EP0097906B1 - Kontakte für Vakuumschalter - Google Patents

Kontakte für Vakuumschalter Download PDF

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Publication number
EP0097906B1
EP0097906B1 EP83106046A EP83106046A EP0097906B1 EP 0097906 B1 EP0097906 B1 EP 0097906B1 EP 83106046 A EP83106046 A EP 83106046A EP 83106046 A EP83106046 A EP 83106046A EP 0097906 B1 EP0097906 B1 EP 0097906B1
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EP
European Patent Office
Prior art keywords
contact
boron
less
vacuum
component
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
Application number
EP83106046A
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English (en)
French (fr)
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EP0097906A1 (de
Inventor
Tsutomu Okutomi
Seishi Chiba
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Toshiba Corp
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Toshiba Corp
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Publication date
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Application filed by Toshiba Corp filed Critical Toshiba Corp
Priority to AT83106046T priority Critical patent/ATE22365T1/de
Publication of EP0097906A1 publication Critical patent/EP0097906A1/de
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C9/00—Alloys based on copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C5/00—Alloys based on noble metals
    • C22C5/06—Alloys based on silver
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/02—Contacts characterised by the material thereof
    • H01H1/0203—Contacts characterised by the material thereof specially adapted for vacuum switches

Definitions

  • This invention relates to a vacuum switch of the type which comprises a vacuum vessel and a pair of relatively separable electroconductive rods disposed in said vacuum vessel and provided with contact members at the opposing ends of said rods and in which each of said contact members contains 0.003-0.5% by weight of boron, a highly electroconductive component and a welding prevention component.
  • a vacuum switch has excellent characteristics in comparison with other circuit breakers in respects of small size, light weight, maintenance cost, and adaptability for various environments.
  • the quantity of brittle welding prevention components which tend to decrease breakdown strength should be limited to be as small as possible and (2) quantity of gas impurities and pin-holes should be highly suppressed.
  • a contact alloy containing elements having high vapor pressures such as Bi, Pb, Te or the like
  • air voids are liable to be formed in an ingot. More particularly, in pouring the alloy into a mold having a small diameter, serious casting problems often occur. For example, a lot of air voids are formed near the surface of the ingot and shrinkage holes are formed in the interior.
  • the contact alloy containing welding prevention components described above exhibits drawbacks such as low workability and generation of segregation because of low solubility of these components into matrix, which results in brittleness of the contact alloy.
  • An object of this invention is to provide a vacuum switch having separable electrode rods provided with improved contact members capable of exhibiting little or no drawbacks in respect of art restriking phenomenon.
  • a vacuum switch of the type which comprises a vacuum vessel and a pair of relatively separable electroconductive rods disposed in said vacuum vessel and provided with contact members at the opposing ends of said rods and in which each of said contact members contains boron, a highly electroconductive component and a welding preventing component, characterized in that each of said contact members contains 0.005-2% by weight of boron and is provided with a worked contact surface having a disc shape and finished to obtain surface roughness of less than 6 um and the total members of surface roughing portions, spallings, and breaks appearing on said worked contact surface are less than ten correspondingly in case the contact material has a diameter of 75 mm.
  • a vacuum switch shown in Fig. 1 comprises a cylindrical insulating casing 2, i.e. vacuum vessel, which defines an air tight vacuum circuit breaking chamber 1 and metallic caps 4 and 5 are provided at both ends of the casing 2 through seal members 3 and 3a.
  • the casing 2 is made of an insulating material.
  • a pair of separable electroconductive rods 6 and 7 provided with stationary and movable electrodes 8 and 9 at the opposing ends are disposed within the vacuum chamber 1 and a bellows 10 is attached to the lower end cap 5 for permitting reciprocation of the movable electrode 9 while maintaining the vacuum condition in the chamber 1.
