Improvements in Electric Arc Lamps.
Year: 1899

page_text: Date of Application, 23rd May, 1899-Accepted, 27th Jan., 1900
CF BOLTIVATION
Improvements in Electric Arc Lamps.
We, THE BRITISH THOMSON-HOUSTON COMPANY, LIMITED, of 83, Cannon Street,
in the City of London, Electrical Engineers, do hereby declare the nature of
this invention (which has been communicated to us from abroad by Richard
Fleming, residing at Lynn, in the County of Essex, State of Massachusetts,
United States of America, Electrical Engineer). and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement;
The present invention relates to electric arc lamps, and more particularly to
alternating current lamps designed for use on constant current series circuits,
although certain of the features of novelty are applicable to other types of lamps.
The invention has for its object to improve the construction of electric arc
lamps and to that end consists in the parts and combinations of parts as herein-
after more fully described and claimed.
In the accompanying drawings which show an embodiment of the invention,
Fig. 1 is a side elevation of a lamp with the outer casing and outer globe
removed; Fig. 2 is a section taken on line 2-2 of Fig. 1; Fig. 3 is a longitudinal
section of the actuating magnets taken on line 3-3 of Fig. 1; Fig. 4 is a
diagram; Fig. 5 is a detail of the frame construction, and Figs. 6 and 7 are
detailed views of a spring supported reactance.
two
Referring first to Fig. 1, A is a cast metal U-shaped piece forming the upper
part of the frame, and extending downwardly therefrom are two side tubes B.
These tubes are secured in place by fixing the upper ends of the tubes into the
projection A of the frame. Connecting the lower ends of the tubes is a yoke B₁
which supports the lower carbon holder B2 and the inner globe holder B³.
Mounted for vertical movement within the tubes are rods 13 which carry the outer
globe holder B5. Mounted on the tubes in such manner that they may be moved
up and down for the purpose of assembling or repairing the lamp, are
heads C and C. These heads are separated by an air space on the outer edge
and are connected in the centre by a hub C3. The air space between the heads
is to prevent the heat from the arc from rising upward and affecting the operation
of the lamp. Screw-threaded or otherwise secured to the upper head C are four
vertically extending rods D. These rods are arranged in pairs, the members of
which stand parallel to each other and form supports for the series magnets
and the shunt magnets F. In assembling the lamp the rods D are first screwed
into the head C, the heads are then mounted on the tubes, after which the
magnets are slipped over the rods and the whole secured to casting A by screws D¹,
as shown in Fig. 5. This is a very desirable arrangement, since it permits the lamp
parts to be readily assembled during the process of manufacture, and it also
permits the lamp to be taken down for the purpose of repairs with very little
labor. After the screws D' are in place the heads C and C are retained in tho
position shown, and no other support is required.
The heads of the magnets E and F are provided with projections a having

page_text: holes therein for receiving the rods D. These heads serve to support the magnet
and keep them in proper alignment: Between the upper head of the lower or
shunt magnet F and the lower head of the series magnet E are separators H.
There are four of these separators, one for each of the rods D. This arrangement
serves to hold the magnets E and F at the proper distance apart.
Secured by screws to the under side of the frame A is a rectangular laminated
armature I. This armature is separated from the upper spool head of the
magnet E by a slight space; separators or collars H being employed to hold
the upper magnets in place. In the present instance there is shown four magnets,
two included in the series circuit and two in the shunt circuit. In certain
instances the series magnets may be omitted and a spring or springs substituted
therefor; this construction admits of shortening the lamp considerably. Still,
however, to preserve the same arrangement of parts, the shunt magnet F and
the heads C and C¹ are supported by the rods D in the same manner as before.
Heretofore great difficulty has been experienced in making a satisfactory arc
lamp to work on constant current alternating circuits, the chief difficulty being
to get a shunt magnet which had a substantially constant pull over a wide range
of movement. In the present invention these difficulties are overcome by the
.peculiar construction and arrangement of the moving core and the stationary
armature.
Referring to Fig. 3, the construction of the core and its armature will be
plainly seen. Screwed to the frame casting A is a laminated iron core I, which
is rectangular in out line. This forms the armature for completing the circuit
of the upper portion of the core Q. The armature for the shunt magnet F differs
from that of the series magnet E by reason of the projections which extend upward
into the coil. It has been discovered that in certain types of lamps if these
projections extend about one-third of the way into the coils a magnet of sub-
stantially constant pull is obtained, but this invention is not limited to the
proportions shown, since changes in the winding necessitates changes in the core
and armature.
In arc lamps designed for direct current use, particular inconvenience is
unexperienced in making magnets which will have a substantially constant pull
over a wide range. This is due to the fact that the resistance of the winding
is practically the only thing to be considered; whereas in a magnet designed
for alternating current work the reactance has to be considered as well as the
resistance of the winding; in other words when the position of the core is changed
in an alternating current magnet the effect of that magnet on the circuit is
changed. It is well known that an iron core moving into and out of a solenoid
magnet which is energized by an alternating current will vary the amount of
current passing through said magnet, the flow of current, in a given instance,
being least when the core is inserted to its fullest extent, and greatest when the
core is withdrawn to its limit. It is also well known that a pull between two
magnetized pieces of iron or other material is greatest when the parts are in
close proximity, and that as they are separated the attraction between them
diminishes very rapidly. The construction of the magnets of this lamp is in
accordance with the well known laws above referred to, and by properly propor-
tioning the parts a magnet is produced which is so constructed that as the core Q
moves into the magnet coils and the magnetic pull between the core and the
armature increases the current flowing in the coil, and consequently the attractive
effect of the coil and armature is correspondingly decreased; thus the sum of
the two forces remains practically constant and consequently the pull of the
core. This arrangement is shown as being applied only to the shunt winding,
as it has its greatest utility in this connection, but if desired it can be applied
to the series magnets.
Extending upward through the centre of the lamp is a carbon tube J; this 5
tube is guided at the top and bottom by detachable guides J¹ and J2. On the lower
end of the tube is mounted a clutch J³ of any suitable pattern; the one shown

