Patent GB-599970-A (GB)
Title: Improvements in or relating to electric circuit-breakers of the gas-blast type
IPC: H01H33/70
Filed: 1945-09-25
Abstract: 599,970. Gas-blast switches. REYROLLE & CO., Ltd., A., and ALLAN, A. Sept. 25, 1945, No. 24861. [Class 38(v)] In each phase of a three - phase, pneumatically - actuated gas - blast circuitbreaker intended for out-door use, a seriesbreak isolator is totally enclosed within one end of an elongated casing A<1>, which may enclose current transformers E<1> as described in Specification 599,966, the contact H of the isolator being movable relatively to a main arcing-electrode F. The electrode F is attached to a metallic tube F', which is surrounded by an insulating bushing E so as to form an annular space E<2>, which at one end communicates past a flange F<6> with an arcing - chamber F<2>, and at the other is closed by a metallic b o s s E<3> having a garter - contact E<6> within which the contact H is slidable by a piston H<4>, movable within a cylinder H<5> formed within the tube F' by a flangedpartition H". The cylinder H<5> is surrounded by a tube H<7> extending between the partition H<6> and the boss E<3>, the annular space thus formed being sub-divided by radial bulkheads J, (Fig. 4) to form three conduits J', J<2>, J<3>, the conduit J<1> being joined to the space E<2>. When a main blastvalve C' is opened, air passes via a space E<7> to the blast-chamber F<2>, whereupon a piston F<4> separates an arc-initiating contact F<3> from the electrode F, the arc being blown through a nozzle F<5> on to an auxiliary-electrode G<1> in a cooler G, and exhausted through a non-return valve G<2>. Part of the blast passes from the chamber F<2> via the space E<2>, conduit J<1> and a port J<4>, to the piston H<4>, part of this air being by-passed through a non-return valve J<5> so that the contact H separates from a contact H' in a pressure atmosphere, which is exhausted through a non- return valve H<8>. In nearing the end of its travel the right-hand end of the piston H4 uncovers a transfer-port H<9> in the conduit J<2>, through which air passes to a pneumatically - actuated auxiliary switchunit so as to close the valve C'. As soon as the pressure within the chamber F<2> falls to normal, the piston F<4> is returned by a spring to close the contact F<3>. The isolator is re-closed by opening an electricallycontrolled valve, and supplying air via a passage J<7>, the conduit J<3> and a port J", to the back of the piston H<4>, part of the air being by-passed through a non-return valve J<8> so that the contact H closes in a pressure atmosphere. In nearing the end of its travel the left-hand end of the piston H<4> uncovers the transfer-port H'', air passing, via the conduit J<2>, to cause the auxiliary switch-unit to close the electrically - controlled valve. The auxiliary switch-unit is arranged to produce the opening and closing operations alternately, when actuated by successive air-impulses. In Fig. 6 (not shown), a resistance coil connected to an electrode lying adjacent the electrode G<1>, is wound on an insulating sleeve carried by the tube F\ and positioned within the bushing E so as to be swept by the blast. The three phases are laterally spaced on a reservoir C which is supported by a pedestal B, Fig. 1 (not shown).