IMPROVEMENTS IN ARC LAMPS
Year: 1884

page_text: 1 JAMES BROCKIE of Brixton in the County of Surrey, Electrical Engineer, do
hereby declare the nature of said invention for IMPROVEMENTS IN ARC LAMPS, to
be as follows:-
According to this Invention I construct arc lamps in an improved manner
whereby they may be made more simple and certain in action. In most lamps
hitherto constructed, the carbons are permitted to approach each other when the
arc becomes too resisting, by means of a brake or detent being lifted off the last
wheel of the retarding trains usual in arc lamps. This brake is generally controlled
by a magnet wound in a shunt circuit bridging the arc; in some lamps of this class
the shunt magnet has a vibratory movement imparted to it when the current
exceeds a certain prearranged limit by a circuit breaker worked by the magnet
itself. I propose to use a star wheel as the last or regulating wheel in any arc
lamp train and its teeth are engaged by a detent controlled by the shunt magnet ;
the detent is insulated from the positive parts of the lamp. Now I wind the
regulating shunt magnet with two coils in series but in opposite directions so that
although a current may exist in the circuit the magnet will be practically non-
magnetized. I now attach a flexible or other conductor to the shunt circuit where
the winding begins in the reverse direction and connect the other end of this
flexible conductor to the insulated detent which engages the star wheel. Now it
will be seen that as long as any of the metal arms of the star wheel make contact
with the detent, one of the coils of the shunt magnet will be cut out, the path of
the current being from the positive star wheel and detent through the coil whose
free end is in contact with the negative of lamp.
Now this coil is the regulating coil and magnetizes the regulating magnet; when
the arc gets too long, this magnet will of course become more powerful and will in
due time lift the detent clear of the metal star wheel, this latter then revolves and
the carbons will approach but as the second or reversing coil is instantly put in
circuit the magnet becomes powerless and the detent drops into the teeth of the
star wheel permitting in practice only, say one tooth to escape at a time. This up
and down movement will continue until the carbons have approached sufficiently to
reduce the arc to its normal resistance. It will be seen that by this method of
arranging the shunt circuit and putting the duty of contact making upon the star
wheel the sparking at the contacts will be much reduced and as each limb of the

page_text: star wheel is a contact, the small sparking is distributed amongst many contacts.so
that they will remain in good condition for a considerable time, the oxidization of
contacts in make and break lamps being a serious objection to their use.
Instead of adopting the reverse winding of the shunt magnet as just described
I sometimes wind it partly on the regulating magnet and partly on a separate
bobbin the flexible conductor attached to the insulated detent being connected at
the junction of the two coils so that, as long as any arm of the star wheel is in
contact with the detent the resistance bobbin is cut out but when the detent is
lifted clear this resistance is put in and so reduces the strength of the regulating
magnet sufficiently to let the detent drop again into the star wheel. This resistance
coil I propose to utilize as a cut out for the lamp should the are become abnormally
long. Or according to a modification of the above I may use the aforesaid star
wheel and split shunt circuit for a step by step feed, viz. to make two detents like
the anchor of a clock escapement which at each oscillation permits only one tooth
to escape at a time. I insulate one of the detents however entirely from every
other part, I attach the flexible conductor which splits the two coils to the anchor
itself which is also in turn insulated from the positive of lamp. Now the normal
condition of this arrangement is that the shunt current traverses both coils because
that detent which is entirely insulated is normally the one engaging the star wheel
so that the current must traverse both coils the short circuit being pratically
broken at the star wheel; when however the regulating magnet becomes too strong
the anchor is rocked and the insulated detent is lifted out and the metallic detent
engages an opposite tooth, the moment this 'takes place, the magnet circuit is cut
out leaving only the resistance bobbin in circuit and thus the magnet is instantly
demagnetized and the anchor is restored to its former position putting in both coils.
again. Instead of using an insulated anchor and detent, the star wheel itself may
be insulated from the positive parts of the lamp, and the short circuiting of the
regulating coil will be effected when the detent is lifted out of the teeth of the
insulated star wheel, for when this lifting takes place, the detent will strike against
a metal stop and so short circuit the magnet momentarily allowing the detent of
course to drop into the insulated wheel as before explained. These two last
methods are simply the reverse of that previously described, viz. in the former case
the resistance coil is cut out, in this latter, the regulating magnet coil is cut out at
each contact of the star wheel.
It will be readily seen that a relay may be used to put any of the above systems
into operation if desired; should the star wheel have a somewhat sluggish
movement all sparking at the relay contacts will be avoided. When a relay is
used the star wheel may be replaced by a simple disc having an insulated brake
piece or shoe instead of a detent to which the flexible conductor is attached, I prefer
in this case to put a sinuous or zigzag band of platinum or other suitable material
on the said disc in order to distribute any sparking which may take place between
the brake contact piece and the disc. A very slow feed of the carbon can be
obtained by this method as the contact making and breaking on the disc is
exceedingly rapid thus stopping and starting the disc at very minute portions of a
revolution. I mount the wheels in an iron frame so that the main magnet usual
in such lamps may attract the frame directly as an armature for the purpose of
obtaining the arc, this method saves levers and armatures and is otherwise
convenient.
Dated this roxanth 3 T. 1001

