Improvements in Electric Arc Lamps.
Year: 1899

page_text: Date of Application, 30th Oct., 1899-Accepted, 23rd Dec., 1899
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, 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:-
In electric arc lamps as ordinarily constructed, a magnet or magnets are
employed to control the action of the feeding mechanism. This control in
certain types of lamps is accomplished through the medium of a friction clutch
which acts either directly on the carbon or upon the carbon carrier or support,
and as the carbons are consumed, one or both are fed to compensate therefor,
and to maintain in the arc at the proper length.
Under normal conditions the voltage across the arc remains practically con-
stant, differing perhaps by only a single volt between the time the carbons
last fed and the time the clutch strikes the tripping floor. If the tripping
of the clutch offered no resistance to the action of the lamp, this would be
satisfactory, but the clutch does not trip as soon as it strikes the floor, and it
often happens that the voltage around the arc increases from ten to fifteen
volts before the clutch will permit the carbons to feed. This is an objectional
feature, and one of the objects of our invention is to provide, in a lamp having
a friction clutch for regulating the feeding of the carbons, mechanisin so
arranged that the voltage at the arc will remain practically constant, both
during the normal burning of the arc and the feeding of the carbons. A further
object of our invention is the improvement of the construction of arc lamps,
and to that end, consists in the parts and combination of parts more fully
described and claimed hereinafter.
In the accompanying drawings, which illustrate this invention, Fig. 1 is a
side view of an arc lamp; Fig. 2 is a front view of the lamp frame with the
feed mechanism removed; Fig. 3 is a front elevation of the clutch; Fig. 4 a
section of the clutch taken on the line 44 of Fig. 3; Fig. 5 is an enclosed
detail view of the lamp feeding mechanism: Fig. 6 is a detail of the moving
contact; Fig. 7 is a diagram of the circuit connections; and Fig. S is a detail
view of the flange of the magnet spool.
Referring more particularly to Figs. 1 and 2. A represents the main frame
of the lamp, which consists of a rectangular body portion having a cylindrical
head or base A¹ with upward extensions A² forming a series of steps, the size
of the frame decreasing as it extends upward. The object of these steps is
to permit the mounting of a suitable reactance when the lamp is intended for
alternating current work, or a resistance when the lamp is designed for constant
high-potential circuits. By using a frame of this construction, we are enabled
to employ one type of frame for a variety of different lamps. thereby greatly
reducing the cost of construction. Formed integral with the sides of the frame
are flat cylindrical lugs A3 which support a part of the feed mechanism, and
also serve as guides to hold the outer casing (shown in dotted lines) in place.

page_text: Mounted on top of the frame is an inverted U-shaped metal plate B having
lugs B, B extending outwardly therefrom, the said lugs extending parallel
with the main body of the plate, but at a different level. Mounted on the
lug B is a stationary binding post c, which also acts as a terminal for the
switch D. Mounted on the lug B' is a binding post D (shown only in diagram,
Fig. 7) and also a support for the switch D. To prevent the plate from turning,
a lug or projection is formed thereon, which engages with a slot cut in the
upper part of the frame A. The plate is secured in place by the hanger R
which is screw-threaded to the frame A. Mounted within the frame is a
magnet coil E; in the present instance this is shown as consisting of two parts,
a series coil E¹ and a shunt coil E differentially wound with respect to each
other. Formed on the lower part of the frame are lugs A+, and on the top
of the frame are similar lugs A³. Engaging with these lugs are lugs e formed
integral with the flanges or heads E of the magnet, best shown in Fig. 8; the
frame and magnet lugs are secured together by means of screws.
To remove the magnet E from the frame, the hanger R is unscrewed, which
permits the withdrawal of the carbon tube G after the clutch has been removed
therefrom. After removing the screws which secure the magnet to the frame,
the magnet by disconnecting the winding may be removed from one side. It
will be seen that only a very small amount of labour is required to take down
and set up the lamp.
