US2772334A - Refractory body for electrical apparatus - Google Patents

Refractory body for electrical apparatus Download PDF

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US2772334A
US2772334A US275639A US27563952A US2772334A US 2772334 A US2772334 A US 2772334A US 275639 A US275639 A US 275639A US 27563952 A US27563952 A US 27563952A US 2772334 A US2772334 A US 2772334A
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grains
arc
electrical apparatus
refractory
insulating
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US275639A
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Latour Andre
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Merlin Gerin SA
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Merlin Gerin SA
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/0038—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by superficial sintering or bonding of particulate matter
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/70—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid
    • H01H33/72—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid having stationary parts for directing the flow of arc-extinguishing fluid, e.g. arc-extinguishing chamber
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S174/00—Electricity: conductors and insulators
    • Y10S174/01—Anti-tracking

Definitions

  • the invention is concerned with insulating, refractory bodies and methods of making the same for use as, or for presenting, faces whereupon in electrical apparatus an arc plays or which otherwise are exposed to the action of such an arc.
  • the invention thus refers to electrical apparatus such as circuit breakers or switches or other apparatus where there are provided pieces or facings of insulating, refractory material for the purpose of confining the arc to a predetermined path.
  • An object of the invention thus is the improvement of the quality, durability or other characteristics, of such pieces or facings which, of Whatever type or for whatever purpose they may be, blow cheeks or flanges, partitions, deflecting walls or barriers, bafiles, arc chambers, or the like arcing plates, are, an indefinite number of times, in more or less close contact with the electrical arcs while the arcs are conveyed on a predetermined path along the faces of these arcing plates and develop and expand until extinction.
  • the invention thus is concerned with arcing plates where, an indefinite number of times and during short periods of time or transitorily, the faces of these arcing plates are exposed to the action of the arc are heated with extreme rapidity and intensity and then allowed to cool down.
  • the invention thus has for its object the extention of the lifetime of such apparatus by removing the causes or possibilities of local fusings, followed by sealing or flaking of the material or the fissuring thereof or its allotropic transformation or deterioration owing to the rapidly alternating expansion and contraction of the material under the action of the arc.
  • the invention contemplates the making of the pieces of facings on which the arc plays or which otherwise are exposed to the action of the are as bodies in which insulating, refractory material is employed in its purest condition and which are formed as a briquette of a particular physical structure.
  • the insulating pieces or their facings, or the bodies used as, or presenting, faces exposed in electrical apparatus to the "action of electrical arcs, in contrast with such bodies of the conventional type, are no longer homogeneous but are composed of grains of insulating, refractory material, con- Patented Nov. 27, 1956 tiguous grains being bound together at their contacting edges or surface areas and with voids left at and between the non-contacting surface areas of the grains.
  • This binding together of contiguous grains is made by briquetting in particular by fritting the grains together at contacting edges or surface areas, areas which are very small relatively to the total or proper surfaces of the grains.
  • flitting as employed in this specification and in the claims is to be understood as a vitrifying process under such conditions of temperature and pressure that the grains are only imperfectly vitrified so as to fuse only superficially and particularly only to such an extent that contiguous or neighboring grains fuse together at the small contacting edges or areas without the grains or the individual grains being fused down as a whole.
  • the fritting process may be carried out without or with the aid of a binding or fluxing agent.
  • any appropriate refractory material natural or artificial, may be employed, such as quartz, smelted silica, corundum, zirconia, glucina, magnesia, or the like, now-argillous materials.
