GB357973A - Improvements relating to alternating electric current circuit breakers - Google Patents

Abstract

357,973. Oil-break switches. PEARCE, H., Green Mount, Barrington Road, Altrincham, Cheshire, and ASSOCIATED ELECTRICAL INDUSTRIES, Ltd., Crown House, Aldwych, London. June 24, 1930, No. 19280. [Class 38 (v).] Arc-rupturing devices.-In an A.C. circuit-breaker of the kind in which a fixed and a movable contact are located in a secondary oil-containing vessel mounted within a main oil tank the fixed contact being of tubular construction located at the upper end of the secondary oil vessel so that as the contacts open oil and gases generated by the arc formed therebv are caused to be discharged out of the secondary vessel and through the tubular fixed contact into the outer oil-containing vessel by the pressure of the gas. The pressure within the secondary vessel may be augmented by producing a preliminary current break at auxiliary contacts mounted therein. As shown in the Figure, the lowering of the bridge member 16 draws down the rod 15 and causes a current interruption between contacts 20, 30 within the explosion chamber 4 the contact 7 being held in engagement with the tubular fixed contact 6 by springs 18 acting between insulated bridge members 9, 14. The arc formed between contacts 20, 30 creates a gas pressure within the chamber and on further downward movement of the roof 15 when the bar 14 engages nuts 17 on rods 12 depending from the bar 9 and draws the rod 17 downwardly from the end of the passage 6 a stream of oil and gas is forced between the separator surfaces of the contacts 1, 7, owing to pressure produced by the arc augmented by the pressure produced by the preliminary break. The stream of gas and oil escapes through the passage 6, so quickly extinguishing the arc formed between these contacts 1, 7. To retain the pressure within the chamber during the switch-opening movement the rod 15 passes upwardly through a gland in a central orifice of the lower insulating-plate 5 of the chamber. In a modified form, Figs. 3 and 4 (not shown), the upper contact 1 is secured directly to the lower end of the insulator bushing, the passage 6 being curved so as to have a lateral outlet.