Improvements in Controlling Electric Aros.
Year: 1896

page_text: Date of Application, 17th Nov., 1896-Accepted, 13th Feb., 1897
COMPLETE SPECIFICATION.
Improvements in Controlling Electric Aros.
We, THE BRITISH TUOмSON-HOUSTON COMPANY, LIMITED, of 83, Cannon
Street, in the City of London, Electrical Engineers, do horeby declare the nature
of this invention (which has been communicated to us from abroad by Elihu
Tbomson, of Swampscott, in the County of Essex, State of Massachusetts, United
States of America) and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
Our invention relates to that class of electric lamps in which an aro is formed
between two carbon pencils, the arc being maintained in a definite position with
respect to the axis of the carbons, by the influence of a coil or magnet near
thereto.
It is well known that a magnetic field will displace an are formed between two
electrodes, whether those electrodes are in the same line or at an angle, or parallel,
as in the Jablochkoff candle; or whether alternating or direct currents are used
to maintain the field. In our present invention however we use a compound field
for acting upon the arc; to this end we employ two sources of electro-magnetism,
one rising and falling with the current traversing the arc, and the other rising and
falling with the potential difference between the carbons or electrodes producing
it. That is, we may use a coil in series with the arc, or a coil the current in which
is controlled by the series current, either directly or indirectly; we may also use
in conjunction with the former coil, an electro-magnetic coil in shunt to the arc,
the latter coil of fine wire aud comparatively high resistance, the electro-magnetic
effect being opposed to that of the former coil. We may instead of this employ a
magnetic coil responsive to differences of potential and the current in which is
controlled by such differences of potential of the two electrodes.
Referring to the accompanying drawings,
Figs. 1, 2, 3 and 4 are diagrams showing various forms of our invention;
Figs. 5 and 6 are merely illustrative.
Fig. 7 is a plan of the parts shown in Fig. 4.
Fig. 8 shows circuit arrangements.
Figs. 9, 10 aud 11 show the application of our invention to a special form
of lamp.
Fige. 12, 13 and 14 are diagrams of circuit arrangements in a three-phase
lamp.
In Fig. 1, two carbons E E are shown placed in any desired relation, as in a
vertical line, with the arc drawn between them. An electro-magnetic coil in the
form of a hollow four-sided figure is made up of two coils closely wound together,
one of which, the inner coil marked C, may be placed in series with the arc or be
traversed by a current depending thereon, and the other, S, is placed in shunt, or
carries a current depending upon the potential difference. The deflective action
of the coil C may be, such as to throw the arc to the right, as indicated in the
figure, while that of the coil S may be to throw it to the left. By properly
adjusting the electro-maguetic power of the two coils, any desired position or
dieplaceinent of the arc may be obtained without risk of its becoming excessive;
if the arc should become too greatly displaced, the potential difference between the
two carbons will rise, causing an extra energizing of the coil S, tending to bring

page_text: the arc back to its former position. This in fact is the principle of our invention
-to differentiate the effects of two doflecting coils upon an arc for any purpose
whatever, whereby an increase or extension of the arc in one direction of deflection
may be met by an opposing influence depending on the potential difference between
the electrodes forming the arc. We have found this principle particularly useful
in applying the arc to blow-pipe work, or deflecting an are for blow-pipe purposes;
it may be carried out as in Figs. 2 and 3, where (in Fig. 2) the carbous are in the
same line with the are between them, the latter being deflected outward by the
magnetic effect of the two poles M M enclosing the arc. These poles are part
of a horse-shoe or other magnet upon which are wound two sets of coils, one set
in series with the are, or depeudent in its action on the series current, and the
other coil or set of coils is in derived circuit around the arc or dependent either
directly or indirectly for its energizing action upon the potential difference. By
selecting the relative magnetizing actions of the two coils, whether the current
supplied be alternating or direct in character, a proper displacement of the arc
may be maintained which is not likely to become excessive, as would be the case if
either the series or shuut coil alone were used as the deflecting agent.
Fig. 3 shows the carbons placed parallel to each other with the arc deflected
downward between the poles M M, and the arrangement would be the same in
essence as before.
Figs. 4 and 7 indicate the preferred placing of the coils where carbons are
parallel, and are to be used for illuminating purposes, Fig. 7 being a plan of the
arrangement shown in Fig. 4. Here the combined coils C S are duplicated on the
two sides of the are (as shown in the plan) and the carbons extend down between
them. The direction of the current in the series coil C or coil dependent upon
the series current, is such as to carry the arc downward, and tend to project it from
the points the carbons at their lower end, while the effect of the current in the
coils SS is to counteract this tendency when it bas too great a value, and to
counteract it according to the potential difference developed between the carbons.
In this way the arc can be kept at a particular point of displacement at the ends
of the carbons where it should be maintained, and the latter become an effective
source of light. The magnetic effect is much the same as if a permanent magnet,
as in Figs. 5 and 6, were so placed as to enclose the electrodes, and the magnetism
given such a direction as to tend to expel the arc from their lower extremities;
the permanent magnets are represented in the figure by the bent piece M M',
between the legs of which are the electrodes supplied with current in any ordinary
way. It will of course be manifest that where one of the coils, such as the series'
coil, has a constant magnetic effect or generates a substantially constant magnetic
field (as would be the case in ordinary series are lamp circuits where the current is
maintained constant), its pluce may be taken by a permanent magnet furnishing a
field of substantially the same intensity. Inasmuch as the magnet could not
furnish a variable field or vary in accordance with the potential across the arc, it
could not replace the potential coil or shunt field. In the sense and to the extent
described, therefore, the permanent magnet would be an equivalent of the electro-
magnetic device furnishing one of the fields.
Circuit connections which may be employed in our invention are shown
in Fig. 8, the plane of the electrodes with respect to the coils being however at
right angles, as in Figs. 4 or 7, the arrangement shown in Fig. 8 being adopted
for clearness of illustration. In this case a set of mains ab have branches taken
through the arcs at A A. Leaving the main a, tor example, a line extends
through an inductive coil 1, the self-induction of which can be regulated, or which
is automatically regulated by any known means, as by a movable cord H and a
lever controlling it; after passing the coil I the line is carried through the coil C,
through the arc at A, and back to main b, forming the series connection. In
addition to this, the coil S is connected across the are, or from carbon to carbon in
derived circuit, and means may be provided if desired for regulating the current
in the coil S, as by another self-inductive coil l' and regulating core H. This of

