Electrical equipment for the generation, transmission and / or distribution of electrical energy

Abstract

The present invention relates to an electrical device for the generation, transmission and / or distribution of electrical energy, comprising a housing enclosing an electrical device interior space, at least a portion of which defines an insulating space in which an electrical component is disposed and which contains an insulating medium surrounding the electrical component. The insulating medium contains an organofluorine compound. The electrical device further comprises an adsorber containing a zeolite for removing at least a portion of the contaminants and / or decomposition products resulting from arcing or partial discharge in the insulating space. The device is characterized in that the zeolite contains less than -0.5 atomic % magnesium (Mg), less than -0.5 atomic % calcium (Ca) and less than -0.5 atomic % iron (Fe).

Description

[Technical Field]

[0001] The present invention relates to an electrical device for the generation, transmission and / or distribution of electrical energy according to the preamble of claim 1 and to the use of a particular adsorber in an electrical device for the generation, transmission and / or distribution of electrical energy. [Background technology]

[0002] In electrical equipment, dielectric insulating media in gaseous or liquid state are conventionally applied to insulate electrical components.

[0003] For example, in metal-enclosed switchgear, the active components are disposed within a gas-tight housing that defines an insulating space containing an insulating gas, which further functions as an arc-quenching gas, for example to interrupt current in high voltage switchgear.

[0004] Sulfur hexafluoride (SF6) is a well-established insulating gas due to its excellent dielectric properties and its chemical inertness. Despite these properties, efforts are intensifying to find alternative insulating gases, particularly considering alternatives with a lower Global Warming Potential (GWP) than that of SF6.

[0005] With a view to providing a non-SF6 alternative, organofluorine compounds have been proposed for use in the dielectric insulating medium.

[0006] WO 2010 / 142346 suggests a dielectric insulating medium comprising a fluoroketone containing 4 to 12 carbon atoms.

[0007] Fluoroketones have been shown to have high dielectric strength. At the same time, they have very low Global Warming Potential (GWP) and very low toxicity. This combination of characteristics makes fluoroketones a viable alternative to SF6.

[0008] A further development in this regard is reflected in WO 2012 / 080246, which suggests a dielectric insulating gas comprising a fluoroketone containing exactly five carbon atoms, in particular 1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-butan-2-one (hereinafter also referred to as C5-FK), in a mixture with a carrier gas, in particular air or an air component, which, together with the fluoroketone, results in a nonlinear increase in the dielectric strength of the insulating medium relative to the sum of the dielectric strengths of the gas components of the insulating medium.

[0009] Further attempts to find an alternative "non-SF6" insulating medium are reflected in WO 2013 / 151741, which suggests using heptafluoroisobutyronitrile, (CF3)2CFCN (hereinafter also referred to as "C4-FN"), or 2,3,3,3-tetrafluoro-2-(trifluoromethoxy)propanenitrile (CF3CF(OCF3)CN) as the dielectric fluid.

[0010] WO 2015 / 040069 describes a medium or high voltage electrical appliance comprising a housing containing a gaseous medium comprising heptafluoroisobutyronitrile, carbon dioxide and oxygen.

[0011] All of the above organofluorine compounds have in common that they are less inert than SF6. Considering the reduction of the GWP of organofluorine compounds, a reduction in inertness is desirable, but reactions with other compounds contained in electrical equipment are undesirable, since on the one hand, this has a negative effect on the performance of the dielectric insulating medium (mainly due to the reduction in the concentration of organofluorine compounds). On the other hand, the decomposition products or by-products formed may impair the functionality of the equipment and / or increase health and safety risks.

[0012] This is particularly the case for hydrofluoric acid, which is highly toxic and can be formed as a by-product from the reaction of fluoroketones with water. Also, with regard to fluoronitriles, moisture (or humidity) within the insulating space has been found to be an important driving factor for decomposition and therefore the generation of potentially harmful by-products.

[0013] It is therefore essential that the moisture contained in the insulating space is at least partially removed so that moisture is not available, or is only available in very limited amounts, as a reaction partner for the organofluorine compounds.

