US2704381A - Arc chute - Google Patents

Arc chute Download PDF

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Publication number
US2704381A
US2704381A US312251A US31225152A US2704381A US 2704381 A US2704381 A US 2704381A US 312251 A US312251 A US 312251A US 31225152 A US31225152 A US 31225152A US 2704381 A US2704381 A US 2704381A
Authority
US
United States
Prior art keywords
phosphoric acid
chute
phosphate
asbestos
weight
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US312251A
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English (en)
Inventor
Russell A Nelson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to FR942906D priority Critical patent/FR942906A/fr
Application filed by General Electric Co filed Critical General Electric Co
Priority to US312251A priority patent/US2704381A/en
Priority to FR64600D priority patent/FR64600E/fr
Priority to JP1735153A priority patent/JPS3110892B1/ja
Application granted granted Critical
Publication of US2704381A publication Critical patent/US2704381A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/34—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing cold phosphate binders
    • 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
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/34—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing cold phosphate binders
    • C04B28/342—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing cold phosphate binders the phosphate binder being present in the starting composition as a mixture of free acid and one or more reactive oxides
    • 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
    • H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
    • H01B3/06—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances asbestos
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
    • H01H9/30—Means for extinguishing or preventing arc between current-carrying parts
    • H01H9/34—Stationary parts for restricting or subdividing the arc, e.g. barrier plate
    • 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
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/90—Electrical properties
    • C04B2111/92—Electrically insulating materials

