Improvements in Electric Arc Lamps.
Year: 1889

page_text: Date of Application, 9th Apr., 1889-Accepted, 3rd Aug., 1889
COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps.
I FERDINAND AUGUSTE GOBERT, Electrician of 831 rue Notre-Dame-des-Champs
Paris, France 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:-
The object of my invention is the construction of an electric arc lamp in which the
regular feeding of the carbon points is automatically obtained and controled by the
action of a magnetic brake, the focus remaining at a fixed point.
The feeding of the carbons is due to the action of gravity through which the carbon
points are made to approach each other.
The magnetic brako is constituted by means of a piece of soft angle iron or by a
hinged bar attached to the core of a solenoid and acting by friction or pressure upon
a soft iron grooved wheel mounted on a support fixed to the top part of the lamp,
A fine cord, attached by one of its ends to the upper carbon holder and by its other
end to the brake or to the top part of. the lamp passes over the stationary grooved.
wheel and also round another grooved pulley attached to the lower carbon carrier so
that the upper and lower carbon carriors are both suspended from it.
:
The varied motions of the brake and of the grooved wheel determine, regulate and
control the kindling of the lamp, the regular feeding of the carbon points and, con-
sequently the regulation of the apparatus.
In the accompanying sheet of drawings.
Fig. 1. is a side view of the lamp, showing a section through the solenoid. In this
lamp the magnetic brake is constituted by a piece of anglo iron.
Fig. 2. is an elevation of the same lamp. Fig. 4 is a view of the lower carbon
holder.
Fig. 3. is a plan of Fig. 1.
.
Figs. 5 & 6. are an elevation and side view respectively of a lamp provided with a
fine wire coil placed in parallel with the solenoid, the brake being constituted by a
hinged bar.
It will be seen that when the lamp is at rest the action of gravity causes the carbon
points to be in contact. The current on being turned on will circulate through the
carbon points and the solenoid a the moveable core of which will be attracted by the
fixed core c and become magnetized. A thumb screw d regulates the position of
the said core c.
The brake f following the motion of the core 6 and exerting a magnetic influence
over the grooved wheel g carries the later with it in its descent causing it to turn of
a certain quantity.
The cord i, which is attached by one of its ends to the hook fixed inf, and by its
other end to the weight k, passes over the stationary grooved wheel g and supports the
upper carbon holder; it also passes over another pulley ; fixed on the lower carbon
holder, thereby also supporting the latter. The result of the circular motion of the
wheel g is to cause the two carbon points to recede from each other therefore to strike
the arc.
As the carbon points waste, the arc becomes larger its resistance increases and the
current passing through the lamp decreases in intensity; the core 6 therefore becomes
gradually demagnetised and the brake fattracted upward by the action of the
antagonistic spring 1, looses its grip of the wheel 9 and the two carbon points are
brought nearer each other through the action of gravity.
The process of self regulation continues up to the complete wearing out of the
carbon points. It is obtained by a slight variation of current in the solenoid and con-
sequently in the magnetism of the brake f; this variation is adjusted by means of the

page_text: thumb screw d another screw m regulates the tension of the spring 1. The lower
carbon holder n Fig. 4 is moveable in the cross bar o which supports it; the lower
carbon point can therefore be centred to a nicety. It is secured in position by means
of the two screws p. P.
.
The weight k is guided by means of two columns at the lower end of which is
a disc of mica q which, being placed between the arc and the lamp, act as a guide to
the upper carbon, and as a screen against the external dust and that arising from the
wasting of the carbon points.
Instead of being made in the shape of an angle iron, the brake may consist of a
hinged bar (Figs. 5 & 6) the part of which becomes magnetised in the same
manner but in this case the lever facts upon the wheel 9 by pressure instead of by
friction."
With my system of magnetic brake; the simplicity of which is evident, all
mechanism is done away with and the regulation is simple.
The two carbon rods travelling toward each other as explained, the focus remains
at the same point for the two slips of the cord being parallel and vertical, the distance
travelled by the lower carbon is only one half of that travelled by the weight k or at
the upper carbon.
The lamp may be provided with a resistance coil of fine wire A, placed in parallel
with the solenoid a so as to divert the current from the latter in the case of an increase
of the arc resulting from an increase of potential.
The result is to demagnetise the core 6 which will then be attracted by the spring
the weight will descend; causing the lower carbon to ascend and. a corresponding
decrease of the arc will take place.
This is the consequence of the law according to which the current always travels
along the path of less resistance. Should the resistance of the arc increase two or
three fold through the increase of the latter, the current during the period of increase
will pass through the fine wire coil and the effect above described will be produced.
This will allow of the lamps being placed in tension and to be worked by either
continuous or alternate currents.
Having now 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:
1º. The mode of automatic regulation of an electric arc lamp by means of the
action of a magnetic brake constituted by an angle or a hinged lever of soft iron
substantially as herein before described, and illustrated in figs. 1. 2. 3. and 5. 6.
respectively.
20. The mode of suspension of the carbon holders by means of pulleys or blocks
and a cord so as to obtain a fixed focus substantially as hereinbefore described and
illustrated.
30. The use of a fine wire coil mounted in parallel with the solenoid, for
regulating the tension of the current and allowing the lamp to be used in 'series
and with continuous or alternating currents, substantially as herein before described
and illustrated.