Claims:1. A fuse-link (106) for use in electrical systems, said fuse-link (106) comprising:
a composite fuse element (202);
a filler material (204) that acts as an arc quenching medium by absorbing arc energy before reaching its vitrified state;
at least one insulating liner (206); and
a fuse body (208), wherein the composite fuse element (202) is a conductor that comprises of an overlay composite alloy of silver and copper.
2. The fuse-link as claimed in claim 1, wherein the at least one insulating liner (206) prevents thermal impact of arc energy on the fuse body (208) and molten plasma within the fuse body (208).
3. The fuse-link as claimed in claim 1, wherein the fuse body (208) acts as a cartridge with two open sides that enclose the composite fuse element (202), the filler (204) and the insulating liner (206), and wherein the fuse body (208) is secured from both sides by end caps (104).
4. The fuse-link as claimed in claim 3, wherein the composite fuse element (202) is in the form of a straight conductor that is curved at its ends to provide a conductive connection to the end caps (104).
5. The fuse-link as claimed in claim 3, wherein the composite fuse element (202) is conductively connected to the end caps (104), and wherein external electric connections are made through the end caps (104).
6. The fuse-link as claimed in claim 1, wherein the composite fuse element (202) further comprises of two ends that act as cathode and anode during initiation of arc.
7. The fuse-link as claimed in claim 1, wherein grain size and packing density of the filler (204) and thermal conductivity of the insulating liner (206) equalizes the increase in let through energy on account of the fuse element (202).
8. The fuse-link as claimed in claim 7, wherein the grain size of the filler (204) aids radial conduction of heat generated by the composite fuse element (202) during pre-arcing period.
9. The fuse-link as claimed in claim 1, wherein the fuse-link (106) interrupts both high and low level of fault currents.
10. A fuse holder configured to house the fuse-link (106) as claimed in claim 1.
, Description:TECHNICAL FIELD
[0001] The present disclosure relates generally to a fuse system with alloy type current carrying medium for protecting electrical circuits against overcurrent and fault conditions. In particular, the present disclosure pertains to a fuse-link that consists of a varied composition of conductive and arc suppressing materials.

BACKGROUND
[0002] In a conventional fuse, a low melting fusible alloy piece to which a flux is applied is used as a fuse element. When an electric apparatus on which such a fuse is mounted is accompanied with high current, a phenomenon occurs in which the low melting fusible alloy piece is liquefied by the generated heat, the molten metal is spheroidized by the surface tension under the coexistence with the flux that has already melted, and the alloy piece is finally broken as a result of advancement of the spheroidization, whereby the power supply to the apparatus is interrupted.
[0003] United States Patent US7268661 B2 discloses a composite fuse element that includes a matrix of conductive material that is in contact with arc suppressing materials at particle level. Further, when the conductive matrix melts or vaporizes, the resulting conductive vapors are adsorbed into the arc suppressing particles in a short time due to large contact area between conductive and arc suppressing materials and short diffusion distance that the conductive vapors are required to travel before they are absorbed by the arc suppressing material.
[0004] United States Patent US6819215 B2 discloses a thermal fuse and a fuse element of low-melting fusible alloy wherein the fuse element has an alloy composition of 37 to 43% Indium, 10 to 18% Tin, and the balance is Bismuth. Further, the operating temperature of the fuse element is in the range of 65 to 75° C.
[0005] United States Patent US7064648 B2 discloses an alloy type thermal fuse wherein a Bismuth-Tin alloy is used as fuse element that has an operating temperature of about 140° C. The alloy composition used comprises of 50% and 56% Bismuth and the rest proportion of the alloy comprises of Tin.
[0006] United States Patent US4320374 A discloses a high voltage current limiting fuse that employs composite metal fuse elements. One metal of the composite is aluminum which is of high conductivity and high melting point while the other is cadmium which is of low melting point wherein melting of the low melting point metal occurs at any and all locations along the element when its temperature reaches said low melting point.
[0007] United States Patent US4375629 A discloses a fuse element in the form of a ribbon of aluminum or aluminum alloy having a terminal at each end of the ribbon. Each terminal is made of copper sheet material having a portion that is tin plated. The tin plated portion is folded over the end of the ribbon to contact both sides and is welded to the ribbon to form a connection capable of carrying short circuit currents and able to withstand repeated temperature changes.
