Improvements connected with Arc Lamps.
Year: 1894

page_text: Date of Application, 15th Feb., 1894-Accepted, 24th Mar., 1894
COMPLETE SPECIFICATION.
Improvements connected with Arc Lamps.
We ARTHUR CHESTER and JOHN JAMES RATHBONE both of 4 Kingsley
Mansions, West Kensington, London, Electricians 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 :-
The object of this invention is to provide an automatic cut out for arc lamps in
order that when the feeding mechanism sticks, or the carbons break or if from any
other cause the arc resistance becomes unduly great in any particular lamp no
interruption will occur in the working of any of the lamps in the series, as the
beforementioned cut out comes into action to put a low resistance coil in series with
the main circuit, through which the current can freely pass for feeding the other
lamps in the circuit and magnetising the core of the said low resistance coil to hold
the armature down until the carbons meet.
In carrying our invention into practice say, to an arc lamp controlled by a high
resistance shunt circuit, we arrange a low resistance coil in parallel with the main
circuit but operative by its magnetic force upon the same armature as is controlled
by the high resistance coil or electro-magnet the said low resistance coil being put
into circuit when the arc resistance increases beyond the normal in the manner
hereinafter more fully described in connection with the accompanying sheet of
drawings, in which
Figure 1 is a back elevation of an arc lamp constructed as before mentioned,
Figures 2 and 3 being a side elevation and plan respectively, and Figure 4
detached view of the swinging arm and contact post.
Figure 5 side elevation of alternative arrangement to accomplish the same
result.
Upon the base plate A of the lamp are fixed standards B. 13, between them the
swinging forked carriage C is pivotted at its upper part, the lower end having an
india rubber or other suitable roller D inserted between said forked carriage for
pressure against a stop E, against which the roller D is held and partially rotated
by the movement of the swinging carriage C.
The edge of stop E is preferably inclined so as to prevent a sudden shock when
roller D engages or disengages same.
Attached to the top of the forked carriage C is a plate F to one end of which is
fixed a laminated or other armature G of sufficient width to serve for both a low
resistance coil H and a high resistance coil I. To the other end of the armature
plate F is secured a spring J as a counterpoise or check to the too sudden move-
ment of the armature F. G. As a further precaution, we may fix an india rubber
strip K between the standards B. B, to act as a buffer to the action of the armature.
As before mentioned, the low resistance coil is in parallel with the main circuit,
being connected to the terminal L on one side and the terminal M on the other,
and thence to a terminal N fixed to the armature plate F so placed as to make
contact with the plate P, which is electrically connected to the main terminal Q.
The high resistance coil is connected to the terminals Q and L respectively.
Referring to Figures 1. 2. 3 and 4 the various parts are brought into operation
as follows:
The current is switched on, and as the carbons are at starting, at arc distance,
a high resistance to the flow of the current is the result, which consequently is
caused to pass through the high resistance coil 1 to magnetise its core and attract
the armature G down a sufficient distance to swing the carriage C for the roller D
to come in contact with the stop E to rotate the rubber roller D (over which the cord R
D

page_text: is suspended) on the edge of said stop E and allow the carbons to meet by raising
one end of said cord R and lowering the other, the resistance then decreases and
the magnetic force of the high resistance coil I is consequently weakened allowing
the spring J to overcome it, and draw the lever down at that end to swing the
carriage C back and partially rotate the roller D in the opposite direction which by
the cord R moves the carbons to strike the arc. Should the are now become
abnormally long by the carbons breaking away, or from any other cause, such as
sticking of the carbon carriers, our improved cut out comes into action by reason of
the resistance increasing to such an extent that the high resistance coil draws down
the armature for the terminal N to make contact with the plate P and put the low
resistance coil H in series with the main circuit through which the current can
consequently freely pass to feed the other lamps in the circuit without interruption;
also as the current passes the low resistance coil H it magnetises the core sufficiently
to hold the armature to the position the shunt coil has pulled it, the roller D is then
free of the stop E so that the carbons may come together whereby a reaction
immediately takes place to re-establish the arc in the same manner as previously
-explained.
From the foregoing, it will be seen that the action is automatic and approximately
instantaneous.
In some cases, it may be necessary that there should be a low resistance or that
the carbons should meet at starting for which purpose armatures G. G¹, may be
provided at each end of the plate F as shown in Figure 5, and a spring J is
preferably placed between the high and low resistance coil H and I to free the
roller D and from the stop E and cause the carbons to touch each other. The
armature G' is operated by one or two series coils H' through which the current
at starting passes to magnetise their cores, and attract the armature G¹ and cause
the forked swing carriage to move the roller D against the stop E, and partially
rotate same to draw the carbons apart by means of the cord R and thus strike the
arc as the resistance increases from any cause, the high resistance coil becomes
magnetised and draws the armature G down to swing the forked carriage C in the
opposite direction to that before mentioned and partially rotate the roller D to feed
the carbons together, but if the resistance in the arc still increases the armature G
is drawn down for the terminal N to make contact with the plate P and excite the
coil H through which the current may pass for the purpose, as before described
with reference to Figures 1, 2, 3 and 4.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. In or with an are electric lamp of the kind described and shown, the combination
of a high resistance coil and a low resistance coil with a single armature therefor,
said armature acting when necessary as an automatic switch to cause the current to
flow through the low resistance coil for the purposes described.
2. In combination in an arc lamp a swinging forked carriage C, a roller D, and
stop E, for controlling the rotation of roller D as determined by the electro-
magnets H. I. respectively.
Dated this 12th day of February 1894.
H.
GARDNER,
Agent for the said A. Chester and J. J. Rathbone.