Definitions

  • the present invention relates to are chutes or shields commonly used in blowout type circuit breakers, such as magnetic or gas blast circuit breakers, for the purpose of confining and extinguishing the are drawn between the opening electrical contacts of such devices. It is particularly concerned with an improved inorganic molding composition for the manufacture of such are chutes.
  • Fig. 1 illustrates a circuit breaker in partial sectional view including an arc chute of the type with which the present invention is concerned;
  • Fig. 2 is a cross-sectional View taken along line 22 of Fig. 1;
  • Fig. 3 is a view taken along line 33 of Fig. 1;
  • Fig. 4 is a view in cross section of a slab or block of molded heat-resistant insulating material which, by suitable machining, is converted to a chute of the desired shape and size.
  • a circuit breaker comprising an arc chute 1 which in the circuit breaker is associated with a pair of relatively movable contacts, not shown. Relative movement between these contacts is obtained by means of an operating mechanism generally indicated at 2.
  • the are chute 1 is in two sections which together form spaced side walls 3 with each side wall having on the side facing the other wall a plurality of parallel fins 4 integral with the side wall.
  • the sections are suitably clamped together by means of members 5 and bolts 6 to form a chute-like structure with the fins 4 extending perpendicularly into the chute opening in staggered interleaved relation with respect to each other to form an extended sinuous or zigzag passageway for the are as is best shown in Fig. 2 of the drawing.
  • the insulating material is an inorganic composition essentially comprising concentrated (at least 60%, and preferably 75%) ortho-phosphoric acid and asbestos of the chrysotile type. In addition to the asbestos and phosphoric acid, the composition may also contain substantial quantities of zircon, talc or other filler.
  • the asbestosphosphoric acid compositions can readily be hot-molded. During the molding, there is a reactlon between the phosphoric acid and the asbestos so that the molded product can be extracted from the mold.
  • the asbestos-phosphoric acid compositions are ordinarily molded mto the form of a block or slab having the approximate cross section shown in Fig. 4 of the drawing. Such a slab is composed of a thinner section 8 and a thicker section 9.
  • a plurality of grooves are cut in the thicker portion 9 of the slab at spaced intervals to form the fins 4 of the arc chute section.
  • the machined articles are then subjected to a heat treatment for the purpose of further removing any water from the molded product and completing the cure or hardening reaction between the asbestos and phosphoric acid.
  • a heat treatment is ordinarily carried out at temperatures from about 250 to 700 F., preferably about 600 F., for a period of time ranging from about 8 to 12 hours.
  • the flame conditioning treatment ordinarily comprises playing an oXy-acetylene or other high temperature flame over the surface of the chute until a glazed or fused film is obtained.
  • the present invention is based on the discovery that the warpage problem can be entirely eliminated or substantially alleviated by including in the composition from which the chutes are molded from about 3 to 10%, by weight, of an organic ester of orthophosphoric acid based on the weight of the composition. While the effect of the organic phosphate is not completely understood, it has been found that its use has reduced losses due to warpage during baking of the machine chutes by an average of 93% while a further decrease in warpage is also obtained during the flame conditioning process. The phosphate ester does not affect the final use of the material as an arc chute or are interrupter.
  • Tricresyl phosphate is a preferred phosphoric acid ester for the practice of the present invention.
  • other organic esters of ortho-phosphoric acid may also be employed in place of or in combination with the tricresyl phosphate.
  • Examples of such compounds are tri-ethyl phosphate, tributyl phosphate, tri-Z-ethylhexyl phosphate, tributoxyethyl phosphate, tri-phenyl phosphate, cresyl diphenyl phosphate, tri-dimethyl phenyl phosphate, diphenyl mono-o-xenyl phosphate, tri-ptert-butylphenylphosphate, mono-cresyl phosphate, di-cresyl phosphate and the like.
  • chutes 20" in length molded from a composition consisting of 52 parts zircon, 35 parts asbestos and 18 parts of 75% phosphoric acid will, on the average, show a warpage of about 81) mils over the 20" length during the baking cycle following the machining operations, and an additional 180 mils during the flame conditioning treatment.
  • the addition of 4 /2%, by weight, of tri-cresyl phosphate to this molding composition before molding reduced the average warpage during the baking cycle following the machining operation to less than 20 mils and the additional warpage after the flame treatment to an average of about mils.
  • the invention is, of course, not limited to any specific phosphoric acid-asbestos composition and zircon, talc and other inert fillers may be included along with the asbestos and phosphoric acid. However, it is desirable for best results that the phosphoric acid and asbestos be present in certain proportions.
  • the preferred molding compositions will ordinarily contain about 1 part, by weight, of concentrated ortho-phosphoric acid for each 1.7 to 3.5 parts, by weight, asbestos with the optimum ratio depending to some extent on the texture of the asbestos, i. e., the fiber diameter and length, and the nature of any filler which may be included in the composition.
  • Zircon is a preferred filler and may be present in amounts from to 4 parts, by weight, zircon for each part asbestos.
  • Talc or other fillers may replace part or all of the zircon.
  • the phosphate ester because of its cost, is not employed in amounts substantially exceeding about by weight, of the molding composition.
  • thermosetting composition comprising a reaction mixture of chrysotile asbestos, concentrated ortho-phosphoric acid having a concentration of at least 60% and from 3 to by weight, of a phosphate ester.
  • a molding compound containing, by weight, about one part concentrated ortho-phosphoric acid, from 1.7 to 3.5 parts chrysotile asbestos, and 3 to 10%, by weight based on the combined weight of acid and asbestos, of an organic ester of phosphoric acid.
  • thermoset molded product comprising a heat and pressure reacted mixture of chrysotile asbestos fibers, concentrated ortho-phosphoric acid and from 3 to 10%, by weight, of an organic ester of phosphoric acid.
  • thermoset molded product of claim 5 in which the organic ester is tricresyl phosphate.
  • An are chute for air circuit breakers comprising the molded product of claim 5.
  • An are chute for air circuit breakers comprising the molded product of claim 6.
  • thermoset molded product produced by reacting under heat and pressure a mixture of chrysotile asbestos fibers, zircon, concentrated ortho-phosphoric acid and from about 3 to 10%, by weight, tri-cresyl phosphate.
  • an arc chute by a process which comprises hot-molding a reaction mixture of chrysotile asbestos and concentrated phosphoric acid and machining one surface of the molded body to form thereon a plurality of spaced projections followed by a baking of the machined product at an elevated temperature, the step of including in the reaction mixture from 3 to 10% of an organic ester of phosphoric acid for the purpose of preventing warpage of the machined product during the baking step.
  • arc chutes by a process which comprises hot-molding a composition essentially comprising chrysotile asbestos and concentrated orthophosphoric acid into the form of a slab, machining the slab into the form of an arc chute having a plurality of fins extending from one surface thereof, baking the machined product for the purpose of removing moisture therefrom and finally playing a flame on the machined surface to obtain a glazed surface coating thereon, the improvement which comprises including in the hot-moldcomposition from 3 to 10%, by weight, tri-cresyl phosphate for the purpose of alleviating warpage during the baking and flame treating operations.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Breakers (AREA)
  • Arc-Extinguishing Devices That Are Switches (AREA)
  • Organic Insulating Materials (AREA)
US312251A 1952-09-30 1952-09-30 Arc chute Expired - Lifetime US2704381A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
FR942906D FR942906A (fr) 1952-09-30 1946-11-19 Compositions minérales de moulage et produits dérivés
US312251A US2704381A (en) 1952-09-30 1952-09-30 Arc chute
FR64600D FR64600E (fr) 1952-09-30 1953-09-23 Compositions minérales de moulage et produits dérivés
JP1735153A JPS3110892B1 (2) 1952-09-30 1953-09-25

