becomes instantaneously void of current and
the rings descend by their own weight so that the running gear is again arrested,
and the carbon pencils are separated, thus forming the arc of light.
The further regulating of the arc is effected in the following manner :-
On the maximum tension of the same being reached, the induction rings are
raised so far that the fly k is released a moment from the contact tongue g, and thus
the carbons can approach one another a little, whereupon the rings correspondingly
descend and again effect the stoppage of the running gear.
In order to increase the inductive repulsion with equal magnetic proportions, the
arrangement shown in Figures 3 and 4 is employed, which consists in causing the
magnet cores to project through the rings whereby the diverging of the lines of
force is considerably diminished.
A further increase of the repulsion is obtained by closing the magnetic circuit
by means of a bridge or armature h. This is explained from the fact that the few
lines of force which are not absorbed in passing the one ring are then conveyed to
the other ring where they still come into action.

page_text: In place of a shunt coil, the magnet may also have a main circuit coil with a
suitable alteration in the transmission of the movement. Both coils may also be
utilized in order to produce a differential action in the ordinary well known
manner.
For this latter object two magnets may also be employed, one of which is
provided with a shunt coil and the other with a main circuit coil;
both magnets
may then act either on common or on separate induction rings.
A spring may also be used in place of the weight as counter force to the inductive
repulsion.
The thick induction rings c c may be replaced by a number of thinner discs or
rings or by wire coils short circuited on themselves."
Although of advantage, it is not exactly absolutely necessary that the geometric
axis of the rings shall coincide with the magnetic axis, the induction rings may
therefore also assume an oblique position as shown in Figure 5.
The magnet cores may also have pole pieces arranged at any suitable angle as
shown in Figure 6.
Having now particularly described and ascertained the nature of the said inved-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is :-
1. An alternating current arc lamp characterised by an electromagnet having its
core projecting into or placed opposite to one or more rings or wire coils short
circuited on themselves so as to produce an inductive repulsion in the direction of
the magnetic axis between the magnet core and the rings whereby the striking and
regulation of the are is obtained, substantially as herein before set forth.
2. An arc lamp such as described, characterised by an electro-magnet having its
core projecting through one or more rings or wire coils short-circuited on themselves,
and having its magnetic circuit closed by iron for the purpose of increasing the
inductive repulsion between the magnet and the rings, substantially as hereinbefore
set forth.
Dated this 26th day of November 1895.