Improvements in Electric Arc Lamps.
Year: 1890

page_text: Date of Application, 31st Mar., 1890
Complete Specification Left, 30 h Dec., 1890-Accepted, 31st Jan., 1891
PROVISIONAL SPECIFICATION.
Improvements in Electric Arc Lamps.
We, ALBERT GAY, of 47 Gloucester Road, Brighton, in the County of Sussex,
Electrical Engineer, and ROBERT HAMMOND, of 117 Bishopsgate Street Within,
London, Electrical Engineer, do hereby declare the nature of this invention to be
as follows:-
In an electric arc lamp according to our invention the motive power for regulating
the positions of the electrodes is obtained from two electric motors operated by the
current which feeds the lamp. One motor is traversed by the main current, and is
so proportioned in relation to the resistance against which it works that it remains
at rest when the normal current is flowing; when the current is greater than the
normal this motor commences to rotate and draws the carbons apart.
The second motor is placed in a shunt circuit around the arc, and it is likewise
so proportioned that when there is a normal difference of potential at the terminals
of the motor, it is stationary. When this difference of potential increases beyond
the normal the second motor commences to rotate, and moves the carbon's nearer
together.
The intermediate mechanism between the motors and the electrodes may be of
any suitable kind, such as screws and nuts, or by preference pulleys and cords or
chains. According to one arrangement the two motors are arranged on the same
shaft on which are two pulleys or drums. Secured to these pulleys or drums are
two cords connected to the two carbon holders, and so disposed that rotation of the
shaft moves the carbons in opposite directions. The two motors oppose each other;
at starting, with the carbons in contact, the motor in series with the arc turns the
shaft to establish the arc, and then as the carbons waste the second motor gradually
overpowers the first and feeds the carbons towards each other. When the lower
carbon is stationary, as is often the case, the motor shaft needs only to be connected
to the upper carbon. In a focus-keeping continuous current lamp means are
provided for giving the lower carbon half the motion of the upper one.
The motors may be of any suitable kind. When working with alternate currents,
for which are lamps constructed as herein described are more particularly designed,
care should be taken that the motors are self starting and have no dead point. An
impedance coil is placed in the circuit of the shunt motor when working with
alternate or intermittent currents, for the purpose of regulating its action and the
length of are caused by its operation in one direction.
To obviate an enormous rush of current through the series motor when the carbons
fall together an impedance coil (in the case of alternate or intermittent currents) is
also inserted in the main circuit. This coil is proportioned to allow only the desired
amount of current to pass through it.
n
11-
1000
W. LLOYD WISE,
Per F. J. Brougham.
COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps.
We, ALBERT GAY, of 47 Gloucester Road, Brighton, in the County of Sussex,
Electrical Engineer, and ROBERT HAMMOND, of 117 Bishopsgate Street Within,
5 London, Electrical Engineer, 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 :-
In an electric arc lamp according to this invention the motive power for regulating
Price 8d 1

page_text: the positions of the electrodes is obtained from two electric motors whose rotating
parts are mechanically connected together and operated by the current which feeds
the lamp. One of these motors is connected in series with the electrodes and is
traversed by the main current of the lamp, and the other is connected as a shunt
across the voltaic are in such a manner that the rotative force of the one motor is
opposed to that of the other. By this arrangement in whatever position the
electrodes may be at the time the current is caused to pass through the lamp, the
lighting up of the lamp will be ensured for if the electrodes be in contact at the time
the current is switched on, no current will pass through the shunt motor and
consequently the friction of the lamp will be the only force to be overcome by the
series motor which will therefore draw the electrodes apart and cause the voltaic
arc. If on the other hand the electrodes be separated no current will pass through
the series motor and the shunt motor will move the electrodes together when the
previously described action will ensue. The series and shunt motors are so
proportioned that the rotative force of the one is exactly balanced by that of the
other when the arc is of its normal length, but if the are becomes too long the power
of the shunt motor, will exceed that of the series motor, and cause the electrodes to
approach each other, and if the arc becomes too short, the power of the series motor
will exceed that of the shunt motor, and cause the electrodes to recede from each
other.
