Improvements in or relating to Electric Switches and like Apparatus for Making and Breaking Electric Circuits.
Year: 1899

page_text: Date of Application, 29th July, 1899
Complete Specification Left, 30th Apr., 1900-Accepted, 23rd June, 1900
PROVIDIUNAL DIUITIVATION.
Improvements in or relating to Electric Switches and like Apparatus
for Making and Breaking Electric Circuits.
We, GERALD WILLIAM PARTRIDGE, of 25A, Cockspur Street, in the County of
Lendon, Civil Engineer, and GEORGE KEITH BULLER ELPHINSTONE, of 101, St.
Martin's Lane, in the County of London, Electrical Engineer, do hereby declare
the nature of this invention to be as follows:-
According to this invention the electric arc set up upon breaking an electric
circuit, especially a high tension circuit, is extinguished and prevented from
causing damage by arranging the fixed and movable contacts or parts between
which the circuit is made and broken within a chamber or space wherein there
is produced at the time of breaking the circuit a partial vacuum that is after-
wards destroyed by sudden admission of air to the chamber or space before the
arc has attained dangerous dimensions.
For this purpose the fixed and movable contacts are arranged within a chamber
or space adapted to be closed, and in connection with the movable contact there
are provided means whereby a partial vacuum will be set up in the said chamber
or space when the movable contact is withdrawn from the fixed contact to break
the circuit between them, and whereby also air will afterwards be allowed to
suddenly enter the chamber or space so as to destroy the partial vacuum therein
and extinguish any arc that may have been formed between the separated
contacts.
Apparatus to operate in the manner set forth can be constructed in various
forms.
According to one construction, the movable contact is carried by a suitably
guided rod provided with a piston adapted to slide air tight in a cylinder con-
taining the fixed contact and which is closed at one end and open at the other
or provided with one or more air inlet apertures in its wall, the arrangement
being such that upon withdrawing the movable contact from the fixed contact, a
partial vacuum will be set up in the cylinder or tube until the piston leaves
the open end thereof or uncovers the air inlet aperture or apertures whereupon
air will enter the cylinder or tube and destroy the partial vacuum therein.
The cylinder, piston or piston rod is or may be provided with suitable means
such for example as a non-return valve that will open and allow of air escaping
from between the piston and the closed end of the cylinder when the piston
moves inward to complete the circuit between the pair of contacts but which
will close and prevent the passage of air past it when the piston is moved out-
ward to break the circuit. Also suitable means such for example as a spring or
weight may be connected to the piston and piston rod in such a way that the
piston when moved outward shall open the cylinder or tube to the external
atmosphere suddenly and allow of a sudden admission of air.
Apparatus according to this invention can be constructed with two or more

page_text: board or support 6, and open at the other end. The arrangement is such that
upon withdrawing the movable contact 1 from the fixed contact 5, a partial
vacuum will be set up in the cylinder or tube 4 until the piston 3 leaves the
open end thereof whereupon air will suddenly enter the cylinder or tube and
destroy the partial vacuum therein and thereby extinguish any arc that may
have been produced between the movable and fixed contacts 1 and 5. The con-
tacts may be of any suitable kind, the movable ones being connected to piston
rods 2 of conducting material, and the fixed ones to suitably insulated con-
ductors 5 extending through the back of the board 6. The two piston rods 2
may be electrically connected together, as shown, as also may the two fixed
contacts 5.
The two piston rods are connected through suitable insulating devices 7 to a
common cross bar 8 that is connected through side bars 8 to a ring or guide
piece 9 mounted to slide upon a horizontal hollow guide bar 10 fixed to the
board so that the said piston rods will be caused to move parallel with each
other and be kept co-axial with their cylinders 4 after being withdrawn there-
from.
Each cylinder 4, piston 3, or piston rod 2 is or may be provided with suit-
able means, such for example as a non-return valve, that will open and allow of
air escaping from between the piston and the closed end of the cylinder when
the piston moves inward to complete the circuit between the pair of contacts 1
and 5, but which will close and prevent the passage of air past it when the
piston is moved outward to break the circuit. In the example shown, each
piston 3 is for the purpose just mentioned, made to loosely fit its rod 2 and to
work between two collars 11 and 12 fixed to the said rod, the arrangement being
such that when the rod is pushed inward, air can escape outward between the
piston and the collars and rod, but when the rod is drawn outward, the piston
will be caused to fit closely against the collar 11 as well as against the cylinder
wall so as to ensure the production at this time of a partial vacuum within
the portion of the cylinder containing the contacts 1 and 5.-
Suitable means, such for example as a spring or weight, may be connected
to the piston and piston rod, or each piston and piston rod, in such a way that
the piston when moved outward shall open the cylinder or tube to the external
atmosphere suddenly and allow of a sudden admission of air. In the arrange-
ment shown for this purpose in the switch illustrated, a coiled spring 13 is
arranged to surround the hollow guide rod 10 between the switch board 6 and
the guide ring 9, which, through longitudinal bars 8 and the cross bar 8, is
connected to an ell-shaped bar 14. which is arranged within the hollow guide
rod 10 and works endways in a longitudinal slot 10 in such rod. The bar 14
is fixed to a hollow rod 15 arranged to slide in the hollow rod 10 and having a
stirrup shaped outer end 15ª carrying a handle made in two parts 16 and 16"
of which 16 is fixed. to the outer end 15 of the rod 15, and 16 is connected
to the stirrup shaped outer end 17* of a rod 17 and is normally pressed away
from the part handle 16 by a spring 16. The inner end of the hollow rod 15
is formed with a slot 18 into which can take a catch 19 that extends through
a slot in the rod 10 and is carried by one end of a spring blade 19 the other
end of which is fixed to the said rod 10. To the bar 14 is pivoted a pusher 20
provided with a lower projection 20 adapted to act upon the spring catch 19,
and an upper projection 20 adapted to be acted upon by a tappet 21 fixed to
the inner end of the rod 17. The arrangement is such that by pushing the
handle 16 inward, the movable contacts I will be forced into engagement with
the fixed contacts 5 'and the coiled spring 13 will be compressed, the spring
catch 19 automatically entering the slot 18 in the rod 15 so as to retain the
various parts in the closed positions shown. The switch is opened by drawing
back the part handle 16 against the action of the spring 16, whereby the
spring catch 19 is forced out of engagement with the rod 15 by the action of