Patent GB-532080-A (GB)
Title: Improvements in or relating to liquid-immersed electric circuit interrupters
IPC: H01H33/06
Filed: 1939-08-16
Abstract: 532,080. Liquid-blast switches. WESTING- HOUSE ELECTRIC INTERNATIONAL CO. Aug. 16, 1939, No. 23630. Convention date, Sept. 8, 1938. [Class 38 (v)] An arc-quenching structure adapted to be inserted in an insulating cylindrical strain member in an oil-containing tubular weatherproof housing, Fig. 1 (not shown), comprises an insulating cylinder 37 in which fixed contacts 53 are carried on arms 61 pivoted to supports 41 to which terminal leads 95, 97 are connected. The contacts are normally spring-pressed into engagement with one another through an aperture 79 in an insulating plate 71 which carries cam-surfaces 75 engageable with rollers 77 on arms 51. A spring, Fig. 1 (not shown), forces down the plate 71 when the breaker is opened, and the cams 75 separate the contacts before the upper edge of aperture 73 comes between them and forces the arc downwards into the arc-lengthening passage 59. The latter is of rectangular cross-section and formed of suspended slotted plates such as to provide corrugations for retaining fluid. The plate 71 is as wide as the slots, except that it is reduced at both narrow edges below the aperture 73 so as to form shoulders which act as pistons. The thickness of plate 71 is, however, such as to leave a narrow space on either side of it, as shown. The plate 71 passes closely through the apertured bottom plate 65 of the passage and through a spring-piston 103, where it is coupled at 85 to closing mechanism. The arc-pressure depresses the piston 103 by driving oil through the apertures in plate 65 and when the pressure subsides, the piston returns the oil to the passage and expels arc-gases. In a modification, Fig. 2 (not shown), a bridging contact may be located at the lower edge of the aperture in the plate 71, so enabling the cams thereon to be dispensed with, but in another form, Fig. 6 (not shown), the bridging contact is employed without an aperture, the individual contact faces preventing the two series-connected arcs from looping and unduly lengthening under the electrodynamic action of the current. In another form, the bottom of the plate 71 is wedge-shaped, the greatest width of which is greater than the thickness of the plate and the point just above the engaging contacts. The cross-section of the arcpassage is correspondingly shaped so that smallcurrent arcs are not quenched until near the end of the stroke of the plate 71. This form employs cams on the plate 71 to produce the separation of the contacts, Fig. 10 (not shown). In Fig. 14 a fixed contact rod 153 carrying an insulating filling member 175, co-operates with four contacts 167 pivoted on brackets 165 and urged inwards by springs 169. Extensions 209 thereon co-operate with a ring 211 which, when the breaker is being opened, is lifted to raise the contacts 167 from the rod 153. The ring has upstanding) arms 213 pivoted to a bell-crank lever 215 operated by a cam 225 on a sleeve 197 pivoted at 199 to the operating mechanism. The sleeve 197 supports a pair of levers 195 to which are pivoted the operating rod 205 and a pair of levers 183, which are pivoted in turn to the insulating tube 179 and to blocks 187 slidable in slots 189. The tube 179 is driven downwards into an arcchamber of annular cross-section formed by the filling member 175 And circular apertures in the plates 171, 173. The whole is located in an oilcontaining casing as described with reference to Fig. 2.