Improvements in Electric Arc Lamps.
Year: 1892

page_text: Date of Application, 15th Nov., 1892-Accepted, 31st Dec., 1892
Improvements in Electric Arc Lamps.
A communication from THE HIGHAM ELECTRIC COMPANY, of Portland, Maine,
United States of America.
I, CHARLES AUBREY DAY, of 321 High Holborn, in the County of London,
Chartered Patent Agent, do hereby declare the nature of the said 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 electric arc-lighting, and the object of the invention is
to provide means whereby the feeding of the carbon of an arc lamp in a circuit
will not materially affect the current supplied to the other are lamps in the same
circuit, the general object being to increase the stability and steadiness of the
current.
In the accompanying drawing:
:-
Fig. 1, represents diagrammatically a simple and well-known form of clutch
lamp having differential coils and provided with the present improvements.
Fig. 2, is a view illustrating a modification which may be employed in carrying
out the invention.
Referring to the particular construction of arc lamp illustrated in Fig. 1,
A represents the upper carbon carried by the movable carbon holder A', while B.
represents the lower fixed carbon. The upper movable carbon or carbon holder
is controlled by a clutch D, one end of which rests upon a support d, on the frame,
while the other end is connected through a link d', to a lever L, pivoted at l. One
arm of this lever carries a solenoid core l', acted on by a coarse wire coil C, in the
main circuit which tends to draw the core within the coil and also acted upon by a
fine wire coil S, in a shunt circuit which tends to move the core l', in a direction
the opposite of that imparted to it by the coil C. A spring Q may be employed
to act upon the lever L, against the magnetic action of the coil C. The same arm
of the lever L, which is provided with the spring Q, has a yielding connection with
a variable resistance K, in the main circuit. In the construction shown in Fig. 1,
this yielding connection is through the medium of a dash-pot P, while in the con-
struction illustrated in Fig. 2, the yielding connection is through a rotary fan Pl.
In this modification (Fig. 2), the outer end of the arm L, has a segmental gear
meshing with a pinion 5, having on the same shaft the gear wheel 6, meshing with
a pinion 7, on the axis of the fan, the pinions and gear wheel 5, 6, 7, being carried
by an arm or arms 8, connected with the variable resistance K. In both modifica-
tions the variable resistance is shown as consisting of a series of carbon plates K,
the conductive property of which is lessened or increased by the pressure brought
to bear thereon by the lever L.
The circuits are as indicated by the arrows in Fig. 1, the fine wire coil S, being
connected in shunt between the terminals X, Y, of the lamp. It should here be
mentioned, however, that it is not essential that this shunt coil S, should be con-
nected around the whole lamp, including the variable resistance K, for the lamp
could be adjusted to work with almost equally satisfactory results if the shunt
coil S, were connected around the arc alone, as indicated by the dotted line 9, as
will be readily understood.
The operation is as follows:-
Imagine the lamps to be all adjusted and when burning quietly the movable
carbon of one of the lamps to feed down a little too much. The result, of course,
will be that the shunt coil S, which opposes the effect of the series coil C, will be
weakened, thus causing the coil C, to ease up the weight or pressure upon the
carbon plates K, through the dash-pot P, and thereby to increase the resistance in

page_text: the main circuit of the lamp to compensate for the fall of resistance at the arc.
As the dash-pot or other yielding connection will gradually let go, however, the
resistance of the plates K, will gradually come back to its normal condition and
likewise gradually reduce the current in the shunt coil S, to allow the series coil C,
to gradually raise the movable carbon until the normal potential is restored at
the arc.
If, on the other hand, the currents applied to the lamp should drop or rise in
intensity, the effect will be to increase the resistance at K, when the current rises,
and to decrease the resistance at that point when the current falls. This, as will
be readily understood, is a very valuable feature for insuring steadiness of current
in the working circuit.
It will be readily understood that although but one form of arc lamp with these
improvements has been illustrated, they may be employed in connection with
various other forms of arc lamps.
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 :-
:-
1. An electric arc lamp provided with carbon-feeding mechanism in combination
with a variable resistance connected in series with the carbons and a yielding
connection between the feeding mechanism and the variable resistance whereby
the latter is acted upon by the feeding mechanism to compensate for variations of
the resistance at the arc, substantially as described.
2. An electric are lamp provided with carbon feeding mechanism in combination
with a variable resistance connected in series with the carbons, and means whereby
said variable resistance is acted upon by the current supplied to the lamp through
the medium of a yielding connection, substantially as and for the purpose set
forth.
3. An electric arc lamp provided with differential coils and carbon-feeding
mechanism controlled thereby in combination with a variable resistance and a
yielding connection between the feeding mechanism and the said resistance, sub-
stantially as and for the purpose set forth.
4. An electric lamp provided with a carbon-feeding mechanism in combination
with a variable resistance connected in series with the carbons, a yielding connection
between said feeding mechanisin and variable resistance and means whereby the
current supplied to the lamp increases the variable resistance when the current
rises in intensity and decreases the variable resistance when the current falls in
intensity.
5. An electric arc lamp having shunt and series coils and carbon-feeding
mechanism controlled thereby in combination with a variable resistance in series
with the lamp, and means whereby the said variable resistance is acted upon
through the medium of a yielding resistance, by the shunt coil to reduce its
resistance and by the series coil to decrease its resistance substantially as set
forth.
Dated this 10th day of November 1892
DAY, DAVIES & HUNT,
321, High Holborn, London, W.C., Agents for the Applicant.