Patent GB-479412-A (GB)
Title: Improvements in or relating to electric circuit breakers having arc-extinguishing devices
IPC: H01H33/18
Filed: 1937-06-04
Abstract: 479,412. Liquid - blast switches ; arc - rupturing in switches. WESTINGHOUSE ELECTRIC & MANUFACTURING CO. June 4, 1937, No. 15581. Convention date, June 5, 1936. [Class 38 (v)] In a circuit-breaker having an arc-extinguishing device formed with an arc passage containing an extinguishing liquid which evolves a gas under arc-action, and a fixed and movable contact-member in said passage, means operatively coupled to the movable contact-member and utilizing the pressure created by an arc on closing the contacts under load, are provided for assisting the closing of the movable contact-member against said pressure, and being operative during the opening operation to cause a flow of liquid against the arc establistied between the spaced contact-members. Figs. 2, 3 show the upper and lower ends, respectively, of a structure comprising a number of arcquenching units 17, each associated with one break of a multiple-break switch. Such a structure may be screwed on to the end of each of two lead-in conductors 13 in a tank, Fig. 1 (not shown), containing the extinguishing liquid, such as oil. Fig. 5 shows a form which may be applied to a single unit, or to each unit of a multiple-unit structure. In Figs. 2-4, the structures terminate in releasable contacts 19 which are adapted to be bridged by a bridging-bar operable by a lift-rod. The contacts 19 are mounted on the lower ends of the respective common operating-rods 69 for the movable contacts 59, Fig. 3. The contacts 59 co-operate with fixed contacts 57 in the widened parts of arc-passages 31, and are connected by straight-line linkage 67 to the rod 69 for simultaneous operation. Linkage 67 comprises a rocking-lever 75 pivoted at 77 and having a pivotal connection to a lever 71, which in turn is pivoted at 81 to rod 69. A link 82 has a fixed pivot 83 and also pivotally engages 81. A pivot pin 73 on lever T1 engages a slot in contact 59 and bears on a spring 85 in the bore of the contact, which spring provides the contact-pressure and assists in accelerating the opening movement. Each fixed contact 57 has a cylindrical bore 95 which communicates with passage 31 by an opening 98. Within this bore 95 works a piston 96 secured to an extension of the movable contact 59 of the unit 17 above. In the case of the upper unit, Fig. 2, the bore communicates over passage 104 to the underside 103 of a piston 102 on the upper end of rod 69, which piston works in a casing 101 serving as an abutment for an opening spring 108. When the contacts 59 move upwards to close circuit, the liquid displaced by them and by the gas pressure produced by any circuit-closing arc which forms, moves into the cylinder 95 and acts on the piston 96 to assist the closing force, or, in the case of the upper unit, acts on piston 102. In opening circuit, this liquid is forced back into the passages 31 and, by means of deflecting members 99, directed on to the arc to tend to move the latter on to an arc-horn. Provided the areas of the pistons and contacts are the same, exact compensation of the counter-force in closing may be obtained. If piston 102 is dispensed with, complete balance may be got by arranging the ratio of pistonarea to contact-area to be N : N + 1, where N is the number of units 17. Each unit 17 is provided with a further accelerating-spring 110, Fig. 3, acting on a pin 111 on lever 71. Structurally, each unit 17 comprises magnetic end-plates 45, 47, insulating end-plates 25, and a stack of insulating plates arranged as shown at 26 ... 30 in Fig. 2. The latter plates have curved, tapering slots which are aligned to form the passage 31, and Fig. 4 shows the shapes of the slots in three plates 28 ... 30. Plate 29 has a slot 33, whereas plates 28, 30, which are respectively above and below plate 29, have each a slot 35 provided with indentures 37 for retaining liquid, the indentures in the plates being staggered. The parts 39 between the indentures remote from the contacts are not slotted, as are the nearer ones, but are left solid. Plates 26 are slotted to receive upper and lower arc-horns 41, 43, and to form annular chambers 141 which are concentric with passage 31 and serve to conduct arc-gases to vents 145 cut in the plates 25, 45, 47, Fig. 3. The unit is secured as a whole by insulating rods 49 and the structure is secured by rods 51 and nuts 54 to member 55 which screws on to conductor 13. Magnetic means for moving the arcs along the passages 31 comprise upper series coils 61 and coils 116 in end plates 45, and coils 120 in plates 47, a series-coil 125 being mounted also in plate 47 of the lower unit 17. One end of coil 61 of the upper unit is connected by screw 115 to plate 45, which in turn is connected at 131 to member 55, and the other end of 61 is connected to fixed contact 57. One end of coil 116 of the upper unit is connected at 117 to plate 45 and the other at 118 to horn 41. Coil 120 of the upper unit is connected at one end to horn 43 and plate 47, and at the other by conductor 123 to one end of coil 116 of unit 17 below. In the lower unit, the series-coil 125 is connected by lead 127 to contact 19 at one end, and at the other to plate 47. One end of 120 is connected to plate 47 and the other to horn 43. Plate 47 of one unit is connected at 133 to plate 45 of the unit below. On first striking the arc, series-coils 61 act to move their upper ends on to horns 41, so energizing coils 116. Since each coil 116 is in series with the coil 120 of the unit above, excepting for the upper unit, the lower ends of the arcs are moved to horns 43 and moved therealong into the narrow part of the passage 31. The movement of the arc to horn 43 of the lower unit is effected by coil 125 of that unit, since there is no coil 116 below to energize coil 120. Fig. 5 shows an alternative means for compensating for the cloning-force. The passage 31 leads into an adjacent passage 151, in which works a piston 153 connected to contact 59 by a lever 155 which is pivoted at 156 to a bracket 157 on plate 47. Any pressure set up in passage 31 acts on piston 153 and, through lever 155, on contact 59 in the closing direction, and conversely, in opening, a flow of liquid is forced by the piston between the contacts.