Installation and method for distributing a dielectric gas mixture to a gas-insulated switchgear.

Description

[0001] The present invention relates to a system for distributing a dielectric gas mixture intended for use in gas-insulated electrical equipment, particularly high-voltage equipment. The system makes it possible to produce the dielectric gas mixture at the point of use and to distribute the mixture thus produced directly into the equipment to provide electrical insulation. The invention also relates to a method for distributing the mixture using such a system.

[0002] In particular, an installation and a method according to the invention are intended to distribute mixtures comprising at least one insulating fluid such as perfluoroketone or perfluoronitrile and at least one carrier gas such as carbon dioxide (CO2), nitrogen (N2), oxygen (O2), air, or synthetic air. It should be noted that the insulating fluid is designated as such because of its high dielectric strength and breaking capacity, and that the at least one carrier gas may also have electrical insulating properties.

[0003] The term electrical equipment in this application refers to both equipment constituting distribution stations and electrical power transmission lines.

[0004] Among the gas-insulated distribution stations, we know in particular the stations called Metal Enclosed Post (PSEM), also designated in English by the terms "Gas Insulated Switchgear" (GIS).

[0005] High-voltage gas-insulated lines are known as Gas Insulated Lines (GILs), whether welded or bolted assemblies, also referred to in English as "Gas Insulated Line" (GIL) for welded assemblies or "Gas Insulated Busduct" (GIB) for bolted assemblies.

[0006] Note that the invention can also be applied to any type of electrically insulated device under gas pressure, i.e. comprising a closed enclosure containing gas, in particular circuit breakers, disconnectors, current transformers, voltage transformers,..., as well as to devices combining all or part of the aforementioned devices

[0007] Note that the term "high voltage" covers the former designation "medium voltage" (or high voltage A) which designates a voltage greater than 1000 volts in alternating current and greater than 1500 volts in direct current, and the former designation "high voltage" (or high voltage B) which designates a voltage greater than 50000 volts in alternating current and greater than 75000 volts.

[0008] One of the main technologies for insulating electrical equipment is insulation using a dielectric gas or gas mixture confined under pressure around the live parts and components. This insulating gas or gas mixture also performs the function of extinguishing the arc resulting from the electrical interruption.

[0009] Currently, the most commonly used gas in this type of appliance is sulfur hexafluoride (SF6). This gas exhibits relatively high dielectric strength, good thermal conductivity, and low dielectric losses. It is chemically inert and non-toxic to humans and animals, and after being dissociated by an electric arc, it recombines rapidly and almost completely. Furthermore, it is non-flammable and its price remains moderate. However, SF6 has a major drawback: its global warming potential (GWP) is 24,000 times greater than that of CO2, and it has an atmospheric lifetime of 3,200 years, placing it among the most potent greenhouse gases. SF6 was therefore included in the Kyoto Protocol (1997) on the list of gases whose emissions must be limited.

[0010] The best way to limit SF6 emissions is to limit the use of this gas, which has led manufacturers to seek alternatives to SF6. So-called "simple" gases like air or nitrogen, which have no negative impact on the environment, have a much lower dielectric strength than SF6. For example, the dielectric strengths of air and nitrogen under alternating voltage (50 Hz) are approximately three times lower than that of SF6.

[0011] Therefore, the use of these simple gases for electrical insulation and / or arc extinguishing in electrical devices implies drastically increasing the volume and / or filling pressure of these devices, which goes against the efforts made over the last few decades to develop compact and safe electrical devices with increasingly smaller footprints.

[0012] Manufacturers have therefore sought alternatives offering the same insulation and arc-cutting properties as SF6. To this end, new alternative gas mixtures with a reduced environmental impact have been developed. These gas mixtures are based on at least one insulating gas chosen from a five-carbon perfluoroketone or a four-carbon perfluoronitrile, mixed with a carrier or dilution gas with a very low GWP, such as CO2, which has a GWP of 1, or with a GWP of zero, such as nitrogen or air.

[0013] The composition of these new gas mixtures varies depending on the features of the equipment to be filled, particularly its voltage level and electrical characteristics. The concentration of each component in the mixture may also vary. Therefore, it is essential to be able to fill the equipment with the appropriate mixture.

[0014] For filling electrical equipment, one solution is to prepare the mixtures in dedicated packaging centers, pack them into storage containers such as bottles or bins, and deliver the containers to the site of use. The equipment is then filled directly from the container.

[0015] This solution presents several problems. Dielectric gas mixtures are packaged in liquefied form and require a homogenization step. Indeed, the liquefied mixture consists of two phases, liquid and gas, in equilibrium with each other. The different physical properties of the mixture's components, particularly boiling points and saturated vapor pressures, make the mixture inherently heterogeneous within the storage container. Furthermore, taking it in either the gaseous or liquid phase alters the respective proportions of the mixture's constituents.

[0016] Furthermore, the use of cylinders leads to limited autonomy, with interruptions in distribution detrimental to operational efficiency. Since gas mixture delivery times can be relatively long, the user must manage their cylinder inventory to ensure operational continuity. Different types of mixtures may be required, further complicating logistics. Connecting and disconnecting cylinders is also a time-consuming process and increases the risk of contaminating the gas mixture with ambient air.

[0017] Another problem concerns the accuracy of the mixing process, which may prove insufficient. In addition to the uncertainty in the concentration values ​​of the manufactured mixture, there are manufacturing variations that can exist between different cylinders. Such variations can significantly alter the results produced by the consuming unit each time the cylinder is changed. Furthermore, the composition of the pre-prepared mixture is susceptible to alteration, particularly due to leaks of the gaseous or liquid phase.

[0018] Another solution is to prepare the dielectric gas mixture on-site. One such method is flow control. This method involves drawing the mixture components into separate containers and sending them to a gas mixer. The concentration of each component is controlled by adjusting their respective flow rates to the mixer. However, the accuracy of the resulting mixture is limited. Flow controllers are sensitive to ambient temperature, which restricts their use outdoors. They are also sensitive to the temperature of the gas they regulate and require a supply of pure gas at a stable pressure for optimal stability. Furthermore, some insulating fluids, such as perfluoroketone, are liquids and cannot be drawn in the gaseous phase at atmospheric pressure.One solution is to pressurize the container with nitrogen or CO2 to extract the liquid phase, then vaporize the liquid phase. Besides the complexity and constraints imposed by this solution, diffusion of the nitrogen or CO2 into the liquid phase is observed, which impairs the operation and accuracy of the flow regulators.

[0019] Documents XP055945991 ("Cart for gas tank: a ready-to-use autonomous storage", Air Liquide 2021), EP1014521A2, WO2014037031A1, US6105631A, and WO2017093259A1 disclose examples of known insulating gas distribution systems. Documents CN204063559U and JP2008232226A show methods for heating gas tanks.

