Improvements in Arc Lamps.
Year: 1889

page_text: Date of Application, 1st May, 1889
Complete Specification Left, 30th Jan., 1890-Accepted, 8th Mar.,
1890
PROVISIONAL SPECIFICATION.
Improvements in Arc Lamps.
I, SEBASTIAN ZIANI DE FERRANTI, of 120 Fellows Road, Hampstead, in the County
of Middlesex, Electrician, do hereby declare the nature of this invention to be as
follows:-
This invention has for its object to produce an arc lamp which shall work
efficiently without the use of clockwork or dash pots now used for controlling the
movement of the carbons towards one another.
I construct the lamp in such a manner that when the carbons are too far apart
they are free to be brought towards one another by the action of a weight but if
brought too close are locked and restrained from approaching nearer by a pawl or
clutch which when the distance between the carbons again becomes too great is
put out of action by the movement of the moveable core of a solenoid coil through
which either the current feeding the lamp or a current passing in a shunt around
the lamp passes. I also control the speed at which the carbons when set free can
move towards one another by an electro magnetic brake the electro magnet of
which is sensitized by the passing through its coils of an alternating of inter-
mittent current with which the lamp is fed I use for the purpose a magnetic brake
with closed circuit or circuits preferably with numerous magnetic poles as herein-
after explained. The magnet I cause to hold and retain a disc or other part which
has to move before the carbons can move towards one another At each alternation
the magnet ceases to hold the parts and for an instant the part is free to move-but
the distance it can move at each pulsation of the current is extremely small.
I also construct a lamp in such a way that the two slides which carry the two
carbons are moved towards one another by both being connected to an endless
chain which passes over conducting pullies-one slide being connected to a part of
the chain which moves in one direction when the chain is revolved and the other
to another part which moves in the opposite direction. In this way as the endless
chain is always sustained by the pullies over which it passes the lamp can be used
in any position either in a vertical position with the box containing the controlling
mechanism at the top, or at the bottom or it can be used in a horizontal or any
inclined position as may be desired so long as provision is made for rotating the
endless chain by a weight in a direction to bring the carbons together.
To control the revolving of the chain to bring the carbons towards one another I
preferably cause it to pass over and gear with a spur pinion on the axis of which
is a disc preferably of iron close to one side of which are placed the pole pieces of
the electro magnetic brake.
Preferably I form the magnet of a number of narrow parallel projections standing
out from an iron plate and with the insulated wire through which the current 19 to
be passed wound in between the projections in such manner that on the passing of
a current the projections are magnetised alternately, north, south, so that they form
as it were a number of narrow electro magnets ranged side by side.
Preferably for locking the disc I use a pawl engaging with ratchet teeth formed
around the periphery of the disc This pawl I carry by a lever which is coupled by
a link to the moveable solenoid core.
When the lamps fed by a line of conductors are to be in parallel branch circuits,
the current passing in a branch to the carbons of a lamp is led through the solenoid
coil of the lamp. In this case when the carbons are too close together and too much
current passes the core is drawn in and then permits the pawl to lock the disc or
to turn it back in a direction to separate the carbons. If on the other hand the
carbons become too far apart and too little current passes the solenoid cord drops
and in doing so disengages the pawl by bringing it against a fixed pin or otherwise-

page_text: the disc is then fiee to revolve the speed at which it can do so being controlled
by the magnetic brake
In place of using a pawl adapted to engage with ratchet teeth formed around the
edge of the disc other forms of pawl or clutch might be used to act in a similar
manner
When the lamps fed by a line of conductors are in series and a shunt coil is
provided to convey current past the lamp the solenoid coil may be in the shunt and
the action of the solenoid reversed so that when the carbons are too close and too
little curient is passing through the shunt the dropping of the solenoid core shall
lock the disc or rotate it in a direction to separate the carbons.
In place of the armature of the closed circuit magnetic brake being a disc it
might be a rod or plate attached to either of the carbon slides or to other part of
the lamp which has to move to allow the carbons to be brought together.
For example an iron rod may be used to carry a carbon in the ordinary way and
the guides through which the rod falls be made to form a magnetic brake so as only
to let it fall slowly whilst a clutch or pawl on a lever may be used to raise the rod
and so separate the carbons-or if allowed to fall may become disengaged from the
rod and so perunt the rod to descend and bring the carbons together.
Where continuous or approximately continuous currents are used, the magnetic
brake may have substituted for it a copper wheel placed in a strong magnetic field
obtained from the current passing through the lamp, preferably the field should be
made of a circle of magnets such as are used in my alternating dynamo, as this would
give the greatest amount of Foucault currents and consequent retardation in the
disc.
Dated this 1st dose 1000
CARPMAEL & Co.,
Agents.
COMPLETE SPECIFICATION.
Improvements in Arc Lamps.
I, SEBASTIAN ZIANI DE FERRANTI, of 120 Fellows Road, Hampstead, in the County
of Middlesex, Electrician, 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 has for its object to produce an arc lamp which shall work
efficiently without the use of clockwork or dash pots now used for controlling the
movement of the carbons towards one another.
I construct the lamp in such a manner that when the carbons are too far apart
they are free to be brought towards one another by the action of a weight but if
brought too close are locked and restrained from approaching nearer by a pawl or
clutch which when the distance between the carbons again becomes too great is put
out of action by the movement of the moveable core of a solenoid coil through
which either the current feeding the lamp or a current passing in a shunt around
the lamp passes.
I also control the speed at which the carbons when set free can
move towards one another by an electro magnetic brake the electro magnet of which
is sensitized by the passing through its coils of an alternating or intermittent current
with which the lamp is fed. I use for the purpose a magnetic brake with closed
circuit or circuits preferably with numerous magnetic poles as hereinafter explained.
The magnet I cause to hold and retain a disc or other part which has to move before
the carbons can move towards one another. At each alternation the magnet ceases
to hold the parts and for an instant the part is free to move-but the distance it can
move at each pulsation of the current is extremely small.
I also construct a lamp in such a way that the two slides which carry the two
carbons are moved towards one another by both being connected to an endless chain
which passes over conducting pulles-one slide being connected to a part of the
chain which moves in one direction when the chain is revolved and the other to

