An Improvement for Cutting Out Electric Arc Lamps.
Year: 1894

page_text: Date of Application, 25th Oct., 1894
Complete Specification Left, 25th July, 1895-Accepted, 31st Aug., 1895
PROVISIONAL SPECIFICATION.
An Improvement for Cutting Out Electric Arc Lamps.
I HENRY JAMES CREFFIELD of 3 St. Fidelis Road Erith County of Kent
Electrical Instrument Maker do hereby declare the nature of this invention to he
as follows:-
The
My improvement consists of a device for cutting out the lamp when the carbons
are burnt out or nearly so, or at any point which may be previously arranged for,
without any perceptible or important increase in the length of the arc.
carbon rod holder is provided with a stop of insulated material; and when the
carbons are burnt out, or nearly so, or have reached any point previously arranged
for; the said stop comes in contact with my device and compresses it in contact
with the contact body of the lamp. Immediately above contact is made the
current is switched through the combination magnets. The combination magnets
in turn attract the rocker and the current can then pass through the existing
contact or through the contact made by my device.
Dated this 24th day of October 1894.
HENRY JAMES CREFFIELD.
COMPLETE SPECIFICATION.
An Improvement for Cutting Out Electric Arc Lamps.
I, HENRY JAMES CREFFIELD, of 3 St. Fidelis Road, Erith, in the County of
Kent, Instrument Maker, 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 :—
My invention relates to electric arc-lamps and has for its object to provide a
simple and efficient contrivance or arrangement for cutting out an arc-lamp when
the carbons are burned out or nearly so, or when they have been consumed to any
predetermined extent. In arc lamps as hitherto constructed the operation of the
cut-out device for short circuiting the arc has depended on the increasing resistance
of the are due to the burning away and separation of the carbons. This increased
resistance causes a sufficiently large current to pass through the main coils of
the lamp whereby the armature of the rocker is gradually attracted to such
an extent as to bring into operation the cut-out device and thus short-circuits
the lamp.
According to my invention instead of depending upon the gradual lengthening
of the arc for cutting out the lamp as above stated, I provide means whereby the
lamp can be instantly cut out at any predetermined time.
In order that my invention may be clearly understood I will now describe the
same with reference to the accompanying drawings in which:
Figures 1 and 2 are diagrammatic front and side views of an arc-lamp provided
with my improvements and showing the position of things when the lamp is
burning.
Figures 3 and 4 are similar views showing a modification.

page_text: A A' are the carbon holder rods; B, B' are the carbons; C is the rocker
and D the armature at the extremity thereof. The said rocker C is pivoted at E
to the frame of the lamp. F is a contact-piece secured to the rocker C but
insulated therefrom. G is the clutch by which the feed of the upper carbon A is
controlled. H is an electro magnet by which the armature D'of the rocker is
attracted when the current flows through the coils. I is an electro magnet in the
main lamp circuit: J is its armature which is spring controlled. The said
armature J is adapted to make contact with the contact piece J' when no current
is flowing through the lamp but when current is passing through the lamp the electro
magnet attracts the armature J thus causing it to break contact with the piece J.
The contact piece F is so arranged that when the armature D of the rocker C is
drawn down a certain distance by the attraction of the magnet H the part F¹ of
the said piece F will make contact with another piece K which latter is insulated
from the frame of the lamp. L is a spring which is fixed to the lamp frame at
one end and at the other end to a projection or extension Cou the rocker C. The
said spring L brings back the rocker into a substantially horizontal position when
the armature D is no longer attracted towards the magnet H.
Referring now more particularly to Figures 1 and 2 my improvement consists
essentially in providing on the upper carbon holder rod an insulated stop M of any
suitable shape but preferably conical as shown, the said stop acting in conjunction
with a spring or flexible blade of metal K₁ forming part of or secured to the
insulated contact piece K. At the time when the carbon is nearly burned out
the stop M will descend and press the said spring or flexible blade K' against the
contact F. This will cause an immediate flow of the current through the coils of
the electro magnet H or in other words will at once cut out the arc. By altering
the position of the stop M the arc can be cut out at any predetermined time.
I will now describe the courses of the current in the lamp.
The first operation is to "strike the arc "the carbons being normally apart. At
the moment of switching on the current to the lamp the current enters by the
positive wire a through the wire 6, the series coil H' and the wire c to the contact .J*,
thence through the armature J and wire d to the negative main wire e. The
current passing around the coil H¹ of the electro magnet H
causes the
immediare attraction of the armature D of the rocker C which 'latter operating
on the clutch G causes the upper carbon holder rod A to be fed forward till the
two carbons B, BI touch in order to strike the arc. The contact of the two
carbons enables the current to now pass through the wires a and f, around the coil
of the electro magnet I to the carbon holder rod A, thence across the arc to carbon
holder rod A' and by the wire to the negative wire e. The electro magnet.I
being now energized attracts its armature J thus breaking contact between the
part J and the armature J. Part of the current entering the lamp by wire a will
pass through the wire, the series coil H and shunt coil H2, and thence by the
wire g to the negative wire e. The amount of current passing around the magnet H
will now not be as great as previous to striking the arc, as the much greater part
of the current will pass between the two carbons. The attraction on the armnature D
of the magnet H will therefore be less and the spring L will cause the rocker C
and armature D to regain the normal position, thus slightly raising the upper
carbon rod by means of the clutch G and separating the carbons to the requisite
extent.
The lamp will continue burning with the carbons at the proper distance apart.
The regulation of the length of arc is automatically governed by the varying
resistance of the arc enabling a larger or smaller current to pass through the coils
of the electro magnet H regulating the feed.
My improved cut-out arrangement is operated as follows, that is to say when the
upper carbon is nearly burned out the descent of the upper carbon holder rod A
causes the stop M of insulating material to press the spring or flexible blade K'
against the contact piece F. The effect of this contact is to cause the current to
now pass through wire around the series coil H¹ and thence by the wire to the