[0020] The invention aims to overcome all or part of the aforementioned disadvantages, in particular by providing a distribution system for a dielectric gas mixture suitable for the gaseous insulation of electrical equipment which allows precise control of the composition of the mixture, which offers continuity and flexibility of distribution, in particular in terms of composition and content of the components of the gas mixture and which allows the distribution of a mixture of stable composition and with a flow rate sufficient for industrial-scale use.

[0021] To this end, the solution of the invention is a distribution system for an electrically insulating gas mixture to gas-insulated electrical equipment, in particular high-voltage electrical equipment, said system comprising: a first container intended to contain an insulating fluid in a liquid or liquefied state, first heating means configured to heat the insulating fluid in the first container such that said first container produces at a first outlet a gaseous phase of the insulating fluid, a second container intended to contain a carrier fluid and configured to produce a gaseous phase of the carrier fluid at a second outlet of the second container, a first transfer circuit configured to transfer the gaseous phase of the insulating fluid from the first outlet of the first container to a combining point, the first transfer circuit comprising a first upstream part connected to the first container and a first downstream part connected on the one hand to the first upstream part and on the other hand to the combining point,a second transfer circuit configured to transfer the gaseous phase of the carrier fluid from the second outlet of the second vessel to the combining point; a distribution circuit fluidically connected to the combining point and configured to distribute an electrically insulating gas mixture comprising the gaseous phase of the insulating fluid and the gaseous phase of the carrier fluid to the high-voltage electrical equipment; the first downstream part of the first transfer circuit comprising a first flow control device configured to regulate and / or adjust the flow rate of the gaseous phase of the insulating fluid flowing to the combining point; said installation further comprising second heating means configured to heat the gaseous phase of the insulating fluid at least at the combining point and the downstream part of the first transfer circuit.

[0022] Depending on the case, the invention may include one or more of the features listed below.

[0023] The second heating means are further configured to heat the gaseous phase of the insulating fluid at the level of at least a portion of the first upstream part of the first transfer circuit.

[0024] The first upstream part of the transfer circuit includes at least one fluid line, the second means of heating including a first heating device arranged around all or part of said fluid line, in particular the first heating device is of the resistive or inductive type.

[0025] The second heating means include a second heating device arranged around the combination point and the first downstream part of the first transfer circuit.

[0026] The second heating device includes a thermally insulating envelope defining an internal volume in which the downstream part of the first transfer circuit, the first flow regulating device, and the combination point are arranged, and a heating element adapted to heat said internal volume, in particular the heating element is of the resistive type.

[0027] The thermally insulating envelope comprises at least one layer of a flexible material, in particular the flexible material comprises at least a woven fabric of yarns formed from a thermally insulating material or a non-woven fabric of fibers formed from a thermally insulating material.

[0028] The thermally insulating envelope is formed of several panels connected to each other by removable fastening means.

[0029] The second transfer circuit includes a second upstream part connected to the second vessel and a second downstream part connected to the combination point, said second downstream part having a second flow control device configured to regulate and / or adjust the gaseous phase flow of the carrier fluid flowing towards the combination point, the second heating device preferably being configured to heat the second downstream part of the second transfer circuit.

[0030] The installation further includes at least one additional vessel for holding an additional carrier fluid and configured to produce a gaseous phase of said additional carrier fluid at an outlet of the additional vessel, the installation including an additional transfer circuit configured to transfer the gaseous phase of the additional carrier fluid from the outlet of the additional vessel to the combination point, the additional transfer circuit including an additional upstream part connected to the additional vessel and an additional downstream part connected to the combination point, said additional downstream part including an additional flow control device configured to regulate and / or adjust the flow of gaseous phase of the additional carrier fluid flowing to the combination point, the second heating device preferably being configured to heat the additional downstream part of the additional transfer circuit.

[0031] The first heating means are configured to heat the liquefied insulating fluid in the first container to a first temperature, the second heating means being configured to heat the vapor phase of the liquefied insulating fluid to a second temperature higher than the first temperature at least at the level of the combination point and of all or part of the first transfer circuit.

[0032] The first heating means are configured to deliver variable heating power, the installation comprising at least one pressure sensor configured to measure the pressure in the first vessel and a first control unit connected to the pressure sensor and the first heating means, the first control unit being configured to vary the heating power delivered by the first heating means according to the pressure measured by the pressure sensor.

[0033] The first heating means are configured to deliver variable heating power, the installation comprising at least one temperature measuring device configured to measure the temperature of the first container and a first control unit connected to the temperature measuring device and to the first heating means, the first control unit being configured to vary the heating power delivered by the first heating means according to the temperature measured by the temperature measuring device.

[0034] The second container is intended to contain the carrier fluid in liquefied form, the installation including third heating means configured to heat the liquefied carrier fluid in the second container so as to vaporize at least a part of the liquefied carrier fluid and to distribute a gaseous phase of the carrier fluid into the second transfer circuit.

[0035] The second transfer circuit includes an expansion device configured to reduce the pressure of the gaseous phase of the carrier fluid, and a heater arranged upstream of the expansion device to heat the gaseous phase before its expansion by the expansion device.

[0036] The distribution circuit includes at least one of the following: a mixing device configured to mix the gaseous phase of the insulating fluid and the gaseous phase of the carrier fluid, a pressure-lifting device arranged downstream of the mixing device, a buffer tank arranged upstream of the pressure-lifting device.

[0037] According to another aspect, the invention relates to a method for distributing an electrically insulating gas mixture to high-voltage electrical equipment, said method comprising the following steps: a) heating an insulating fluid in liquid or liquefied form in a first container by first heating means so as to vaporize at least a part of the liquefied insulating fluid and to produce a gaseous phase of the insulating fluid in the first container, b) passing the gaseous phase of the insulating fluid through a first transfer circuit so as to transfer the gaseous phase of the insulating fluid from the first container to a combining point, the first transfer circuit comprising a first upstream part connected to the first container and a first downstream part connected on the one hand to the first upstream part and on the other hand to the combining point, c) passing a gaseous phase of a carrier fluid from a second container through a second transfer circuit so as to transfer the gaseous phase of the carrier fluid to the combining point,d) combination of the gaseous phase of the insulating fluid and the gaseous phase of the carrier fluid at the combination point and passage of the combined gaseous phase of the insulating fluid and the gaseous phase of the carrier fluid through a distribution circuit adapted to distribute to high-voltage electrical equipment an electrically insulating gaseous mixture comprising the gaseous phase of the insulating fluid and the gaseous phase of the carrier fluid, e) regulation and / or adjustment of the flow rate of the gaseous phase of the insulating fluid flowing towards the combination point by means of a first flow control device arranged on the first downstream part of the first transfer circuit, f) heating of the gaseous phase of the insulating fluid at least at the combination point and the downstream part of the first transfer circuit by second heating means.