[0008] European Patent EP0016467 A1 discloses a high voltage current limiting fuse that employs a composite metal fuse element that consists of at least two portions of different metals with different electro thermal properties extending through the melt and arc zone wherein the two portions are bonded to one another along their adjoining faces for good thermal exchange. One metal of the composite is of high conductivity and high melting point while the other is of low melting point, so that melting of the low melting point metal occurs at any and all locations along the element when its temperature reaches the said low melting point. The metals are selected from the group consisting of silver, copper, tin, nickel, lead, magnesium, zinc, aluminum and cadmium while the preferred combination is zinc and aluminum or cadmium and silver.
[0009] As can be seen, these references disclose different fuse-links to protect electrical circuits against high current but none of these fuse-links disclose a fuse-link with a composite overlay alloy with a combination of materials with high conductivity and comparatively low melting points.
[0010] There is therefore a need for a fuse-link that can interrupt both high and low level of fault currents and overcome shortcomings of known systems.

OBJECTS OF THE INVENTION
[0011] A general object of the present disclosure is to provide a fuse-link that protects an electric circuit against overcurrent and short-circuit fault conditions.
[0012] Another object of the present disclosure is to provide a fuse-link that protects electrical equipments and components from damage.
[0013] Another object of the present disclosure is to provide a fuse-link that interrupt both high and low level of fault currents.
[0014] Another object of the present disclosure is to provide a fuse element that consists of an overlay composite alloy with a combination of materials with high conductivity and comparatively low melting points.
[0015] Another object of the present disclosure is to provide a fuse-link that is cost efficient.

SUMMARY
[0016] The present disclosure relates to a fuse-link that protects electrical circuits against overcurrent and short circuit fault conditions. In particular, the present disclosure pertains to a fuse-link that consists of a composition of conductive and arc suppressing materials wherein an overlay of composite alloy of copper and silver is configured as a fuse element. The fuse-link further consists of a filler material such as but not limited to quartz sand and at least one insulating liner and a fuse body.
[0017] In an aspect, the filler acts as an arc quenching medium by absorbing arc energy before reaching its vitrified state and the insulating liner prevents thermal impact of arc energy on fuse body and the molten plasma within the fuse body, Further, the fuse body acts as a cartridge with two open sides that encloses the fuse element, the filler and the insulating liner and it is secured from both sides by end caps.
[0018] In an aspect, the fuse element is conductively connected to the end caps and external electric connections are made through the end caps wherein the fuse element is in the form of a straight conductor that is curved at its ends to provide a conductive connection to the end caps and the ends of the fuse element act as cathode and anode during initiation of arc.
[0019] In an aspect, grain size and packing density of the filler and thermal conductivity of the insulating liner equalizes the increase in let through energy on account of the composite fuse element. Further, the grain size of the filler aids the radial conduction of the heat generated by the fuse element during the pre-arcing period. Moreover, the filler protects the fuse element from atmospheric attack and also reduces the physical impact to the fuse element during transit.
[0020] In an aspect, the disclosed fuse-link interrupts both high and low level of fault currents. Further, in a sustained overcurrent condition, the M-effect composite alloy of copper and silver reaches its melting point and the alloying of these metals commence. Thereafter, metal diffusion leads to the formation of molten plasma that pertains high relative resistivity. Moreover, thermal performance of the fuse element is improved by depositing solder on the silver side. As melting point of the silver is 960°C which is lower than copper, enthalpy of heat required to transfuse the alloy is paralleled.
[0021] In an aspect, at elevated temperatures (typically > 500°C), both copper and silver perform similarly. Thus, in case of short circuit protection, notches or reduced sections similar to the existing condition are heated and starts melting that result in a succession of arcs. Additionally, magnet effect of current forces the elements to break and the additional voltage is supplied by the entrapped inductive energy of the fuse-link.
