IMPROVEMENTS IN ARC ELECTRIC LAMPS
Year: 1885

page_text: I, ROBERT PERCY SELLON, Electrical Engineer, of Claremont Villas Surbiton, in
the County of Surrey S.W. do hereby declare the nature of my invention for
IMPROVEMENTS IN ARC ELECTRIC LAMPS and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement
My Invention relates to improvements in electric arc lamps whereby steadiness
of regulation or light and non-liability to derangement are ensured; and fracture
of a whole circuit owing to accidental damage to or extinction of one lamp are
guarded against.
.
In order to separate the carbon points when the current passes, so as to strike an
"are" I employ a solenoid or preferably an electro-magnet placed at the base of
the lamp to the armature core is attached in any convenient manner the lower,
usually the negative carbon; so that on the passage of a current through the
solenoid or electro-magnet the armature core is attracted down, and carries with it
the lower carbon, thus separating the carbons to the required distance and
establishing the "arc."
I effect the regulation of the distance apart of the carbon points in my lamp by
means of mechanism placed preferably in the upper portion of the regulator, above
the upper carbon, and enclosed in a suitable box or cylinder.-The feed mechanism
is constructed substantially as follows; a rod, on to which a rack is fixed or cut
carries the upper carbon: a train of any convenient number of wheels gear with
this rack and with one another, and finally terminate in a brake wheel or fly.
When this train of gearing is released the rod descends by gravity.
The gearing is locked by means of a pin or lever impinging on the fly; this pin
or lever being attached to the core of a magnet or preferably a solenoid, wound
with fine high resistance wire on a shunt with the terminals of the lamp, if it is
desired to run the lamps in series, and with heavier wire in series with the arc
striking spool, if the lamps are to be run in parallel. While the lamp is not in action
or during the time that the difference of potential between the terminals of the
lamp, consequent upon the partial separation of the carbon points, is less than that at
which it is desired the carbons should approach one another, the lever or pin before
mentioned locks the gearing and prevents the descent of the carbon rod: but
o soon as the excessive distance apart or consumption of the carbons makes a

page_text: downward feed desirable, the solenoid above mentioned draws down its core, and
allows of the upper rod descending until such time as the diminished difference of
potential between the terminals of the lamp due to an approach of the carbon
points weakens the pull of the electromotive force solenoid and permits the pin or
lever to again lock the gearing, and prevent the descent of the upper carbon rod.
Now should the carbons of the lamp consume to such an extent that the
maximum approach of the upper carbon rod does not allow of the lamp main-
taining an arc' or should the carbons become broken from shock or any accident,
it will be necessary to insert some automatic "short circuiting" arrangement,
whereby the whole circuit shall not be extinguished owing to the failure of a single
lamp.
<r
"
'
For this I provide an electro magnet wound with a sufficient quantity of coarse
wire, forming under certain conditions a "short circuit " across the terminals of the
lamp. In addition to the coarse wire, I wind a suitable amount of fine wire upon
the same magnet, which fine wire I prefer to put in series with the fine wire
surrounding the releasing magnet spool; though they may both be placed inde-
pendently of each other across the terminals of the lamp. When the difference of
potential between the terminals of the lamp becomes too great, owing to con-
sumption of the carbons or accident, sufficient current is shunted through the fine
wire on the "cut out" spool, as I prefer to call it, to enable it to attract an
armature and by so doing to establish a "short circuit" for the series wire wound
upon the
cut out" spool across the terminals of the lamps, which will then of
itself hold up by attraction the armature lever, until such time as the current in
the coarse wire ceases or becomes weakened.
"
Now, it will be obvious that in my Invention as at present described, should a
sudden stoppage of the current occur and the lower "are" striking spool in
releasing its armature, not permit it to come thoroughly into contact with the upper
carbon, or should the attendant in placing fresh carbons into the lamp omit to
provide for contact between the carbon points, a fracture of the circuit will occur
at the lamp; and though the lamp may "cut out" special provision will be
required to enable the gearing to be unlocked and the carbon points to come into
contact, so that the lamp may again produce light. I attain this end, which
constitutes an important feature in my Invention in a simple & reliable manner by
the following device :-I wind upon the "releasing" spool, in addition to the fine
wire requisite for permitting the gearing to be unlocked when the difference of
potential demands it, a suitable quantity of coarser wire which I connect in series
〃 device.
with the heavy wire, wound upon the "cut out" spool and "cut out
This coarse wire therefore only comes into play when the "cut out" operates,
the action of it being as follows: when the current is passing in the circuit, but
from any of the causes previously described the carbons do not form an arc, the
'cut out" will come instantaneously into operation owing to the slight amount of
current passing in the fine wire of the lamp, on the circuit of the heavy wire of the
"cut out" being completed, a current will also circulate in the coarse wire wound
upon the "releasing "spool which will then attract its armature, and by so doing
arc will
unlock the gearing and permit the carbons to come together; when an
at once be struck.]
In order to make my Invention more clearly understood I will now proceed to
describe the accompanying drawing:-
〃
"M M" is the main magnet fixed at the lower end of the lamp, which upon the
current passing, attracts its armature "a" and draws down the lower carbon "c¹,"
thus establishing an arc. The upper carbon "c" is attached to the rack rod "H,"
which engages with the gearing "G," the gearing terminating in the fly "f" and
locked by the lever "L." This lever is attached to the armature core "r" of the
spool "R." This spool is wound with fine wire, and in conjunction with the fine
wire wound upon the "cut out" spool "O," is connected across the terminals of the
lamp, as shewn by the light line surrounding either magnet: and is further wound
with coarse wire, which is connected with the "cut out" device "t" and "cut out'

page_text: spool "O," across the terminals of the lamp, as shewn by the heavy line on the
drawing. Thus when, owing to the consumption of the carbon, the distance between
their points becomes great, the armature of the "releasing" spool "R" is drawn
down and the gearing unlocked, allowing the carbons to approach.
When, owing to total consumption of the carbons or other accidental cause, the
distance between the carbon points becomes excessive, so that the circuit is in
danger of being entirely broken, the increased current shunted through the fine
wire on the spools "R" & "O" causes the latter spool "O" to attract its
armature "t" and establish a short circuit through the coarse wire wound upon
both spools. The coarse wire upon the spool "R" which up to such point had been
inoperative, will now magnetize and attract its armature core "r and thus allow
the upper carbon to feed down to its full or the desired limit.
"
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is
(i) In are electric lamps, wherein a rack rod or rods and gearing are employed,
the combination of the are striking device placed at the base of the lamp, the feeding
mechanism, and short-circuiting device, substantially as hereinbefore described and
illustrated in the accompanying drawings.
(ii) In arc electric lamps, wherein a downward feed of the upper carbon is only
allowed to take place when the Electro Motive Force is above or the current below
its normal, the arrangement consisting of the short-circuiting device and doubly
wound releasing magnet R, substantially as hereinbefore described and illustrated
in the accompanying drawings.