WO2000007202A2 - Medium- and/or high-voltage circuit breaker - Google Patents

Medium- and/or high-voltage circuit breaker Download PDF

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Publication number
WO2000007202A2
WO2000007202A2 PCT/EP1999/005487 EP9905487W WO0007202A2 WO 2000007202 A2 WO2000007202 A2 WO 2000007202A2 EP 9905487 W EP9905487 W EP 9905487W WO 0007202 A2 WO0007202 A2 WO 0007202A2
Authority
WO
WIPO (PCT)
Prior art keywords
circuit breaker
medium
voltage circuit
high
characterized
Prior art date
Application number
PCT/EP1999/005487
Other languages
French (fr)
Other versions
WO2000007202A3 (en
Inventor
Silvio Stangherlin
Silvia Volponi
Original Assignee
Abb Adda Spa
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 ITMI98A001750 priority Critical
Priority to ITMI981750 priority patent/IT1301953B1/en
Priority to ITMI99A000893 priority
Priority to ITMI990893 priority patent/IT1312252B1/en
Application filed by Abb Adda Spa filed Critical Abb Adda Spa
Publication of WO2000007202A2 publication Critical patent/WO2000007202A2/en
Publication of WO2000007202A3 publication Critical patent/WO2000007202A3/en

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Classifications

    • 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
    • H01H33/02Details
    • H01H33/04Means for extinguishing or preventing arc between current-carrying parts
    • H01H33/22Selection of fluids for arc-extinguishing

Abstract

A medium and/or high-voltage circuit breaker, comprising an insulating casing inside which there is at least one interruption chamber which contains at least one fixed contact and at least one moving contact and a dielectric fluid for quenching electric arcs, the particularity of which is the fact that the dielectric fluid for quenching electric arcs comprises a fluoridized dielectric fluid which contains dissolved oxygen and that it comprises at least one first active filter located in the volume occupied by the fluoridized dielectric fluid, the first active filter being suitable to neutralize the chemically reactive species that originate from the decomposition/recombination of the fluoridized dielectric fluid following an electric arc.

Description

MEDIUM- AND/OR HIGH-VOLTAGE CIRCUIT BREAKER

DESCRIPTION

The present invention relates to a medium- and/or high-voltage circuit breaker which contains, as electric arc quenching means, a fluoridized dielectric fluid ^ whose decomposition products generated as a consequence of electric arcs have an extremely limited environmental impact.

It is known that medium- and high-voltage circuit breakers comprise an insulating casing in which there is an interruption chamber with interruption mechanisms constituted by at least one fixed contact and at least one moving lo contact. Opening/closure maneuvers of the circuit breaker are performed by engaging/disengaging the fixed contacts with respect to the moving contacts by using known actuation devices.

Generally, during opening the mutual separation of the moving contact and of the fixed contact is accompanied by the generation of an electric arc between i the two contacts; these arcs are quenched by using known kinds of dielectric fluid whose use. in the current state of the art, entails various drawbacks and disadvantages.

For example, one of the most common fluids used to quench the electric arc in medium and/or high-voltage circuit breakers is constituted by a mineral oil: 0 mineral oils, however, in addition to being dangerously flammable, can sometimes lead to unacceptable drawbacks, such as the generation of hydrogen, methane and carbon residuals.

Many applications commonly use gaseous substances such as nitrogen, noble gases, compressed air, sulfur hexafluoride (SF6) and mixtures thereof. With 25 these substances it is indispensable to use devices for monitoring the pressure of the gas used and for replenishing it in order to maintain the dielectric performance of the system.

Another drawback is due to the fact that both when using gaseous fluids and when using liquid fluids it is necessary to adopt particular refinements and to use safety systems in order to avoid and/or indicate any losses and leaks of said fluid; in this case, the losses and consequent leaks of the fluid might in fact cause malfunctions of the circuit breaker and environmental contamination problems. This obviously affects the constructive complexity of the circuit breaker and its overall reliability.

