Improvements in the Regulating Devices of Alternate Current Arc Lamps.
Year: 1892

page_text: Date of Application, 19th Oct., 1892-Accepted, 25th Feb., 1893
UUMIDELE
[Communicated from abroad by Messrs. SCHUCKERT & Co., of Nürnberg,
Germany, Engineers.]
Improvements in the Regulating Devices of Alternate Current
Arc Lamps.
I, JOSEPH SINCLAIR FAIRFAX, of 433 Strand, in the County of London,
Patent Agent and Consulting 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, as communicated to me by my foreign correspondents, relates to
improvements in the regulating devices used for adjusting the carbons of alternate
current arc lamps, whereby simplicity and efficiency are attained.
Hitherto alternating current arc lamps have generally been constructed with
regulating or releasing devices_consisting of gearing, and having some form of
brake acting intermittingly. Such devices are dispensed with in the present
invention, while the regulating devices act continuously, and are of great
simplicity.
The invention is based on the known physical principle of rotation by a
periodically shifting magnetic field; and the system adopted is described with
reference to the example following, and the accompanying diagramatic drawings.
In the elevation Fig. 1, a rotatable copper disc c is placed in front of an electro
magnet a, the core of which consists of iron wire, with a horn like or other suitable
shaped pole piece b. If the magnet coils are fed by an alternating current, the
copper disc is rotated, owing to the alternate shifting or travel of the magnetic
wave from the core outwards along the horn shaped pole piece, in the known
manner; the turning power corresponding to the strength of the current and
number of alternations. If the disc c is suitably connected to a carbon holder d,
shown in the diagrams Figs. 1, 2 and 3 by a weighted cord e passing over a
pulley f, tending to bring the top carbon into contact with a bottom carbon
the elements of an arc lamp are enumerated. They may be applied to a single
coil lamp with the main current circulating in the said coil, or as a shunt circuit
lamp having two coils and acting as a differential lamp.
then
In Fig. 2 and following figures, modifications are introduced, which are also
shown in diagram. In the sectional plan Fig. 2 and elevation Fig. 4 a plate of
copper h is placed between the disc c and the pole of the magnet a, and the eddy
currents produced in this plate by the current alternations also effect a periodical
shifting of the field.
In Figs. 5 and 6 are shown an electro magnet a whose poles enclose the disc c
(on the left hand side of the drawing), while the influence of an additional core b¹
A further
also produces the shifting of the field by the currents induced therein.
modification is indicated by the two additional electro magnets on the right hand
side of the said figures (shown by dotted lines) in which the arrangement is thought
to be a differential one. Instead, however, of this latter arrangement, four electro
magnets may be placed symmetrically about one or more dises c, at angles of 90°,
as in Figs. 7 and 8; or grouped two and two together as indicated in Fig. 6.
A periodical shifting of the field may also be produced by putting both electro
magnets in the main current circuit, or both in a derived current circuit, but with
differential windings in each pair, or different shaped cores; whereby different
co-efficients of induction are obtained, and differences effected in the steps of
development.
Finally, Figs. 7 and 8 show an arrangement whereby the magnetic field is
shifted in the well known manner (due to Ferraris) and exerts a turning moment

page_text: upon metallic bodies. In this case the copper disc c may be replaced by a cylinder
of copper or other conducting material; but in the Figures (7 and 8) by a rotating
body of thin iron plates.c, insulated from each other; so that the action of the eddy
currents is replaced by retarding magnetism.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is: :-
In alternate current arc lamps, a constantly acting regulating mechanism or device
having as an essential part a rotating body of metal in which a turning moment is
produced by a shifting magnetic field excited by the carbon consuming current,
substantially as and for the purpose herein shown and described.
Dated this 19th day of October 1892
FAIRFAX. & WETTER,
433, Strand, London, Agents for the Applicant..