  • the bellows 10 is covered with a metallic shield 11 to prevent metal vapor from depositing on the inner surface of the vacuum vessel 2 and a cylindrical metallic shield 12 is also disposed in the chamber 1 as shown in Fig. 1 to prevent the metal vapor from depositing thereon.
  • the movable electrode 9 is fixed to the conductive rod 7 by a brazing member 13 or tightly connected thereto by calking and a movable contact 14 is attached to the upper portion of the movable electrode 9 by brazing means 15.
  • the stationary electrode 8 has substantially the same construction as that of the movable electrode 9 and is provided with a stationary contact 14a at its front end.
  • the contact material is used for contacts 14 and 14a.
  • the contact material has a composition which is not specifically different from that of a conventional contact material including the addition of boron.
  • Cu and/or Ag are usually used as a highly electroconductive composition, if necessary, these metals can be replaced in part with less than 5% (based on the total weight of the conductive composition) of Fe, less than 5% of Co or less than 1% of Cr.
  • the electroconductive composition Cu or a copper rich alloy is suitable for the purposes of this invention.
  • These conductive components are used in an amount of the balance of the composition as described hereinafter.
  • the welding prevention component are used one or more elements of Bi, Pb, Te, Sb, and mixtures thereof which are incorporated into the contact material,according to this invention in an amount of from 0.1 % to 15%. If the amount of the welding prevention component is less than 0.1 %, the welding resistance property against large current decreases and if the amount thereof exceeds 15%, the segregation will occur during manufacture of the contact material, thus hardly obtaining a suitable contact material.
  • 0.005% to 2% preferably from 0.01% to 2% of boron is added to the highly conductive component and the welding prevention component. If the amount of added boron is less than 0.005%, the object of adding it cannot be expected and more than 2% of boron does not improve its function than a case of adding boron of 0.005%-2%. Thus, it was found that boron tends to segregate from the highly conductive component when the contact material is prepared by melting technique. This means that the use of more than 2% of boron is not suitable.
  • the range of the boron to be added should be defined as content of boron present in the resulting contact material rather than the amount of additive thereof by taking into consideration the effects of grades of the used high conductive component and of the used welding prevention component, melting temperature of the composition, and the fluctuation of the degree of the vacuum in the vacuum chamber.
  • the highly conductive component is melted under vacuum of from about 1.3 ⁇ 10 -3 to 1.3 ⁇ 10 -5 m bar at a temperature of from 1000° to 1300°C and the welding prevention component is then added thereto so as to be uniformly dissolved into the molten high conductive component. Thereafter, the resulting mixture is cooled and solidified in a mold, but if necessary, oriented solidification process can be used.
  • the order of addition of boron and the welding prevention component is optional and in order to prevent vaporization and scattering, it is advantageous to add the components after increasing the pressure in the melting furnace by introducing argon gas thereinto.
  • the source of the boron to be added can be used mother alloys such as Cu-B or borides such as FeB, Fe 2 B as well as boron itself.
  • Contacts made of the contact material and having desired shape, can be obtained by subjecting the resulting contact material to mechanical workings such as cutting, polishing or the like, or plastic deformation such as rolling, as required.
  • contact alloys having the compositions shown in Table 1 were prepared by a method comprising the steps of melting Cu under vacuum of about 1.3x10-5 mbarand at a temperature of 1200°C, completely degassing, adding and melting Cu-B mother alloy (containing 2.2% of B) and welding prevention components (Bi, Pb, Te, or Sb), pouring the molten alloy thus obtained into a mold and cooling and solidifying the poured alloy.
  • the end surface of a rod shaped contact material having a diameter of 75 mm was finished to obtain surface roughness of less than 6 pm (6-s; Japanese Industrial Standard 0601) by using a WC-Co super hard alloy cutting tool while the contact material was rotated at 180 r.p.m.