It is also known in the technical literature to use non-flammable liquids, such as for example mixtures of chlorofluorocarbons (CFC) or of perfluorocarbons (PFC): these liquids are highly limited in their use because in the presence of ιo electric arcs they undergo a decomposition which produces reactive and toxic by-products. Since these reactive substances are unacceptable from the point of view of environmental impact, they require the adoption of disposal procedures typical of toxic waste. The main aim of the present invention is to provide a medium and/or high- ι voltage circuit breaker (i.e. for voltages greater than 1000V) which contains, as an arc quenching means, a dielectric fluid in which the decomposition products generated as a consequence of electric arcs have an extremely low environmental impact, thus allowing to avoid the disposal problems typical of known circuit breakers. 0 Within the scope of this aim. an object of the present invention is to provide a medium and/or high-voltage circuit breaker which is compact and has a total volume which is comparable to the volume of known types of circuit breaker. Another object of the present invention is to provide a medium and/or high- voltage circuit breaker in which it is possible to minimize the use of the

2s associated safety systems while increasing its overall reliability.

Another object of the present invention is to provide a medium and/or high- voltage circuit breaker which is highly reliable and relatively easy to manufacture at competitive costs. This aim. these objects and others which will become apparent hereinafter are achieved by a medium and/or high-voltage circuit breaker, comprising an insulating casing inside which there is at least one interruption chamber which contains at least one fixed contact and at least one moving contact and a dielectric fluid for quenching electric arcs, characterized in that said dielectric fluid comprises a fluoridized dielectric fluid which contains dissolved oxygen and in that it comprises at least one first active filter located in the volume occupied by the fluoridized dielectric fluid, said first active filter being suitable to neutralize the chemically reactive species that originate from the decomposition/recombination of the fluoridized dielectric fluid following an electric arc.

It has in fact been found experimentally that the fluoridized dielectric fluid, following an electric arc, decomposes producing both reactive gaseous substances and, to a larger extent, stable gaseous substances; the latter, being nonreactive, cannot be neutralized chemically. Advantageously, the presence of oxygen dissolved in the fluoridized dielectric liquid allows to alter the recombination reaction of the gases produced by the decomposition of the fluoridized fluid so as to avoid producing the stable compounds and produce only the reactive ones. In this manner one has the advantage of obtaining compounds which can be neutralized chemically by the provided active filter very simply and effectively, in the manner described in greater detail hereinafter.

Further characteristics and advantages of the invention will become apparent from the description of preferred but not exclusive embodiments of the circuit breaker according to the invention, illustrated only by way of nonlimitative example in the accompanying drawing, which is a schematic view of a high- voltage circuit breaker according to the invention. The circuit breaker according to the invention is described with particular reference to the use of a perfluoropolyether as fluoridized liquid; as an alternative, and in a fully equivalent manner, it is possible to use a perfluorocarbon or a mixture of perfluoropolyether/perfluorocarbon. Furthermore, reference is made specifically to a high-voltage circuit breaker in the description that follows without thereby limiting the scope of its application in any way.

With reference to the figure, the circuit breaker according to the invention comprises a shed insulating casing 5 inside which there is an interruption chamber 1 1 which contains interruption mechanisms constituted by at least one fixed contact 3 and by a corresponding moving contact 14. In the embodiment shown in the figure, the insulating casing 5 is constituted by an insulator which is formed monolithically; as an alternative, and according to an embodiment which is widely known in the art, the casing 5 can be made of two parts which are mutually connected by a metallic flange: a first base part which acts as a support and a second part which contains the interruption chamber, the fixed contact and the moving contact. Said casing 5 can be constituted, for example, by a shed tubular body made entirely of porcelain, or by a tube made of composite material, for example fiberglass-reinforced plastic, on the outer surface of which there are sheds made of silicone rubber. The moving contact 14 is operatively connected to an actuation rod 4 which runs, inside the insulating casing 5, from the moving contact 14 to the base of said casing and slides in a guide 6. The opening/closure maneuver of the circuit breaker is performed by appropriately moving the rod 4 and accordingly engaging/disengaging the fixed contact 3 with respect to the moving contact 14. In particular, the actuation of the rod 4 occurs by means of kinematic systems 7 located in a housing 8 which is fixed to the base of the insulating casing 5: said kinematic systems 7 are operatively connected by means of a shaft 9 to an actuation device which is not shown in the figure. The actuation device that can be used in the circuit breaker according to the invention can be, for example, of the mechanical or hydraulic or electric type, according to solutions which are widely known in the art and accordingly are not described further. 5 Generally, during the opening of the circuit breaker, the separation between the moving contact 14 and the fixed contact 3 is accompanied by the generation of an electric arc which forms between the contacts; accordingly, a dielectric fluid suitable to quench said electric arcs is provided in the insulating casing 5. Advantageously, in the embodiment of the circuit breaker according to the o invention, the dielectric fluid comprises a fluoridized dielectric fluid, preferably a perfluoropolyether (PFPE) in liquid form of the family having the following chemical formula: endcap-0-( ,Fft0)n-(CF20)m-endcap; (a) OI¬ S endcap-0-(C F40)n-(CF20)m-endcap. (b)

In the figure, the reference numerals 13 and 10 schematically designate the volume in which the dielectric liquid is placed and its free surface, respectively.

