Patent GB-515888-A (GB)
Title: Improvements relating to electrical circuit interrupters having arc-extinguishing arrangements
IPC: H01H33/16
Filed: 1938-06-13
Abstract: 515,888. Fluid - blast switches. BRITISH ELECTRICAL & ALLIED INDUSTRIES RESEARCH ASSOCIATION, GOSLAND, L., and WHITNEY, W. B. June 13, 1938, Nos. 17527/38 and 5005/39. [Class 38 (v)] In a circuit - breaker of the side - blast type, auxiliary electrodes are carried by the steps of a ported ladder-like structure participating in the relative movement of the main arcing electrodes, and are connected through resistances to that one of the main electrodes with respect to which they are relatively fixed. The relatively moving parts act as valve and seating of a slide valve which controls the successive opening of passages to enable quenching-fluid to flow through the ports to the vent. The arrangement is such that a passage through a port at which the arc-section is already out is shut off from the vent so that the blast is concentrated on the arcs at the other ports. The blast may be of liquid or gas and produced by an external source of pressure, or generated by the arc itself, various known methods being mentioned in the Specification. the ports beween the auxiliary electrodes may be subdivided by insulating baffles to minimize arc-lengthening, and the electrodes themselves may each have high melting-point tips. The auxiliary electrodes may be spaced from the walls of the vent, as by mounting them between insulating projections from the side of the vent outlet, so exposing them to the maximum blast. The main movable electrode 3 has an insulating insert 24 and is mounted on a sliding carrier to which the ladder-like structure 17 is secured. The main fixed electrode 2 is spring-pressed against the electrode 3 and auxiliary electrodes 18, and mounted in a cut-away part 12 of an insulating block 9, the part 12 forming a part of a rectangular passageway, the opposite wall of which is formed by a fibre plate 13. The latter is apertured at 15 corresponding to the vent 14 in the insulating block 10. The electrodes 18 are mounted between fibre side - members 19 and have white-fibre tips 21, packing pieces 21a of white fibre being inserted between the steps. When the circuit is opened a blast of fluid from cylinder 7 is released by a valve and guided by surface 22 of the block 9 so as to act on the arc the moment it is formed between electrodes 2, 3. The electrode 3 and structure 17 move downwards together and arc is transferred to the lowermost electrode 18 and subsequently a chain of arcs between the main and auxiliary electrodes is formed, each of the latter in turn being exposed to the blast through the vent 14. The blast may be further guided by a fibre member slidable on that face of electrode 3 which is opposite electrode 2, the member being urged upwards by a spring compressed during the closing operation by engagement between the member and the bottom of electrode 2, and being arranged so that in opening circuit its rounded surface merges into that of the electrode 3. The electrodes 3, 18 are interconnected by resistances constructed as described for example in Specification 485,463 and arranged within the breaker-framework, the flexible or rubbing connections to the electrodes being accommodated in the side-members 19. The individual arcs are shunted in turn and the further arcs formed are in series with resistance ; whereby the current and arc energy are reduced. Details of construction and performance for a breaker clearing 1,600 amps. at 6,600 volts are given in the Specification. In the modification shown in Fig. 4, the auxiliary electrodes 28 with white fibre extensions 29, are fixed in the vent 27. The main moving electrode 30 is mounted in a sliding carriage 31 and urged by springs 32 against electrodes 28 and the main fixed electrode 26. Resistances are provided between the fixed and auxiliary electrodes. The carriage 31 forms a movable wall of the container 25 and acts also as a shutter having a blast-aperture 35. One Provisional Specification describes modifications in detail.