[0038] The invention will now be better understood through the following detailed description, given by way of illustration and not limitation, with reference to the attached figures described below. [ Fig.1 ] There [ Fig.1 [ ] diagrams an installation according to an embodiment of the invention. ] Fig.2 ] There [ Fig.2 ] diagrams an installation according to another embodiment of the invention.

[0039] There [ Fig.1 [This] represents an installation comprising a first container 1 of insulating fluid and a second container 2 of carrier fluid. The fluids are of different natures. They are preferably pure substances, simple or compound. Each of the containers can be a bottle, typically a bottle with a water volume of up to 50 L, a set of bottles connected together to form a bottle frame, or a larger tank, notably one with a capacity of up to 1000 L, such as a cryogenic storage tank or a tank mounted on a truck-trailer.

[0040] The installation according to the invention is adapted to produce dielectric gas mixtures with at least two components. Of course, the installation can comprise more than two vessels and produce mixtures with more than two constituents, in particular ternary or quaternary gas mixtures. Thus, the [ Fig.1 This illustrates the case where the installation is configured to produce a four-component gaseous mixture from the first and second containers 1, 2 and possibly two additional containers 3, 4. In particular, containers 3, 4 are adapted to contain any additional carrier fluids and configured to produce gaseous phases of said additional carrier fluids at their respective outlets.

[0041] Within the framework of the invention, distribution includes preparation, i.e. the manufacture of the mixture and its delivery towards the apparatus.

[0042] A first transfer circuit 6 is fluidically connected on one side to a first opening of the first container 1 and on the other side to a combination point 60. A second transfer circuit 7 is fluidly connected on one side to a second opening of the second container 2 and on the other side to the combination point 60. Additional transfer circuits may be provided for each of the additional containers 3, 4, if necessary.

[0043] The first transfer circuit 6 comprises a first upstream part 6a connected to the first container 1 and a first downstream part 6b connected on the one hand to the first upstream part 6a and on the other hand to the combination point 60. The second transfer circuit 7 comprises a second upstream part 7a connected to the second container 2 and a second downstream part 7b connected to the combination point 60.

[0044] The downstream part of the first transfer circuit 6 includes a first flow control device 61 configured to regulate and / or adjust the flow rate of insulating fluid flowing towards the combination point 60 according to a first flow setpoint D1. The first setpoint D1 can be determined as a function of a target content C1 of the mixture in the insulating fluid.

[0045] By "insulating fluid" we mean a fluid with high insulating power, that is to say having electrical insulation and arc-quenching capabilities sufficient to be used for gaseous insulation of high-voltage electrical equipment.

[0046] As an insulating fluid, a fluid containing at least one fluoroketone and / or at least one perfluoronitrile may be used. In particular, the insulating fluid may be selected from the Novec™ range of dielectric fluids marketed by 3M, for example, the insulating fluid with the trade name 3M™ Novec™ 4710 (hereafter referred to as C4-FN) and the insulating fluid with the trade name 3M™ Novec™ 5110 (hereafter referred to as C5-FK). Preferably, the insulating fluid is the minor component in the distributed gas mixture.

[0047] The term "carrier fluid" refers to a gas suitable for diluting the insulating fluid to make the overall properties of the mixture suitable for its intended use. The gas mixture may contain at least one carrier fluid chosen from among carbon dioxide (CO₂), nitrogen (N₂), oxygen (O₂), air, or synthetic air. It should be noted that the carrier fluid may also possess electrical insulating properties. Preferably, the gas mixture contains at least CO₂ as the carrier fluid. At least one carrier gas can thus perform a dilution function and / or be an active gas, for example, by increasing the oxygen content of the insulating gaseous atmosphere surrounding the equipment. In particular, oxygen can be used to counteract the effects of arc interruption, which cause CO₂ to decompose.

[0048] In the context of the invention, the insulating fluid is stored in liquid form or as a liquefied gas in the first container 1. In particular, an insulating fluid of type C4-FN is a liquefied gas. An insulating fluid of type C5-FK is a liquid.

[0049] The installation includes first heating means 10 configured to heat the liquefied insulating fluid in the first container 1.

[0050] This allows at least part of the insulating fluid in container 1 to be heated and increases its saturated vapor pressure. Indeed, the saturated vapor pressures of insulating fluids are relatively low at room temperature, for example, 2.5 barA at 20 °C for C4-FN and 0.8 barA at 20 °C for C5-FK. By heating the first container 1, the amount of insulating fluid that can be vaporized in container 1 is increased, and therefore the flow rate of gaseous phase that can be dispensed from container 1 is also increased.

[0051] Furthermore, the liquefied fluid consists of two phases, liquid and gas, in equilibrium with each other. When the gaseous phase is withdrawn from a container of liquefied gas, some of the liquid must be vaporized to regenerate the gaseous phase as it is used, thus maintaining equilibrium within the container. The liquid therefore begins to cool due to the energy expended during the transition from one phase to the other.

[0052] Heating container 1 compensates for the vaporization energy of the insulating fluid, particularly in the case of perfluoronitrile as the insulating fluid, and, if necessary, also maintains a higher saturated vapor pressure than at ambient temperature, particularly in the case of perfluoroketone as the insulating fluid. This results in maintaining the gaseous phase at a stable temperature, flow rate, and pressure.

[0053] Preferably, the first heating means 10 are external to the containers. In one embodiment, the heating means 10 are arranged around all or part of the container 1 and extend over all or part of the height of the container 1, preferably at least at the level of the lower part of the containers.

[0054] The first heating means can be configured to heat at least part of the external surface of container 1. Heat transfer to the liquid phase occurs between the heated surface and the liquid phase of the insulating fluid. It is also possible for the first heating means 10 to be internal to the container. Note that the first heating means can be configured to heat the surface of the first container 1 to temperatures ranging from 15 to 65 °C, preferably from 50 to 55 °C for perfluoroketone and preferably from 20 to 35 °C for perfluoronitrile.

[0055] The first heating means 10 may take the form of at least one heating belt, heating cord, or heat transfer fluid circulating shell. Depending on the case, the first heating means 10 may be inductive or resistive. For example, the body of the container 1 may be heated using at least one resistive conductive element through which the passage of an electric current produces heat.