  • a preferred form of carrying out the invention will be the utilization of such refractory material in pure condition, particularly in the form of electro-cast refractories or more specifically electro-cast magnesia, all of which refractories may be brought into proper grain or particle size by grinding, crushing, or otherwise.
  • the grains of insulating, refractory material are designated by 11. Contiguous or neighboring grains are, as indicated at 12, bound together at contacting edges or surface areas small in size relatively to the proper or total surfaces of the grains. Voids, indicated at 13, are thus left between the individual grains 11. 14 represents a face of the body to be exposed to the action of an electric arc. On this face, grains and voids thus alternate, the face thus having an aspect similar to that of the surface of an abrasive.
  • a surface of grains interspaced by voids, formed in accordance with the invention withstands advantageously the strains of an electric arc. Should even the out- Ward faces of the grains start to volatilize, the lateral and inward faces of the grains would not be affected since obviously these faces are less exposed to the arc and consequently are not liable to volatilize. In any case, the voids cannot contribute to the generation of vapor and it has been established that for a given refractory body and under equal other conditions a dis continuous surface produces less vapor than a continuous surface.
  • the numerous cavities or voids left between the grains constitute as many condensation chambers capable of absorbing and condensing the vapor released by the thermal action of the are. For the same reason, the counter-pressure developed by the vapor will be reduced.
  • the discontinuity of the surface presents another actvantage. Through this discontinuity, the increase in superficial conductivity at the extremely high temperature of the arc, or, in other words, the decrease in superficial insulating power which might result from this very considerable raise of the temperature, is less noticeable. in fact, the line along which the arc moves and vanished on the surface presents itself as'a zigzag line, a line thus which under otherwise equal conditions is longer than the line would be on a smooth and continuous surface.
  • the section of the passage offered to the leakage current is likewise greatly reduced through the presence of these cavities or voids and also owing to the fact that the grains are in contact with one another only at surface areas of very small dimensions.
  • the size of the grains may vary within wide limits. Practically, good results are obtained with grain sizes so small that the grains pass 0.59 to 0.074 mm. sieve openings, corresponding to sieves Nos. 30 to 200, U. S. Standard.
  • the grains are bound together simply by fritting, a process analogous to autogenous welding
  • the refractory body may be produced under full preservation of its purity.
  • Such fiuxing agent may be constituted by aluminous, magnesic, calcic, or alkaline silicates or analogous borates or any other more or less vitrifiable agent and are employed for the purpose of combining with the siliceous material of the grains by superficial attack or reaction and of thus yielding a vitrified surface layerglass, enamelwhich thus binds the grains together.
  • Water or an organic binder may be employed, as also conventional in the art, for holding the grains together in the preliminary stage of the process. Whichever the composition of such fiuxing or binding agent may be, it should be employed in a proportion sufiiciently small so as for the voids left between the grains not to be filled up by the fiuxing or binding agent.
  • a satisfactory product for the purposes of the invention may be obtained by employing a composition which contains a few percent of a fiuxing agent of the aforesaid vitrifiable or vitrifying type, 10 percent of kaolin, the remainder being constituted by grains of periclase of a size to pass 0.125 mm. sieve openings, corresponding to sieve No. 120, U. S. Standard.
  • a conventional cold binder such as water or an organic binder, is admixed with this composition, the mass brought into a mold and therein subjected to a pressure of several hundreds of kilograms per square centimeter at a temperature of about 1000 C. and the grains thus bound together at the contacting edges or surface areas.
  • Arcing plates for circuit breakers, switches and the like electrical apparatus comprising a porous refractory body consisting essentially of grains of a refractory insulating substance bonded together by autogenous fritting only at the contacting areas of their surfaces to leave a substantial portion of voids between said grains.
  • Arcing plates as defined in claim 1 wherein the said grains are selected from the group consisting of quartz, smelted silica, corundum, zirconia, glucina and magnesia.