page_text: contact F and through the spring or flexible blade K¹ and wire i to the negative
wire e.
The contact above described is only temporary as the whole current could
not be carried for any length of time through it. The said contact therefore only
continues long enough to bring into play the sufficiently large contact between F¹
and K similar to that already in use. By this temporary contact the current is.
short circuited through the coil H' which causes the electro magnet H to attract
the armature and tilt the rocker C which, carrying with it the contact piece F,
brings the extremity F1 of the contact F against the fixed contact K. The
lamp is now short circuited through the coil H and wires and leading to
the wire e.
In Figures 3 and 4 I show a modification of my invention in which I employ a
metallic stop M on the upper carbon holder rod instead of an insulated one as
above described. This stop is uninsulated from the carbon holder rod which
necessitates the employment of somewhat different lamp connections to that
described with reference to Figures 1 and 2.
I will first describe the various paths of the current. On switching on the
current to the lamp the said current enters by the positive wire k, passes through
the armature J, the contact J', the wire 1, the coils of the electro magnet H, the
wire m and thus to the negative wire n. The flow of current through the coils of
the electro magnet causes the armature D of the rocker C to be attracted against
the action of the spring L. This action, by means of the clutch G, allows the
upper carbon B to move forward by gravity so as to come into contact with the
lower carbon B thus striking the arc. The path of least resistance is now that
through the carbons B and B' therefore the current flows by wire k, to the wire o
surrounding the electro magnet I then to the carbon holder rod A and through the
are finally passing away by the wires
The electro magnet I being now
energized attracts its armature J and thus breaks the contact between the
armature J and the contact piece J, therefore as hardly any current passes by the
wire 9 through the shunt coil, the armature D will not be so much attracted and
will be raised by the action of the spring L, to its normal position. This causes
the clutch G to lift the upper carbon holder A and thus to draw the carbons the
correct distance apart for the proper burning of the lamp.
and n.
The lamp is cut out by short circuiting the current thron the main coils in
the manner which I will now describe.
When the carbon bolder rod A descends far enough its metal stop M comes into
contact with the part K¹ of a metal contact piece K. The immediate effect of
this contact is that the current, entering by the positive wire k, flows through the
coils of the electro magnet I and up the upper carbon holder rod A, thence
through the stop M, and contact K K', then through the wire and around the
coil Hand by way of the wire m reaches the negative wire n. A small but
negligible amount of current also passes through the shunt coils H². By these
means the electro magnet H is suddenly energized with the result that the
armature D is immediately attracted and the part F₁ of the contact piece Fis
brought against the contact K which provides a sufficiently large area to carry the
full current. The current now passes through the wire s, the contact piece F, the
contact K, the wire r, the coils of the electro magnet H and finally flows away by
the wire m to the negative wire n. The arc is thus short circuited.
The coils of the electro magnet I are now also short circuited so that the amount
of current which will pass through the said coils will not be sufficient to hold the
armature J out of contact with the piece J. Therefore the parts J' and J will
again make contact with one another which will allow a portion of the current to
pass through the wire k, the contacts J and J, the wire 1, the coil H', and away by
the wires in and n. By this means two points of contact viz. one between F1 and K
and the other between J and J are provided in the paths of the current instead
of one.
This will ensure proper contact being made to carry the current under all
conditions of working.

page_text: Having now particularly described and ascertained the nature of my said inven
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The means for enabling an electric arc lamp to be automatically cut out of
circuit independently of the lengthening of the arc substantially as described and
for the purpose specified.
2. A cut-out device for arc lamps comprising an insulated conical stop carried by
the upper carbon holder, an insulated flexible blade, and an insulated movable
contact piece carried by the rocker substantially as described with reference to
Figures 1 and 2 of the accompanying drawings.
3. The modified construction of the cut-out device substantially as described
with reference to Figures 3 and 4 of the accompanying drawings.
Thi orth do of T..1.. 1905
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.