page_text: ong a contar and two arms which are arranged to grasp the upper carbon K
between them when the tube is raised, and release the carbon when the tube is
lowered. Secured to the tube at any suitable point is a collar J, and connected
to this collar is a flexible cable J for conveying current to or from the tube J.
5 Secured to the carbon tube at a point midway of its length is a support L, and
secured to the support but insulated therefrom by insulating material b is a
right-angle piece L₁ to which the dash-pot M is connected. Mounted for move-
ment within the magnets E and F is the H-shaped core Q. This core is connected
to the support L by a flat spring plate N and a coil spring N¹, the latter is
0 mounted on the upwardly extending portion of the. L-shaped support L'. To
the upwardly extending portion of the spring plate is connected an extension
spring O, the upper end of which is secured to the frame A by a suitable adjusting
means; this extension spring is designed to compensate to a certain degree for
the weight of the moving core.
5 the carbon tube to pass through it, and extending downwardly from one end is
The spring plate N has a central hole to permit
a projection N2 to which is secured to core Q. The arrangement of the spring
for supporting the core is a very desirable one, since it reduces the vibration between
the parts of the lamp and also the noise to a minimum, and at the same time
forms a very simple construction. The cylinder of the dashpot M, which dash-pot
is employed to check the too rapid movement of the core,
support L and the piston is supported by a clamp M¹ which is secured to the
secured to the moving
side tube B.
Mounted on the H-shaped core Q, but insulated therefrom, is a contact R which
engages with a contact R¹ when the core settles to its lowest position. The
contact R¹ is mounted in such a manner that it can be adjusted vertically on the
tube B. These contacts form a mechanical cut-out for the lamp, that is to say,
the contacts will engage whenever the core drops to its lowest point; and also
as an electro-magnetic cut-out, since when the resistance of the arc increases to
an abnormal amount the current flowing through the shunt widing F will be
sufficient to overpower the effect of the series winding E and pull the core down-
ward so that the contacts will be in engagement with each other. Situated in
the right hand side of the lamp and mounted on a suitable insulating support
is a resistance P, the action of which will be described hereafter.
Referring to Fig. 4, the circuit connection will be described.
enters at one binding post, as T for example, flows through the wire t and
The current
resistance P, thence to the binding post T
post T through the series winding E to the upper and lower carbon, thence to
A second circuit is from binding
binding post T, the resistance being so arranged that a certain amount of current
is diverted through this winding. A third circuit is from the binding post T
through the coils of the shunt magnet F to the binding post T¹. The lamp shown
is differentially wound and operates in the ordinary manner, now well understood.
Referring to Figs. 6 and 7, a reactance is shown such as is employed when the
lamp is used on alternating current constant potential circuits. The reactance
is mounted under the cover of the lamp and is so arranged that the carbon
carrier J is free to move within the central opening St. This reactance com-
prises a bundle of laminae S, each lamina being circular in outline and provided
vith an air gaps in the magnetic circuit. No particular means are shown for
olding the laminae together, but it is to be understood that any of the well
known means may be employed. Mounted on the core and connected in series
vith the lamp in the ordinary manner is a suitable insulated winding S¹.
In
To avoid the humming due to the vibration of the reactance a spring support
provided consisting of three screws S2, each screw being mounted in the lamp
rame A, and surrounded by a coil spring S³, upon which the core rests.
ounting the core it is preferable to place a screw of non-magnetic material
n each side of the air gaps and to place the third screw about opposite the
ir gap. By arranging the screws in this manner they do not interfere with the
inding of the core, since the winding may readily be divided into two sections

