Current limiting fuse
AssigneeMcGraw-Edison Company
InventorsStephen P. Hassler, Theodore O. Sokoly
Life of this patent
Estimating the term…
Abstract
A current limiting fuse has a main fusible element and an auxiliary fusible element each helically wound over an insulative support member. Each end of the auxiliary element is connected to conductive metal clips or electrodes in which blocks of metal oxide varistor material are fixedly secured and placed in contact with the main fusible element. Subsequent to the initial burn back of the main fusible element, the metal oxide varistors precisely initiate electrical arcs between the terminal clips at the ends of the auxiliary fusible element and the main element at points adjacent to these terminal clips. The presence of these arcs quickly sever the main element or elements at these points thereby producing additional burnback areas in the main fusible element or elements.
Claims10
A current limiting fuse comprising a main fusible element of a predetermined length, element interrupting means for interrupting the flow of current through said main fusible element in response to a prolonged over-current condition in said main fusible element, said element interrupting means being located at a predetermined point along said main fusible element, an auxiliary fusible element having first and second ends and non-linear resistor means having a predetermined voltage break down level, each end of said auxiliary fusible element being connected electrically to said main fusible element at points therealong on opposite sides of said element interrupting means, at least one of said first and second ends of said auxiliary fusible element being connected electrically to said main fusible element through said non-linear resistor means.
A current limiting fuse comprising an elongated housing, electrical terminals for electrical connection of said fuse into an electrical circuit, a core extending longitudinally within the housing, a main fusible element of a predetermined length connected to said electrical terminals and helically wound around said core, current interrupting means for interrupting the flow of current through said main fusible element in response to a prolonged over-current condition in said main fusible element, said current interrupting means being located at a predetermined point along said main fusible element, non-linear resistor means having a predetermined breakdown level, an auxiliary fusible element having first and second ends for electrical connection thereto, said auxiliary fusible element being helically wound around a portion of said core and electrically connected to said main fusible element at said first and second ends, at points along said main fusible element on opposite sides of said current flow interrupting means, at least one of said ends of said auxiliary fusible element being connected electrically to said main fusible element through said non-linear resistor means.
Dependencies are inferred from the claim text.