IE42983L - Current limiting circuit breaker - Google Patents

Abstract

1511881 Automatic circuit-breakers; electromagnetically operable switches SQUARE D CO 23 April 1975 [29 April 1974 (6)] 16721/75 Heading H1N An automatic circuit breaker is combined with a series current limiting electromagnetic switch in a single mounted two parts housing for the three phase switch. In each phase compartment 44, 45, 46 of the housing a resiliently mounted fixed contact assembly 50 is connected to terminal 60 and has main and arcing contacts 53, 54 co-operating with a movable contact 70 in region surrounded by a magnetic plate structure 130 adjacent a arc shoot 133. The movable contact is on a lever 67 coupled to a bar 63 common to the three phases and operable by toggle links mechanism 73 which includes a latch lever 76 retained by engagement in the centre phase armature of an adjustable overload electromagnet 111. The armature of the overload electromagnets 111 are all connected to a common bar 118 which is also movable by a lever 106 when the latter is released by a common thermal trip bar 105 acted upon by the phase bimetal strips 145. The bar 108 may be moved to the trip position by a manually operable push-button (Fig. 34, not shown). Current is carried from the movable contact lever by a flexible connector to a bar 133 on which the bimetal 145 is mounted and which connects to a conductor 142 coupled by a screw 146 to a part 148a of an approximately box-shaped structure 148 arranged in relation to a yoke 156 so that current passes along part 148a and the box sides to a part 150 in parallel with current in a part 150alpha. The current then passes through normally closed contacts 153, 155 on arms 152, 154 pivoted respectively at 168 and 170. On very heavy overload (e.g. 1000 amps) sufficient current will flow in part 148alpha for a biased armature 158 to be attracted to the yoke 156 so that a link 164 is moved upward and a pin 166 thereon rotates arm 152 about its pivot 168 and a further pin 167 is moved to permit arm 154 to move under the repulsion forces of the currents in the two arms 152, 154. As the contacts open within a rectangular magnetic yoke 182, which assists movement of the arc between contacts 153, 155 towards an arc chute 202 current passes in parallel with the arc along conductor 188b (assisting the effect of current in part 148a), conductor 188d (assisting in the magnetization of yoke 182), a connector 190 and through a positive temperature coefficient resistor 192 embedded in ceramic compound in a recess 45alpha in the moulded base 41. The other end of the resistor 192 is connected through a conductor 199 (which also passes through the yoke 182) to the same terminal member 184 as a flexible connector 178 coupled to the arm 154. Features of the combined breaker and switch are claimed in divisional Specifications 1,511,882, 1,511,883, 1,511,884, 1,511,885 and 1,511,886. [GB1511881A]