[0022] In another aspect, during fault conditions, arc initiation melts the fuse element, wherein the two ends of the fuse element act as cathode and anode. Thereafter, erosion starts and the arc energy is dissipated through the filler by heat of fusion. Additionally, latent heat of fusion forms a tube of molten matter that is referred to as fulgurite. The conduction assists the transmission of entrapped gases through the filler. Further, the molten mass and the gaseous fumes exert pressure over the fulgurite tube and eventually permeates to the fuse body through the grains of the filler. Thereafter, fulgurite solidifies on cooling and builds an insulating channel. Fulgurite so formed subsequently develops dielectric and prevents the emergence of arc. Hence, the disclosed fuse-link prevents the flow of high current during overcurrent and fault conditions and thus, protects the components of an electrical system from damage and overheating.
[0023] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0025] FIGs. 1A and 1B illustrate exemplary perspective views of a fuse holder in accordance with embodiments of the present disclosure.
[0026] FIG. 2 illustrates exemplary representation of a fuse body and other components of the fuse-link in accordance with embodiments of the present disclosure.
[0027] FIG. 3 illustrates exemplary cross-sectional view of fuse element in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION
[0028] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such details as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0029] Embodiments explained herein relate to a fuse-link that protects electrical circuits against overcurrent and short circuit conditions. In particular, the present disclosure pertains to a fuse-link that consists of a composition of conductive and arc suppressing materials wherein an overlay of composite alloy of copper and silver is configured as a fuse element. The fuse-link further consists of a filler material such as but not limited to quartz sand and at least one insulating liner and a fuse body.
[0030] In an aspect, the filler acts as an arc quenching medium by absorbing arc energy before reaching its vitrified state and the insulating liner prevents thermal impact of arc energy on fuse body and the molten plasma within the fuse body, Further, the fuse body acts as a cartridge with two open sides that encloses the fuse element, the filler and the insulating liner and it is secured from both sides by end caps.
[0031] In an aspect, the fuse element is conductively connected to the end caps and external electric connections are made through the end caps wherein the fuse element is in the form of a straight conductor that is curved at its ends to provide a conductive connection to the end caps and the ends of the fuse element act as cathode and anode during initiation of arc.
[0032] In an aspect, the present disclosure relates to a fuse-link for use in electrical systems, said fuse-link comprising a composite fuse element; a filler material that acts as an arc quenching medium by absorbing arc energy before reaching its vitrified state; at least one insulating liner; and a fuse body, wherein the composite fuse element is a conductor that comprises of an overlay composite alloy of silver and copper.
[0033] In an aspect, the least one insulating liner prevents thermal impact of arc energy on the fuse body and molten plasma within the fuse body. In another aspect, the fuse body acts as a cartridge with two open sides that enclose the composite fuse element, the filler and the insulating liner, and wherein the fuse body is secured from both sides by end caps.
[0034] In another aspect, the composite fuse element is in the form of a straight conductor that is curved at its ends to provide a conductive connection to the end caps.
[0035] In another aspect, the composite fuse element is conductively connected to the end caps, and wherein external electric connections are made through the end caps.
[0036] In yet another aspect, the composite fuse element further comprises of two ends that act as cathode and anode during initiation of arc.
[0037] In yet another aspect, grain size and packing density of the filler and thermal conductivity of the insulating liner equalizes the increase in let through energy on account of the fuse element.
[0038] In another aspect, the grain size of the filler aids radial conduction of heat generated by the composite fuse element during pre-arcing period.
[0039] In another aspect, the fuse-link interrupts both high and low level of fault currents within its breaking capacity.
[0040] In another aspect, the present disclosure relates to a fuse holder configured to house the disclosed/proposed fuse-link.
[0041] FIG. 1A and FIG. 1B illustrate exemplary perspective views of a fuse holder 102 in accordance with embodiments of the present disclosure. The exemplary fuse holder 102 supports the fuse- link 106 in an elevated position so as to reduce the impact of mechanical vibrations and provide harness to the fuse link 106. Further, the fuse holder 102 is configured with two end caps 104 that provide closure to the open ends of the fuse-link 106. The fuse-link 106 protects electrical systems from overcurrent conditions and short circuit fault conditions by insulating the conductive electrical connections associated therewith.
[0042] In an embodiment, the fuse-link 106 is configured with fuse bases or switch disconnector fuses (SDF). Moreover, the end caps 104 provide external electrical connections to the fuse-link 106.