page_text: another part which moves in the opposite direction. In this way as the endless chain
is always sustained by the pullies over which it passes the lamp can be used in any
position either in a vertical position with the box containing the controlling mechanism
at the top, or at the bottom or it can be used in a horizontal or any inclined position
as may be desired so long as provision is made for rotating the endless chain by a
weight in a direction to bring the car bons together
To control the revolving of the chain to bring the carbons towards one another I
preferably cause it to pass over and gear with a spur pinion on the axis of which is
a disc preferably of iron close to one side of which are placed the pole pieces of the
electro magnetic brake.
Preferably I form the magnet of a number of narrow parallel projections standing
out from an iron plate and with the insulated wire through which the current is to
be passed wound in between the projections in such manner that on the passing of a
current the projections are magnetised alternately north, south, so that they form as
it were a number of narrow electro magnets ranged side by side
Preferably for locking the disc I use a pawl engaging with ratchet teeth formed
around the periphery of the disc. This pawf I carry by a lever which is coupled by a
link to the moveable solenoid core
When the lamps fed by a line of conductors are to be in parallel branch circuits,
the current passing in a branch to the carbons of a lamp is led through the solenoid
coil of the lamp. In this case when the carbons are too close together and too much
current passes the core is drawn in and then permits the pawl to lock the disc or to
turn it back in a direction to separate the carbons If on the other hand the carbons
become too far apart and too little current passes the solenoid core drops and in doing
so disengages the pawl by bringing it against a fixed pin or otherwise-the disc is
then free to revolve the speed at which it can do so being controlled by the magnetic
brake.
In place of using a pawl adapted to engage with ratchet teeth formed around the
edge of the disc other forms of pawl or clutch might be used to act in a similar
manner
When the lamps fed by a line of conductors are in series and a shunt coil is
provided to convey current past the lamp the solenoid coil may be in the shunt and
the action of the solenoid reversed so that when the carbons are too close and too
little current is passing through the shunt the dropping of the solenoid core shall
lock the disc or rotate it in a direction to separate the carbons.
In place of the armature of the closed circuit magnetic brake being a disc it might
be a rod or plate attached to either of the carbon slides or to other part of the lamp
which has to move to allow the carbons to be brought together.
For example an iron rod may be used to carry a carbon in the ordinary way and
the guides through which the rod falls be made to form a magnetic brake so as only
to let it fall slowly whilst a clutch or pawl on a lever may he used to raise the rod
and so separate the carbons-or if allowed to fall may become disengaged from the
rod and so permit the rod to descend and bring the carbons together.
Where continuous or approximately continuous currents are used, the magnetic
brake may have substituted for it a copper wheel placed in a strong magnetic field
obtained from the current passing through the lamp, preferably the field should be
made of a circle of magnets such as are used in my alternating dynamo, as this
would give the greatest amount of Foucault currents and consequent retardation in
the disc.
This arrangement may also be used for alternating currents.
In order that my said invention may be fully understood and readily carried into
effect I will proceed to describe the drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 of the drawings annexed is a vertical section and Figure 2 a side
elevation partly in section of a lamp constructed according to my invention.
Figure 3 is another side elevation of the lamp with the solenoid core in its lowest

