GB191048A - Improvements in and relating to electric switching apparatus - Google Patents

Abstract

191,048. British Thomson - Houston Co., Ltd., (Assignees of French, H. G.). Dec. 27, 1921, [Convention date]. Switchboards; sliding switch carriage arrangements.-Cases for electrical switch gear of the enclosed unit panel type are arranged with the oil switches attached to a front cover which can be swung outwardly for inspection and repair, the switch at the same time being isolated from the supply as the movable front carries isolating contacts co-operating with fixed contacts in the interior of the panel when the panel is swung back into position. The box-like casing 1 is built up from metal plates 2 and angles 3 and contains a terminal board 4 carrying supply terminals 5 and circuit terminals 7, bus-bars 6 running through side openings in the casing being connected to the terminals 5 and leads 8 passing out from the terminals 7, current transformers &c. 9 being included. The oil switch 11 is attached behind the front plate 10 and has its terminals connected by leads 14 to contact jaws 17 on a board 16 which are arranged to register with fixed contacts attached to the terminals 5, 7. An insulating barrier 19 is disposed between the fixed and movable contacts 17, 18, the terminals 7 projecting through suitable slots therein. The plate 10 is arranged to be swung outwardly by means of parallel links 21 secured between pivots 22 in the casing 1 and pivots 23 in the switch head 24, one pair of links 21 co-operating with stops 39 to limit the outward swing of the switch panel. Springs 25 are provided between the case 1 and links 21 to assist the return motion of the switch. In order to lock the switch plate in position, a pair of pivoted bell crank levers 44, 41 are provided with operating handles 45 which on being depressed cause pins 42 to engage fixed plates 43 in the casing 1. The levers 44, 41 have a third arm 46 which co-operates with an arm 47 of the oil switch operating lever 48 to prevent the withdrawal of the front plate 10 while the oil switch is closed. Further, closure of the oil switch operates the locking means if the panel is not already locked in position. In Fig. 5 is shown an alternative form of link mechanism in which the parallel links 27 and 28 are pivotally connected to a shorter pair of links 32 pivoted to the casing 1 at 33. A horizontal distance link extends across the lower ends of the links 27, 28 and the latter has a crank-like extension 29 terminating in a roller 34 which moves along guides 35. When the switch is drawn the switch moves along a flattened arcuate path 36 approaching a straight line in form and by preventing excessive lowering of the switch enables it to be restored with a minimum of effort, assisted by the spring 37. A hasp 49 is provided to carry a padlock to prevent tampering with the latching handle 45, and instruments may be mounted on the front of the panel 10.