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US312251A US2704381A (en) 1952-09-30 1952-09-30 Arc chute

Publications (1)

Publication Number Publication Date
US2704381A true US2704381A (en) 1955-03-22

Family

ID=23210574

Family Applications (1)

Application Number Title Priority Date Filing Date
US312251A Expired - Lifetime US2704381A (en) 1952-09-30 1952-09-30 Arc chute

Country Status (3)

Country Link
US (1) US2704381A (2)
JP (1) JPS3110892B1 (2)
FR (2) FR942906A (2)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4006330A (en) * 1975-04-16 1977-02-01 General Electric Company Circuit breaker arc chute having components of refractory inorganic material with surfaces of an amorphous fused material, a major proportion of which is silica, and method for making same
US4413062A (en) * 1981-07-20 1983-11-01 General Electric Company Molding composition and product produced therefrom

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2220019A (en) * 1939-02-11 1940-10-29 Power Patents Co Refractory and method of manufacture
US2323951A (en) * 1941-09-27 1943-07-13 Titanium Alloy Mfg Co Refractory composition
US2366485A (en) * 1941-12-18 1945-01-02 Gen Electric Inorganic molding compositions and products produced therefrom
US2383812A (en) * 1942-09-09 1945-08-28 Gen Electric Mold and fabrication method
US2479504A (en) * 1943-07-12 1949-08-16 Ransom & Randolph Company Investment material

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2220019A (en) * 1939-02-11 1940-10-29 Power Patents Co Refractory and method of manufacture
US2323951A (en) * 1941-09-27 1943-07-13 Titanium Alloy Mfg Co Refractory composition
US2366485A (en) * 1941-12-18 1945-01-02 Gen Electric Inorganic molding compositions and products produced therefrom
US2383812A (en) * 1942-09-09 1945-08-28 Gen Electric Mold and fabrication method
US2479504A (en) * 1943-07-12 1949-08-16 Ransom & Randolph Company Investment material

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4006330A (en) * 1975-04-16 1977-02-01 General Electric Company Circuit breaker arc chute having components of refractory inorganic material with surfaces of an amorphous fused material, a major proportion of which is silica, and method for making same
US4413062A (en) * 1981-07-20 1983-11-01 General Electric Company Molding composition and product produced therefrom

Also Published As

Publication number Publication date
FR64600E (fr) 1955-11-14
JPS3110892B1 (2) 1956-12-27
FR942906A (fr) 1949-02-22

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