page_text: I, JAMES BROCKIE of Brixton in the County of Surrey Electrical Engineer do
hereby declare the nature of said Invention for IMPROVEMENTS IN ARC LAMPS
and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement :-
According to this Invention I construct arc lamps in an improved manner
whereby they may be made more simple and certain in action. In most lamps
bitherto constructed, the carbons are permitted to approach each other when the
arc becomes too resisting, by means of a brake or detent being lifted off the last
wheel of the retarding trains usual in arc lamps. This brake is generally controlled
by a magnet wound in a shunt circuit bridging the arc; in some lamps of this
class, the shunt magnet or armature has a vibrating movement imparted to it when
the current exceeds a certain pre-arranged limit by means of a circuit breaker
worked by the magnet itself. Referring to Figure of the accompanying
drawings I propose to use a star wheel C as the last or regulating wheel in an arc
lamp train, and its teeth are engaged by a detent D controlled by the shunt
magnet A, the detent D is insulated from the lever L in contact with the positive
parts of the lamp. Now I wind this regulating shunt magnet with two coils A
and B in series but in opposite directions, so that although a current may exist in
the circuit, the magnet will be practically non-magnetized. I now attach a flexible
or other convenient conductor F to the shunt circuit where the winding begins in
the reverse direction as at R and connect the other end of this flexible or other
conductor to the insulated detent D which engages the star wheel C. Now it will
be seen that as long as any of the metal arms of the star wheel make contact with
the detent as shown one of the coils B of the shunt magnet will be cut out or short
circuited; the path of the current being from the positive star wheel and detent D
through the coil A the free end of which is in contact with the negative of lamp.
Now this coil is the regulating coil and magnetises the regulating magnet; when
the arc gets too long this magnet of course becomes more powerful and will in due
time lift the detent D clear of the metal star wheel, this latter then revolves and
the carbons will approach, but as the second or reversing coil B is instantly put in
circuit, the magnet becomes practically powerless and the detent D drops into the
teeth of the star wheel permitting in practice only one tooth to escape at a time.
This up-and-down movement and consequent partial rotation of the star wheel will
continue until the carbons have approached sufficiently to reduce the arc to its
normal resistance. It will be seen that by this method of arranging the shunt
circuit, and putting the duty of contact making and breaking upon the star wheel,
the sparking at the contacts are much reduced, and as each limb of the star wheel
is a contact the reduced sparking is again distributed amongst many contacts so
that they will remain in good condition for a considerable time; the oxidation of
important contacts in make and brake lamps being a serious objection to their use.
The resistance of the reversing coil B may be very small in comparison with that
of the regulating coil A as it is not necessary to reverse the polarity of the magnet
absolutely, it is only necessary to weaken it sufficiently to allow the lever L
(carrying the detent D) to fall away from the pole of the magnet when the coil is
put in. The regulating coil A may be wound with iron or german silver wire and
the reversing coil B with copper wire, in which case the resistance of the reversing
coil B may be very small in proportion to the other A and the sparking due to the
change of potential be thus reduced if required.
Instead of adopting the reverse winding of the shunt magnet as just described, I
sometimes wind it partly on the regulating magnet and partly on a separate

