US3929660A - Arc-extinguishing materials - Google Patents

Arc-extinguishing materials Download PDF

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Publication number
US3929660A
US3929660A US36459673A US3929660A US 3929660 A US3929660 A US 3929660A US 36459673 A US36459673 A US 36459673A US 3929660 A US3929660 A US 3929660A
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Prior art keywords
arc
compound
extinguishing material
primary ingredient
greater
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Joseph M Khalid
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Schneider Electric USA Inc
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Schneider Electric USA Inc
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Priority claimed from AU68829/74A external-priority patent/AU494140B2/en
Priority to US36459673 priority Critical patent/US3929660A/en
Application filed by Schneider Electric USA Inc filed Critical Schneider Electric USA Inc
Priority claimed from GB1925674A external-priority patent/GB1476241A/en
Priority to DE19752539013 priority patent/DE2539013C3/de
Application granted granted Critical
Publication of US3929660A publication Critical patent/US3929660A/en
Anticipated expiration legal-status Critical
Application status is Expired - Lifetime legal-status Critical

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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/70Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid
    • H01H33/76Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid wherein arc-extinguishing gas is evolved from stationary parts; Selection of material therefor
    • AHUMAN NECESSITIES
    • A62LIFE-SAVING; FIRE-FIGHTING
    • A62CFIRE-FIGHTING
    • A62C3/00Fire prevention, containment or extinguishing specially adapted for particular objects or places
    • A62C3/16Fire prevention, containment or extinguishing specially adapted for particular objects or places in electrical installations, e.g. cableways

Abstract

Arc-extinguishing materials are selected in accordance with criteria such as first ionization potential of each of the constituents, carbon content, boiling, sublimation, or decomposition temperature, endothermic character of decomposition, electronegativity of decomposition products, rate of reformation, dimensional and chemical stability, ease of application, cost, toxicity, and coefficient of thermal conductivity.

Description

United States Patent [191 Khalid 1 Dec. 30, 1975 ARC-EXTINGUISHING MATERIALS [75] Inventor: Joseph M. Khalid, Cedar Rapids,

Iowa

[73] Assignee: Square D Company, Park Ridge, 111.

[22] Filed: May 29, 1973 [21] Appl. No.: 364,596

OTHER PUBLICATIONS Bailar et a1., Comprehensive Inorganic Chem, 1973, pp. 880-882.

Dove 252/63.5

Hawley, Condensed Chemical Dictionary, 8th Ed, (1971).

Grant, Hackhs Chemical Dictionary, 4th Ed, (1969).

The Merck Index, (1968), 8th Ed.

Primary Examiner-Leland A. Sebastian Assistant Examiner-B. Hunt Attorney, Agent, or Firm-Harold J. Rathbun; Ernest S. Kettelson [57] ABSTRACT Arc-extinguishing materials are selected in accordance with criteria such as first ionization potential of each of the constituents, carbon content, boiling, sublimation, or decomposition temperature, endothermic character of decomposition, electronegativity of decomposition products, rate of reformation, dimen sional and chemical stability, ease of application, cost, toxicity, and coefficient of thermal conductivity.

9 Claims, N0 Drawings ARC-EXTINGUISHING MATERIALS This invention relates to arc-extinguishing materials usable as molding compositions for molding arc shields, arc chute frame components, cases of electrical devices, and the like and also usable in coating formfor coating surface portions of a member wholly or partly defining an arc chamber in which separable contacts of an electrical circuit interrupting device aredisposed.

Arc interruption requires the establishment of conditions promoting a higher rate of recombination than the rate of ionization. The problem reduces to one of recognizing the basic factors that control these two rates. 1.

One of the factors which should be considered in the selection of arc-extinguishing materials is the first ionization potential of each of the constituents of the material. The first ionization potential of an element is the amount of energy required to remove one electron away to infinity from a neutral atom of that element. For silver, the first ionization potential is 7.54 electron volts, while the first ionization potential for aluminum is 5.98 electron volts. To appreciate the significance of a difference of one electron volt between the first ionization potentials of two elements, consider that the temperature difference between two particles having an energy difference of one electron volt is 7730 C.