page_text: position and the carbon holders brought together. Figure 4 is a transverse section
through the line A B Figure 2. Figure 5 a transverse section through the line C D
Figure 2, and Figure 6 a plan view Figure 7 is a transverse section through the
line EF Figure 2, and Figure 8 a section through the line GH Figure 9 is a
diagram view of a modification in which the magnet is applied to hold a rod which
is attached to one of the slides that carry the carbons. Figure 10 shows a modifica-
tion applicable to continuous current lamps
In Figures 1 to 8 A is a cylindrical casing, B B two tubular rods descending
from the bottom of the casing and at their lower end coupled together by a cross
bar B. A is the cover of the casing A it has projections descending from it
which carry solenoid coils C and bearings for the axis of a toothed pinion D which
has fast with it an iron disc E. The cover also carries an iron plate which has a
number of parallel projections M standing out from it which come into close
proximity to one side of the disc and form the pole pieces of a multiplo pole
electro magnet
F is an endless chain passing over and gearing with the pinion D
and over guide pullies G G G G which are at the top and bottom of the tubes B.
The chain passes down through the tubes and on one side is coupled by a pin H¹
to a slide H which slides over the exterior of the rod The pin H₁ passes through
a slot in the tube. Similarly on the opposite side the chain is coupled by a
pin I to a slide 1. The slides H I carry the carbons J as shown and the upper-
most slide His made heavier than the slide I and its weight tends to revolve the
chain in a direction to bring the slides together
The holder in which the uppermost carbon is held is insulated from the slido H
and is coupled by a flexible insulated conductor to an insulated conductor K¹ coming
from the terminal K. Another conductor coming from the other terminal Lis
wound in and out amongst the iron pole pieces M so as when a current is passed
through the conductor to magnetize them alternately North-South-the
ductor is then coupled to the coils C and from them to the upper end of the
rod B on which the slide I slides
con-
The disc E has ratchet teeth formed around its periphery and a pawl N carried
by one arm of a lever O engages with the teeth when the arm is drawn into its
downward position by the spring 01. The other arm of the lever is coupled by a
link O to the movable iron core P of the solenoid. When too little current is
passing the solenoid the core drops and the pawl N is carried upwards; its inclined
lower end then comes against a fixed pin R and the pawl is thereby disengaged
from the teeth on the disc-the carbons then begin to move together as above
explained. When by the bringing together of the carbons more current is allowed
to pass and the core is consequently drawn upwards into the solenoid the pawl is
carried downwards away from the pin R and again engages with the ratchet teeth
on the disc and if too much current is passing it turns the disc in a direction to
separate the carbons So long as the pawl is engaged the distance between the
carbons is controlled by the position of the solenoid core
As the iron pole pieces of the electro magnet M are magnetized alternately
North South and their extremities are in close contiguity with one side of the iron
disc E a series of closed magnetic circuits are created which securely hold the disc
from rotating so long as current passes but momentarily release it at each alternation
in the current as above explained.
At Figure 9 I have shewn a diagram view of a modification of the construction
shewn in the above described figures. In this modification the upper slide His
shewn to have an iron rod S rising up from it and having ratchet teeth on one of
its edges. The multiple pole electro-magnet M acts upon this rod. The movable
core of the solenoid C is coupled to a lever O carrying a pawl N as in the first
described construction. The pawl engages with the ratchet teeth of the rod S when
the solenoid core is raised and is disengaged from the teeth by a fixed pin R when
the core drops A ring or other clutch may be substituted for the pawl and, ratchet
teeth In other respects the lamp may be constructed as shewn in the previously
described figures and acts just in the same way.

page_text: At Figure 10 I have shown a diagram view of a modification to be made in the
lamp shewn at Figures 1, 2 and 3.
In this modification the iron disc E on the axis of the pinion D with which the
endless chain F gears is replaced by a tooth wheel T which is made to gear with a
small pinion U on an axis which carries a copper or other metallic disc E¹ the
multiple alternate magnet poles are ranged in a circle or circles concentric with this
axis and are brought into close proximity with the disc. In this way the disc has to
be rotated to bring the carbons together, the Foucault currents generated in the
disc when it is turned greatly retard its movement and consequently the carbons can
only move slowly towards one another.
-
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. An electric arc lamp in which a multiple pole electro magnet energized by the
alternating or intermittent current with which the lamp is fed acts on an iron disc
or other part so that magnetic circuits are completed through the disc which con-
sequently is locked by the magnet except for an extremely short interval between
successive pulsations.
2. An electric arc lamp in which a disc of copper or other metal has to be revolved
within a strong magnetic field produced by the current feeding the lamp to allow of
the carbons moving together and thereby retards their movements.
3. The combination of a multiple pole or closed circuit magnet; an iron disc or
part moving with the carbons under the control of the magnet, a clutch or pawl
acting to stop the carbons from approaching one another if sufficient current is
passing and a solenoid acting to release the clutch or pawl when too little current is
passing.
4. The combination of a disc or part moving with the carbons and under the
control of suitable retarding mechanism, a pawl or clutch engaging with the said
disc or part; a solenoid and core controlling the pawl or clutch and releasing it when
from the burning of the carbons it becomes necessary to permit the said disc or part
to advance independently of the solenoid.
5. The construction of electric arc lamps substantially as herein before described
and illustrated in the drawings annexed.
Dated this 21st day of January 1890.
CARPMAEL & Co.,
Agents for the Applicant.