[0056] According to an advantageous possibility, the first heating means 10 comprise magnetic induction means capable of creating a magnetic field in at least a portion of the container 1's shell and heating the container 1's material by means of the induced electric current. The use of first inductive heating means eliminates the need for energy transfer by conduction, since the currents induced by the inductor directly heat the bottle material throughout its thickness. This improves energy transfer and leads to higher distribution rates.

[0057] The carrier fluid can be stored in the second container 2 in liquid form or as a liquefied gas. Preferably, the carrier fluid is a liquefied gas, in particular CO2.

[0058] In this case, as illustrated on the [ Fig.1 The installation includes third heating means 30 configured to heat the liquid or liquefied carrier fluid in the second vessel 2 so as to vaporize at least a portion of the liquefied carrier fluid and distribute a gaseous phase of the carrier fluid into the second transfer circuit 7. This provides the necessary energy to the second vessel to compensate for the energy loss during the evaporation of the carrier fluid and ensures a sufficient and stable distribution flow rate. Preferably, the third heating means 30 are of the inductive type, in particular of the same type as the first heating means 10. Note that the third heating means can be configured to heat the surface of the second vessel 2 to temperatures ranging from 15 to 65 °C, from 50 to 55 °C for perfluoroketone, and preferably from 20 to 35 °C for perfluoronitrile.

[0059] If the carrier fluid is stored in a gaseous state, it is not necessary to provide means of heating the container. This applies to the second carrier fluid container, as well as to any other carrier fluid containers in the installation, if applicable. Thus, the [ Fig.1 [The diagram] illustrates an installation comprising additional containers 3, 4 containing additional carrier fluids. In particular, the additional carrier fluids may be oxygen and nitrogen stored in gaseous state in their respective containers.

[0060] As can be seen on the [ Fig.1 The gaseous phases of the insulating fluid and the carrier gas are conveyed via their respective transfer circuits 6 and 7 to a combining point 60, where the phases are combined. The combined phases then flow into a distribution circuit 8 adapted to supply the high-voltage electrical switchgear with an electrically insulating gas mixture comprising the gaseous phase of the insulating fluid and the gaseous phase of the carrier gas. The electrical switchgear can be connected to a distribution point 90 for refilling.

[0061] One problem concerns the temperature control of the vaporized insulating fluid. The gaseous phase of the insulating fluid must be maintained at a temperature equal to or greater than its vaporization temperature throughout its entire path from the container to the point of use. The presence of cooler spots along the fluid path downstream of the container can cause condensation of the gaseous phase at these points. These condensates suspended in the gaseous phase lead to malfunctions in the flow controllers and instability in the flow rate, and consequently, in the concentration of the insulating fluid.

[0062] To remedy this, the installation further includes second heating means 21, 22 configured to heat the gaseous phase of the insulating fluid at least at the level of the combination point 60 and the downstream part 6b of the first transfer circuit 6.

[0063] The invention thus allows for more efficient control of the insulating fluid's temperature. The gaseous phase of the insulating fluid can be maintained at a temperature equal to or greater than its vaporization temperature at the combination point 60 and the downstream section 6b. It is important to heat the insulating fluid to its combination point 60 with the carrier fluid, since the risk of condensation is highest when the insulating fluid is in its pure state. Once diluted in the carrier fluid, the risk of condensation is eliminated because its partial pressure will be significantly lower than it was in its pure state, and therefore lower than its saturated vapor pressure at the given temperature.

[0064] Thanks to this invention, the insulating fluid is heated in the downstream section, which includes the first flow control device, to prevent condensation of the gaseous phase. This avoids the risk of blockage or changes in the fluid passage cross-section at this point, which would be detrimental to the accuracy of the mixture. Furthermore, the second heating device controls the temperature of the first flow control device, thus eliminating the effects of external temperature variations. The stable operating conditions of the flow control device ensure greater accuracy and a stable concentration of the insulating fluid in the mixture, even during on-site use.Simultaneous heating of the fluid at the point of combination prevents the appearance of cold spots on the first transfer circuit 6 until the gaseous phase of the insulating fluid is combined with the gaseous phase of the carrier fluid.

[0065] Another advantage of the invention is that, instead of drawing off the insulating fluid in liquid form and then vaporizing it as in prior art installations, the installation draws off the insulating fluid in its gaseous phase. To achieve this, the first container 1 is heated to increase its internal pressure, rather than being pressurized by a secondary fluid. This preserves the purity of the fluid, and therefore the accuracy of the flow rate and final concentration.

[0066] Preferably, the second heating means 21, 22 are further configured to heat the gaseous phase of the insulating fluid at least a portion of the first upstream part 6a of the first transfer circuit 6. This makes it possible to heat the gaseous phase over most, if not all, of its path to the combination point and to further minimize the risk of recondensation of the vapor phase downstream of the first vessel 1.

[0067] Preferably, the first upstream section 6a comprises at least one fluid line 6a connected to the first opening of the first container 1. The second heating means 21, 22 comprise a first heating device 21 arranged around all or part of said fluid line 6a. Preferably, the first heating device 21 is of the resistive or inductive type. The first heating device may be in the form of a heating pipe or sleeve. The first heating device may, for example, be an electrical resistance integrated into a flexible structure, optionally covered with a thermally insulating outer sheath. Preferably, the first heating device extends from the first opening along the entire length of the fluid line 6a.

[0068] Advantageously, the second heating means 21, 22 comprise a second heating device 22 configured to heat at least the gaseous phase of the insulating fluid at the combination point 60 and at the downstream part of the first transfer circuit 6 connected to said combination point 60. Preferably, the second heating device 22 is arranged all around the combination point 60 and the first downstream part 6b of the first transfer circuit 6.

[0069] Preferably, the second heating device 22 is physically separate from the first heating device 21 in order to be able to adapt as best as possible to the components to be heated in the area concerned.

[0070] Preferably, the second heating means can be configured to heat the surface of the transfer circuit 6 to temperatures ranging from 15 to 65 °C, preferably from 30 to 55 °C.

[0071] Advantageously, the second heating device 22 comprises a thermally insulating casing 22a defining an internal volume in which at least the downstream portion of the first transfer circuit 6 and the combining point 60 are arranged. Furthermore, the second heating device 22 comprises a second heating element 22b adapted to heat said internal volume.

[0072] The use of a heated, thermally insulating envelope allows for more effective temperature control of the vaporized insulating fluid, simultaneously at the mixing point and in the downstream section of the transfer circuit. Arranging the main distribution components within a single heated volume enables simpler and more efficient temperature control than if the components were heated by independent heating systems.

