IMPROVEMENTS IN ELECTRIC ARC LAMPS
Year: 1884

page_text: I, CHARLES LEVER of Bowdon in the County of Chester Electrical Engineer
do hereby declare the nature of said Invention for "IMPROVEMENTS IN ELECTRIC
ARC LAMPS" and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement.
This Invention relates to improvements in the electric are light apparatus
described in the Specification of a former Patent granted to me on the 3rd May
1882 N° 2092 and is intended to accomplish the following objects :-
1 To enable the electric arc lamps constructed according to my said previous
Invention to be more effectively worked in single circuit from a series wound
dynamo electric machine than that described in the said previous Patent
Specification, and also to combine with the improved device an arrangement
of the parts which will "cut out" the lamp should the circuit through the carbons
be broken.
2nd To provide improved means of regulating the "dash pot" in the lamp
whereby compensation can be made for the different viscosities of glycerine or
other similar fluid which may be used in the said dash pot.
Figure 1 is a diagram illustrating the first part of my improvements with the
electrical connections therefor. A resistance R, greater than that of the normal
arc, is fixed in the lamp as will be described further on. One end of the resistance R
is connected to a bolt & by means of a nut n, the other end being connected to tho
negative terminal of the lamp as shown by wire w. The bolt b is insulated from
the bracket or part J by means of washers of suitable insulating material i, i.
The bracket J is screwed to the top part of the frame of the lamp which is connected
electrically positive to the thick wire W. A magnet M wound with coarse insulated
wire is secured to the top part of the frame of the lamp and has one of its ends
connected to the negative carbon C³ the other end being connected to the negative
terminal of the lamp. A spring S carrying a small armature a is secured into the
core of the electro-magnet M. The end or head of the bolt b which makes contact
on the spring S may be made of platinum.
The carbons in the lamp being separated by means of the arrangements described
in my Patent Specification Nº 2092 it will be readily seen that if a number of

page_text: these lamps are arranged in series or single circuit and are worked by a series
wound dynamo the lamps cannot form their arcs except by means of the automatic
exciter of the machine as is fully described in the said Specification. With the
arrangement, however, shown in Figure 1 it will be seen that the lamp is cut out
before the current is sent through the lamp, and the resistance R, greater than the
normal arc, is in circuit. The current from the dynamo will therefore pass through
the top part of the lamp frame represented by connection W through the magnet
core, spring S, bolt b and through the resistance R to the negative terminal of the
lamp.
The resistance R is purposely made greater than the normal are in order that
the shunt magnet in the lamp shall attract its armature and allow the carbons to
make contact. As soon however as this occurs the resistance R is entirely cut out,
for the current flowing in the circuit through tho carbons and through the electro
magnet M. causes same to attract its armaturea and thus break the circuit through
the resistance R, and as long as the circuit through the carbons is completed the
electro-magnet M will continue to hold down the armature a. But, should from
any cause the carbons be separated so far as to break the arc, the spring S completos
the circuit through resistance R and the lamp is cut out. The electro-magnet M is
connected on the negative side of the lamp as shown in Figure 1 this being the
simplest method of arranging the electrical connections.
Figure 2 shows the lamp complete with the cut out device and resistanco coils.
The coils are preferably wound upon cylinders of slate or earthenware or other
suitable insulating material not deleteriously affected by heat, and are secured in
the lamp as shown in the Figure. The essential feature of having the coils of
greater resistance than that of the normal are together with the arrangement of
magnet M and spring contact forms one important part of my Invention. The
resistance coils are preferably made of German silver wiro. This arrangement of
cut out may also be used when the lamps are worked in series from a shunt or
compound wound dynamo or from a separately excited dynamo.
Figures 4 and 5 show my improved adjustable dash pot made in the interior of
the solenoid. It may however be similarly constructed outsido the saine and
Occupy a place between the coils as shown at with my old form of dash pot in
Figures 2 and 3:
In Figures 4 and 5 O is the core of the solenoid the spool or bobbin being
preferably made of brass. The core O is turned to act as a plunger as shown in
Figure 4 and at its lower end it is formed with an annular recess and a part e is
slotted out leading into the recess as shown in Figuro 5. P Figure 4 is an iron
plug by means of which the attraction of the solenoid may be regulated. T is a
screw to which the valve d shown also in Figure 5 is fixed. The said screw passes
loosely through core O and is provided with a lock nut n by means of which it can
be made secure. The space between the ends of core O and plug P is filled with
glycerino O or other suitable viscous fluid. It will be seen then that by turning the
screw T the valve d may be made to cover more or less of the slot e so that the
movement of core may be accelerated or retarded as the case may be and
the dash-pot regulated accordingly. The glycerine or other viscous fluid cannot
be spilt whatever position the lamp may be placed in.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is
First: In electric are lamps regulated on the shunt circuit principle, the
employment of a resistance greater than that of the normal arc whereby the lamp
is cut out in its normal condition by means of a spring contact and the current
diverted through the said resistance, thus causing the shunt electro magnet or
solenoid in the lamp to allow the carbous to make contact with each other and to
form the arc, in combination with an electro magnet or solenoid included in the
circuit through the carbons which breaks the said spring contact as long as the

page_text: circuit through the carbons is completed and diverts the whole of the current
through the carbons substantially as described with reference to Figures 1 and 2.
Second-In electric arc lamps the employment of the adjustable dashpot
constructed either within or without the solenoid substantially as described with
reference to Figures 4 and 5.
Dated this Thirtieth day of May 1884.