The intermediate mechanism between the motors and the electrodes may be of
any suitable kind, such as screws and nuts, or by preference pulleys and cords or
chains.
The motors may be of any suitable kind. When working with alternate currents
for which are lamps constructed as herein described are more particularly designed,
care should be taken that the motors are self starting and have no dead point. An
impedance coil may, in some cases, be placed in the circuit of the shunt motor when
working with alternate or intermittent currents, for the purpose of regulating the
action of the motor and the length of are caused by its operation in one direction.
With a shunt motor constructed as hereinafter described however, this impedance
coil will not be necessary, the action of the motor being regulated by the position
of the closed coil encircling the armature.
To obviate an enormous rush of current through the series motor when the
carbons fall together, an impedance coil (in the case of alternate or intermittent
currents) may be also inserted in the main circuit. This coil is proportioned to allow
only the desired amount of current to pass through it.
If the series motor is a very quick starting one and without gearing so that the
movement of the carbons immediately follows the rush of current, as with a series
motor constructed as hereinafter described, an impedance coil will be unnecessary.
The magnets of the series motor may also be wound so as to give sufficient
impedance thereby dispensing with a separate impedance coil.
In the accompanying drawings,
Fig. 1 is an elevation of an electric arc lamp constructed according to this inven-
tion and adapted to be worked by alternating or intermittent currents.
Fig. 2 is a plan with some of the parts removed.
Fig. 3 is a diagrammatic view.
1 (Fig. 3) is an alternate current motor having its field winding in the main
circuit of the lamp and in series with the carbons 2 and 3, so as to constitute what
is herein referred to as the series motor. 4 is another alternate current motor
having its field winding arranged in a shunt circuit between the carbons and con-
stituting what is herein referred to as the shunt motor. 1ª is an impedance coil in
the main circuit of the lamp, and 4" is an impedance coil in the circuit of the shunt
motor for the purposes hereinbefore mentioned. In the example shown in Figs. 1
and 2, each of these motors comprise a circular field magnet core wound with two
sets of bobbins 6 so as to develop magnetic polarity at two opposite points 7 7" of
the core;
an armature 8 consisting of a disc of metal, surrounded by the field
magnet, and one or more (two in the example shewn) closed coils 9 that extend

page_text: around the armature, and are fixed in planes inclined to the plane passing through
the poles of the field magnet. When an alternating current is sent through the
field winding of such a motor the armature will be caused to revolve, the direction
and speed of rotation depending upon the position of the coils 9.
The construction
and operation of such motor is well understood. The armature 8 of the two
motors are fixed upon a shaft 10 and the coils surrounding them are so arranged
that the one armature tends to turn the shaft in a contrary direction to that in
which the other armature tends to turn it. The shaft 10 is mounted between
pivots 11 and is provided with a fan 12 the object of which is to make the armatures
as dead beat as possible. 13 is a pulley driven by a train of wheel work 14 from a
pinion 15 on the shaft 10. Around this pulley is wound a cord 16 one end of which
is connected at 17 to a cross bar 18 carrying the upper carbon holder 19, the other
end of the cord being connected at 20 to a cross bar 21 that carries the lower carbon
holder 22. Two cords may be used in lieu of the one cord 16, if desired. In this
case the upper ends of the two cords are wound in opposite directions upon and
secured to the pulley 13, their lower ends being connected to the cross bars 18
and 21 like the lower ends of the cord 16. 23 is a lower cord that has one of its
ends connected to the upper cross bar 18, and its other end to the lower cross
24 and 25 are guide pulleys for the cords 16 and 23 respectively. The
cross bars 18 and 21 are each arranged to move freely upon the vertical rods 26.
