Patent GB-621452-A (GB)
Title: Improvements in or relating to electric gas-blast circuit interrupters
IPC: H01H33/825
Filed: 1947-02-27
Abstract: 621,452. Fluid-blast switches. WESTING- HOUSE ELECTRIC INTERNATIONAL CO. Feb. 27, 1947, No. 5657. Convention date, Oct. 24, 1945. [Class 38(v)] In a gas blast switch having resistanceshunted main arcing contacts, gas blasts are provided to extinguish the residual arcs formed when the series isolating contacts are opened. The switch, Fig. 1 (not shown) has a spherical pressurized tank in which two arc-extinguishing units, each having main arcing and series isolating contacts, Fig. 2, are mounted on the lower ends of terminal bushings and are connected in series by a conducting cross-bar 9 when the switch is closed. Each arc-extinguishing unit has a ceramic chamber 15 which is filled with gas under pressure through an opening 20. A resistance winding 22 on the outer surface of the chamber is connected between the fixed orificeshaped main arcing contact 23 and by way of the internal structure to a moving main arcing contact 25. The contact 25 is surrounded by a blast valve 36, which cooperates with a resiliently mounted insulated valve seating 40. A container 28 inside the chamber 15 communicates with the atmosphere through the main contact structure and hollow terminal bushing 5. The blast valve 36 and contact 25 are actuated by a piston 32 in a cylinder 33 when gas is admitted to the upper side of the piston by a valve 46. When the switch is opened series isolating contacts 53, 61 move downwards, the contact 53 carrying with it a ratchet member 56, which in engaging with pivoted plates 69 causes the downward movement of links 71. The links open an inlet port 63 and close an exhaust port 64 of the valve 46 to permit pressure gas to pass through the body of the valve 46 and passage 67 to the piston 32. The piston 32 is forced downwards to open the blast valve 36 during the first part of its travel D, and then by bearing on washers 83 to move the arcing contact 25 downwards. A blast of gas from within the chamber 15 passes into and through the hollow contacts to extinguish the main current arc. The continued movement of the isolating contacts 53, 61 frees the ratchet member 56 from the plates 69, which enables springs 74 to close the inlet port 63 and open the exhaust port 64, to enable the gas above the piston 32 to escape to the atmosphere via the container 28. This results in the re-closing of the main arcing contacts and the blast valve 36, but in the meantime the movement of the isolating contact 53 has been arrested by a flange 87 so that the isolating contacts separate whilst gas is still entering the chamber 15 through the opening 20 and before the main contacts reclose. During the reclosure of the switch, the ratchet member 56 is re-set without operating the valve 46 as the pivot pins 76 of the plates 69 are able to move downwardly in slots 77. A plurality of notches 58 on the ratchet 56 enables the full blast effect to be obtained in the event of the operation of protective gear under fault conditions causing the reversal of motion of the cross-bar before it has reached the fully closed position. Specification 582,599 is referred to.