[0014] Several desiccants have been proposed to remove moisture from the insulating space of electrical equipment. For example, European Patent No. 2904617 mentions the use of a desiccant selected from the group consisting of calcium, calcium sulfate, in particular drierite, calcium carbonate, calcium hydride, calcium chloride, potassium carbonate, potassium hydroxide, copper(II) sulfate, calcium oxide, magnesium, magnesium oxide, magnesium sulfate, magnesium perchlorate, sodium, sodium sulfate, lithium aluminum hydride, montmorillonite, phosphoropentoxide, silica gel, and cellulose filters.

[0015] International Publication No. 2020 / 254004 discloses a dielectric insulating fluid or arc-quenching fluid containing a dielectric compound that has similar dielectric properties to octafluorobutene and exhibits greater stability when subjected to partial discharge in the presence of oxygen. The disclosed fluid is a mixture containing a fluoroolefin and oxygen, where the fluoroolefin is a monohydrofluoroolefin containing 4 to 5 carbon atoms, and a hydrogen atom is attached to the double-bonded carbon atom or directly adjacent to the double bond. Electrical insulation equipment is also disclosed in which the dielectric insulating fluid or arc-quenching fluid can be used with conventional adsorber designed primarily to remove water and impurities from insulation spaces without encountering the problem of monohydrofluoroolefins being adsorbed by the adsorber. The adsorber can be a zeolite with a pore size of 3 to 5 Å, which is used to dry insulation spaces because there is no or negligible adsorption of monohydrofluoroolefins containing 4 to 5 carbon atoms.

[0016] European Patent Application Publication No. 3,671,764 discloses an electrical insulation system for medium- or high-voltage electrical switchgear, comprising a gaseous medium consisting of a mixture of one or more fluoroketones of 5 to 6 carbon atoms, one or more non-flammable hydrofluoroolefins of 4 carbon atoms, and one, two, or three carrier gases selected from N2, O2, dry air, helium, or mixtures thereof, and a molecular sieve having a pore size of 3 to 6 Å and a polar surface area. The molecular sieve may be a zeolite sieve. The zeolite may be natural or synthetic.

[0017] U.S. Patent Application Publication No. 2018 / 005727 discloses an electrical device for generating, transmitting, distributing, and / or using electrical energy, comprising a housing enclosing an insulating space and an electrical component disposed within the insulating space. The insulating space contains a dielectric insulating gas containing an organic fluorine compound. The device further includes a desiccant disposed in contact with the insulating gas. The desiccant contains lithium bromide, which does not adsorb either organic fluorine compound molecules or carrier gas molecules and therefore does not affect the composition of the insulating gas. In addition to the lithium bromide-containing desiccant, the device may further include at least one molecular sieve in the form of zeolite disposed in contact with the insulating gas.

[0018] Additionally, zeolites are currently used as adsorbents in several industrial applications, including high-voltage switchgear that use SF6, and a wide variety of zeolites are commercially available, some based on natural minerals (moederite, stilbite, etc.) and some synthetic (types A, X, Y, and L crystalline types). For handling reasons, zeolites are often used in the form of beads or pellets, and may contain some binder, typically clay, to provide mechanical stability.

[0019] The use of zeolites makes it possible to achieve favorable properties in terms of adsorption, but investigations have revealed that the problem of the formation of decomposition products is not completely solved.

[0020] For example, in the case of devices using perfluoroisobutyronitrile (C4-FN), various decomposition products can form, some of which have been found to form crystalline deposits inside the devices. In this regard, Juhre et al., Cigre Report ID 1114, ("Investigations on the long-term performance of fluoronitrile-containing gas mixtures in gas-insulated systems"), reported a study using a zeolite type with a pore size of 3 Å, which nevertheless resulted in the formation of solid decomposition products. Furthermore, the formation of decomposition products when C4-FN is exposed to a moisture-containing environment has also been reported by Kessler et al., "Compatibility of a Gaseous Dielectric with Al, Ag, and Cu and Gas-Phase Synthesis of a New N-Acylamidine Copper Complex," Eur. J. Inorg. Chem. 2020, 1989–1994.

