General Electric Company

John H Van Noy

George A Farrall

Gerhard Frind

James J Carroll

John G Leach

Radha K Ranjan

An exothermically assisted electric fuse, having at least one exothermic body disposed in heat transfer relationship with at least a portion of each fusible element of the fuse, a triggering circuit for initiating an exothermic reaction in response to an overcurrent through the fuse, and a containment body partially enclosing the exothermic body for directing the heat energy released by the exothermic reaction. The containment body is disposed so as to confine and direct the heat energy in a direction which is substantially perpendicular to a plane containing the portion of the fusible element which is in heat transfer relationship with the exothermic body. In a preferred embodiment of such a fuse, the fusible element is wound around a support so that the fuse windings form the general shape of a cylinder, and the containment body is disposed so that the heat energy is directed in a radial direction with respect to the cylinder formed by the fuse windings. The exothermic body preferably comprises a two-part structure in which a mixture of boron and potassium perchlorate acts as a primer for a larger body of exothermic material formed from a mixture of aluminum and potassium perchlorate.

Exothermically assisted electric fuse

A synchronously operable electrical current switching apparatus which may be used to switch multiple circuits, or to lower the contact resistance in one or more circuits, or both, includes a plurality of piezoelectric benders of the type having at least two electrically conductive layers separated by a piezoelectric material, and which exhibit bending motion in a direction substantially perpendicular to the plane in which the benders lie in response to an applied electrical signal. The apparatus also includes at least one pair of switching contacts, with one contact being movable and mechanically linked to at least one bender so that the bending motion causes corresponding movement of the contact and produces a change in the relative position of the contacts between open and closed positions. One of the electrically conductive layers of each bender is connected to the electrical signal by a common electrical conductor. For predetermined ones of the benders, a second one of the electrically conductive layers is connected to the electrical signal by a separate conductor, so that those benders exhibit bending motion in response to the signal. One pair of contacts may be provided for each bender, or a number of benders may be mechanically linked to one movable contact, so that the force exerted on the contact by the benders is increased.

Synchronously operable electrical current switching apparatus having

A synchronously operable, piezoelectrically actuated electrical current switching apparatus is provided which has increased separation between the switching contacts when they are in the open position, and increased contact closing force when they are in the closed position. The apparatus includes a pair of spaced-apart, opposing multimorph piezoelectric benders and at least one pair of electrical current switching contacts mounted on the opposing surfaces of the pair of benders, with one contact being mounted on each of the surfaces. The benders are disposed so that they bend toward each other in response to a first electrical signal, moving the contacts to a closed position. In response to a second electrical signal, the benders bend away from each other and move the contacts to an open position. In this manner, the distance achievable between the contacts in the open position is greater than the displacement available from either of the benders alone. Preferably, the benders are also disposed so that the distance between the contacts, in the absence of any applied electrical signal, is less than the sum of the displacements available from the two benders. The principles of the invention may be extended to a set of three piezoelectric benders, configured similarly to the manner described above, so that a three-position switch is provided.

Improvement of the peak current interruption performance of a vacuum interrupter is obtained by configuring the conductive leads to the vacuum interrupter in a manner whereby the magnetic field generated by current in the conductive leads and impinging upon the space between a pair of contacts of the vacuum interrupter is minimized, thereby resulting in better performance of the vacuum interrupter.

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Ballston Spa, NY, United States of America

John H Van Noy