GB1094596A - Circuit interrupters - Google Patents

Abstract

1,094,596. Air blast switches; automatic circuit breakers; switchgear assemblies. CENTRAL TRANSFORMER CORPORATION. Aug. 16, 1965, No. 35082/65. Heading H2B. An arc shoot comprises an insulating casing 169 containing a plurality of spaced parallel insulating plates 185, 189 divided into three groups by a pair of conducting electrodes 191, 193 between which are connected a pair of blow-out coils L1, L2 each wound as in Fig. 11 to provide a high-intensity field over a lower region B2 of the shoot and a lower intensity field over an upper region B1. The coils are mounted upon the outside surfaces of the shoot which is engirdled by a laminated core MC of grain-orientated silicon steel which is continued downwards on either side of the shoot by extensions (MCE) (Fig. 10, not shown). The shoot is provided with arc runners 181, 183 and the upper ends of these and of the electrodes 191, 193 are provided with heavy arcing portions of silver-molybdenum alloy. The central portion of the shoot is extended to form a chimney 199 while the other portions are vented through perforated baffle plates 201. Air blast switches.-The arc runner 181 of the shoot is connected to the fixed contact assembly of a switch by a flexible conductor 223 the shoot being pivoted to the assembly at 179. The other runner 183 is connected by a removable link (211) to the moving contact assembly (Fig. 6, not shown). The fixed contact assembly (Fig. 8, not shown) comprises a conducting plate (81A) silver brazed (at SB) to a cap (82) of a tubular plugging isolator contact (67) insulated by a sleeve (78); a J-shaped conducting member (81B) carrying a fixed arcing contact (83); a main contact member (84) pivotally mounted to the J-shaped member at (85A) and spring biased away from the plate (81A) by insulated springs (86); and a pair of side plates (87) attached to plate (81A) and formed with inspection apertures (89, 89A) placed to allow contact wear to be gauged and the contact correctly adjusted. Apart from the joint (SB), plate (81A) is insulated from cap (82) by an insulating sheet (88A) (Fig. 8, not shown). This together with the insulated springs (86) causes the current to main contact (84) to follow a U-shaped path so that contact pressure is electrodynamically reinforced. An aperture (94) is formed in contact (67) to allow the flow of cooling air through the fixed contact assembly. The movable contact assembly (Fig. 6, not shown) is pivoted at (107) to a second hollow isolator contact (69); coiled conductive springs (105) provide electrical continuity. Pivoted to the assembly at (109) with similar conductive springs is a double-armed arcing contact (108) biased by tension spring (111) to engage fixed contact (83). A link on a fixed pivot (124) is moved by a pin (127) on the movable contact to move a piston (117) in the hollow contact (69) to direct a blast of air through a nozzle (115). Automatic circuit breakers.-The movable contact is coupled by an adjustable link (14) to a crank (18) (Figs. 1-4, not shown) on a fixed pivot (20). The crank (18) is coupled to a toggle linkage (23, 25) held set by a latched sector (35) also pivoted at (20). The latch arm (37) engages a rectilinearly movable conical cam (40) (Fig. 12, not shown) movable against spring bias (41) by a releasing electromagnet (42) energized by overload responsive means. A detachable handle (not shown) may be inserted at (66) to release the switch manually. Release of latch (37) allows toggle (23), (25) to collapse to the left (Fig. 3, not shown) and contacts to open under a spring (22). A roller (46) at the knee of the collapsing toggle strikes a latch arm (30) releasing the lower pivot (26) of the toggle which moves to the right under a spring (53) to reset the toggle (Fig. 4, not shown) and latch (37). The switch is reelosed by re-engaging pivot (26) with latch (30) either by an electromagnet (55) or by a roller (56) on a crank (57) operable by a second detachable handle (61). The opening movement of the contacts is controlled by dashpots (44) coupled to crank (18). Switchgear assemblies.-The three-phase switch together with its arc shoots, puffers, tripping and actuating mechanisms is assembled on a wheeled trolley (10) by which means isolator contacts (67, 69) can be engaged with fixed sockets (149) (Figs. 1, 15, not shown) associated with cables (128) and bus-bars (71, 72, 74). The sockets (149) also carry current transformers (147). A shutter (155) (Fig. 13, not shown) drops to cover live sockets (149) when the trolley is withdrawn. A linkage (47, 50) (Fig. 12, not shown) is arranged to trip the switch if the trolley is withdrawn.