  • the number of defects such as spallings, breaks and the like on the end surface were visually measured and the minimum and maximum numbers of the observed defects of six samples are shown in Table 1.
  • a disc-shaped contact piece having a diameter of 30 mm and a thickness of 5 mm was attached to the end of each electrode rod of a demountable vacuum switch and a circuit having a rating of 6KV and 500 A was interrupted 2000 times.
  • the observed frequency of the arc restriking was represented by a range of difference (maximum and minimum values) of two circuit breakers.
  • the attachment of the contacts was performed only by baking for 30 minutes at a temperature of 450°C and not only no brazing material was used but also no heating operation was carried out.
  • the conventional boron-free contact materials exhibit significant surface roughness caused by working. Accordingly, restriking occurs with high probability.
  • the boron containing contact materials it can be understood that these materials exhibit remarkably improved workability and low probability of arc restriking.
  • the boron free contact material of the Control Example 1 exhibit 96-97% I.A.C.S. (International Annealed Copper Standard), whereas the contact material of Example 1 exhibits 95-97% I.A.C.S. This fact shows that the improved workability can be achieved without substantial reduction of the conductivity according to the contact material of the present invention.
  • oxygen content of the contact material of the Control Example 1 is 7 ppm, whereas that of the Example 1 is from about 1/2 to 1/7 of the Control Example 1. This fact shows that the added boron acts as a deoxidizer and the reduction of the oxygen content contributes to the prevention of the arc restriking.
  • a silver brazing plate consisting of 72% of Ag and 28% of Cu and having a diameter of 10 mm and a thickness of 0.1 mm was inserted between a pure copper electrode and a disc-shaped contact piece having a diameter of 15 mm and a thickness of 4.2 mm.
  • the structure thus prepared was heated for 30 minutes in H 2 atmosphere at a temperature of 820°C to thereby firmly bond together the materials used.
  • the amount of silver brazing crept up to the contact surface by passing through the contact piece during the heat treatment was measured as count numbers (C.P.S) by an X-ray microanalyzer under conditions of the absorption current of 5 ⁇ 10 -8 A, a scanning time of 50 seconds and an acceleration voltage of 25 KV. Background value of a contact piece to which silver brazing is not applied is shown in Table 2.
  • the boron-containing contact materials exhibit an extremely small amount of crept-up silver brazing in comparison with the conventional boron-free contact materials and also exhibit count numbers nearly equal to the background.
  • contact materials were prepared in substantially the same manner as that of the Example 1 except that in place of the highly conductive component consisting only of Cu were used highly conductive components in which a portion of the copper was replaced with Fe, Co, or Cr in a proportion shown in Table 3. Thereafter, the probability of arc restriking was measured for each of these examples in substantially the same manner as that of the Example 1. The results obtained are shown in the following Table 3, from which it will be found that the probability of the arc restriking was remarkably decreased by the addition of boron.
  • contact materials were also prepared in substantially the same manner as that of the Example 1 except that an Ag-Cu alloy (Example 16) and Ag alone (Example 17) were used as the highly conductive component.
  • the workability and the probability of the arc restriking were examined in substantially the same manner as that of the Example 1. The results obtained are shown in the following Table 4 from which advantageous effect caused by the addition of boron will be clearly confirmed.
  • contact materials for separable electrodes of a vacuum switch can be obtained by adding a small amount of boron to a contact material consisting of highly conductive components (mainly Cu and/or Ag; partially replaced with Fe, Co or Cr and welding prevention components (such as Bi, Pb, Te, Sb and the like).
  • the contact materials thus obtained exhibit improved workability and arc restriking prevention characteristics without impairing fundamental characteristics required for the contact material such as electroconductivity.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)
  • Contacts (AREA)
  • Keying Circuit Devices (AREA)
  • Driving Mechanisms And Operating Circuits Of Arc-Extinguishing High-Tension Switches (AREA)