[0073] Preferably, the second heating device 22 is of the resistive type. It may include at least one electrical resistance element mounted on or near one of the walls of the insulating enclosure 22a. Heat transfer occurs by convection, preferably by forced convection. The second heating device 22 may be associated with an air circulation means 23 configured to circulate air from the second heating device 22 towards the internal volume of the enclosure 2. This allows the entire internal volume of the insulating enclosure to be efficiently heated. In particular, the air circulation means 23 may include at least one fan. Preferably, the air circulation means 23 is configured to draw in cold air from inside the insulating enclosure, preferably from a central region of the insulating enclosure, to be heated by the second heating device 22, and to discharge the heated air.Air can circulate within the oven in a closed circuit, in particular the air put into circulation is heated, circulates in the internal volume and is then drawn in by the circulation means to be directed again to the second heating device 22.

[0074] In particular, the second heating device 22 can be configured to heat the internal volume of the envelope 22a to temperatures ranging from 15 to 65 °C, preferably from 50 to 55 °C for perfluoroketone and preferably from 20 to 35 °C for perfluoronitrile.

[0075] Preferably, the thermally insulating envelope 22a is a flexible one. This allows it to enclose complexly shaped components that would be difficult to heat individually. Besides the flow regulator(s), the transfer circuit may include various components, valves, conduits, fluid connectors, etc. The envelope can be arranged around these different components while minimizing the internal volume to avoid unnecessary heating. The thermally insulating envelope also has the advantage of stabilizing the operating temperature of the flow control devices, thereby optimizing flow rate stability.

[0076] The envelope may include at least one layer of a flexible material, such as a woven fabric made of yarns formed from a thermally insulating material, such as glass or Teflon yarns, or a nonwoven fabric made of fibers formed from a thermally insulating material, such as glass or Teflon fibers. The term "fabric" refers to a manufactured product obtained by weaving yarns, that is, interlacing yarns to create a woven fabric. "Nonwoven" refers to a manufactured product made of fibers arranged in a sheet, oriented randomly or directionally, and bonded together by mechanical, chemical, and / or thermal processes, excluding weaving. In particular, nonwoven fabrics may be made of fibers bonded by friction, cohesion, or adhesion. The use of a fabric or a nonwoven fabric provides adequate flexibility to the envelope.

[0077] In particular, the thermally insulating envelope is a flexible, double-walled envelope comprising at least one heat-insulating material arranged between the walls. The walls hold the heat-insulating material in place. Each wall can be formed from a layer of flexible material as described above. The heat-insulating material can include, for example, glass, silicone, etc., in the form of wool or foam. An advantageous option is the thermally insulating envelope, which is formed from several panels connected by removable fasteners. This allows the envelope to be modular and adapted to the shapes and dimensions of the system components. In particular, the dimensions of the envelope can be modified according to the number of components in the gas mixture to be distributed.For example, panels can be added and the dimensions of the envelope increased if the number of fluids to be used increases, since this leads to an increase in the number of transfer circuits and associated regulating devices.

[0078] Removable fastening means may include, for example, Velcro® type fasteners, each comprising a hook component arranged on at least one panel and a complementary loop component arranged on another panel, a removable connection being achieved by bringing the components into contact.

[0079] Advantageously, the second transfer circuit 7 includes a second downstream part 7b connected to said combination point 60, which downstream part preferably includes a second flow control device 13 connected on one side to the second container 2 and on the other side to the combination point 60. The second flow control device 13 is configured to regulate and / or adjust the flow rate of carrier fluid flowing towards the combination point 60 according to a second flow setpoint D2 which can be determined as a function of a target content C2 of the carrier fluid mixture.

[0080] The second heating device 22 is configured to heat the downstream section of the second transfer circuit 7. This allows for temperature control of the second flow regulator 13 and eliminates the effects of external disturbances, enabling highly accurate distribution of the gas mixture on-site. Specifically, the downstream section of the second transfer circuit 7 is arranged within the internal volume defined by the insulating casing 22a.

[0081] In the case where the installation includes one or more additional carrier fluid containers 3, 4, each of these additional containers can be connected to the combination point 60 or to a connection point 70 located downstream of the combination point 60, as shown for example in the [ Fig.2 Preferably, each additional carrier fluid is transferred in the gaseous state from its container by a respective additional transfer circuit comprising a downstream part equipped with additional flow control devices 18, 19.

[0082] The flow control devices regulate the flow rate of each additional carrier fluid according to a third flow setpoint D3 and a fourth flow setpoint D4, respectively. Downstream of the mixing point 60, or the connection point 70 as applicable, a mixture of the gaseous phases of each fluid is obtained, with a total flow rate corresponding to the sum of the individual flow rates of each fluid. Controlling the flow rates therefore allows for the control of the concentration of each of the fluids constituting the resulting gas mixture.

[0083] Preferably, the additional downstream part of the additional transfer circuit comprising the additional flow control device(s) 18, 19, is also heated by the second heating device 22, so as to stabilize its operation, as previously described.

[0084] Advantageously, all downstream parts of the fluid transfer circuits of the installation, including flow control devices, are heated by the second heating device 22. In particular, all these systems are arranged within the internal volume defined by the insulating envelope 22a. The fluid control and distribution components are thus heated simultaneously up to the point of combination.

[0085] Note that, within the scope of the invention, flow control devices can be any means configured to regulate, control, or adjust the flow rate of a fluid to bring it to a flow rate value as close as possible to the desired value. Typically, flow control devices each comprise a flow sensor, or flow meter, associated with a pressure-reducing element, such as a valve, for example, a proportional control valve. The valve can be pneumatic or piezoelectric, analog or digital. The valve includes a moving part, typically at least one obturator, which is placed in the fluid flow and whose movement allows the passage area to be varied, thus varying the flow rate to bring it to the setpoint value. In particular, flow control devices can be mass flow controllers comprising a mass flow sensor and a proportional control valve.

[0086] Advantageously, the first heating means 10 are configured to heat the liquefied insulating fluid in the first container 1 to a first temperature, the second heating means being configured to heat the vapor phase of the liquefied insulating fluid to a second temperature higher than the first temperature at least at the level of the combination point 60 and the downstream part of the first transfer circuit 6. This avoids any risk of recondensation of the vapor phase downstream of the first container 1.

[0087] Preferably, the installation according to the invention may include one or more of the regulation modes described below.

[0088] According to one aspect, the first heating means 10 are configured to deliver variable heating power. The heating temperature of the liquefied insulating fluid in the first container 1 can thus be adjusted. Preferably, the installation also includes at least one pressure sensor PC configured to measure the pressure in the first container 1. The PC sensor can be internal or external to the container and / or connected to the container 1 or to a pipe connected to the container 1. A first control unit 41 is connected to the pressure sensor PC and the first heating means 10. The first control unit 41 is configured to vary the heating power delivered by the first heating means 10 based on the pressure measured by the pressure sensor PC.

