GB464205A - Improvements in and relating to thermally controlled electrical switches or circuit breakers - Google Patents

Abstract

464,205. Automatic circuit-breakers. COMBI, U. A. July 13, 1935, No. 20109. [Class 38 (v)] Handles.-A circuit-breaker comprises a switch arm stressed to break circuit when not constrained, and contacts associated therewith, mechanism for engaging and moving said arm to complete the circuit through the contacts, and a thermo-electric element adapted when heated by excessive overload, to expand longitudinally and cause said mechanism to be disengaged from the arm to break circuit, and means for manipulating the mechanism to move the arm to open and close circuit, independently of the thermo element. The operating knob b with the finger-operated pointer b<1> extending through the cover a<1>, Fig. 3, carries an arm b<2> to which is pivoted at b<3> a link c, the end of which engages a pin e<2> in a slot e<3> in the spring- controlled switch-arm e, whereby rotation of b to the Fig. 6 position closes and retains the switch with a toggle action. The end of c co-operates with the edge g of a release element g<1> pivoted at g<2>, and the element g<1> is rotatable on overload due to the expansion of a currentcarrying strut h, which is adjustably attached at h<1> to a terminal abutment and hinged at g<3> to g<1>. The strut may be of nickel, or nickelchrome or nickel-manganese alloy, and may be relieved of compressive force by a spring acting on the element g<1>, Fig. 2 (not shown). The arrangement shown is for a single-pole switch, but modifications for a multi-pole circuit are described. The link c, Fig. 7, has the edge c<4> which co-operates with pin e<2> formed as an arc struck from a centre c<5> displaced from the pivot-centre so as to neutralize friction-effect during release. The surface c<8> is arranged during closure to engage edge g and displace c upwardly. The surface c<9> travels over edge g without affecting the position of pin e<2> on surface c<4>, and surface c<10> prevents cooperation between c, g at this stage. When the toggle c, b<2 >is fully overset, as determined by a stop a<3>, the surface c<7> is forced against the edge g, and c<4>, e<2> are in sensitive engagement. After the switch is tripped and opened by its spring f, the spring d restores the parts c, b to the Fig. 1 position, and causes c<4> to re-engage e<2>. Arc-rupturing devices ; contacts.-The fixed contact o has a carbon extension o<1> with which co-operates a button n<2> on an arm n, which is slotted at n<7> to produce an arm n<3> and an arm n<1> bent at n<4>, n<5>, n<6>. In closing circuit, the first contact occurs between n<2>, o<1>, then n<2> is bent backwards and n<3> engages o. The bend n<4> then engages o, whereupon n<2> pivots about n<4> and moves clear of o<1> while main contact m makes contact with o. The various movable contact surfaces slide on the fixed contact surfaces and are thereby kept clean. Covers.-The cover is retained by means of a nut q<2> screwing on to a stud q mounted in the base and passing through a hole in the cover. A wire q<3> secured by a seal q<4> passes through a hole q<2> in the stud. Indicators.-Luminous paint may be applied to one side or an area b<5> of the pointer.