In addition to the magnets E1, E2, we have provided a small shunt-wound
magnet F, normally out of circuit, but which is included in circuit each time
the carbon tube G moves downward a certain amount and it is desired to feed
the upper carbon. This magnet is supported from the top flange or head of
magnet by an extension F, which is formed integral with the lower head
of the magnet spool. Secured to the upper end of the carbon tube and insu-
lated therefrom by mica or other insulating material G¹, is a two part frame H;
to one end of this frame is secured a cork R arranged to work within a
magnet F. On the other part of the frame is carried a contact-piece H2 having
a silver tip for making good contact which is arranged to make contact with
the spring-pressed plunger I under normal operation, and the cut-out contact I¹
when for any reason the lamp fails to operate, due to the sticking of the carbons
or to their being entirely consumed. The portion of the frame which carries
the contact H2 is slotted and between the contact and the sides of the frame
are sheets of insulating material in the present instance mica has been
employed, but any other form of insulating material may be used if desired.
In Fig. 6 is shown a detailed construction of the spring pressed contact. I.
This contact is mounted in a plate 13 having a tubular extension I containing
the spring 15 and under normal conditions the plunger is in the position shown.
the pin preventing it from being removed. The contacts I. It are insulated
from each other by means of mica or other insulating material I². The cut-out
contact I and the plate 13 are mounted on an inverted U-shaped support I,
the extensions of which rest on the lugs A³ of the frame A. To prevent the
too rapid movement of the frame H a dash pot J is employed. the piston being
carried by the frame H. and the cylinder by a fixed portion of the lamp. Situated
at one side of the dash-pot is an adjustable extension spring K, more clearly
shown in Fig. 5; this spring is arranged to compensate for the weight of the
moving parts.
Extending parallel with the magnets E1 and E2 in a vertical direction is
a frame L. upon which is wound a starting resistance wire L¹, which is normally
out of circuit, but is cut in at the time the moving contacts H2 strikes the
stationary contact II.
Situated below the frame head A¹ is a similar frame head A6, and between
these heads is a layer of asbestos or other heat resisting material A7: the
object of this material is to prevent the passage upward through the lamp
mechanism of the heat generated by the arc.

page_text: Extending downwardly from the head A" are two side tubes which support
the lower carbon-holder S, and mounted for vertical movement within these
tubes are rods T which carry the globe-holder T¹.
Mounted on the lower end of the carbon tube G is "floating clutch," so
called because it floats up and down with the armature and carbon tube; this
clutch is best shown in Figs. 3 and 4, and consists of a collar M, which is
clamped to the carbon tube by a screw M. Formed integral with and extending
downwardly from the collar are four arms M2; these are best shown in Fig. 4.
The arms on opposite sides of the carbon N are connected by the horizontally
extending pieces M³; these pieces serve to make the arms of the clutch more
rigid, and at the same time acts as stops for limiting the downward movement
of the shoes M. The shoes M are mounted eccentrically, so that they tend
to grip the upper carbon N when the tube G is raised and, by reason of their
being pivoted at a considerable distance from the carbon. are very sensitive,
and the effect required to release the carbon is very small; at the same time
the carbons are held very firmly and prevented from dropping down, due to
jarring. Mounted in the shoes are pins M5 which extend on both sides thereof,
and are adapted to engage with the side-pieces M³ of the frame to limit the
downward movement of the shoes. It will be seen that the construction of
this clutch is very simple, and that the machine work required amounts to
very little, the only portions of the clutch requiring machine work are the
collar M, the holes in the frame and shoes for the reception of the pivots M6
and the pins M. and the gripping surfaces of the shoes M, which are cut in
such a manner that they present surfaces curved concentric with the carbon.