The endcaps can be constituted by HCF2 (one or both) or CF (preferably no 0 more than one); in particular, the presence of the HCF2 endcap (hydrogen- endcapped perfluoropolyether) is highly important for environmental impact, since it makes the molecule reactive in the upper atmosphere and therefore does not contribute to the greenhouse effect. In general, perfluoropolyethers can be chosen from a wide range of molecular weights; for example, for 5 molecular weight 2.000 it is possible to have m and n equal to approximately 1 1. or m and n can be chosen in a ratio of 1 :3.

In the presence of an electric arc, the perfluoropolyether (PFPE) decomposes and produces various species of gas which can be classified into two main types:

— part of the generated gases is constituted by reactive gases, mainly carbonyl fluoride (COF2);

— a predominant part is constituted by gases which are chemically stable and therefore nonreactive, mainly carbon tetrafluoride (CF4) and to a lesser extent C2F(„ C F4. et cetera.

Advantageously, the reactive gases can be eliminated chemically, as described in greater detail hereinafter, by using at least one active filter, arranged in the volume 1 occupied by the perfluoropolyether and designated by the reference numeral 12: said active filter 12 can be fixed to an internal wall of the casing 5 or can be arranged on a supporting element located inside said casing. The stable gases, being chemically nonreactive, could neither be eliminated by the active filter 1 2 nor be fully dissolved in the liquid; moreover, since they are greenhouse gases, they cannot be released into the atmosphere. Advantageously, in the circuit breaker according to the invention the presence of dissolved oxygen in the dielectric liquid allows to alter the recombination reaction of the gases produced by the decomposition of the liquid during the electric arc. It has in fact been found experimentally that the presence of oxygen alters the main reaction from the formation of CF4 to the formation of reactive gases, such for example COF2, as preferential reaction; in this way only gaseous substances are produced that can be neutralized chemically by the active filter 12.

The oxygen contained in the circuit breaker must be present in an amount which is at least stoichiometrically sufficient to ensure the exclusive formation of reactive gases throughout the life of the circuit breaker. For this purpose, the circuit breaker according to the invention uses a tank, designated by the reference numeral 1. which contains the oxygen. In the embodiment shown in the figure, the tank 1 is arranged at the top of the insulating casing 5 and is connected thereto by means of a coupling flange 15.

Advantageously, the oxygen is placed in the tank 1 under pressure, so as to reduce the volume required. For example, a tank with a volume of no more than 30 liters is sufficient to contain 300 liters of oxygen at a pressure of 10 bar. In this manner one has a very compact tank which does not entail excessive constructive complications and allows to have a circuit breaker with an overall volume comparable to that of known kinds of circuit breaker. In order to check the pressure of the oxygen, the tank 1 can be provided with a pressure gauge 2 and with a tap 16 for optional replenishment of said oxygen. Furthermore, the casing 5 of the circuit breaker, which contains the interruption chamber, and the tank 1 are sealed hermetically: in this manner, in addition to sealing the pressurized oxygen, losses and external leaks of the fluids contained therein are avoided. In a preferred embodiment, the active filter 12 is constituted by granules of soda lime contained in a containment means made of inert and gas-permeable material.

In a second embodiment, the active filter 12 comprises a supporting means and chemically active means for the chemical neutralization of the products generated by the decomposition/recombination of the perfluoropolyether. Said chemically active means comprise a primary or secondary amine, for example a substance of the Jeffamine family adsorbed on the supporting means, or a zeolite resistant to an acid environment associated with the substance of the Jeffamine family; the supporting means can be constituted, for example, by Chromosorb or alumina or a zeolite resistant to an acid environment. Merely by way of example, the substance of the Jeffamine family can be the one known commercially as T 403, produced by the Texaco Chemical Company. The substance of the Jeffamine family that is used is in liquid form and once supported on Chromosorb, alumina or zeolite it assumes the form of granules whose diameter depends on the supporting means chosen and is generally of few millimeters: in this case also, the filter is inserted in a containment means.