Another factor which should be considered in the selection of arc-extinguishing materials is electronega: tivity of decomposition products. This is a measure of the affinity of an atom of an element for electrons. .As an arc current approaches zero it would be desirable to have an electronegative gas in the arc chamber that would capture the cooling and slowing electrons. Such electrons would otherwise be accelerated by the rising recovery voltage and cause further ionization and possible reignition.

Yet anotherfactor which should be considered in the selection of arc-extinguishing materials is the boilingsublimation, or decomposition temperature. During the few microseconds preceding and following the passing of the current through zero in an alternating current system, the arc column temperature decreases rapidly until it reaches the temperature of the arc chamber walls, which actas a constant temperature sink. The higher the boiling temperature of the material of the arc chamber walls is, the lower the recombination rates will be.

Endothermic processes have their primary importance at current zero, particularly in the mode of arc interruption wherein a post-arc current flows. Under this latter condition the energy being absorbed in an endothermic process taking place in the arc chamber on a modest scale may approximate the energy being put into the chamber by the post-arc current. This effect, complemented by a favorable boiling temperature, significantly contributes to the success of arc extinction.

lf an arc-extinguishing material decomposes to yield free carbon, this carbon may be oxidized to carbon dioxide. The process is exothermic, and its timing is bad, because it is as the arc current approaches zero and the temperature drops and recombination of ions and dissociated molecules starts to take place that the exothermic formation of carbon dioxide occurs. Deposits of free carbon can also cause tracking and dielectric failure. However, to limit arc-extinguishing materials to those containing no carbon would too severely limit the choice of materials. Moreover, hydrogenhas been found to be a desirable component of the gas medium surrounding an arc, especially when an application makes it desirable to force motion of the arc by' a' transverse magnetic field, and carbon and hydrogen'generally occur together. It has been found that the number of carbon atoms as a percentage of the total number of atoms in an arc-extinguishing material should not exceed a value of about fifteen percent.

An endothermic process of decomposition is exothermic on'formation. Therefore, it is desirable to select materials having formulas such that the probability of reformationafter decomposition is small. Aluminum oxide (Al O and boron oxide (B 0 are materials with such formulas, because the. probability of two aluminum or baron atoms colliding simultaneously with three oxygen atoms, or with one molecule and one atom of oxygen, is small. However, aluminum oxide is undersirable as an arc-extinguishing material because the ionization potential of aluminum is low and the boiling temperature ofaluminum oxide is too high. In this'respec't=,-the present invention is a departure from the prior" art as represented by U.S. Pat. Nos.

- 2,768,264, and 3,071,666 which tout aluminum oxide as a good arc-extinguishing material.

SUMMARY OF CRITERIA In accordance with the invention, the first ionization potential of each of the constituents of a suitable arcextinguishing material should be equal to or greater than 7.54 electron volts, which is the first ionization potential of silver. The atomic concentration of carbon in the material should not be greater than about 15 per cent. The boiling, sublimation, ordecomposition temperatu're of thematerial should be as low as possible consistent with other requirements, preferably below 2,000 C. Decomposition of the material should be a strongly endothermic process, the more endothermic the better. The products of decomposition of the material should be as electronegative as possible consistent with other requirements. The material should have a formula such that the rate of reformation after decomposition is vanishingly small near the zero point of the alternating current, such as that for B 0, or H BO The material should be non-toxic, non-caustic, noninflammable, easyto process and apply, and dimensionally and chemically stable under operating conditions. Further, it should have good thermal conductivity for an electrically insulating material, preferably greater than 0.001 calories per second per square centimeter per degree Centigrade per centimeter.

