GB723052A - Electro-magnetic, automatically-operated safety switch - Google Patents

Abstract

723,052. Protective cut-out arrangements; electrically-released switches. PEGURRI. G. July 31, 1952, No. 19349/52. Class 38 (5). A device for controlling the supply of current from a low voltage supply 17 through a transformer 18 to a high voltage circuit 19, such as that of a neon sign 20, comprises a manuallyoperable main switch 6 and an electrically-released switch having its coil 3 and contacts 7, 8 connected in series in the primary circuit of the transformer. In operation, the switch 6 is closed and a push button 5 is depressed to move an armature 10 against the bias of a spring 13 to close a contact 7 onto contact 8. This completes the primary circuit and the coil 3 is energized to retain the armature 10 when the push button 5 is released. Should the current flowing in the coil 3 be reduced due to an open circuit fault the armature is released and the contacts 7, 8 are opened to interrupt the supply to the transformer. If an overload occurs, the current in the coil 3 creates a magnetic field strong enough to move a catch 14 out of abutting engagement with the contact 8 which is then moved by a spring 15 away from the contact 7 to open the primary circuit. This de-energizes the coil 3 causing the release of the armature 10, so that it is necessary to reset both the armature and the contact 8 to restore the supply.