page_text: ..
and the screw located between the sections. The arrangement above described
permits the reactance to move freely in a vertical direction, but at the same
time prevents it from twisting out of line, and the springs act as cushions.to
reduce the vibration and humming. It is to be understood that when the lamp
is used on constant potential circuits, some slight changes are. desirable, as for
example, omitting the cut out.
+
1..
We are aware that it is not new in direct current lamps to have magnets which
will give a constant pull over a wide range of movement, but in. so far as we
are aware, we are the first to provide in an alternating current electric arc lamp
a shunt magnet having a substantially constant pull over a wide range of move-
ment. It is essential in arc lamps of the enclosed type that the core shall have an
extended movement, since it is necessary for the successful operation of enclosed
arc lamps to draw a long arc, as inch to inch for example, and to do. this it
is either necessary to have a very powerful magnet and to multiply the movement
cf its armature by suitable levers, or else employ a magnet having a core adapted
to work over a wide range. The latter is by far preferable; and by the arrange-
ment shown in the drawings we are enabled to provide a very simple lamp, yet
one capable of perfect regulation.
Having now particularly described and ascertained the nature of our said
invention (as communicated to us from abroad) and in what manner the same
is to be performed, we declare that what we claim is; —
1 The method of operating an arc lamp on alternating current circuits, which
consists in varying the attraction between two bodies of magnetic material in
accordance with the changes in the amount of reactance in said circuit.
2-The method of operating an arc lamp on alternating current circuits, which
consists in correspondingly decreasing the current flow through an actuated coil
as the pull between two pieces of magnetic material increases.
3-The method of obtaining a substantially constant pull from a shunt wound
magnet included in an alternating current circuit which consists in automati-
cally decreasing the current flow in the coil by an amount corresponding to the
increase in magnetic attraction between the moving and the stationary core as
the parts of the core approximate.
4 In an alternating current are lamp, the combination of the shunt wound
operating magnet having a fixed and a moving core, the fixed and moving core
both extending within the coil, the arrangement of the magnetic material in
the cores being such that as they assume a position where the magnetic attraction
would normally be greater the current flow in the coil is decreased, so that the
pull is maintained substantially constant at all times.
5 In an arc lamp, the combination of a frame, a side tube or rod depending
from said frame, a head mounted on the tube in such a manner that it is capable
of being moved up and down for the purpose of assembling or repairing the lamp,
and rods for holding the head in its proper position.
6-In an arc lamp, the combination of the frame, a pair of side tubes depending
from the frame, a head mounted on the said tubes in such a manner that it can
be moved up and down, and a pair of parallel rods which are screwed to the
head and the frame for holding the parts.
7-In an arc lamp, the combination of a frame, a pair of side tubes depending
upon the frame, a head mounted on the side tubes, a pair of parallel rods which
are secured to the head of the frame for holding the parts and magnets mounted
on the parallel rods and held in place thereby.
8 In an arc lamp, the combination of a clutch carrier, a magnet core secured
thereto, a depending side tube forming a part of the lamp frame, a dash-pot for
checking the movements of the core and an adjustable clamp secured to the side
tube by which the second element of the dash-pot is supported.
9 In an electric arc lamp, the combination of a magnet, a moving core
therefor, a clutch carrier, a spring plate secured to the core through which the

page_text: carrier extends and a spring which is secured to the plate and assists in sustaining
the weight of the core and also that of the clutch carrier.
10 In an electric arc lamp, the combination of a magnet, a core therefor, a
clutch carrier, a spring plate secured to the core through which the carrier
extends, a clamp carried by the carrier and a spring connection between the clamp
and the spring plate.
11-In an electric arc lamp, the combination of parallel supporting rods,
magnets mounted on said rods one above the other, spacers between the magnets,
and means for clamping the magnets and spacers in place.
12-In an electric arc lamp, the combination of two pairs of magnets, one pair
being arranged above the other, a rectangular fixed core for one pair of magnets,
and a U-shaped fixed core for the second pair of magnets, and an H-shaped
movable core common to all the magnets.
13-In an alternating current arc lamp, the combination of a frame, a reactance
mounted on the frame and an elastic medium between the reactance and the
frame.
14-In an alternating current arc lamp, the combination of a frame, a reactance
having an air gap core mounted thereon, supports and guides for the core and
springs for absorbing the vibration of the core.
15 In an alternating current arc lamp, the combination of a reactance having
an air gap core, a frame, supports secured thereto and arranged to extend through
the core in such a manner that the core is free to move, and springs situated
under the core and arranged to absorb the vibration.
16 In an alternating current are lamp, the combination of a frame, a carbon
carrier, a reactance which surrounds the carbon carrier and is provided with an
air gap core, springs for supporting and absorbing the vibration of the core,
and supports which direct the movement of the core.
17-In an alternating current arc lamp, the combination of the frame, a reactance
having an air gap core, screws which pass through the core into the lamp frame,
and springs surrounding the screws between their heads and the lower portion of
the core for absorbing the vibration of the reactance.
Dated this 16th day of May 1800
THE BRITISH THOMSON-HOUSTON CO. LTD.,
A. R. MONKS,
W. MARTINDALE,
Directors.
ALFRED CLEMENTS,
Assistant Secretary