Representative Materials In general the oxides, borides, borates, silicates, and the ammonium complexes of the elements having a first ionization potential equal to or greater than that of silver (7.54eV) are suitable arc-extinguishing materials, and so are their hydrated forms. A preferred selection of such elements, with their first ionization potentials shown in parentheses, is tantalum (7.70eV), copper (7.72eV), cobolt (7.86eV), rhenium (7.87eV), iron (7.90eV), tungstem (7.98eV), silicon (8-.l5eV), boron (8.29eV), palladium (8.30eV), antimony (8.64eV), tellurium (9.0leV), zinc (9.39), and selenium (9.75eV). These substances may also be used as fillers in suitable resins provided that the atomic carbon concentration does not exceed the nominal limit of fifteen percent. Silicone resins are suitable. The use of 3 resins becomes mandatory when the filler material cannot be used in its pure form. For example, pure silicon dioxide cannot be used because its boiling tem-v perature is too high, and pure boric acid cannot be used because it is water soluble and therefore dimensionally unstable, but these materials are suitable when used in suitable resins.

Beryllium (9.32eV), arsenic (9.8leV), and mercury (10.43eV) have first ionization potentials higher than that of silver, but these elements are toxic and therefore undesirable. Sulphates, phosphates, nitrates, and halogens are also undesirable as toxic.

Silver, platinum, and gold oxides, borates and silicates, with or without ammonium complexes, would be suitable arc-extinguishing materials except for high cost.

In particular, a material composed of 55.8 per cent by weight Firebrake Z8 and 44.2 per cent Sylgard 182 has been found to be a very suitable arc-extinguishing material. Firebrake ZB is made by United States Borax and Chemical Corporation of Los Angeles, Calif., and has a formula 2ZnO.3B O .3/l-l O. Sylgard 182 is made by Dow Corning Corporation of Midland, Mich. and is a dimethyl silicone resin having a basic monomer represented by the following structural formula:

SiO

I claim:

1. An arc-extinguishing material consisting of a compound comprising a primary ingredient having arcextinguishing properties, and a binder, said primary ingredient including an element having a first ionization potential no less than 7.54 electron volts and selected from a class consisting of silver, tantalum, copper, rhenium, tungsten, boron, palladium, tellurium, zinc and selenium, the relative proportions of said primary ingredient and said binder being a silicone resin, the carbon atoms of said total compound being no greater than fifteen percent of the total concentration of atoms thereof.

2. An arc-extinguishing material as set forth in claim 1, wherein said compound has a boiling temperature no greater than 2,000 C, and said element is selected 4 from a class consisting of silver, tellurium, zinc and selenium, the boiling points of such elements in pure form being less than 2,000 C.

3. An arc-extinguishing material as set forth in claim 1, wherein said compound has a boiling temperature no greater than 2,000 C, and said element is selected from a class consisting of tantalum, copper, tungsten, boron and palladium, the boiling points of such elements in pure form being greater than 2,000 C, said binder and said selected element comprising said compound having a boiling temperature no greater than 2,000 C.

4. An arc-extinguishing material consisting of a compound characterized by a negligible rate of reformation after decomposition, said compound being boron oxide and a silicon based resin.

5. An arc-extinguishing material consisting of a compound characterized by a negligible rate of reformation after decomposition, said compound being boric acid and a silicone based resin.

6. An arc-extinguishing material as set forth in claim 1, wherein said primary ingredient comprises at least 40 percent by weight of said compound.

7. An arc-extinguishing material as set forth in claim 1, wherein said primary ingredient comprises at least 55 percent by weight of said compound.

8. An arc-extinguishing material as set forth in claim 1, wherein said primary ingredient comprises about 56 percent by weight of said compound.

9. An arc-extinguishing material consisting of a compound characterized by negligible rate of reformation after decomposition, a first ionization potential no less than 7.54 electron volts, a boiling temperature no greater than 2,000 C, for which decomposition is an endothermic process, having thermal conductivity of at least one-thousandth of a calorie per second per square centimeter per degree Centigrade per centimeter, said compound comprising a primary ingredient and a binder, said primary ingredient including an element selected from a class consisting of silver, tantalum, copper, rhenium, tungsten, boron, palladium, tellurium, zinc and selenium, said binder being a silicone resin, the carbon content and proportion thereof relative to said primary ingredient being such that the carbon atoms are no greater than 15 percent of the total atoms of said compound.

