Patent GB-460219-A (GB)
Title: Improvements in or relating to electric circuit-breakers
IPC: H01H33/18
Filed: 1935-07-23
Abstract: 460,219. Liquid - blast switches. REYROLLE & CO., Ltd., A., LEESON, B. H., WILD, R. W., and ALLAN, A. July 23, 1935, No. 20910. Addition to 435,308. [Class 38 (v)] The invention described in the parent Specification is modified by arranging that the two leadin conductors which are respectively connected (either directly or through connecting members) to the fixed contact and to the moving contact rod at opposite ends of the arc control device, approach the same end of the device so that one of such conductors (or its connecting member) extends through or past the device from end to end, thereby forming a current loop or partial loop for producing the deflecting magnetic field. The arc-enclosure may be constituted by aligned apertures in a series of superimposed baffle plates, or made in the manner disclosed in Specification 452,146, and its walls may be of phenol-formaldehyde condensation product, e.g. bakelized paper, or a thio-urea product, e.g. that known under the Registered Trade Mark " Beetle," or a vitreous material, e.g. porcelain, or a natural insulating material such as slate or non-absorbent wood. In Fig. 1, the enclosure is formed by baffle plates of pear-shape, the alternate plates C<1> having radial or offset vents and the other plates may have magnetic laminµ C<5> arranged in them to increase the magnetic action on the arc. The narrow end of the structure is bored to receive the lead-in conductor A and its insulating tube B, the movable contact F being connected by flexible lead F<4> to A. The other lead-in conductor A<1> is concentric with A, and a metal housing D<1> for the fixed contact structure is formed in a plate D which is threaded to bear on a shoulder A<4> on the lead-in R<1>, so mechanically supporting and electrically connecting the contact to A<1>. The latter is surrounded by insulation B<1>. The remainder of the baffle structure consists of insulating plates C<7>, E<1>, a metal plate E<3>, a nut E<4>, and a plate E having stiffening ribs, as E<6>, provided with bosses through which screws E<8> are threaded to engage plate E<3> and finally compress the structure. The contact F is a flat bar having rounded edges and an arcing tip F<2>. Fixed main contacts D<2> and an arcing contact D<3> respectively engage the sides of the bar F and the tip F2. The arrangement may be modified by arranging the lead-in conductors side-by-side. In Figs. 4, 6, the outer lead-in A<6> is connected by a ring G to a sleeve G<1> shrunk on the insulating sleeve B<2>. The fixed contact structure is housed in a member D<5> which is bored to receive the tube B<2> and lead-in A<5> and is slotted at D<8>. A pair of bolts D' serve to secure the housing D<5> on the sleeve G<1> and the latter is correspondingly slotted so as to receive the bolts and locate the housing. The arc-enclosure comprises blocks K, L, and side plates J which are cut away to receive and locate the housing D<5>. The block L is formed with surfaces L<3>, L<4>, Fig. 6, forming enclosure walls at the apex of which the throats L<6> of the vents L<5> are located. The other wall K<4> of the enclosure is constituted by part of the block K, and a plate M closes the bottom of the structures and is in two halves so as to be readily placed round the sleeve B<2> and. adjustable throat washer M<1>. The movable rod contact F<6> is secured to a conducting plug F<8> slidable within the lead-in A<5>, good contact between the latter parts being obtained by splitting the plug F8 at F<9> and pressing the segments outwardly by springs F<10>. Contact F<6> is operated by arm F" and co-operates with two pairs of sector-shaped contacts H, Fig. 6, each of which is urged by a spring H<1> so that one radial surface engages the side of the rod. Holes H2 cooperate with pins H<3> on a plate D<10> to limit the movement of the contacts H when F<6> is withdrawn. The fixed arcing contact is a block H<4> apertured to pass the rod F<6> and having a final separating surface H' adjacent the uppermost vent. This contact is slidable in the plate D<10> under spring action so as to bear against sleeve G<1> when F<6> is withdrawn. The arc is thus formed at the side of F<6> which is adjacent the vents, and therefore, by inspection of the drawing, is formed away from the normal contacting surfaces, so that the latter are not seriously pitted by the arc and the latter is, in turn, formed at the point most favourable for its extinction. In Fig. 8, a somewhat similar arrangement of blocks is shown, T, U being the end blocks, and the side blocks being formed with extensions, as R<1>, R<2>, by which the structure may be supported from the tank lid. The movable contact O is lowered into engagement with a fixed contact structure at the base of the enclosure, the structure being connected to a lead-in Q. The upper end of O may slide in a lead-in, as in the arrangement shown in Fig. 4. Sector-shaped blocks N<1>, preferably formed by cutting a ring, are located in a metal housing N with springs N<2> to produce the contact-pressure. A metal ring N<4> screwed into the housing N has an arcing tip N<5> adjacent the throat of the lowermost vent U <1>. The vents may be radial or offset, or straight or curved, and may be of diminishing crosssection, as described in Specification 421,552. Spring washers may be provided on the securing bolts in all forms of the invention, in order to prevent excessive pressures being set up in the enclosure. One or more conductors may be arranged on the device and connected to the lead-in conductor and contact, so as to form part of the loop, the central axis of the group (where such is employed) being coplanar with the axes of the movable contact and vent throats. The Specification also states that features disclosed in the parent Specification are applicable to the present invention, and that separate lead-in conductors provide a more rigid support although repulsive forces between them are not avoided.