By way of example, the containment means, in the case of a filter comprising an amine and in the case of a filter made of soda lime, can be constituted by a bag made of an ethylene-chlorotrifluoroethylene copolymer (Halar); as an alternative, it is possible to use a box-like container made of thermoplastic material or thermosetting material or sheet metal provided with gas passage openings. In practice, in the presence of an electric arc the reactive gas species are generated as described above; the reactive by-products that originate directly from the decomposition of the perfluoropolyether and those produced by recombination by the reaction between the oxygen and the perfluoropolyether decomposition gases react with the active filter, depositing on its surface and producing granules; this produces solid compounds which, as such, do not produce overpressures. These products are fully inert and non-toxic and therefore allow to completely avoid the disposal problems that are typical of known kinds of circuit breaker. Another advantage is the fact that inside the tank 1 it is possible to use a second active filter 12, not shown in the figure, also suitable to neutralize the reactive species produced by the decomposition of the fluoridized dielectric liquid. In this manner, the efficiency and performance of the circuit breaker are further improved. The reactive species in fact tend to remain dissolved in the perfluoropolyether and slowly reach equilibrium in the gaseous phase passing into the tank 1 ; accordingly, the part of the reactive substances that has not reacted with the first filter 12 located in the volume of liquid is neutralized by the second filter arranged in the tank 1. In order to accelerate the direct passage of the gases into the tank 1 which contains the oxygen and accordingly facilitate their faster neutralization, in the circuit breaker according to the invention it is possible to provide a suitable preferential duct for the passage of the gases from the interruption chamber 1 1 to the tank 1 ; for example, said duct can be provided by appropriately perforating the fixed contact 3, obtaining a through channel. If necessary due to particular requirements and/or needs of the application, it is possible to arrange a phase separator, not shown in the figure, at the surface 10 of the fluoridized liquid. The phase separator can be constituted, for example, by a plurality of disks made of metal or plastics which are perforated and arranged mutually adjacent with staggered holes; this prevents sprays of fluoridized fluid from directly entering, as a consequence of the arc. the tank 1 where the second active filter is located. In practice it has been found that the circuit breaker according to the invention allows to achieve the intended aim and objects, since it allows to achieve optimized electric arc quenching with dielectric fluid decomposition products which have an extremely low environmental impact.

The fact is noted that the circuit breaker according to the invention has a compact structure and an overall volume which can be compared to that of known circuit breakers; furthermore, according to specific requirements and/or various applications the concepts described above can be effectively applied to various kinds of circuit breaker, such as for example circuit breakers with an interruption chamber of the axial- or transverse-blast type or of the mixed transverse-axial blast type, and also to circuit breakers of the type having a large oil volume and to those having a large oil volume with an open interruption chamber.

The circuit breaker thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; thus, for example, it is possible to use multiple active filters both inside the volume occupied by the dielectric liquid and in the tank. All the details may furthermore be replaced with other technically equivalent elements. In practice, the materials used, so long as they are compatible with the specific use, as well as the dimensions, may be any according to the requirements and the state of the art.