Description

Nov. 27, 1956 A. LATOUR REFRACTORY BODY FOR ELECTRICAL APPARATUS Filed March 8, 1952 Inventor Andr LATOUR B, Kwk MMM United States Patent REFRACTORY BODY FOR ELECTRICAL APPARATUS Andr Latour, Grenoble, France, assignor to Etablissemerits Merlin & Gerin, Socit Anonyme, Grenoble, France, a corporation of France Application March 8, 1952, Serial No. 275,639
Claims priority, application Belgium March 28, 1951 4 Claims. (Cl. 200-144) The invention is concerned with the protection of electrical apparatus at those places where they are exposed to the action of electrical arcs.
More particularly the invention is concerned with insulating, refractory bodies and methods of making the same for use as, or for presenting, faces whereupon in electrical apparatus an arc plays or which otherwise are exposed to the action of such an arc.
The invention thus refers to electrical apparatus such as circuit breakers or switches or other apparatus where there are provided pieces or facings of insulating, refractory material for the purpose of confining the arc to a predetermined path.
An object of the invention thus is the improvement of the quality, durability or other characteristics, of such pieces or facings which, of Whatever type or for whatever purpose they may be, blow cheeks or flanges, partitions, deflecting walls or barriers, bafiles, arc chambers, or the like arcing plates, are, an indefinite number of times, in more or less close contact with the electrical arcs while the arcs are conveyed on a predetermined path along the faces of these arcing plates and develop and expand until extinction. The invention thus is concerned with arcing plates where, an indefinite number of times and during short periods of time or transitorily, the faces of these arcing plates are exposed to the action of the arc are heated with extreme rapidity and intensity and then allowed to cool down.
The invention thus has for its object the extention of the lifetime of such apparatus by removing the causes or possibilities of local fusings, followed by sealing or flaking of the material or the fissuring thereof or its allotropic transformation or deterioration owing to the rapidly alternating expansion and contraction of the material under the action of the arc.
Furthermore it is the object of the invention to improve the functioning of the apparatus by obviating the causes which otherwise, under the action of an arc of high intensity, would render such faces of insulating, refractory material conductive and wouldthus retard the extinction of the arc, or would volatilize superficial portions of the material and thus release vapours whose counter-pressure would impede the desired development of the arc.
In order to achieve these and other objects, the invention contemplates the making of the pieces of facings on which the arc plays or which otherwise are exposed to the action of the are as bodies in which insulating, refractory material is employed in its purest condition and which are formed as a briquette of a particular physical structure.
In accordance with the invention the insulating pieces or their facings, or the bodies used as, or presenting, faces exposed in electrical apparatus to the "action of electrical arcs, in contrast with such bodies of the conventional type, are no longer homogeneous but are composed of grains of insulating, refractory material, con- Patented Nov. 27, 1956 tiguous grains being bound together at their contacting edges or surface areas and with voids left at and between the non-contacting surface areas of the grains.
This binding together of contiguous grains is made by briquetting in particular by fritting the grains together at contacting edges or surface areas, areas which are very small relatively to the total or proper surfaces of the grains.
The term flitting as employed in this specification and in the claims is to be understood as a vitrifying process under such conditions of temperature and pressure that the grains are only imperfectly vitrified so as to fuse only superficially and particularly only to such an extent that contiguous or neighboring grains fuse together at the small contacting edges or areas without the grains or the individual grains being fused down as a whole.
The fritting process may be carried out without or with the aid of a binding or fluxing agent.
The grains which are thus subjected only imperfectly to this fritting process preserve fully their valuable characteristics such as their resistibility against thermal and electrical stresses.
It is thus possible to employ in electrical apparatus for the faces on which an arc plays, or which otherwise are subjected to the action of an are, a body composed of grains of insulating, refractory material in purest condition, the grains being bound together at surface areas small relatively to the total or proper surfaces of the grains but being otherwise separated by voids, so that the whole surface exhibits in any direction a succession of alternating grains and voids.
For the purposes of the invention any appropriate refractory material, natural or artificial, may be employed, such as quartz, smelted silica, corundum, zirconia, glucina, magnesia, or the like, now-argillous materials. A preferred form of carrying out the invention will be the utilization of such refractory material in pure condition, particularly in the form of electro-cast refractories or more specifically electro-cast magnesia, all of which refractories may be brought into proper grain or particle size by grinding, crushing, or otherwise.
In the accompanying drawing which forms part of this specification and is to be understood explicative of the invention but not limitative of its scope, I have illustrated diagrammatically on an exaggerated enlarged scale a portion of an insulating, refractory body of the invention.
The grains of insulating, refractory material are designated by 11. Contiguous or neighboring grains are, as indicated at 12, bound together at contacting edges or surface areas small in size relatively to the proper or total surfaces of the grains. Voids, indicated at 13, are thus left between the individual grains 11. 14 represents a face of the body to be exposed to the action of an electric arc. On this face, grains and voids thus alternate, the face thus having an aspect similar to that of the surface of an abrasive.
