Patent GB-489336-A (GB)
Title: Improvements in and relating to liquid-break electric circuit breakers
IPC: H01H33/34
Filed: 1937-01-22
Abstract: 489,336. Liquid-blast switches ; fluid actuation of switches. FLURSCHEIM, C. H., and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. Jan. 22, 1937, Nos. 1985 and 1986. [Class 38 (v)] A circuit-breaker suitable for E.H.T. systems, and of the kind in which the contacts are submerged in quenching liquid in an enclosure, has at least one set of co-operating contacts of which one contact is movable with respect to, and biassed into engagement with, the co-operating contact and is arranged so as to be displaced away from the said co-operating contact by the development of pressure in the liquid, and at least one other contact, which may be the said co-operating, or another, contact having operating means for mechanically moving said other contact away from the contact co-operating therewith. The breaker also includes means for setting up the pressure from an external source (that is, not are-produced) when the circuit is to be broken, and means for causing a liquid-flow across the path of the pressure-displaceable contact, the flow being produced by the same, or a different, external source. The arrangement is applicable to single and multi-break switches, and in the latter case, one, some or all of the two or more sets of contacts may be arranged as above set forth. The mechanical operating means preferably moves a contact or contacts of the set at the relatively earthed end of the series circuit, which set may comprise one or more pairs of series-connected contacts. The arrangement further provides for rapid separation, and satisfactory insulation, of the oil-displaceable contact or contacts. The oil-displaced contacts may be latched against reclosure by means associated with the mechanical means, such that they are released to close either before, simultaneously with, or after, the mechanicallyoperated contacts. Fig. 4 shows a tubular insulating member 9 with an oil-pressure piston 20 and a contact 1, which is operated by mechanical means (not shown) and co-operates with a contact 31 to form the end set. Two other series breaks are formed by contacts 39, 40 and 41, 42, which, together with contact 31 (as shown), are oil-displaceable. Contacts 31, 39 and 40, 41, and contact 42 are respectively mounted in enclosures 32, 44, 46 provided with ports 33, 48, 49, and the breaks are provided with respective passages 38, 50, 51 for the oil-blast. The contacts 31, 39 .. 42 are all similarly mounted, contact 31 being guided on a bar 34 which is held by support 35 and carries a compression spring 36 bearing against a flange 37 on the contact. Flexible shunts 43, 45, 47 complete the circuit between the contacts, that 47 being connected to the live end, whereas contact 1 is at the relativelyearthed end where the chamber-supporting structure containing the operating mechanism is located. Instead of the oil-pressure acting directly on the contacts, the latter may be linked to pistons, for example, to a common operating piston, as shown in Fig. 6, in which a two-break arrangement employs a pair of tubular blast-receiving contacts 61, 62 at the series break and a similar contact 3 co-operating with the contact 1. Ports 65, 69 are provided, the former having a partition 66. Contacts 3, 61, 62 work in guides 27<1> and have biassing springs 10. Contacts 3, 62 are operated by a piston 52 in a cylinder 53 through links 57 and levers 55, which are pivoted at 56 and engage the contacts at 70, whereas contact 61 is connected to piston 52 through link 60 and a lever 58, which is pivoted at 59 and engages the contact at 71. In Fig. 5 (not shown), a similar operating piston is applied to the construction of Fig. 4, but without the housings 32 &c. and ports 33 &c. Fixed contacts may be provided for the end and subsequent breaks of these Figs. In Fig. 3 (not shown), the contact arrangement 1, 3 of Fig. 6 is shown in a singlebreak switch, and in Fig. 2 (not shown) a further single-break switch has a contact 1 co-operating with a non-tubular contact 3, the oil-blast taking place through lateral passages in the enclosure itself. The operation of these two forms may be by the means described in Specifications 435,419 and 477,006. In Fig. 1 (not shown), a fixed contact of the series break is mounted on an arm pivoted, for limited following movement, at a point which is offset from the path of the oil-displaceable contact, so that the latter, in opening circuit, produces a bending moment at the contact faces, should they be welded together.