[0089] The heating power is thus adjusted to regulate the temperature to which the insulating fluid is heated in the first container 1 in order to stabilize the pressure within the container. In the event of a pressure variation, the control unit adjusts the heating conditions via the primary heating elements 10 to regulate the pressure in the container. This ensures continuous distribution with a stable gaseous phase flow rate. This method of regulation is more efficient and safer than independent regulation of the primary heating elements, since a pressure variation directly and immediately reflects the state of the physical system within the container. Pressure-based heating regulation results in a very stable temperature of the insulating fluid in the first container 1.

[0090] This embodiment is particularly suited to the distribution of pure insulating fluid since the pressure in container 1 corresponds to the gas phase pressure and directly reflects the quantity of insulating fluid that can be vaporized.

[0091] Preferably, the first control unit 41 includes means for comparing the pressure in the first container 1 with a first setpoint pressure. The first control unit 41 is configured to reduce the heating power when the pressure measured inside the container 1 is greater than or equal to the first setpoint pressure, and to increase the heating power when the pressure in the container 1 is less than the first setpoint pressure. Note that the reduction in heating power means heating at a lower power level or stopping the heating altogether, depending on the pressure difference calculated by the control unit 41 between the pressure setpoint and the measured system pressure.

[0092] The regulation of the heating power of the first heating means according to the pressure allows for the distribution of an optimal flow of insulating fluid while avoiding unnecessarily overheating the first container 1.

[0093] According to one variant (not shown), it is possible to replace the PC pressure sensor with a temperature measuring device configured to measure the temperature of at least a portion of the outer surface of a wall of the container 1, i.e., the surface temperature of the container 1. The heating of the first heating elements 10 is thus regulated according to this temperature. The temperature measuring device can be any device configured to perform temperature measurements by contact, in particular a resistance temperature sensor, for example a platinum resistance sensor of the PT100 type, or a thermocouple or thermistor temperature probe.

[0094] The first control unit 41 is connected to the temperature measuring device and the first heating means 10. The first control unit 41 is configured to vary the heating power delivered by the first heating means 10 according to the measured temperature.

[0095] Advantageously, the first control unit 41 includes means for comparing the temperature measured by the temperature measuring device with a first setpoint temperature of a predetermined value. The control unit 41 is configured to reduce heating power when the measured temperature is higher than the first setpoint temperature and to increase heating power when the measured temperature is lower than the first setpoint temperature. It should be noted that the reduction in heating power means heating at a lower power level or stopping the heating altogether, depending on the pressure difference calculated by the control unit 41 between the temperature setpoint and the measured system temperature.

[0096] According to a second aspect, the second heating means are configured to deliver variable heating power. The heating temperature of the liquefied insulating fluid vapors in the transfer circuit 6 and at the combination point 60 can thus be adjusted. Preferably, the heating power of the second heating means can be adjusted and / or regulated based on a temperature measurement at the first heating device 21 and / or the second heating device 22. The first heating device 21 and / or the second heating device 22 can therefore be equipped with one or more temperature sensors TC. It should be noted that it is also possible to position temperature sensors TC in other areas, particularly in the internal volume heated by the second heating device 22.

[0097] A third control unit 43 is connected to the temperature sensor(s) TC and the second heating means. The third control unit 41 is configured to vary the heating power delivered by the second heating means based on the temperature measured by the temperature sensor TC. The heating power can thus be adjusted to vary the temperature to which the insulating fluid is heated in the first transfer circuit 6 and the combination point 60. The [ Fig.1 [ ] shows a common control of the heating power of the first heating device 21 and the second heating device 22. It is also possible to control the heating power of the first heating device 21 and the second heating device 22 independently.

[0098] The third control unit 43 includes means for comparing the temperature measured by at least one temperature sensor with at least one second setpoint temperature. The third control unit 43 is configured to reduce the heating output when the measured temperature is greater than or equal to the second setpoint temperature and to increase the heating output when the measured temperature is less than the second setpoint temperature. Note that the heating output of the first heating device 21 and the heating output of the second heating device 22 can be regulated according to the same setpoint temperature or according to separate setpoint temperatures.

[0099] Advantageously, the third control unit 43 includes a first control loop for regulating the heating power of the second heating elements based on the second setpoint temperature. This control loop regularly determines the difference between the measured temperature and the desired second setpoint temperature and calculates the appropriate command to apply to one or more actuators to reduce this difference as quickly as possible. The control loop operates in a closed loop.

[0100] Preferably, the first control loop includes a first comparator configured to generate at least one first error signal obtained by comparing a measured temperature with the second setpoint temperature. The first loop includes a first controller configured to generate a first control signal from the first error signal and to send this control signal to actuators that, in response to the first control signal, adjust the power of the second heating elements. Preferably, the first controller is of the proportional, integral, and derivative (PID) type.

[0101] According to a third aspect, in the case where the installation includes third heating means 30 configured to heat the liquefied carrier fluid in the second container 2, said third means 30 can be configured to deliver variable heating power. The heating temperature of the liquefied insulating fluid in the second container 2 can thus be adjusted. Preferably, the installation also includes at least one other pressure sensor PC configured to measure the pressure in the first container 2. The PC sensor can be internal or external to the container and / or connected to the container 2 or to a pipe connected to the container 2. On the [ Fig.1 [Figure ] shows the first control unit 41 connected to the other pressure sensor PC and to the third heating elements 30. The first control unit 41 is configured to vary the heating power delivered by the elements 30 based on the pressure measured by the other sensor PC. The heating of the second vessel 2 can also be regulated by an independent control unit. Note that all or part of the features and advantages described in relation to the first heating elements are applicable to the regulation of the third heating elements.

[0102] According to one variant (not illustrated), the regulation of the heating of the means 30 by pressure measurement as described above can be replaced by a regulation by measurement of the external temperature of the second container 2, i.e. the skin temperature of the second container 2. Note that all or part of the characteristics described for the regulation of the first heating means by temperature measurement are applicable to this method of regulation of the third heating means.

[0103] According to a fourth aspect, the installation includes a second control unit 42 which is connected to the first and second flow control devices, 61 and 13 respectively, so as to control their operation in accordance with the desired flow setpoints D1 and D2. The two flow control devices 61 and 13 advantageously include a closed-loop system that receives the flow setpoints D1 and D2 from the control unit 42. Each flow control device 61 and 13 includes at least one flow sensor that measures the fluid flow rate. The closed-loop system compares the measured flow rates with the respective flow setpoints. The positions of the devices are adjusted by said system accordingly to maintain the flow rates as close as possible to D1 and D2 at the combination point 60. Preferably, the flow control loop is of the PID type.