page_text: course assumes that alternating currents are employed. The self-inductive coils.
may also be employed to adjust to a certain extent the phase relations of the two.
coils or circuits. It is desirable however that the circuit of the coil S have a high.
resistance so that only a small fraction of the current shall pass through it, and
being wound differentially to coil C its action is opposite thereto, and affects the
arc as has already been explained. Instead of self-inductive arrangements for
regulating the current strengths in the two circuits, resistance may he employed,
and would be used in case the current was continuous. This is illustrated in the
right-hand portion of Fig. 8 by RR', the resistance R being in circuit with the:
coil C' and the arc A', while Ri is in the derived circuit coil branch S'.
In Fig. 9, ab are as before the mains, and connections are taken from them
through two coils C C applied adjacent to the arc; coils S S in derived circuit,.
with means, such as and R', for adjusting the current strengths, are also shown.
In addition the current may traverse an electro-magnet coil M in series with the.
arc, the function of which is to start the arc by withdrawing a third electrode e
which, when no current is passing rests at the ends of and connects the vertical
carbons seen above it. Tho electro-magnet coil M is provided with a core attached
to the third electrode e, pulling it down on the first passage of the current, thus.
establishing an arc between the two vortical carbons, after which the current
through the coils CC passes in series with the arc, while the current in S S is in
derived circuit to it. The position of the carbons is at right angles to the
proper one, this position being adopted for clearness, the plan view, Fig. 10,
showing the two carbons E L properly mounted in a plane parallel to the
coils C, S, C,S. In this case the carbons may be mounted in an enclosing globe,.
as shown at G, Fig. 11, which shuts off the access of air and retards the
combustion. The carbons are thus maintained in the interior of the globe and.
their combustion is therefore very slow. The regulation of the arc in this position
at the ends of the carbon is, as before, effected by the electro-magnetic actions of
the two circuits passing through the coils CS acting differentially.
In Fig. 12 we show the modification necessary in the application of the invention
to a three-phase circuit. In this case three branches from three mains a b c in
three-phase relation are taken through proper regulating coils, and through
separate coils CCC, each one of which terminates in a carbon pencil as at A..
In three-phase relation from these circuits from pencil to pencil, are connected
the coils S S S of fine wire and high resistance, differentially wound and placed,
as in Fig. 4, relative to the coils CC C. The carbons A, while shown in line, aro-
disposed as shown in plan in Fig. 14, at the three corners of a triangle, and the
compound coils, as CS are similarly disposed in triangular arrangement, as in.
Fig. 14, only one coil being shown in Fig. 13. In this case a three-phase arc is
produced at the ends of the three carbons, and is maintained in its position at the
ends by the action of the three-phase compound coils, each pair of carbons having,.
as it were, its own are controlled by the coil whose plane is coincident with the
plane of the pair, and as the arc shifts or rotates around, this controlling action is
taken up successively by each of the sets of coils in the triangular relation. An
enclosing globe, as before, may be used to protect the arc and prevent too rapid
combustion of the carbons, and a starting third terminal e may be employed
actuated by one of the circuits and by an electro-maguetic coil therein to start the
arc at the beginning of the lighting, as in Fig. 9.
Having now particularly described and ascertained the nature of this 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 improvement in the art of regulating or controlling electric arcs, which
consists in subjecting the arc to the directive influence of a resultant field of force
produced by a plurality of magnetic or electro-maguetic devices, the lines of force
from some of which tend to drive the arc in one direction, while those from other
devices act to oppose or modify the action of the first named.

page_text: 2. The improvement in the art of regulating or controlling electric aros, which
consists in subjecting the arc to the directive influence of a resultant field of force
produced by a plurality of electro-motive force devices, some of which are
dependent for their action upon the ourrent flowing in series with the arc, and the
lines of force from which tend to drive the arc in a given direction, the others of
which oppose the first named devices and depeud for their action upon the
potential existing around the arc.
3. In combination, terminals or electrodes at which an arc is to be maintained,
electro-magnetic devices in series with the are generating lines of force tending
to drive the are in a given direction, and other devices in shunt to the arc, the lines
of force from which tend to oppose or modify the action of those from the first
named device.
4. In combination, terminals or electrodes at which an arc is to be maintained,
a coil or coils in series with the arc, generating lines of force tending to drive it in
a given direction, and another coil or set of coils in shunt to the arc generating
lines of force which tend to oppose or modify the action of those from the first
named coils.
6. In combination, terminals or electrodes at which an arc is to be maintained,
a coil or coils in series with the arc generating lines of force tending to drive it in
a given direction, another coil or set of coils in shunt to the aro generating lines
of force which tend to oppose or modify the action of those from the first named
coils, and an arc-striking means controlled by the series current.