Claims (9)

1. AN ARC-EXTINGUISHING MATERIAL CONSISTING OF A COMPOUND COMPRISING A PRIMARY INGREDIENT HAVNG ARC-EXTINGUISHING PROPERTIES, AND A BINDER, SAID PRIMARY INGREDIENT INCLUDING AN ELEMENT HAVING A FIRST IONIZATION POTENTIAL NO LESS THAN 7.54 ELECTRON VOLTS AND SELECTED FROM A CLASS CONSISTING OF SILVER, TANTALUM, COPPER, RHENIUM, TUNGSTEN, BORON, PALLADIUM, TELLURIUM, ZINC AND SELENIUM, THE RELATIVE PROPORTIONS 0F SAID PRIMARY INGREDIENT AND SAID BINDER BEING A SILICONE RESIN, THE CARBON ATOMS OF SAID TOTAL COMPOUND BEING NO GREATER THAN FIFTEEN PERCENT OF THE TOTAL CONCENTRATION OF ATOMS THEREOF.
2. An arc-extinguishing material as set forth in claim 1, wherein said compound has a boiling temperature no greater than 2,000* C, and said element is selected from a class consisting of silver, tellurium, zinc and selenium, the boiling points of such elements in pure form being less than 2,000* C.
3. An arc-extinguishing material as set forth in claim 1, wherein said compound has a boiling temperature no greater than 2,000* C, and said element is selected from a class consisting of tantalum, copper, tungsten, boron and palladium, the boiling points of such elements in pure form being greater than 2,000* C, said binder and said selected element comprising said compound having a boiling temperature no greater than 2,000* C.
4. An arc-extinguishing material consisting of a compound characterized by a negligible rate of reformation after decomposition, said compound being boron oxide and a silicon based resin.
5. An arc-extinguishing material consisting of a compound characterized by a negligible rate of reformation after decomposition, said compound being boric acid and a silicone based resin.
6. An arc-extinguishing material as set forth in claim 1, wherein said primary ingredient comprises at least 40 percent by weight of said compound.
7. An arc-extinguishing material as set forth in claim 1, wherein said primary ingredient comprises at least 55 percent by weight of said compOund.
8. An arc-extinguishing material as set forth in claim 1, wherein said primary ingredient comprises about 56 percent by weight of said compound.
9. An arc-extinguishing material consisting of a compound characterized by negligible rate of reformation after decomposition, a first ionization potential no less than 7.54 electron volts, a boiling temperature no greater than 2,000* C, for which decomposition is an endothermic process, having thermal conductivity of at least one-thousandth of a calorie per second per square centimeter per degree Centigrade per centimeter, said compound comprising a primary ingredient and a binder, said primary ingredient including an element selected from a class consisting of silver, tantalum, copper, rhenium, tungsten, boron, palladium, tellurium, zinc and selenium, said binder being a silicone resin, the carbon content and proportion thereof relative to said primary ingredient being such that the carbon atoms are no greater than 15 percent of the total atoms of said compound.
US36459673 1973-05-29 1973-05-29 Arc-extinguishing materials Expired - Lifetime US3929660A (en)

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US36459673 US3929660A (en) 1973-05-29 1973-05-29 Arc-extinguishing materials
DE19752539013 DE2539013C3 (en) 1973-05-29 1975-09-02

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Application Number Priority Date Filing Date Title
US36459673 US3929660A (en) 1973-05-29 1973-05-29 Arc-extinguishing materials
CA195,807A CA1014725A (en) 1973-05-29 1974-03-25 Arc-extinguishing materials
GB1925674A GB1476241A (en) 1973-05-29 1974-05-02 Arc-extinguishing materials
ZA00742864A ZA7402864B (en) 1973-05-29 1974-05-06 Arc-extinguishing materials
AU68829/74A AU494140B2 (en) 1974-05-10 Electrical device containing arc-extinguishing materials
IT6865174A IT1011885B (en) 1973-05-29 1974-05-27 Material for the extinction of those who ar electrical
FR7418352A FR2232058B1 (en) 1973-05-29 1974-05-28
DE19752539013 DE2539013C3 (en) 1973-05-29 1975-09-02