Claims (3)

1. Vakuumschalter mit einem Vakuumgefäß und einem Paar, elektrisch leitender, voneinander trennbarer Stangen, die in dem Vakuumgefäß angeordnet sind und die an den gegenüberliegenden Enden der Stangen mit Kontaktelementen versehen sind, wobei jedes Kontaktelement Bor, eine elektrisch gut leitende Komponente und eine das Schewißen verhindernde Komponente enthält, dadurch gekennzeichnet, daß jedes Kontaktelement 0,005-2 Gewichts% Bor enthält und mit einer bearbeiteten Kontaktfläche in Scheibenform versehen ist, die abschließend so bearbeitet ist, daß die Oberflächenrauhheit kleiner als 6 µm ist und die Gesamtzahl der auf der bearbeitetn Kontaktfläche erscheinenden Oberflächenrauhheitsteile, Abspaltungen und Risse bei einem Durchmesser des Kontaktmaterials von 75 mm weniger als 10 ist.
2. Vakuumschalter nach Anspruch 1, dadurch gekennzeichnet, daß die elektrisch gut leitende Komponente aus Kupfer und/oder Silber oder einer Legierung besteht, in welcher ein Teil des Kupfers und/oder des Silbers durch weniger als 5% Eisen, weniger als 5% Kobalt oder weniger als 1% Chrom ersetzt ist.
3. Vakuumschalter nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die das Schweißen verhindernde Komponente wenigstens eines der Metalle Wismuth, Blei, Tellur oder Zinn enthält.
EP83106046A 1982-06-25 1983-06-21 Kontakte für Vakuumschalter Expired EP0097906B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT83106046T ATE22365T1 (de) 1982-06-25 1983-06-21 Kontakte fuer vakuumschalter.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP109276/82 1982-06-25
JP57109276A JPS59819A (ja) 1982-06-25 1982-06-25 真空しや断器用接点材料

Publications (2)

Publication Number Publication Date
EP0097906A1 EP0097906A1 (de) 1984-01-11
EP0097906B1 true EP0097906B1 (de) 1986-09-17

Family

ID=14506059

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EP83106046A Expired EP0097906B1 (de) 1982-06-25 1983-06-21 Kontakte für Vakuumschalter

Country Status (4)

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EP (1) EP0097906B1 (de)
JP (1) JPS59819A (de)
AT (1) ATE22365T1 (de)
DE (1) DE3366257D1 (de)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01129311U (de) * 1988-02-17 1989-09-04
CN114686720A (zh) * 2020-12-28 2022-07-01 广西纵览线缆集团有限公司 稀土合金化Cu-Fe合金的制备工艺

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2310317A1 (de) * 1973-03-01 1974-09-05 Siemens Ag Mehrbereichskontakt fuer vakuumschaltroehren
DE2723749C3 (de) * 1976-05-28 1980-07-24 Tokyo Shibaura Electric Co., Ltd., Kawasaki, Kanagawa (Japan) Kontaktstücke für Vakuum-Trennschalter

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3551622A (en) * 1963-03-22 1970-12-29 Hitachi Ltd Alloy materials for electrodes of vacuum circuit breakers
GB1309197A (en) * 1971-10-28 1973-03-07 Int Standard Electric Corp Vacuum interrupter contacts
JPS5530246A (en) * 1978-08-25 1980-03-04 Sumitomo Electric Ind Ltd Noise elimination system for picture information

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2310317A1 (de) * 1973-03-01 1974-09-05 Siemens Ag Mehrbereichskontakt fuer vakuumschaltroehren
DE2723749C3 (de) * 1976-05-28 1980-07-24 Tokyo Shibaura Electric Co., Ltd., Kawasaki, Kanagawa (Japan) Kontaktstücke für Vakuum-Trennschalter

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DIN 140/Oktober 1954 Handbuch für das Schleifen und Polieren, 4. Aufl. 1974, Eugen G. Lenze Verlag, Saulgan *

Also Published As

Publication number Publication date
DE3366257D1 (en) 1986-10-23
EP0097906A1 (de) 1984-01-11
JPS59819A (ja) 1984-01-06
ATE22365T1 (de) 1986-10-15
JPS6359214B2 (de) 1988-11-18

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