[0021] According to these studies, the main component of the degradation products of C4-FN is perfluorobutyroamide (2,3,3,3-tetrafluoro-2-(trifluoromethyl)propanamide) (degradation product A):

[0022] [ka]

[0023] and the N-acylamidine dimer of this compound (decomposition product B):

[0024] [ka]

[0025] N-acylamidine metal complex (decomposition product C):

[0026] [ka]

[0027] is. In view of the increasing need to minimize the use of SF6, it is desirable to provide "non-SF6 electrical equipment" for the generation, transmission and / or distribution of electrical energy, i.e., equipment that uses alternative gases other than SF6 and thus meets the requirements for improved environmental friendliness, in particular a reduced carbon footprint, but does not have the drawbacks mentioned above. In particular, there is a need to efficiently remove at least moisture from the insulating space of such electrical equipment without compromising the performance and safety of the electrical equipment. Summary of the Invention [Problem to be solved by the invention]

[0028] a gas insulated line; a hybrid switchgear (gas insulated module); a circuit breaker that is a live tank breaker, a dead tank breaker or a circuit breaker unit; a switch that is an earthing switch or earthing switch, an isolating switch or disconnector or a fast acting earth switch; a transformer that is an instrument or measuring transformer, a power transformer or a distribution transformer; a gas insulated surge arrester; or an extension, upgrade or retrofit or component or a combination thereof, which allows for efficient removal of moisture or other undesirable impurities (i.e. contaminants and / or decomposition products resulting from arcing or partial discharges) from the insulating space but has a low tendency to form undesirable decomposition products such as A (amide), B (dimer), C (complex). [Means for solving the problem]

[0029] This problem is solved by the device according to claim 1. Preferred embodiments of the invention are defined in the dependent claims.

[0030] According to claim 1, the invention relates to an electrical device for the generation, transmission and / or distribution of electrical energy.

[0031] The electrical equipment may be energized at a voltage higher than 1 kV, more preferably at a medium or high voltage, and in this regard it may be preferred that the electrical equipment be energized at a voltage higher than 12 kV or higher than 52 kV.

[0032] As further defined in claim 1, the electrical device comprises a housing enclosing an electrical device interior space, at least a portion of the electrical device interior space forming an insulating space, in which electrical components are disposed and which contains an insulating medium surrounding the electrical components.

[0033] The insulating medium contains organic fluorine compounds, in particular C4-FN or C5-FK, which, as mentioned above, have a reduced GWP and a small carbon footprint compared to SF6.

[0034] The electrical equipment further includes an adsorber, specifically an adsorber for removing at least a portion of contaminants and / or decomposition products resulting from arc discharge or partial discharge in the insulating space. For example, the adsorber can be used to remove moisture or other undesirable impurities or gaseous decomposition products (resulting from arc discharge or partial discharge) contained in the insulating space. Note that contaminants such as moisture may be introduced into the insulating space by reactions within the insulating space or during gas filling or use (e.g., during gas handling).

[0035] According to the invention, the adsorber is made of zeolites, in particular Less than 0.5 atomic percent magnesium (Mg) - Less than 0.5 atomic % calcium (Ca) and Less than 0.5 atomic percent iron (Fe) The zeolite contains:

[0036] - As will be seen by way of specific examples, it has surprisingly been found by the inventors that an adsorber preferably comprising a zeolite as defined above does not result in any of the solid decomposition products A, B or C being formed in the insulating space, even when subjected to harsh conditions. Thus, the present invention makes it possible to efficiently remove moisture or other undesirable impurities or gaseous by-products (resulting from arcing or partial discharges) while simultaneously reducing or completely avoiding the formation of potentially harmful decomposition products.

[0037] In particular, it has been found that problems related to incompatibility with organofluorine compounds used in dielectric insulating media can be reduced or completely avoided. Without wishing to be bound by theory, it is assumed that an adsorber according to the present invention may be an adsorber that does not fit the definition of the present invention and therefore does not function as a catalyst for the decomposition reaction, leading to the formation of solid decomposition products.