A surface of grains interspaced by voids, formed in accordance with the invention, withstands advantageously the strains of an electric arc. Should even the out- Ward faces of the grains start to volatilize, the lateral and inward faces of the grains would not be affected since obviously these faces are less exposed to the arc and consequently are not liable to volatilize. In any case, the voids cannot contribute to the generation of vapor and it has been established that for a given refractory body and under equal other conditions a dis continuous surface produces less vapor than a continuous surface.
Moreover, the numerous cavities or voids left between the grains constitute as many condensation chambers capable of absorbing and condensing the vapor released by the thermal action of the are. For the same reason, the counter-pressure developed by the vapor will be reduced.
The discontinuity of the surface presents another actvantage. Through this discontinuity, the increase in superficial conductivity at the extremely high temperature of the arc, or, in other words, the decrease in superficial insulating power which might result from this very considerable raise of the temperature, is less noticeable. in fact, the line along which the arc moves and vanished on the surface presents itself as'a zigzag line, a line thus which under otherwise equal conditions is longer than the line would be on a smooth and continuous surface.
Finally, the section of the passage offered to the leakage current is likewise greatly reduced through the presence of these cavities or voids and also owing to the fact that the grains are in contact with one another only at surface areas of very small dimensions.
The size of the grains may vary within wide limits. Practically, good results are obtained with grain sizes so small that the grains pass 0.59 to 0.074 mm. sieve openings, corresponding to sieves Nos. 30 to 200, U. S. Standard.
In a preferred embodiment of the method of the invention, the grains are bound together simply by fritting, a process analogous to autogenous welding By means of this method the refractory body may be produced under full preservation of its purity.
Whereas this fritting process, ever according to the specific material employed, will require higher baking temperatures, lower, moderate baking temperatures will sufiice, for instance ofthe order of 1000 C., if the grains at their contacting areas are cemented together with the aid of very small quantities of a fiuxing agent whose adhesiveness maybe activated or realized already at such moderate temperature.
Such fiuxing agent, well known in the art, may be constituted by aluminous, magnesic, calcic, or alkaline silicates or analogous borates or any other more or less vitrifiable agent and are employed for the purpose of combining with the siliceous material of the grains by superficial attack or reaction and of thus yielding a vitrified surface layerglass, enamelwhich thus binds the grains together.
Water or an organic binder may be employed, as also conventional in the art, for holding the grains together in the preliminary stage of the process. Whichever the composition of such fiuxing or binding agent may be, it should be employed in a proportion sufiiciently small so as for the voids left between the grains not to be filled up by the fiuxing or binding agent.
For the purpose of exemplification only, it may be indicated that a satisfactory product for the purposes of the invention may be obtained by employing a composition which contains a few percent of a fiuxing agent of the aforesaid vitrifiable or vitrifying type, 10 percent of kaolin, the remainder being constituted by grains of periclase of a size to pass 0.125 mm. sieve openings, corresponding to sieve No. 120, U. S. Standard. A conventional cold binder, such as water or an organic binder, is admixed with this composition, the mass brought into a mold and therein subjected to a pressure of several hundreds of kilograms per square centimeter at a temperature of about 1000 C. and the grains thus bound together at the contacting edges or surface areas.
I claim:
1. Arcing plates for circuit breakers, switches and the like electrical apparatus comprising a porous refractory body consisting essentially of grains of a refractory insulating substance bonded together by autogenous fritting only at the contacting areas of their surfaces to leave a substantial portion of voids between said grains.
2. Arcing plates as defined in claim 1 wherein said grains are bonded together at the contacting surface areas thereof by autogenous fritting in the presence of a fluxing agent.
3. Arcing plates as defined in claim 1 wherein the said grains are selected from the group consisting of quartz, smelted silica, corundum, zirconia, glucina and magnesia.
4. Arcing plates as defined in claim 3 wherein said grains consist of a fused refractory selected from the defined group.
References Cited in the file of this patent UNITED STATES PATENTS 883,366 White Mar. 31, 1908 1,014,098 Sachs Jan. 9, 1912 1,016,443 Sachs Feb. 6, 1912 1,713,580 Williams May 21, 1929 1,812,376 Ross et a1. June 30, 1931 2,119,400 'Nowak May 31, 1938 2,165,819 Albers-Schonberg July 11, 1939 2,200,125 Slepian May 7, 1940 2,206,557 Bennett July 2, 1940 2,223,959 Lohausen Dec. 3, 1940 2,529,566 Monack Nov. 14, 1950 FOREIGN PATENTS 68,409 Germany 1893 98,591 Sweden 1940 385,328 Great Britain 1932 591,551 Great Britain Aug. 21, 1947
US275639A 1951-03-28 1952-03-08 Refractory body for electrical apparatus Expired - Lifetime US2772334A (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3071666A (en) * 1959-04-09 1963-01-01 Westinghouse Electric Corp Circuit interrupters
US3151273A (en) * 1961-12-27 1964-09-29 Gen Electric Current limiting lightning arrester with porous gap structure
US3354345A (en) * 1964-07-06 1967-11-21 Gen Electric Lightning arrester spark gap having arc-confining chamber walls of graded porosity
US3735074A (en) * 1971-07-14 1973-05-22 Gen Electric Arc chute for an electric circuit breaker
US3838375A (en) * 1973-01-29 1974-09-24 Gen Electric Current limiting fuse
US4210774A (en) * 1977-06-16 1980-07-01 Electric Power Research Institute, Inc. Filled polymer electrical insulator
US5670926A (en) * 1995-06-08 1997-09-23 General Electric Company High-voltage fuse having a core of bound silica sand about which fusible elements are wound
US5828026A (en) * 1995-05-12 1998-10-27 Abb Research Ltd. Stock giving off arc-extinguishing gas, and gas-blast circuit breaker comprising such a stock
US6642833B2 (en) 2001-01-26 2003-11-04 General Electric Company High-voltage current-limiting fuse
US20180144900A1 (en) * 2013-10-18 2018-05-24 Littelfuse, Inc. Foam fuse filler and cartridge fuse