[0043] FIG. 2 illustrates exemplary representation of a fuse body and other components of the fuse-link 106 in accordance with embodiments of the present disclosure. The fuse-link 106 is configured with a fuse element 202 that comprises of an overlay composite alloy of silver and copper, a filler material 204 such as but not limited to quartz sand, at least one insulating liner 206, and a fuse body 208.
[0044] In an embodiment, the fuse element 202 is conductively connected to the end caps 104 and external electric connections are made through the end caps 104, wherein the fuse element 202 is in the form of a straight conductor that is curved at its ends to provide a conductive connection to the end caps 104 and the ends of the fuse element 202 act as cathode and anode during initiation of arc.
[0045] In an embodiment, the filler 204 acts as an arc quenching medium by absorbing arc energy before reaching its vitrified state. Further, grain size and packing density of the filler 204 equalizes the increase in let through energy on account of the composite fuse element 202. Additionally, the grain size of the filler 204 aids the radial conduction of the heat generated by the fuse element 202 during the pre-arcing period. Moreover, the filler 204 protects the fuse element 202 from atmospheric attack and also reduces the physical impact to the fuse element 202 during transit.
[0046] In an embodiment, the insulating liner 206 prevents thermal impact of arc energy on fuse body 208 and the molten plasma within the fuse body 208. Additionally, thermal conductivity of the insulating liner 206 equalizes the increase in let through energy on account of the composite fuse element 202.
[0047] In an embodiment, the fuse body 208 acts as a cartridge with two open sides that encloses the fuse element 202, the filler 204 and the insulating liner 206 and it is secured from both sides by end caps 104.
[0048] FIG. 3 illustrates exemplary cross-sectional view of fuse element 202 in accordance with embodiments of the present disclosure. The fuse element 202 comprises of an overlay composite alloy of silver and copper. Further, the fuse element 202 is straight conductor that is curved at its ends to provide a conductive connection to the end caps 104 and the ends of the fuse element 202 act as cathode and anode during initiation of arc.
[0049] In an aspect, the disclosed fuse-link 106 interrupts both high and low level of fault currents within its breaking capacity. Further, in a sustained overcurrent condition, the M-effect composite alloy of copper and silver reaches its melting point and the alloying of these metals commence. Thereafter, metal diffusion leads to the formation of molten plasma that pertains high relative resistivity. Moreover, thermal performance of the fuse element 202 is improved by depositing solder on the silver side. As melting point of the silver is 960°C which is lower than copper, the enthalpy of heat required to transfuse the alloy is paralleled.
[0050] In an aspect, at elevated temperatures (typically > 500°C), both copper and silver perform similarly. Thus, in case of short circuit protection, notches or reduced sections similar to the existing condition are heated and starts melting that result in a succession of arcs. Additionally, magnet effect of current forces the elements to break and the additional voltage is supplied by the entrapped inductive energy of the fuse-link 106.
[0051] In another aspect, during fault conditions, the arc initiation melts the fuse element 202 wherein the two ends of the fuse element 202 act as cathode and anode. Thereafter, erosion starts and the arc energy is dissipated through the filler 204 by heat of fusion. Additionally, latent heat of fusion forms a tube of molten matter that is referred to as fulgurite. The conduction assists the transmission of entrapped gases through the filler 204. Further, the molten mass and the gaseous fumes exert pressure over the fulgurite tube and eventually permeates to the fuse body 208 through the grains of the filler 204. Thereafter, fulgurite solidifies on cooling and builds an insulating channel. Fulgurite so formed subsequently develops dielectric and prevents the emergence of arc. Hence, the disclosed fuse-link 106 prevents the flow of high current during overcurrent and fault conditions and thus, protects the components of an electrical system from damage and overheating.
[0052] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0053] The present disclosure provides a fuse-link that protects an electric circuit from overcurrent and short circuit fault conditions.
[0054] The present disclosure provides a fuse-link that protects electrical equipments and components from damage.
[0055] The present disclosure provides a fuse-link that interrupt both high and low level of fault currents within its breaking capacity.
[0056] The present disclosure provides a fuse element that consists of an overlay alloy with a combination of materials with high conductivity and comparatively low melting points. The present disclosure provides a fuse-link that is cost efficient.