[0038] The technical effect achieved by the present invention is particularly pronounced when the electrical equipment is gas-insulated switchgear or a component thereof due to the fact that the above-mentioned drawbacks are particularly severe in gas-insulated switchgear. However, all other electrical equipment for the generation, transmission, and / or distribution of electrical energy, in particular live-tank breakers, dead-tank breakers, gas-insulated bus ducts, arresters, bushings, and / or transformers, are included within the scope of the present invention.

[0039] Thus, according to a preferred embodiment of the present invention, the electrical equipment is gas insulated switchgear (GIS), whether the GIS is a transmission GIS, a sub-transmission GIS, or an integrated GIS; a gas insulated line; a hybrid switchgear (gas insulated module); a circuit breaker which is a live tank breaker, a dead tank breaker, or a circuit breaker unit; a switch which is a grounding or earthing switch, an isolating switch or disconnector, or a fast acting earth switch; a transformer which is an instrument or measuring transformer, a power transformer, or a distribution transformer; a gas insulated surge arrester; and extensions, upgrades and modifications, or components, or combinations thereof.

[0040] According to a preferred embodiment of the present invention, the adsorber, preferably the zeolite, contains less than 0.25 atomic % Mg, more preferably less than 0.10 atomic % Mg, and most preferably is at least substantially Mg-free. In this preferred embodiment, the tendency to form the above-mentioned decomposition products is even lower.

[0041] Additionally or alternatively, it is further preferred that the adsorber, preferably the zeolite, contains less than 0.25 atomic % Ca, more preferably less than 0.10 atomic % Ca, and most preferably is at least substantially Ca-free, for the same reason further reducing the tendency for the formation of cracking products.

[0042] Additionally or alternatively, it is further preferred that the adsorber, preferably the zeolite, contains less than 0.25 atomic % Fe, preferably less than 0.15 atomic % Fe, and most preferably is at least substantially Fe-free, for the reasons discussed above with respect to Mg and Ca.

[0043] In particular, the organofluorine compounds used in the context of the present invention are fluoroketones, in particular perfluoroketones, and / or fluoronitriles, in particular perfluoronitriles.

[0044] According to a particularly preferred embodiment, the organic fluorine compound is a fluoronitrile, in particular a perfluoronitrile. More particularly, the fluoronitrile may be a perfluoroalkylnitrile, specifically perfluoroacetonitrile, perfluoropropionitrile (C2F5CN) and / or perfluorobutyronitrile (C3F7CN). Preferably, the fluoronitrile is perfluoroisobutyronitrile (according to the formula (CF3)2CFCN) and / or perfluoro-2-methoxypropanenitrile (according to the formula CF3CF(OCF3)CN). Among them, perfluoroisobutyronitrile (C4-FN) is particularly preferred.

[0045] Typically, the dielectric insulating medium further contains a carrier gas (or background gas) selected from the group of air, air components, in particular nitrogen and / or oxygen, carbon dioxide and mixtures thereof.

[0046] The carrier gas used can consist essentially of only one component, such as carbon dioxide or nitrogen. Alternatively, the carrier gas can contain, in addition to carbon dioxide or nitrogen (the first component), at least one additional carrier gas component, particularly in an amount less than the first component. Specifically, the at least one additional carrier gas component can be an oxidizing gas, particularly oxygen, to reduce the formation of soot and / or other undesirable decomposition products. More specifically, the insulating medium of the present invention relates to a ternary mixture containing C4-FN, carbon dioxide, and oxygen, or a ternary mixture containing C4-FN, nitrogen, and oxygen.

[0047] Instead of, or in addition to, the fluoronitrile contained in the specific insulating medium defined above, an alternative insulating medium may contain a fluoroketone, more specifically a perfluoroketone.

[0048] As mentioned above, the adsorber used preferably comprises zeolite in the form of beads or pellets, which are typically disposed within a sachet or casing that allows the insulating gas to at least partially permeate therethrough.