page_text: bobbin as shewn in Figure 2; the flexible or other conductor Fattached to the
insulated detent D being connected at the junction of the two coils at R so that as
long as any arm of the star wheel C is in contact with the detent D, the resistance
bobbin B is cut out or short circuited, but when the detent is lifted clear, this
resistance is put in and so reduces the strength of the regulating magnet A
sufficiently to let the lever and detent D drop again into the star wheel. This
resistance coil I propose to utilize as a means of cutting out the lamp should the
are become abnormally long. This is readily done by placing an armature W near
the pole of the magnet B which armature is attracted by the magnet when an
abnormally strong current exists in the coil B, and is caused to make contact in a
circuit across the lamp in any convenient manner well known to electricians.
According to a modification of the before described methods of controlling the
regulating wheel of an arc lamp I propose to use the aforesaid star wheel and split
shunt circuit for a step-by-step feed as shown at Figure 3. In this case I make
two detents D1 and D2 like the anchor of a clock escapement which at each
oscillation permits only one tooth to escape at a time. The difference between
this method and that previously described is that the star wheel C cannot escape
more than one tooth at each impulse of the magnet A however fast it may be
impelled by the driving weight of the carbon holder rack.
The insulation of the various parts may be varied considerably without affecting
the principle or practical working of the arrangement. For instance one of the
detents may be insulated entirely from every other part of the lamp and the
flexible conductor which splits the two coils connected to the anchor itself which is
also insulated from the positive of lamp. Now the normal condition of this
arrangement is that the shunt current traverses both the magnet coil A and the
resistance bobbin B (Figure 2) because the detent which is insulated entirely is
the one normally in contact with the metal star or escape wheel so that the
current must traverse both coils; the short circuit being practically broken at the
star wheel, when however the regulating magnet A becomes too strong, the anchor
is rocked and the insulated detent is lifted out and the metallic detent engages
another tooth, the moment this takes place, the magnet circuit is cut out leaving
only the resistance bobbin B in circuit, thus the magnet is instantly de-magnetized
and the anchor restored to its former position putting in both coils again. The
star wheel may be insulated and connections male to obtain the same effect, which
is the opposite to the three first methods viz: in the former cases the resistance or
reversing coil is cut out at each contact of the star wheel and in the latter cases
the regulating magnet is cut out.
The advantage of the two latter methods being, that the resistance of the
contacts through oxidization or feebleness does not alter the regulating circuit, the
contacts being merely used to short circuit the regulating magnet momentarily.
It will be readily seen that a relay may be used to put in or close the circuit of
any of the above arrangements, and should the star wheel have a somewhat
sluggish movement, all sparking at the relay contacts will be avoided.
When a relay is used, the star wheel may be replaced by a simple disc having
an insulated brake piece or shoe instead of a detent, to which the flexible conductor
is attached.
I prefer in this case to put a sinuous or zig zag band of platinum or other
suitable material on the said disc in order to distribute any sparking which may
take place between the brake contact piece and the disc. A very slow feed of the
carbons can be obtained by this method as the contact making and breaking on
the disc is exceedingly rapid, thus stopping and starting the disc at very minute
portions of a revolution. I propose to mount the wheel or wheels in an arc lamp
in an iron frame so that the main magnet usual in such lamps may attract the
frame directly as an armature for the purpose of separating the carbons when the
current is first sent; this method saves levers and armatures and is otherwise
convenient.
J

page_text: 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:-
First. In an electric arc lamp, the employment of a star or contact wheel which
revolves as the carbons approach which star wheel is controlled by a regulating
magnet wound in reverse directions in a circuit across the arc, the detent engaging
such star wheel making electrical contact with the wheel and with the shunt
circuit where the winding begins in the reverse direction so that one coil (called
the reversing coil) is short circuited during the contact of any arm of the star
wheel, but when the detent is cleared of the said wheel the current traverses both
coils and the regulating magnet is thereby reversed or weakened all substantially
as described and as shown at Figure 1 of the accompanying drawings.
Second-In an arc lamp arranging the regulating shunt magnet in series with a
resistance coil, which resistance coil is cut out by the contact of a detent against
the arms of a star contact wheel driven by the weight of the carbon holder or
otherwise when the said detent is lifted out of the teeth of the star wheel the said
resistance is introduced the regulating magnet weakened thereby allowing the
detent to engage the teeth again all substantially as described and with reference
to Figure 2 of the accompanying drawings.
Third-In an arc lamp having this said escape or star wheel detent, arranging
the circuit insulation of the detent so that the regulating coil is cut out at each
contact of the star wheel instead of the resistance coil, for the purposes described
and also with reference to Figures 1, 2 and 3.
Fourth In an electric arc lamp utilizing the said resistance coil (introduced
into the circuit by the non contact of the said star wheel) as a means of cutting
out the lamp should the are become abnormally resisting all as described and
with reference to Figure 2 of the accompanying drawings.
Fifth-In an arc lamp; for the purpose of regulating or controlling the
approach of the carbons the employment of an escape wheel and anchor the said
anchor being controlled by a magnet wound in a shunt circuit across the arc in
reverse directions equally or partially, one of the detents of such anchor making
contact with the said escape wheel and with the shunt circuit where it begins in
the reverse direction thus cutting one set of coils out of circuit the other or
reversing coil being put in circuit when the said detent is lifted clear of the escape
wheel, substantially as described and with reference to Figure 3 of the accompanying
drawings.
Sixth-In an arc lamp, placing the regulating wheel or wheels in an iron frame
which is attracted directly by a main magnet in order to separate the carbons
when the lamp is first lighted.
Dated this Cantl
1004