Improvements in Electrical Contact Breakers.
Year: 1898

page_text: Date of Application, 18th Oct., 1898-Accepted, 10th Dec., 1898
COMPLETE SPECIFICATION.
Improvements in Electrical Contact Breakers.
I, REGINALD HADDAN, of the Firm of Herbert Haddan & Co., of 18, Bucking-
ham Street, Strand, London, W.C., Patent Agent, do hereby declare the nature
of this invention a communication to me from abroad by the Allegemeine Elec-
tricitäts Gesellschaft, of Schiffbauerdamm, Berlin, in the Empire of Germany,
and in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement; -
Electrical contact breakers operated by means of mercury are preferable to those
with two fixed contacts since, Firstly by the large and intimate surface of fric-
tion between the contacts the intermediate resistance is very slight, Secondly
the duration of time of the interruption of the current can be altered as desired
with regard to the duration of time of the closing of the circuit and is easy to
regulate according to circumstances and, Thirdly it is possible to interrupt currents
of a higher tension than is possible with platina or fixed contacts.
If for one contact a fixed conductor is used and for the other mercury there
are two different known methods of construction for the same.
The one method consists in the use of a dormant body of mercury into which
a conductor is plunged and withdrawn. The movement of this conductor may be
to and fro or rotary turning on an axle lying outside the mercury. In the first
case the driving power has to be proportional to the size or surface of the movable
conductor and in the second case, if the revolution of the conductor surpasses
a certain ratio of rapidity a movement of the mercury is caused with the result
that its covering liquid is disturbed.
In the second method the conductor is fixed and the mercury is given the
required movement.
The present invention is based on the latter principle of construction.
The fixed conductor has the form of a ring or cylinder and is provided with one
or more slots or gaps at its lower edge. Against this part of the conductor, pro-
vided with the slots or gaps, a stream of mercury is ejected, rotating round within
the ring. The stream of mercury touches the sides or passes through the openings
of the ring in order to produce alternately contact with the metal ring and to
interrupt and close the circuit. The mercury ejection is obtained by the rotation
of a tube bent at a right angle, one arm of which is vertical and lies in the centre
of the ring and dips into the mercury whilst the other which is horizontal rotates
round and on the former. The slotted ring and this horizontal tube lie in an
insulating liquid with which the mercury is covered. As soon as the speed of
rotation has reached a certain point the mercury is drawn up by the centrifugal
force created and is ejected through the horizontal rotating arm. When the
metal ring forms the one pole and the mercury the other pole of the conduct,
the circuit is alternately interrupted and closed. As the only friction to surmount
is at the bearings and on the liquids little force is required for lifting the mercury.
The drawing illustrates the invention. The vessel G is filled with mercury up
to the lower part of its conical enlargement. The other part of the vessel contains

page_text: any insulating liquid. The vessel G is closed by a plate of hard rubber or vulcan-
ite B by means of screws d. In the cover plate B the bearing L is centrally screwed
In this bearing the shaft T of the centrifugal element arranged and is provided
with a driving pulley S at its upper end. The centrifugal element is disc like
and provided with a vertical rising tube a and a horizontal ejection tube b, con-
centrically round this centrifugal element the metallic cylinder C is arranged so
as to be easily removable in a screw socket I). This cylinder can be exchanged
for others with more or fewer openings.
Screws are used to fasten the flange D and terminals kk are used for the intro-
duction of current. The opening e serves for the introduction of the insulating
liquid. Ribs R arranged inside the vessel G prevent rotary movement of this
liquid. In the lower cylindrical part of the vessel one or more wings F are
arranged, these prevent the mercury having any rotary movement and help by
means of their inclined screw like planes, the mounting of the mercury in the
rising pipe a. The direction of revolution of the centrifugal element is in
accordance with the formation of the wings F. The vessel G is preferably con-
structed of cast iron its inside being enamelled except at its lower part which is
plain for electrical contact with the mercury. The vessel G rests in a stand A
and is fixed and joined in a conductive manner by screws c.
The drawn up and
ejected mercury Hows back into the lower part of the vessel along the walls of
the same.
By altering the numbers of the openings in the cylinder C and also
the rapidity of rotation of the centrifugal element any desired rapidity of inter-
ruption is obtained from perhaps 20 to several hundred interruptions per second.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is;-
1. An improved electrical contact breaker in which movable mercury is ejected
against a conductor C provided with openings effecting hereby an alternative
make and break of the circuit.
2. A form of construction of the contact breaker as in Claim 1 in which the
mercury ejection is provided in. an insulating liquid by the rotation of rectangular
centrifugal element (b) which at the same time gives it a rotary movement,
thereby closing and interrupt the circuit by alternately striking against and
passing through cut outs or gaps of a cylindrical body C, which concentrically
surrounds the centrifugal element.
3. The arrangement of the device as in Claim 2 inside a vessel G provided with
ribs R for preventing the rotary movement of the surrounding liquid.
4. In an electrical contact breaker as in Claims 1, 2, 3, the arrangement of one
or more screw like wings in the mercury receiver for the purpose of preventing
the rotary movement of the mercury contained therein and thereby facilitating
the mounting of the same in the rising pipe a of the centrifugal element.
72
31
t
e
1000