Improvements in Electrical Arc Lamps.
Year: 1896

page_text: Date of Application, 3rd Sept., 1896--Accepted, 19th Dec., 1896
COMPLETE SPECIFICATION.
Improvements in Electrical Arc Lamps.
I, HANS CARL MADSEN, of Valby, in the Kingdom of Denmark, 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, and accompanying drawing, that is to say :-
This invention relates to an improved electric arc lamp provided with a simple -
regulating apparatus, not liable to get out of order.
The lamp gives an absolutely steady light, the variation of tension between the
poles of the lamp amounting at the most to one-fourth of a volt.
The improved lamp is illustrated in the accompanying drawing, in which:-
Figure 1 shews the lamp from above, Figure 2 is a side view, Figure 3 a detail,
and Figure 4 a sketch shewing the electrical connections.
Upon the plate B (Figures 1 and 2) which forms the top of the lamp, two
electro-magnets E, and E, are fixed, of which the first E is coupled in series with
the main current, and serves for the production of the arc. The insulated wire of
the other magnet forms a "resistance," or shunt-coil, and this electro-magnet E
serves for the regulation of the lamp, in the manner hereinafter described.
Through the plate B passes the regulating screw S, consisting of a vertical screw
arranged in the lamp itself so that, unlike the arrangement in lamps hitherto used,
it is easily accessible and can be cleaned from dirt and carbon dust without the
lamp having to be taken to pieces. The screw S is supported at its lower end by
a small metal arm a which passes through an opening in one of the supports D of
the lamp, (which is made tubular,) and is attached to the lower end of the bar /
which passes down the tube and the upper end of which is connected to the
armature A of the electro-magnet E which turns upon the centre c. The screw S
is also guided by the metal bracket b, and carries at its upper end a ratchet-
wheel H which is operated by a pawl p upon the armature As, (Figure 1). This
armature As the end of which turns upon the upper end of the screw S, as a pivot,
is acted upon by the electro-maguet E, so that the screw S is turned round through
a space equal to one tooth of the ratchet wheel H every time that this magnet E¹
attracts its armature As.
On the lower side of the armature As (Figures 1 and 2) is a pin or stud » formed
of non-conducting material which is arranged between the two arms of the fork d,
which turns upon
a centre a, connected with the electrical shunt-coil or
"resistance" E, and is normally held against the contact-piece v, so that the
electrical circuit is completed round the electro-magnet E'. If, however, the
current passes through this circuit the electro-magnet is excited and attracts its
armature As, so that the pin r is brought against the other arm of the fork d, which
turns upon its centre, so that the contact at v is broken. The armature A s is then
at once brought back by the spring F, and the pin r brings back the fork into
the position shewn in Figure 1, the circuit being again completed through the
contact. v. The armature As is then again attracted, and turns the fork until
the contact is again broken, and so on as long as the current passes through the
resistance coil E.
Upon the screw S is fitted a nut m which forms part of the upper carbon holder,
and, (if the screw is turned by the arinature As,) is brought down together with
the carbon holder and the positive carbon Ks which is held by the latter. The
nut described and the carbon holder are shewn in Figure 3. The nut m is made
in two halves, each half being carried by one of the arms 3 and 4. The arm 3 turns

page_text: round the pin z in the arm 4, but is held against the latter by the spring u. If
however the knob K is pressed, which is attached to the arm 3 and passes freely
through the arm 4, the arm 3 is pressed out and the nut m opened. In order to
guide the carbon holder during the movement of the nut, it is provided at its other
end with a double fork g.(see also Figures 2 and 3) which fits round the other
vertical support D' of the lamp, and prevents the carbon holder from taking an
inclined position out of its proper place. The latter is also prevented by the lifting
devices which carry the screw S, which ensure the screw always working in a vertical
direction, so that the carbon holder neither binds against the rods which form the
frame, nor can get into an inclined position, which would lead to the light burning
irregularly or going out.
The negative carbon holder is carried in a ball and socket support of the
ordinary kind, consisting of a ball Q which can move in a corresponding socket Q',
so that it can be turned into any position, and the correct position of the carbon
secured. The support or socket Q' is made in two halves which can be drawn
together by screws (not shewn in the drawing,) so that the carbon holder when
once adjusted in position cannot be moved or displaced.
The action of the lamp is as follows (see Figure 4). If the circuit is completed
the current passes from the positive pole, and is divided at o. The principal part
passes through the insulated wire coil of the electro-magnet E, through the carbon
poiuts Ks, and thence to the negative pole, whilst the remainder passes from o
into the "resistance" or shunt coil E', and through the fork d, and the contact v,
and thence to the negative pole. If the circuit through E' is completed as already
described, through the carbons Ks, Ks, becoming too far separated, the armature As
is attracted, the fork d turns on its centre, and the contact at vis interrupted, and so
on as long as the current passes through E'.
By this movement of the armature A s, the screws is turned, and thereby the
nut m and the positive carbon holder are lowered; the screw is evenly and
regularly turned, and the positive carbon point is lowered until the arc is formed.
If new carbons have to be inserted, the knob K is pressed, and the nut m opened
so that it is freed from the screw S, along which it can be moved up and down. The
carbons are then inserted in the usual way.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:-
1. In electric arc lamps, the method of arrangement by which the vertical
screw used for the direct regulation of the lamp is contained in the body of
the lamp itself, so that it can be cleaned without the lamp having to be taken
to pieces.
2. In electric arc lamps, the arrangement of a device for supporting the
vertical screw, so that this screw always works in a vertical direction and
any binding between the moveable carbon holder and the bar on which it works
is prevented.
3. In electrical are lamps, the arrangement of a current breaking device for
breaking at intervals the shunt current, consisting of a fork d turning upon a
centre and connected electrically with the shunt coil, which normally closes the
circuit through the shunt coil, but when the electro-magnet of the latter attracts
its armature, is so turned that the current through this coil is interrupted, the
movement of the armature being rendered in this way absolutely regular, the
current-breaker in its entire movement affording the exact electrical resistance
required, all substantially as described and illustrated.
Dated this 31st day of August 1896
EDWARDS & Co.,
65 and 66, Chancery Lane, London, Agents for the Applicant.