Patent GB-537302-A (GB)
Title: Improvements in or relating to alternating current electric circuit-breakers
IPC: H01H33/12
Filed: 1939-12-15
Abstract: 537,302. Fluid-blast switches; actuation of switches; switchgear structures. REYROLLE & CO., Ltd., A., ALLAN, A., and CHRISTIE, J. Dec. 15, 1939, Nos. 32341/39 and 571/41. [Class 38 (v)] The potential stress across the main contacts of a circuit-breaker having series isolating contacts is rapidly removed, following arc-rupture, by short-circuiting the opened main contacts by means of the movable isolating contact, which may be pivoted or longitudinally movable. In the outdoor type shown diagrammatically in Fig. 2, the fixed main contact is housed in an oil-poor arc-control device A, which may be as described in Specifications 505,604 and 505,606, mounted on a metal casing B for the operating mechanism. Connected to the fixed contact A is a contact A<4> engaged by the isolating arm C in the open position. The main movable contact A<5> is operated by a rack A<6> and pinion E<6> on a shaft E<2> rotatable by a fluid-pressure device E. The arm C is mounted on a shaft C' rotatable through a link F<5> and levers C<5>, F<4> from a further shaft F<2> actuated by a fluidpressure device F. Pipes D' .. D<4> for all three phases, only one of which is shown, are controlled by valves D<5> and solenoids D<6> so as to connect the reservoir D to the devices E, F. The solenoids D<6> are controlled by switches in compartments G', which switches are in turn operated through shafts G<6>, G' by a rack-andpinion arrangement G<5> connected by links G<3> to a floating lever G, which is pivoted to a lever G' and to nut F' on a quick pitch thread F<7> on shaft F<2> A similar thread E<8> on shaft E<2> carries a nut E<9> which is also pivoted to lever G'. To open the circuit from the position shown, the appropriate solenoid D<6> is operated to supply the device E over pipe D'. At the end of the operation, the device E is changed over to prepare the main switch for subsequent reclosure by admission of fluid through the pipe D<2>. During the opening of A<5>, the nut E' rotates lever G<1> about its intermediate pivot G<2>, thus rotating G about its pivot on nut F<8> and driving the rack- and-pinion arrangement whereby the appropriate switches in compartments G<8> are operated to de-energize the solenoid of pipe D' and energize that of pipe D<3>. The device F thus opens the arm C, the nut F<8> rotating the lever G about its pivot on lever G<1> and moving the rack-and-pinion still further in the same direction to shut off the supply to D<3> and prepare energizing circuits for the pipes D<2>, D<4>. The closing operation is performed in the same sequence, but other arrangements are referred to. The rack-and-pinion arrangement may also operate a visual indicator, Fig. 9 (not shown). The shafts E<2>, F<2> are each provided with a snapaction spring (not shown) and manual operating means. The device E, Figs. 5 and 7, comprises a cylindrical casing in which is a vane E<1> on the shaft E<2> rotatable through about 270 degrees and operates at each end of its stroke. A slide valve E' provided in one E' of a pair of blocks E', E<4>. In one position E<5> connects the pipe D' to one side of the vane E<1> for opening the main switch, the other side of the vane being exhausted to atmosphere, whereas in the other position, it connects D<2> to the other side of the vane for closing the switch, the one side being opened to atmosphere. The device F for operating arm C is similar except that it has no slide valve and its rotation is limited to about 225 degrees. The invention is also applicable to a horizontal draw-out switchgear structure; the conducting part of the isolating-rod engaging, in its fullywithdrawn position, a further ring-type contact connected to the main fixed contact. The first Provisional Specification refers to Specifications 516,529, 516,530, and 517,622.