[0104] Advantageously, the control unit(s) 41, 42, 43 include a programmable logic controller (PLC), that is, a control system for an industrial process comprising a human-machine interface for supervision and a digital communication network. The control unit(s) 41, 42, 43 may thus include at least one of the following: a microcontroller, a microprocessor, or a computer. The control unit(s) 41, 42, 43 may be connected to the various control equipment of the installation, in particular to flow regulators and sensors, and communicate with said equipment via electrical connections, Ethernet, Modbus, etc., and / or via radio frequency connections, Wi-Fi, Bluetooth, etc. Optionally, the control units 41, 42, 43 may form a single entity.

[0105] As can be seen on the [ Fig.1 The second transfer circuit 7 may include at least one expansion valve 5 configured to reduce the pressure of the gaseous phase of the carrier fluid. This allows the second flow control device 13 to operate at a pressure acceptable to it. Preferably, a heater 11 is arranged upstream of the expansion valve 5 so as to heat the gaseous phase before its expansion by the expansion valve 5. This compensates for the cooling caused by the Joule-Thomson effect during the adiabatic expansion of the gas. Note that two expansion valves may optionally be arranged in series, possibly with another heater arranged between two expansion valves. At least one heater and at least one expansion valve may also be arranged on the additional transfer circuits, if necessary.

[0106] The distribution circuit 8 advantageously includes a mixing device 50 configured to mix and homogenize the combined gaseous phase of the insulating fluid and the gaseous phase of the carrier fluid upstream. For example, a static mixer can be used, allowing continuous mixing of the fluids entering the mixer. This type of mixer generally includes at least one disruptive element, such as a plate, a section of pipe, or an insert, capable of disrupting the fluid flow and generating turbulent rather than laminar flow to promote fluid mixing and homogenization.

[0107] According to a variant illustrated on the [ Fig.2The mixing device 50 may optionally comprise two separate mixing elements 51, 52. In this way, a combination of the gaseous phases of the insulating fluid and the carrier fluid first takes place at the combination point 60. An intermediate mixture of these phases is produced at the outlet of the first mixing element 51. The carrier fluid from the vessel 3 is combined with the intermediate mixture at the connection point 70 and then mixed with the intermediate mixture in the second mixing element 52. Thus, the additional carrier fluid is only combined with the insulating fluid once the latter has already been diluted with the carrier fluid, which improves the safety of the installation when the carrier fluid is oxygen.

[0108] At the outlet of the mixing device 50, the insulating gas mixture can have an initial pressure ranging from 2.5 to 1 bar absolute.

[0109] Preferably, a pressure-boosting device 53, such as a single-stage or multi-stage compressor, is arranged downstream of the mixing device 50. Thus, once the gas mixture has been prepared with the desired composition, its pressure is raised to the filling pressure of the electrical equipment. Typically, the mixture may have a second pressure ranging from 2.5 to 11 bar absolute at the outlet of the pressure-boosting device 53.

[0110] The distribution circuit 8 may include a buffer tank 12 arranged upstream of the pressure-boosting device 53. This smooths out any flow rate fluctuations before the fluid pressure is increased. The buffer tank 12 also helps to further homogenize the mixture. The buffer tank 12 may consist of a single tank or several tanks fluidically connected to each other.

[0111] The distribution circuit 8 may include a branch to a discharge and / or reprocessing point 91 for the gas mixture. This allows for purging of the fluid circuit, for example, after a filling sequence and before the start of the next sequence. The installation may also include a sampling point 92 for the mixture, intended to be connected to an analysis unit configured to analyze at least one concentration of the insulating fluid and / or carrier fluid in the distributed mixture. This allows, at the start of the installation or during a filling sequence, verification of the gas mixture's compliance with the target concentrations. If the produced mixture does not comply, distribution may be stopped. The distribution circuit 8 may include automatic switching means to selectively supply the distribution point 90, the discharge point 91, or the sampling point 92.

[0112] The installation according to the invention allows for the distribution of a dielectric gas mixture with improved stability and precision. The composition of the mixture can be easily adapted to the required specifications. The gas mixture may contain at least one insulating fluid commonly used for the gaseous insulation of high-voltage electrical equipment. It should be noted that the insulating gas mixture contains a carrier fluid and optionally at least one additional carrier fluid.

[0113] Preferably, the insulating gas mixture has a GWP (Global Warming Potential) of 1000 or less, meaning it is at most 1000 times higher than that of CO₂, or even 500 or less. A carrier fluid and at least one additional carrier fluid may be used in mixture with the insulating fluid. Typically, the gas mixture may comprise 2 to 15% (molar percent) of insulating fluid, 65 to 98% of carrier fluid, and 3 to 20% of at least one additional carrier fluid, such as oxygen.

[0114] Consider the example of an installation configured to produce a three-gas mixture with a distribution flow rate of 100 sL / min. The desired gas mixture is a mixture consisting of perfluoronitrile as an insulating fluid with a target content C1 of 5% (molar %), CO2 as a carrier fluid with a content C2 of 85%, and 10% oxygen as an additional carrier fluid. A first flow setpoint D1 of 5 sL / min, a second setpoint D2 of 85 sL / min, and a third flow setpoint D3 of 10 sL / min are applied to the respective flow control devices.

Claims

1. An installation for distributing an electrical insulating gas mixture to a gas-insulated electrical switchgear, in particular a high-voltage electrical switchgear, said installation comprising: - a first container (1) intended to contain an insulating fluid in the liquid or liquefied state, - first heating means (10) configured to heat the insulating fluid in the first container (1) so that said first container (1) produces at a first outlet a gaseous phase of the insulating fluid, - a second container (2) intended to contain a carrier fluid and configured to produce a gaseous phase of the carrier fluid at a second outlet of the second container (2), - a first transfer circuit (6) configured to transfer the gaseous phase of the insulating fluid from the first outlet of the first container (1) to a combination point (60), the first transfer circuit (6) comprising a first upstream part (6a) connected to the first container (1) and a first downstream part (6b) connected on the one hand to the first upstream part (6a) and on the other hand to the combination point (60), - a second transfer circuit (7) configured to transfer the gaseous phase of the carrier fluid from the second outlet of the second container (2) to the combination point (60), - a distribution circuit (8) fluidically connected to the combination point (60) and configured to distribute an electrical insulating gas mixture comprising the gaseous phase of the insulating fluid and the gaseous phase of the carrier fluid to the high-voltage electrical switchgear, the distribution installation being characterized in that: the first downstream part (6b) of the first transfer circuit (6) comprises a first flow rate regulating device (61) configured to regulate and / or adjust the flow rate of the gaseous phase of the insulating fluid flowing towards the combination point (60), said installation further comprises second heating means (21, 22) configured to heat the gaseous phase of the insulating fluid at least at the level of the combination point (60) and of the downstream part (6b) of the first transfer circuit (6).