Claims

1 . A medium and/or high-voltage circuit breaker, comprising an insulating casing inside which there is at least one interruption chamber which contains at least one fixed contact and at least one moving contact and a
5 dielectric fluid for quenching electric arcs, characterized in that said dielectric fluid comprises a fluoridized dielectric fluid which contains dissolved oxygen and in that it comprises at least one first active filter located in the volume occupied by the fluoridized dielectric fluid, said first active filter being suitable to neutralize the chemically reactive species that i n originate from the decomposition/recombination of the fluoridized dielectric fluid following an electric arc.
2. A medium and/or high-voltage circuit breaker according to claim 1 , characterized in that said fluoridized dielectric fluid is constituted by a liquid perfluoropolyether.
15 3. A medium and/or high-voltage circuit breaker according to claim 2, characterized in that said perfluoropolyether is a perfluoropolyether of the family having the following formula: endcap-0-(C F60)n-(CF20)m-endcap; or endcap-0-(C2F40)n-(CF20)m-endcap. 0 4. A medium and/or high-voltage circuit breaker according to claim 3, characterized in that at least one of the endcaps is HCF2. 5. A medium and/or high- voltage circuit breaker according to one or more of the preceding claims, characterized in that it comprises a tank which is connected to the insulating casing and contains pressurized oxygen. 25 6. A medium and/or high-voltage circuit breaker according to one or more of the preceding claims, characterized in that said first active filter is constituted by soda lime granules. 7. A medium and/or high-voltage circuit breaker according to one or more of claims 1 to 5. characterized in that said first active filter comprises a supporting means and chemically active means for neutralizing said chemically reactive species, said chemically active means comprising a primary or secondary amine. 8. A medium and/or high-voltage circuit breaker according to claim 7, characterized in that said supporting means is constituted by Chromosorb or alumina or by a zeolite which is resistant to an acid environment.
9. A medium and/or high-voltage circuit breaker according to one or more of the preceding claims, characterized in that it comprises at least one second active filter located in said tank.
10. A medium and/or high-voltage circuit breaker according to one or more of the preceding claims, characterized in that each one of said first and second active filters is inserted in a container made of chemically inert and gas- permeable material. 1 1 . A medium and/or high-voltage circuit breaker according to claim 10, characterized in that said container is constituted by an ethylene- chlorotrifluoroethylene copolymer or by a box-like enclosure which is made of thermoplastic material or thermosetting material or sheet metal.
12. A medium and/or high-voltage circuit breaker according to one or more of the preceding claims, characterized in that it comprises, at the free surface of the fluoridized fluid, a plurality of perforated adjacent disks which are arranged so that their holes are mutually staggered.
13. A medium and/or high-voltage circuit breaker according to one or more of the preceding claims, characterized in that said at least one fixed contact comprises a through channel which is suitable to facilitate the passage of said chemically reactive species from the interruption chamber into the tank.
14. A medium and/or high-voltage circuit breaker according to one or more of the preceding claims, characterized in that said insulating casing and the tank are sealed hermetically.
PCT/EP1999/005487 1998-07-28 1999-07-27 Medium- and/or high-voltage circuit breaker WO2000007202A2 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
ITMI98A001750 1998-07-28
ITMI981750 IT1301953B1 (en) 1998-07-28 1998-07-28 Highly reliable medium and/or high-voltage circuit breaker has a dielectric fluid comprising a fluoridized dielectric fluid which contains dissolved oxygen, and at least one first active filter
ITMI99A000893 1999-04-27
ITMI990893 IT1312252B1 (en) 1999-04-27 1999-04-27 Highly reliable medium and/or high-voltage circuit breaker has a dielectric fluid comprising a fluoridized dielectric fluid which contains dissolved oxygen, and at least one first active filter

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AU54163/99A AU5416399A (en) 1998-07-28 1999-07-27 Medium- and/or high-voltage circuit breaker

Publications (2)

Publication Number Publication Date
WO2000007202A2 true WO2000007202A2 (en) 2000-02-10
WO2000007202A3 WO2000007202A3 (en) 2000-04-27

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WO (1) WO2000007202A2 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1113475A1 (en) * 1999-12-30 2001-07-04 ABB Research Ltd. Arcing contact assembly for medium and/or high voltage circuit breakers
EP2791959B1 (en) 2011-12-13 2016-03-09 ABB Technology AG Circuit breaker with fluid injection
EP2791958B1 (en) 2011-12-13 2016-06-15 ABB Technology AG Circuit breaker with fluid injection

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4336414A (en) * 1979-09-21 1982-06-22 Tokyo Shibaura Denki Kabushiki Kaisha Method and apparatus for treating noxious gases
GB2097587A (en) * 1981-04-23 1982-11-03 Isc Chemicals Ltd Switchgear
US4514607A (en) * 1981-04-13 1985-04-30 The Electricity Council Electrical circuit interrupting devices

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4336414A (en) * 1979-09-21 1982-06-22 Tokyo Shibaura Denki Kabushiki Kaisha Method and apparatus for treating noxious gases
US4514607A (en) * 1981-04-13 1985-04-30 The Electricity Council Electrical circuit interrupting devices
GB2097587A (en) * 1981-04-23 1982-11-03 Isc Chemicals Ltd Switchgear

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1113475A1 (en) * 1999-12-30 2001-07-04 ABB Research Ltd. Arcing contact assembly for medium and/or high voltage circuit breakers
EP2791959B1 (en) 2011-12-13 2016-03-09 ABB Technology AG Circuit breaker with fluid injection
EP2791958B1 (en) 2011-12-13 2016-06-15 ABB Technology AG Circuit breaker with fluid injection
EP2791958B2 (en) 2011-12-13 2019-07-17 ABB Schweiz AG Circuit breaker with fluid injection

Also Published As

Publication number Publication date
AU5416399A (en) 2000-02-21
WO2000007202A3 (en) 2000-04-27

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