The adjustment of the lamp is very simple; the contact H2 of the feed magnet F
is first adjusted to the proper distance from the contact I, then the clutch is
moved up or down on the carbon tube until the shoes M' are so disposed that
they will, when gripping a carbon, strike the tripping floor M7 at or about
the time the contacts H2 and I close. It is preferable to adjust the parts so
that the contacts close just ahead of the striking of the clutch shoes, for by
this arrangement there is no opportunity for the are voltage to increase above
normal.
In Fig. 7 is shown a diagram of the circuit connections in which C and D
represent the binding-posts, and D the short circuiting switch. The series
coil E is connected between the binding posts D and the lower carbon N¹.
The shunt coil E2 is connected between the binding post D and the binding
post C.
One end of the starting resistance L¹ is connected to the fixed
contact I, and the other end is connected to the binding post D. Extending
from the binding post C is a connection which is connected to the moving
When the
contact H2 and also to the carbon tube G and upper carbon N.
lamp is operating under normal conditions, the parts will be as shown, and as
the carbons are consumed, the carbon tube and clutch will gradually be
lowered, due to the changes of strength in the magnets E1, E2, until the shoes M*
of the clutch are on the point of engaging with the tripning platform M7.
At or about this instant the contact H2 carried by the frame H will move down-
At the instant the circuit is
ward and strike the spring pressed contact I.
closed at this point, current will flow from one binding-post to the other. which
will energize the magnet F and cause it to attract its core H this will force
the clutch shoes M against the tripping platform M with a slight blow, and
cause them to release the carbon N and permit it to feed.
We have experimented with a lamp of the character shown, as well as with
other lamps, and have found that when the magnet F is rendered inoperative.
the clutch and carbon tube will feed downwards as the carbons are consumed
and the voltage at the are will remain practically constant, varying when the
lamp parts are carefully adjusted not over one volt up to the time that the jaws
as this is done the
of the clutch strike the tripping platform: but as soon
voltage at the arc may increase from ten to fifteen volts before the effect is

page_text: enough to cause the shoes to release the carbon and permit it to feed. On the
other hand, we have found that to place the coil F in circuit as shown, and
to include it in circuit at or about the instant the shoes M* strike the tripping
platform, will cause the carbon to feed without changing the voltage at the
are more than from one to three volts. This variation in voltage is due largely
to inequalities in the carbon and to the sticking of the various parts, but it
will be readily seen that the advantage gained is very marked.
It will be seen that, while we have provided the so-called "drop-feed” for
feeding the carbons, the ordinary feed mechanism of the lamp has still been
retained, and in the event of the failure of the drop feed to operate from any
cause; the lamp is not rendered inoperative, which is a very important feature
where the lamp is employed for street service, and where the aim is to keep
the lamp going at any cost..
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-In an electric are lamp, the combination of a magnet, a floating clutch
for regulating the feeding of the carbons, which under normal conditions is
supported and controlled by the magnet, and means normally inactive for
causing a quick feed of the carbons at or about each time the clutch is tripped.
2-In an electric arc lamp, the combination of a differential magnet for
striking the arc and actuating the feed mechanism, with an auxiliary means
acting on the feed mechanism for giving a quick feed, the said means being
normally inactive but placed in operative relation at or about the instant the
feeding mechanism is placed in a position to feed.
3-In an electric arc lamp, the combination of a solenoid magnet, an armature
moving within the magnet, a feed mechanism controlled by the armature and
capable of feeding the carbons together in the usual manner, with an auxiliary
feed mechanism acting at each feeding point to take the work of feeding the
carbons away from the first named feed mechanism for preventing an increase
of the are voltage.
4-Iu an electric arc lamp, the combination of a floating clutch for regulating
the feeding of the carbons, means for tripping the clutch, a magnet for con-
trolling the clutch, and a second magnet normally inactive during the operation
of the lamp, but which is energized at or about the instant the clutch strikes
the tripping means, for causing a quick release of the clutch.
5-In an electric arc lamp, the combination of a floating clutch, a magnet
for raising and lowering the clutch, a tripping means for the clutch, an auxiliary
magnet, normally inactive, for causing the clutch to strike the tripping means
with a slight blow each time the carbon should feed in order to give a quick
release to the carbon, and a moving and a stationary contact for closing the
circuit of the auxiliary magnet.
