Patent GB-286429-A (GB)
Title: Improvements in connection with coupling-up or isolating switchgear
IPC: H02B11/20
Filed: 1927-02-08
Abstract: 286,429. Whitehead, G. E. Feb. 8, 1927. Sliding switch-carriage arrangements; switchboard details. - Relates to coupling-up cubicletype switchgear of the kind wherein a circuitbreaker connects terminals of incoming and outgoing conductors. The breaker is fixed relatively to the bus-bars and/or cable ends upon or in a cubicle framework and the breaker terminals are in a semi-permanently closed compartment. The bus-bars and/or cable ends have fixed contacts in a permanently closed compartment whilst coupling contacts connected with the breaker terminals are projected by exteriorly-operated mechanism into the permanently closed compartment to engage the contacts therein. The cubicle is divided by a partition 4 into two parts 2, 3, of which 2 is closed by fixed panels and 3 is closed by a door which can be removed under certain safe conditions. The incoming or outgoing 3-phase cable 11 is brought through a trifurcating box 12 and its conductor brought to insulated contacts 17, which contacts are connected bv the circuit-breaker to the contacts 21 in connection with the insulated bus-bars 8. The head 6 of the breaker is permanently mounted on the framework and its terminals 15, 16 are tubular and receive telescopically the coupling contacts 22 which are mounted on a carriage 23. These contacts project through openings 26 in the partition 4 into engagement with the contacts 17, 21 when the isolation is discontinued. To effect isolation, the carriage 23 is lowered by worm-gearing 33, 34 and a screwed spindle 29 engaging a nut 28 in the carriage 23. The ends of the carriage 23 are secured to vertically guided bars 38 which are connected to shutters 27 by links 39 and levers 40 pivoted at 41 to the framework. Upon isolation, therefore, the openings 26 are closed by the shutter 27, and the carriage 23 rests on the frame members 44 with its nut 28 engaging a threadless part 32 of the spindle 29. Subsequent rotation of this spindle, however, effects the lowering of the oil tank 45, which is carried by a pair of vertically guided bars 46 secured on a frame 47 having a nut 48 for co-operating with the lower thread of the spindle 29. Thus the tank cannot be removed before the breaker has been isolated, and by a further interlock isolation cannot be effected before the breaker has been opened, said interlock being shown diagrammatically in Fig. 2 as a member 50 linked to the operating handle 14 of the breaker. The following further interlocks are also provided :-(1) a catch locking the door of the compartment 3 until the breaker has been isolated, and (ii) a catch released by the opening of the door to prevent the isolation being removed until the door is closed. Fig. 4 (not shown) shows a form in which the contacts 22 are cranked so as to be rotatable to engage selectively the main or a duplicate set of busbars. In the modification shown in Fig. 5, isolating blade contacts 22 are provided for engaging the contacts 18, the blades being pivoted at 58 and being operated through links and a vertically guided bar 72 by a handle 68. A shutter 77 is also connected to the bar 72 so as to be moved thereby to cover the opening in the partition 4 when the blades 22 are withdrawn. Preferably there are provided a bar 72 and handle 68 on each side of the cubicle, the bars being interconnected at 73 by a spindle carrying the links 74, and by a bar at 82 constituting the interlock for the oil tank. Continued upward movement of the handle 68 could be arranged to effect consecutively the isolation of the breaker and the lowering of its tank. Current transformers are shown at 63, in the compartment 3, but they may be alternatively placed in compartment 2. The bus-bars 8 may extend into adjacent switchgear cubicles.