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Publication number Priority date Publication date Assignee Title
FR1553672A (en) * 1966-05-04 1969-01-17
FR2576721B1 (en) * 1985-01-30 1987-04-17 Centre Nat Rech Scient CIRCUIT BREAKER CHAMBER WALL AND CIRCUIT BREAKER CHAMBER PROVIDED WITH SUCH WALL

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DE68409C (en) * J. F. fischer und C. A. F. O. PETERS in Worms a. Rh Process for the production of alkali and acid-resistant liquid filters
US883366A (en) * 1907-11-21 1908-03-31 Arthur L White Electric switch.
US1014098A (en) * 1908-05-05 1912-01-09 Sachs Company Thermal cut-out.
US1016443A (en) * 1911-12-08 1912-02-06 Sachs Company Jacket for safety-fuses.
US1713580A (en) * 1929-05-21 of dayton
US1812376A (en) * 1927-07-26 1931-06-30 Donald W Ross Refractory heat insulating material
GB385328A (en) * 1930-06-19 1932-12-19 Norton Co Improvements in articles of bonded granular material and methods of making the same
US2119400A (en) * 1935-06-04 1938-05-31 Gen Electric Insulating band for electrical machines and apparatus
US2165819A (en) * 1934-06-05 1939-07-11 Steatit Magnesia Ag Electric insulator and method of making same
US2200125A (en) * 1938-04-14 1940-05-07 Westinghouse Electric & Mfg Co Electrical contact means
US2206557A (en) * 1937-07-08 1940-07-02 Willard H Bennett Process for making insulating materials
US2223959A (en) * 1937-05-04 1940-12-03 Gen Electric Current limiting fuse
GB591551A (en) * 1945-02-07 1947-08-21 Mycalex Corp Of America Improvements in or relating to electrical insulating compositions
US2529566A (en) * 1948-08-17 1950-11-14 Mycalex Corp Of America Glass bonded insulating composition

