GB187993A - Improvements in and relating to electric switches - Google Patents

Abstract

187,993. British Thomson - Houston Co., Ltd., (Assignees of Tritle, J. F.). Oct. 28, 1921, [Convention date]. Automatic circuit-breakers in which the contact member is released from a retaining electromagnet by the de-magnetizing effect of a straight conductor carrying the load and passing through the gap in the electromagnet as described in Specification 125,279 are provided with loose handle arrangements. The handle 23 or the electromagnet 24 causes the roller 22 to move the contact-member 13 in the closing direction against the action of the spring 14 while holding the contact 10 out of engagement with the fixed contact 1L until the handle is released, whereupon the spring 14 rotates the contact-member in the opposite direction about the pivot 19 on the pivoted armature lever 17 and completes the circuit. The contact-member is supported at its lower end by a strap connector 30 which carries the load and an overload tends to straighten out, automatically, thereby assisting the breaking movement when the de-magnetization on the armature 16, due to the conductor 29, has caused the release of the armature on overload. The intermediate position is shown in Fig. 3, in which the armature is held to the electromagnet, but the switch is not closed until the handle has been released or the operating electromagnet de-energized whereupon the contact-member swings round under the action of the spring 14 and, free of the roller 22, moves into the closed position shown in Fig. 4. On overload, the members 13, 14 move as a whole back to the off position shown in Fig. 1. A weight 39 is placed on the lower end of the contact-member to increase its moment of inertia below the pivot and ensure the correct relative movement of the members 13, 14. In the final closing movement, the lever 17 operates contacts to open the circuit of the operating coil 24.