6 In an electric arc lamp, the combination of a series and a shunt coil dif-
ferentially acting on a floating clutch to control the action of the lamp, and a
shunt magnet normally open-circuited, but acting to give a sudden downward
movement to the clutch each time it should feed, and contacts for closing the
circuit of the shunt magnet.
7-In an electric arc lamp, the combination of a magnet acting on a clutch
to regulate the feed of the carbons, a clutch, a normally open-circuited winding,
arranged when energized to give a sudden downward movement to the clutch
at the instant it should feed. a resistance, and contacts for first closing the
circuit of the said winding and then closing the circuit of the resistance.
8 In an electric arc lamp, the combination of a tube surrounding the carbon,
a clutch carried by the tube and arranged to grip the carbon, a magnet for
raising and lowering the tube as the potential across the are varies, an auxiliary
magnet normally open-circuited, an armature for the magnet, which is connected

page_text: to the tube, and a contact carried by the tube for closing the circuit of the
auxiliary magnet so as to impart a quick movement to the tube and clutch each
time the carbon should feed.
.9 In an electric arc lamp, the combination of a carbon, a tube surrounding
the carbon, a clutch mounted on the tube, a feed magnet, a drop feed magnet
normally open-circuited, a core therefore, a frame mounted on the tube which
carries the core and a contact for closing the circuit of the maguet each time the
carbon should feed.
10--In an electric are lamp, the combination of a carbon-surrounding tube,
a two-part frame carried by the tube and insulated therefrom, a magnet core
carried by one part of the frame, and a contact carried by the other part of
the frame.
11 As an article of manufacture, a contact comprising a plate I³ having a
tubular extension I containing a spring 15 and a contact I.
12 As an article of manufacture, a contact for an electric lamp comprising
an inverted U-shaped bridge or support carrying a spring pressed contact mounted
within a tubular support, and a flat contact which is insulated from the spring
pressed contact.
13 As an article of manufacture, the frame for an electric are lamp, comprising
a rectangular body having a base or head forming one end, and a portion pro-
vided with a series of steps forming the other end, the width of the frame
gradually decreasing toward the end.
14 As an article of manufacture, the frame for an electric arc lamp, comprising
a rectangular body having a cylindrical base or head forming one end, and a
portion provided with a series of steps forming the other end, lugs formed on
the side of the frame which serve to hold the outer casing in position when
mounted on the frame, and tubes extending downwardly from the cylindrical
head and arranged to support the lower carbon holder.
15 In an electric are lamp, the combination of a frame for supporting the
various parts of the lamp mechanism, an inverted U-shaped piece having
extensions B and 132 formed integral therewith mounted on top of the frame,
and a switch and a binding-post mounted on said extensions.
16 In a clutch for an electric arc lamp, the combination of a collar arranged
to be secured to a moving part of the lamp, two downwardly extending arms
situated on each side of the collar, pivoted eccentric shoes mounted between
the arms and side pieces connecting the arms which are on the same side of the
centre of the carbon or its support.
17 In an electric are lamp, the combination of a magnet coil, a spool therefor,
a head for the spool having a lug formed integral therewith, and a frame to
which the lugs on the head of the spool are secured.
18 In an electric arc lamp, the combination of a normally open-circuited
feed magnet, a starting resistance normally open-circuited, and means for closing
one of said open circuits in advance of the other.
19 In an electric are lamp, the combination of a normally open-circuited
magnet, a resistance also normally open-circuited and means for closing the
circuit of the magnet first and of the resistance afterwards.
Tx L 11
1
1
1000
THE BRITISH THOMSON-HOUSTON CO., LTD.,
J. J. MANHEIM,
A. R. MONKS
ALFRED CLEMENTS,
Directors.
Assistant Secretary.