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4098883A (en) * 1975-03-12 1978-07-04 Dr. Madaus & Co. Aluminum compound and pharmaceutical compositions containing same
US4333121A (en) * 1980-08-15 1982-06-01 Bell Telephone Laboratories, Incorporated Fused station protector
US4833190A (en) * 1986-07-28 1989-05-23 General Electric Company Zinc borate as a smoke suppressant
WO1993008585A1 (en) * 1991-10-18 1993-04-29 Square D Company Current limiting circuit breaker with over-molded magnet and metal plates
EP1162640A1 (en) * 2000-06-07 2001-12-12 Abb Research Ltd. Arc extinguishing material
EP1274110A1 (en) * 2001-07-02 2003-01-08 Abb Research Ltd. Fuse

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2610937A (en) * 1949-02-23 1952-09-16 Westinghouse Electric Corp Process of manufacturing spaced plate arc extinguishers
US2768264A (en) * 1953-04-28 1956-10-23 Rostone Corp Arc-suppressing device
US3021460A (en) * 1957-08-20 1962-02-13 Texas Instruments Inc Semiconductor translating device with silicone fluid filler
US3475546A (en) * 1966-08-22 1969-10-28 Mc Graw Edison Co Insulating material for electrical apparatus
US3577346A (en) * 1968-11-14 1971-05-04 Minnesota Mining & Mfg Insulated electrical conductors having corona resistant polymeric insulation containing organo metallic compounds
US3788939A (en) * 1972-07-17 1974-01-29 H Dove High dielectric electronic

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2610937A (en) * 1949-02-23 1952-09-16 Westinghouse Electric Corp Process of manufacturing spaced plate arc extinguishers
US2768264A (en) * 1953-04-28 1956-10-23 Rostone Corp Arc-suppressing device
US3021460A (en) * 1957-08-20 1962-02-13 Texas Instruments Inc Semiconductor translating device with silicone fluid filler
US3475546A (en) * 1966-08-22 1969-10-28 Mc Graw Edison Co Insulating material for electrical apparatus
US3577346A (en) * 1968-11-14 1971-05-04 Minnesota Mining & Mfg Insulated electrical conductors having corona resistant polymeric insulation containing organo metallic compounds
US3788939A (en) * 1972-07-17 1974-01-29 H Dove High dielectric electronic

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4098883A (en) * 1975-03-12 1978-07-04 Dr. Madaus & Co. Aluminum compound and pharmaceutical compositions containing same
US4333121A (en) * 1980-08-15 1982-06-01 Bell Telephone Laboratories, Incorporated Fused station protector
US4833190A (en) * 1986-07-28 1989-05-23 General Electric Company Zinc borate as a smoke suppressant
WO1993008585A1 (en) * 1991-10-18 1993-04-29 Square D Company Current limiting circuit breaker with over-molded magnet and metal plates
US5223681A (en) * 1991-10-18 1993-06-29 Square D Company Current limiting circuit breaker with over-molded magnet and metal plates
EP1162640A1 (en) * 2000-06-07 2001-12-12 Abb Research Ltd. Arc extinguishing material
US6645637B2 (en) 2000-06-07 2003-11-11 Abb Research Ltd Extinguishing medium for quenching electric arcs scope
AU774864B2 (en) * 2000-06-07 2004-07-08 Abb Research Ltd Extinguishing medium for quenching electric arcs scope
EP1274110A1 (en) * 2001-07-02 2003-01-08 Abb Research Ltd. Fuse
US6710699B2 (en) 2001-07-02 2004-03-23 Abb Research Ltd Fusible link

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CA1014725A (en) 1977-08-02
CA1014725A1 (en)

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