2. The installation according to the preceding claim, characterized in that the second heating means (21, 22) are further configured to heat the gaseous phase of the insulating fluid at the level of at least a portion of the first upstream part (6a) of the first transfer circuit (6).

3. The installation according to one of the preceding claims, characterized in that the first upstream part (6a) of the transfer circuit (6) comprises at least one fluid conduit (6a), the second heating means (21, 22) comprising a first heating device (21) arranged around all or part of said fluid conduit (6a), in particular the first heating device (21) is of the resistive or inductive type.

4. The installation according to one of the preceding claims, characterized in that the second heating means (21, 22) comprise a second heating device (22) arranged around the combination point (60) and the first downstream part (6b) of the first transfer circuit (6).

5. The installation according to the preceding claim, characterized in that the second heating device (22) comprises a thermally insulating envelope (22a) defining an internal volume in which the downstream part of the first transfer circuit (6), the first flow rate regulating device (61), and the combination point (60) are arranged, and a heating member (22b) adapted to heat said internal volume, in particular the heating member (22b) is of the resistive type.

6. The installation according to the preceding claim, characterized in that the thermally insulating envelope (22a) comprises at least one layer of a flexible material, in particular the flexible material comprises at least one woven fabric of threads formed of a thermally insulating material or a non-woven fabric of fibers formed of a thermally insulating material.

7. The installation according to one of claims 5 or 6, characterized in that the thermally insulating envelope is formed of several panels connected to each other by removable fastening means.

8. The installation according to one of the preceding claims, characterized in that the second transfer circuit (7) comprises a second upstream part (7a) connected to the second container (2) and a second downstream part (7b) connected to the combination point (60), said second downstream part (7b) comprising a second flow rate regulating device (13) configured to regulate and / or adjust the flow rate of the gaseous phase of the carrier fluid flowing towards the combination point (60), the second heating device (22) being preferably configured to heat the second downstream part (7b) of the second transfer circuit (7).

9. The installation according to one of the preceding claims, characterized in that it further comprises at least one additional container (3, 4) intended to contain an additional carrier fluid and configured to produce a gaseous phase of said additional carrier fluid at an outlet of the additional container (3, 4), the installation comprising an additional transfer circuit configured to transfer the gaseous phase of the additional carrier fluid from the outlet of the additional container (3, 4) to the combination point (60), the additional transfer circuit comprising an additional upstream part connected to the additional container (3, 4) and an additional downstream part connected to the combination point (60), said additional downstream part comprising an additional flow rate regulating device (18, 19) configured to regulate and / or adjust the flow rate of the gaseous phase of the additional carrier fluid flowing towards the combination point (60), the second heating device (22) being preferably configured to heat the additional downstream part of the additional transfer circuit.

10. The installation according to one of the preceding claims, characterized in that the first heating means (10) are configured to heat the liquefied insulating fluid in the first container (1) to a first temperature, the second heating means (21, 22) being configured to heat the vapor phase of the liquefied insulating fluid to a second temperature higher than the first temperature at least at the level of the combination point (60) and of all or part of the first transfer circuit (6).

11. The installation according to one of the preceding claims, characterized in that the first heating means (10) are configured to deliver a variable heating power, the installation comprising at least one pressure sensor (PC) configured to measure the pressure prevailing in the first container (1) and a first control unit (41) connected to the pressure sensor (PC) and to the first heating means (10), the first control unit (41) being configured to vary the heating power delivered by the first heating means (10) as a function of the pressure measured by the pressure sensor (PC).

12. The installation according to one of claims 1 to 10, characterized in that the first heating means (10) are configured to deliver a variable heating power, the installation comprising at least one temperature measuring member configured to measure the temperature of the first container (1) and a first control unit (41) connected to the temperature measuring member and to the first heating means (10), the first control unit (41) being configured to vary the heating power delivered by the first heating means (10) as a function of the temperature measured by the temperature measuring member.

13. The installation according to one of the preceding claims, characterized in that the second container (2) is intended to contain the carrier fluid in liquefied form, the installation comprising third heating means (30) configured to heat the liquefied carrier fluid in the second container (2) so as to vaporize at least a part of the liquefied carrier fluid and to distribute a gaseous phase of the carrier fluid into the second transfer circuit (7).

14. The installation according to one of the preceding claims, characterized in that the second transfer circuit (7) comprises an expansion member (5) configured to reduce the pressure of the gaseous phase of the carrier fluid, a reheater (11) arranged upstream of the expansion member (5) so as to heat the gaseous phase before its expansion by the expansion member (5).

15. The installation according to one of the preceding claims, characterized in that the distribution circuit (8) comprises at least one of: a mixing device (50) configured to mix the gaseous phase of the insulating fluid and the gaseous phase of the carrier fluid, a pressure-increasing member (53) arranged downstream of the mixing device (50), a buffer tank (12) arranged upstream of the pressure-increasing member (53).

16. A method for distributing an electrical insulating gas mixture to a high-voltage electrical switchgear, said method comprising the following steps: - a) heating an insulating fluid in the liquid or liquefied state in a first container (1) by first heating means (10) so as to vaporize at least a part of the liquefied insulating fluid and to produce a gaseous phase of the insulating fluid in the first container (1), - b) passing the gaseous phase of the insulating fluid into a first transfer circuit (6) so as to transfer the gaseous phase of the insulating fluid from the first container (1) to a combination point (60), the first transfer circuit (6) comprising a first upstream part (6a) connected to the first container (1) and a first downstream part (6b) connected on the one hand to the first upstream part (6a) and on the other hand to the combination point (60), - c) regulating and / or adjusting the flow rate of the gaseous phase of the insulating fluid flowing towards the combination point (60) by means of a first flow rate regulating device (61) arranged on the first downstream part of the first transfer circuit (6), - d) passing a gaseous phase of a carrier fluid from a second container (2) into a second transfer circuit (7) so as to transfer the gaseous phase of the carrier fluid to the combination point (60), - e) combining the gaseous phase of the insulating fluid and the gaseous phase of the carrier fluid at the combination point (60) and passing the gaseous phase of the insulating fluid and the gaseous phase of the carrier fluid combined in a distribution circuit (8) adapted to distribute to the high-voltage electrical switchgear an electrical insulating gas mixture comprising the gaseous phase of the insulating fluid and the gaseous phase of the carrier fluid, - f) heating the gaseous phase of the insulating fluid at least at the level of the point of the combination point (60) and of the downstream part (6b) of the first transfer circuit (6) by second heating means (21, 22).