[0049] According to a further preferred embodiment of the invention, the zeolite has a pH of less than 8, as this has been found to further contribute to a reduced tendency for decomposition products to form. In the context of the present invention, the pH of a zeolite refers to the pH of a solution obtained by dissolving 5 g of zeolite in 50 ml of distilled water.

[0050] Surprisingly, it has been found that the amount of clay used as a binder in the zeolite-containing adsorber to provide the latter with the necessary stability also affects the compatibility with the organofluorine compound. In this regard, it has been found that an amount of clay of less than 3 wt. % based on the total weight of the zeolite is particularly preferred. Most preferably, the zeolite-containing adsorber is at least substantially clay-free.

[0051] In a preferred embodiment, the adsorber is primarily a moisture adsorber for removing at least a portion of the moisture (or humidity) contained in the insulating space.

[0052] In consideration of further reducing the tendency to form undesirable decomposition products, the average pore diameter of the zeolite is more preferably within the range of 0.25 to 0.55 nm.

[0053] In addition to the electrical equipment mentioned above, a further aspect of the invention relates to the use of an adsorber for removing at least a portion of contaminants and / or decomposition products resulting from arcing or partial discharges in electrical equipment, in particular medium or high voltage electrical equipment, for the generation, transmission, distribution and / or use of electrical energy, wherein the adsorber comprises: Less than 0.5 atomic percent magnesium (Mg) - Less than 0.5 atomic % calcium (Ca) and Less than 0.5 atomic percent iron (Fe) More specifically, the electrical equipment includes a gas insulated switchgear (GIS) that is a transmission or subtransmission GIS, or an integrated GIS; Gas insulated lines; Hybrid switchgear (gas-insulated modules); Circuit breakers that are live tank breakers, dead tank breakers, or circuit breaker units; a switch that is an earthing or earthing switch, an isolating switch or disconnector, or a fast-acting earthing switch; Transformers that are instrument or measuring transformers, power transformers or distribution transformers; Gas-insulated surge arresters; or an extension, upgrade or modification or component or combination thereof.

[0054] Preferably, the adsorber is a zeolite, more preferably Less than 0.5 atomic percent magnesium (Mg) - Less than 0.5 atomic % calcium (Ca) and Less than 0.5 atomic percent iron (Fe) The zeolite contains:

[0055] Example The present invention is further illustrated by the following examples and accompanying drawings. [Brief explanation of the drawings]

[0056] [Figure 1] FIG. 1 shows a photograph of an adsorber bead falling within the definition of the present invention after exposure to a dielectric insulating medium containing C4-FN and air in a test vessel at 70° C. [Figure 2] FIG. 2 shows a photograph of an adsorber bead outside the definition of the present invention after exposure to a dielectric insulating medium containing C4-FN and air in a test vessel at 70° C. [Figure 3]FIG. 3 shows the FTIR spectra of the adsorber shown in FIG. 1 (i.e., according to the present invention) before (A) and after (B) exposure. [Figure 4] FIG. 4 shows the FTIR spectra of the adsorber shown in FIG. 2 (ie, the comparative example) before (A) and after (B) exposure. DETAILED DESCRIPTION OF THE INVENTION

[0057] In the first series of tests, beaded adsorber containing type A zeolite, 4A, was exposed to a dielectric insulating medium containing C4-FN and air in a test vessel at 70°C and inspected after exposure.

[0058] The composition of the zeolite of this adsorber (Sample 1), determined by EDX analysis, was as follows and therefore met the definition of the present invention: Referring to Figures 1 and 2, it was observed that crystals formed in Comparative Sample 2 (Figure 2), but no such crystals were detected in Sample 1 (Figure 1). FTIR spectra confirmed the formation of N-acylamidine dimer (degradation product B), but no degradation product was identified for Sample 1 (the spectra for each range after exposure essentially correspond to those before exposure).