With the arrangement described, when the pulley 13 is rotated in the direction
of the arrow by the series motor at starting or when the arc becomes too short, the
carbon holders will be moved apart, and when it is rotated in the opposite direction
by the shunt motor, either at starting or when the are becomes too long, the carbon
holders will be moved towards each other, the carbon holders in each case moving
to an equal extent and thereby keeping the focus of the lamp constant.
bar 21.
When the lower carbon is stationary the pulley 13 is connected by the cord 16
to the upper cross bar 18 only, the upper portion of the cord being wound upon and
connected to the pulley. The two motors will in this case operate in the manner
herein before described, but the striking of the arc and the regulation of its length
will be effected by movement of the upper carbon holder alone. When the lamp is
worked by a continuous current and it is desired to keep the focus constant, any
known or suitable means can be provided for giving the lower carbon holder half
the motion of the upper one. Fig. 3 is a diagrammatic view of an arrangement
for this purpose, in which the upper and lower carbons are moved by cords 16
and 16 that lead in opposite directions over two pulleys 13 and 13ª respectively
fixed upon the motor shaft 10, the diameter of 13 being twice that of 13".
Fig. 4 is a diagrammatic view illustrating a modified construction of lamp whereby
the tendency of the carbons to be sometimes forcibly moved into contact by the
shunt motor and to remain in contact for a time due to this motor racing on first
lighting up, (thereby producing a large increase of current through the lamp) is
prevented. This construction forms the subject matter of another application for
Letters Patent filed by us bearing date the 27th day of December and numbered
21116 and is not claimed as part of the invention forming the subject matter of the
present application for Letters Patent, but is described herein because its use is
advantageous in carrying out the present invention.
To prevent the shunt motor racing, a brake is provided to retard the rotation of
the shaft driven by the two motors. This brake comprises in the example shewn a
number of spring arms or blades 27 fixed to the motor shaft 10 and into the path of
which an arm or abutment 28 is brought when the carbons come into contact, and
cause an excessive current to pass. This arm or abutment is moved into its
operative position by the core 29 of a solenoid 30 in the circuit of the series motor,
and into its inoperative position by gravity or by a spring or equivalent.
The closed field coil of the shunt motor is so arranged that when the are of the
lamp becomes too long and the armature of this motor tends to rotate so as to bring
the carbons nearer together, the action of the field coil on the armature is increased
so as to assist the motion of the armature and increase the action of the motor to

page_text: shorten the arc. To this end instead of fixing the closed field coil 9 of the shunt
motor as in the lamp herein before described, we mount it so that it can partly turn
around the armature and so vary the strength of the motor. For this purpose the
closed coil 9 is connected at one side of its pivot to the core 32 of a solenoid 33
arranged either in the shunt or series circuit, as may be found most convenient, and
at the other side to a spring 34 or its equivalent. In the arrangement shewn, the
solenoid 33 is placed in the series or main circuit of the lamp, but when it is placed
in the shunt circuit the points of connection of the core 33 and spring 34 with the
coil 9 will change places. The arrangement in each case is such that when the
rotative force of the shunt motor armature begins to overcome that of the series
motor armature due to the lengthening of the are, the solenoid 33 will allow or
cause the core (according as it is in the series or shunt circuit) to move the coil 9
partly around the shunt motor armature in the direction of the arrow and thereby
increase the speed and regulating action of this armature.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. An electric are lamp in which the position of the carbons is regulated by two
rotary electric motors one of which is traversed by the main current of the lamp
and is in series with the carbons, and the other of which is in a shunt circuit around
the voltaic arc, the two motors being so arranged that the rotative force of the one
is opposed to that of the other and balances it when the voltaic arc is of its normal
length substantially as herein described.
2. The construction of electric are lamp substantially as hereinbefore described
and shown in Figs. 1, 2 and 3 of the drawings annexed.
Dated this 30th day of December 1890.
ALBERT GAY.
W. Lloyd Wise,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.