Patent GB-225666-A (GB)
Title: Improvements in or relating to electrical switch gear
IPC: H02B11/167
Filed: 1923-10-11
Abstract: 225,666. Davies, D. R., Johnson, E. M., and Metropolitan-Vickers Electrical Co., Ltd. Oct. 11, 1923. Sliding switch-carriage arrangements of the type employing removable plug contacts the position of which relative to co-operating sets of sockets can be varied to enable alternative connections to be separately established include means for obviating the inadvertent simultaneous establishment of these alternative connections. Means may be provided, for instance, to prevent insertion of the plug contacts into more than one set of sockets prior to the closure of the switch gear or to prevent the closure of the gear with the plug contacts inserted into more than one set of sockets. In the form shown in Fig. 1, the truckmember 1 is provided with double-ended plug contacts which may be inserted into one or other of the upper sets of sockets 5, 6, 7 and 8, 9. 10 corresponding to duplicate bus-bars. A sliding plate 17 is arranged on bars 18, 19 so as always to have one set of socket openings. The plate 17 is connected by a rod 21 to an indicator 20 denoting which set of bus-bars is in use. In a similar modification, Fig. 2, a hinged flap 24 covers one or other of the sets of socket apertures. In this form, although it is possible to insert plug contacts in both sets of sockets simultaneously, no connection can be established as the plate 24 engages the fixed casing before the truck 1 can be moved completely against the fixed switch gear element. In Fig. 9 in which the invention is applied to switch gear having the fixed socket apertures provided with hinged shutters 45 which are operated by bars 50 - - 52 carried by the movable switch-carriage 49, these bars are so arranged that the socket openings corresponding to both sets of bus-bars cannot be uncovered simultaneously. This is effected by connecting the ends of the levers 50, 51 to two arms of a pivoted 3- armed lever 59, the third arm of which is operated by a lever mechanism 61, 62 to advance the ends of one of the bars 50, 51, so that only one set of socket openings is uncovered as the switchcarriage is moved inwards. Each plug 66 is provided with an auxiliary feeler 67, Fig. 12, which normally enters a recess in the fixed gear 44 adjacent to the socket aperture 68, but if the plugs have been wrongly inserted the feelers 7 foul the closed shutters 45, Fig. 11, so preventing further inward motion of the switch-carriage. In Fig. 13, plug members 70 are carried in a frame 72 held on horizontal rods 75 projecting from supporting members 74 which are provided with gear to enable them to occupy either of the alternative positions shown in Fig. 15 in which the plugs 70 are opposite one or other sets of sockets. On moving the switch carriage 49 inwards, the horizontal rods 85 or 86 carried by the bars 80 enter holes 87 in the frame 72, moving it clear of the rods 75. At the same time the plugs 70 enter sockets in the carriage 49 so that on further inward movement, as the wheels 82 on the bars 80 move down the incline 84, the frame 72 is moved downwards, leaving the plugs held in the sockets by hooked catches 90 or 91. In the final position of the switch carriage, shown in Fig. 16, the frame 72 rests between adjacent socket shields on the fixed switch gear 44, the plug contacts completing the circuit to the set of bus-bars in use. As only one set of plug contacts is employed, simultaneous connection to both bus-bars is obviated. The plug contacts may, alternatively, be attached rigidly to the frame so that there is no necessity to release them before the switch-carriage is forced home, and such a frame 103, Figs. 24 and 25, may be pivotally mounted so as to be swung round as shown to engage the sockets corresponding to one or other of the sets of duplicate bus-bars. Specification 217,290 is referred to.