Gould Inc.

Other

Robert J Panaro

Richard A Belcher

Philip C Jacobs, Jr

Richard W Robbins

Charles F Smith

A holder for an electric fuse is provided with apparatus which senses the flow of electric current along the current path of the fuse holder, and, which responsive to such sensing, electromagnetically induces an ascertainable signal. The signal may be detected and processed to provide an indication of whether current is flowing through the fuse holder.

Electric fuse holder having an integral current sensor

An electric fuse is provided with heat dam elements interconnecting the fusible element and the fuse end terminals, which are provided with one or more raised ribs integrally formed therein. The heat dams include a plurality of planar sections and interconnecting bends to which the ribs impart a high degree of stiffness and dimensional stability.

Electric fuse heat dam element having stiffening ribs

An electric low-voltage current-limiting fuse completely or substantially complying with the Underwriters Laboratories Inc. Standard Class R fuses. The current carrying part of the fuse comprises a fusible element having serially arranged perforations. This part may be of silver or of copper. The current carrying part of the fuses further comprises tabs of copper bent over the rims of the casing and conductively interconnecting the ends of the fusible element with the terminal caps of the fuse. The fusible element is provided with an M-effect metal to limit the temperature rise of the fusible element and of the casing. The tabs are considerably thicker than the fusible element. If the fusible element is of silver the thickness of the tabs of copper is larger than the thickness required to fully compensate for their higher resistivity. The ratio of the thickness of a pair of tabs of copper to the thickness of a fusible element of silver depends upon the geometrical configuration of the latter and is in the range of 2:1 to somewhat less than 5:1. Since the tabs are thicker than the fusible element both cannot be joined by conventional rolling operations. Each of the pair of tabs is formed by a part separate from the fusible element. These tabs are affixed by electroconductive bonds such as, e.g. spot-welds, to the fusible element.

Electric fuse having composite fusible element

A fusible element for electric fuses including a core or layer of copper, an outer layer of silver plating, and an M-effect overlay on the silver layer of a low fusing point metal, e.g. tin, capable of severing the current path through the plating of silver and the core of copper by a metal diffusion process. The M-effect overlay is arranged in spaced relation in regard to the point of the fusible element where the highest temperature prevails to maximize the temperature difference, or temperature gradient, between the M-effect overlay and the hottest point of the fusible element when the latter is carrying current.

Fusible element for electric fuses and electric fuse including the

A welded composite fusible element utilizing weld joints, or welded hinges, to interconnect the component parts of it. The above referred-to weld joints or hinges interconnect portions of a fusible element which are fragile and easily damaged with portions of the fusible element which are rugged and which involve little or no danger of damage in the process of assembly. The function of stress relieving hinges or weld joints according to this invention is to protect the delicate component of the composite fusible element.

Stress relieving weld joint for composite fusible element

A fusible element for electric fuses capable of combining time-lag in the range of overload currents with current-limiting action for currents in the range of short-circuit currents. The fusible element comprises a relatively wide perforated center section and axially outer heat dam sections. The center section has points of reduced cross-section imparting to it a predetermined fusing i.sup.2 .multidot.t. The center section of the fusible element is folded in a direction longitudinally thereof to effect mutual heating of the portion, or portions, thereof to different sides of the fold, or folds. This allows to increase the mass of the center section and results in an increase of time-lag. Relatively narrow heat-dam-strip sections extend from the ends of said center section. The fusing i.sup.2 .multidot.t of the heat-dam-strip sections is larger than that of the center section to avoid fusion of the heat-dam-strip sections prior to that of the center section, or to entirely preclude fusion of said heat-dam-strip sections. The heat-dam-strip sections are folded in transverse direction which increases their length for given casing dimensions and consequently their resistance to axially outward heat flow from the center section, thereby enhancing the same effect that results from the reduced width of the heat-dam-strip sections relative to the width of the center section. The points of reduced cross-section of the center section are of a metal having a low fusing i.sup.2 .multidot.t, in particular silver, to minimize its fusing i.sup.2 .multidot.t. The heat dam sections are of a metal other than silver in the interest of greater economy and greater flexibility. Electroconductive bonds connect the center section to the heat-dam-strip sections.

Method of making electric fuse having folded fusible element and heat

A fusible element for electric fuses combining considerable time lag with current-limiting action. Time lag is achieved by providing the fuse with a combination of a plurality of means for achieving this end, such as folding the perforated center portion of the fusible element twice in a direction longitudinally thereof to achieve mutual heating of the folded portion, providing the center portion with end portions or heat dams of reduced cross-section which limit the flow of heat from the center portion to the terminals of the fuse, and are folded in transverse direction, and providing the fusible element with means capable of severing the fusible element by a metallurgical reaction, widely known as M-effect. The M-effect means increase time lag because of their mass and because they derate the fusible element. They cause severing of the center portion of the fusible element and are heated, in addition to i.sup.2 .multidot.r losses occurring in the center portion of the fusible element, by convection, conduction and radiation across a gap formed between the center portion of the fusible element and a section of one of the end portions of the fusible element. In the interest of economy only the perforated center portion of the fusible element is of silver having a fusing i.sup.2 .multidot.t of 8.00.multidot.10.sup.8 (amp/cm.sup.2).sup.2 .multidot.sec., while the end portions are of a metal other than silver, such as copper, which has a fusing i.sup.2 .multidot.t of 11.72 (amp/cm.sup.2).sup.2 .multidot.sec.

Fusible element for time-lag fuses having current-limiting action

Electric fuse having folded fusible element and heat dams

This invention relates to electric fuses having rectangular terminal members which facilitate the insertion of the fuses into an electric circuit. According to this invention one arm of each terminal member is provided with a drawn-out cylindrical projection, or drafted hole, and the ferrules of the fuse are pressfitted into said cylindrical projection, or drifted hole, thus avoiding the use of any solder means between said ferrules and said cylindrical projections, or drifted holes.

Electric fuse

Capacitor fuses differ from fuses intended for other purposes by the nature of their terminal elements. Their terminal elements must be adapted to be gripped by wrenches and hence be hexagonal in cross-section. Disclosed is a capacitor fuse having hexagonal elements press-fitted upon the ferrules of a fuse, the length of ferrule-receiving cavities in said hexagonal elements being substantially equal to the length of the ferrules of the fuse. One of the hexagonal elements is provided with an internally screw-threaded bore and the other of said hexagonal elements is provided with an externally screw-threaded projection extending in a direction away from said casing of the fuse.

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Byfield, MA, United States of America

Robert J Panaro