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DE425862C (en) * 1924-09-06 1926-02-25 Ernst Moyat Process for the production of highly refractory fittings
DE487018C (en) * 1926-11-19 1929-11-29 Const Electr De Delle Sa Atel Spark chimney for electrical switches
DE594815C (en) * 1930-10-14 1934-03-22 Aeg Electrical insulating material
DE713856C (en) * 1935-02-17 1941-11-17 Frida Strauss Geb Ruppel Electric circuit breaker
US2303964A (en) * 1937-04-20 1942-12-01 Ungewiss Alfred Porous ceramic insulating material
DE734174C (en) * 1937-05-06 1943-04-09 Aeg Electric gas switch
DE915956C (en) * 1941-02-27 1954-08-02 Aeg Electric circuit breaker, in particular hard gas switch
DE734385C (en) * 1941-04-23 1943-04-14 Telefunken Gmbh Process for the production of a ceramic mass that does not shrink during firing
CH247847A (en) * 1943-03-31 1947-03-31 Skoda Kp Current interruption device.
US2434451A (en) * 1946-06-28 1948-01-13 Permanente Metals Corp Refractories
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Publication number Priority date Publication date Assignee Title
DE68409C (en) * J. F. fischer und C. A. F. O. PETERS in Worms a. Rh Process for the production of alkali and acid-resistant liquid filters
US1713580A (en) * 1929-05-21 of dayton
US883366A (en) * 1907-11-21 1908-03-31 Arthur L White Electric switch.
US1014098A (en) * 1908-05-05 1912-01-09 Sachs Company Thermal cut-out.
US1016443A (en) * 1911-12-08 1912-02-06 Sachs Company Jacket for safety-fuses.
US1812376A (en) * 1927-07-26 1931-06-30 Donald W Ross Refractory heat insulating material
GB385328A (en) * 1930-06-19 1932-12-19 Norton Co Improvements in articles of bonded granular material and methods of making the same
US2165819A (en) * 1934-06-05 1939-07-11 Steatit Magnesia Ag Electric insulator and method of making same
US2119400A (en) * 1935-06-04 1938-05-31 Gen Electric Insulating band for electrical machines and apparatus
US2223959A (en) * 1937-05-04 1940-12-03 Gen Electric Current limiting fuse
US2206557A (en) * 1937-07-08 1940-07-02 Willard H Bennett Process for making insulating materials
US2200125A (en) * 1938-04-14 1940-05-07 Westinghouse Electric & Mfg Co Electrical contact means
GB591551A (en) * 1945-02-07 1947-08-21 Mycalex Corp Of America Improvements in or relating to electrical insulating compositions
US2529566A (en) * 1948-08-17 1950-11-14 Mycalex Corp Of America Glass bonded insulating composition

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3071666A (en) * 1959-04-09 1963-01-01 Westinghouse Electric Corp Circuit interrupters
US3151273A (en) * 1961-12-27 1964-09-29 Gen Electric Current limiting lightning arrester with porous gap structure
US3354345A (en) * 1964-07-06 1967-11-21 Gen Electric Lightning arrester spark gap having arc-confining chamber walls of graded porosity
US3735074A (en) * 1971-07-14 1973-05-22 Gen Electric Arc chute for an electric circuit breaker
US3838375A (en) * 1973-01-29 1974-09-24 Gen Electric Current limiting fuse
US4210774A (en) * 1977-06-16 1980-07-01 Electric Power Research Institute, Inc. Filled polymer electrical insulator
US5828026A (en) * 1995-05-12 1998-10-27 Abb Research Ltd. Stock giving off arc-extinguishing gas, and gas-blast circuit breaker comprising such a stock
US5670926A (en) * 1995-06-08 1997-09-23 General Electric Company High-voltage fuse having a core of bound silica sand about which fusible elements are wound
US6642833B2 (en) 2001-01-26 2003-11-04 General Electric Company High-voltage current-limiting fuse
US20180144900A1 (en) * 2013-10-18 2018-05-24 Littelfuse, Inc. Foam fuse filler and cartridge fuse
US10685804B2 (en) * 2013-10-18 2020-06-16 Littelfuse, Inc. Manufacturing method for foam fuse filler and cartridge fuse

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FR1050023A (en) 1954-01-05
GB716998A (en) 1954-10-20
BE502180A (en)
DE977206C (en) 1965-06-10

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