[0059] [Table 1]

[0060] For comparison, a type A, 4A zeolite (Sample 2) was used under exactly the same conditions as described for Samples 1 and 2, with the following composition:

[0061] [Table 2]

[0062] This finding was confirmed by measurements carried out in a further series of tests examining the zeolites mentioned below after exposure to the conditions defined above for Samples 1 and 2. Of these, the zeolites according to Samples 3 and 6 (with compositions falling within the definition of the present invention) showed no crystal formation after testing at 70°C in an insulating medium (containing C4-FN and air), whereas for Samples 4 and 5 (with compositions not falling within the definition of the present invention), crystals formed when exposed to the same insulating gas and conditions:

[0063] [Table 3]

Claims

1. An electrical device for generating, transmitting, and / or distributing electrical energy, comprising a housing enclosing an electrical device interior space, at least a portion of the electrical device interior space forming an insulating space in which an electrical component is disposed and which contains an insulating medium surrounding the electrical component, the insulating medium containing an organic fluorine compound, the electrical device further comprising an adsorber containing zeolite for removing at least a portion of contaminants and / or decomposition products resulting from arc discharge and / or partial discharge in the insulating space, the zeolite comprising: - Less than 0.5 atomic percent magnesium (Mg) - Less than 0.5 atomic percent calcium (Ca) and Less than 0.5 atomic percent iron (Fe) An electrical device comprising:

2. The electrical equipment is Gas insulated switchgear (GIS), which can be a transmission GIS, sub-transmission GIS, or integrated GIS; Gas insulated lines, Hybrid switchgear (gas insulated module), Circuit breakers that are live tank breakers, dead tank breakers, or circuit breaker units, a switch that is an earthing or earthing switch, an isolating switch or disconnector, or a fast-acting earthing switch; Transformers that are instrument or measuring transformers, power transformers or distribution transformers; Gas-insulated surge arrester, or any extensions, upgrades or modifications or components or combinations thereof; The electrical device according to claim 1 ,

3. 3. The electrical device of claim 1, wherein the adsorber contains less than 0.25 atomic percent Mg.

4. 3. The electrical device according to claim 1, wherein the adsorber contains less than 0.25 atomic percent Ca.

5. 3. The electrical device according to claim 1, wherein the adsorber contains less than 0.25 atomic percent Fe.

6. 3. The electrical device according to claim 1, wherein the organic fluorine compound is perfluoroisobutyronitrile.

7. 3. The electrical device of claim 1, wherein the zeolite has a pH of less than 8.

8. 3. The electrical device according to claim 1, wherein the amount of clay contained in the zeolite is less than 3% by weight based on the total weight of the zeolite.

9. 3. The electrical device according to claim 1, wherein the average pore diameter of the zeolite is in the range of 0.25 to 0.55 nm.

10. 3. The electrical device according to claim 1, wherein the insulating medium further comprises a carrier gas selected from the group consisting of air, air components, carbon dioxide, and mixtures thereof.

11. 3. The electrical appliance according to claim 1, wherein the electrical appliance is energized with a voltage higher than 1 kV.

12. 1. Use of an adsorber for removing at least a portion of contaminants and / or decomposition products resulting from arcing or partial discharge in electrical equipment for the generation, transmission, and / or distribution of electrical energy, the adsorber comprising: - Less than 0.5 atomic percent magnesium (Mg) - Less than 0.5 atomic percent calcium (Ca) and Less than 0.5 atomic percent iron (Fe) Contains 10. Use of an adsorber, characterized in that the adsorber comprises a zeolite.

13. The electrical equipment is Gas insulated switchgear (GIS), which is a transmission GIS or sub-transmission GIS, or an integrated GIS; Gas insulated lines, Hybrid switchgear (gas insulated module), Circuit breakers that are live tank breakers, dead tank breakers, or circuit breaker units, a switch that is an earthing or earthing switch, an isolating switch or disconnector, or a fast-acting earthing switch; Transformers that are instrument or measuring transformers, power transformers or distribution transformers; Gas-insulated surge arrester, or any extensions, upgrades or modifications or components or combinations thereof; 13. Use of the adsorber according to claim 12, wherein

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