WO2023274498A1

WO2023274498A1 - Power component for insulated switch gear assembly

Info

Publication number: WO2023274498A1
Application number: PCT/EP2021/067733
Authority: WO
Inventors: Rongsheng Liu
Original assignee: Hitachi Energy Switzerland Ag
Priority date: 2021-06-28
Filing date: 2021-06-28
Publication date: 2023-01-05

Abstract

The present invention relates to a power component (101-107, 119) for a switch gear assembly (100), the power component (101-107, 119) being configured for use at voltages of at least 36 kV, the power component comprising at least a first housing (108), and comprising one or more conductors (109) for conducting power being arranged in said first housing (108), wherein a first chamber volume (110) between said first housing (108) and said one or more conductors (109) comprises an insulation material (111) insulating said conductors (109) from said housing (108) characterized in that the insulation material (111) comprises a thermo reversible gel. The invention also relates to a switch gear assembly (100) comprising one or more power components (101-107, 119). The invention also relates to a power station comprising a switch gear assembly. Further, the invention relates to a method of assembling a power component.

Description

POWER COMPONENT FOR INSULATED SWITCH GEAR ASSEMBLY TECHNICAL FIELD

The present disclosure relates to a power component for a switch gear assembly, the power component being configured for use at voltages of at least 36 kV. The disclosure also relates to a switch gear assembly comprising one or more power components, to a power station comprising one or more switch gear assemblies and to a method for assembling a power component.

BACKGROUND OF THE INVENTION Power components configured for use at relatively high voltages, i.e. voltages of at least 36 kV, are used for example in power stations and in switch gear assemblies. Such power components may generally form a housing comprising one or more conductors, which housing may be filled with an insulation medium. The insulation medium may be subject to relatively high discharge and high temperatures such as at electric arc formation.

One example is gas-insulated switch gear assemblies wherein an insulation medium in the form of insulation gas is widely used. For example, different components of a switch gear assembly, such as a breaker, a bushing, an instrument transformer may be insulated with gas. A gas usually selected for the insulation medium is SF₆ gas.

An alternative to gas as insulating medium for a switch gear assembly is a dielectric liquid, such as oil.

There is a desire for improved or alternative solutions for switch gear assemblies. For example, there is a desire to obtain a switch gear assembly which can stand relatively high voltage. Further, there is a desire for a switch gear assembly with a reduced environmental impact and a safe performance. Also, it is desired to provide a switch gear assembly which is suitable for arrangement in a limited space. The object of the invention is to provide a power component for a switch gear assembly, providing an improvement or an alternative in view of existing solutions, for example in view of one or more of the above-mentioned desires. SUMMARY OF THE INVENTION

The above-mentioned object is achieved in a first aspect by a power component for a switch gear assembly, the power component being configured for use at voltages of at least 36 kV, the power component comprising at least a first housing, and comprising one or more conductors for conducting power being arranged in said first housing, wherein a first chamber volume between said first housing and said one or more conductors comprises an insulation material insulating said conductors from said housing, wherein the insulation material comprises a thermo reversible gel. Thus, the proposed power component comprises a thermo reversible gel as insulation material. A thermo reversible gel has a transition temperature, which is defined as the temperature where the tangent value of viscosity shows the maximum value, sometimes called knee temperature. With thermo reversible is meant that at a temperature higher than the transition temperature, the gel is a liquid and at a temperature lower than the transition temperature, the gel is semisolid. The gel can function as an insulation material both in the liquid phase and in the semisolid phase dependent on the service temperature.

The thermo reversible gel comprises an insulating oil and a thickener. The thickener renders the dielectric gel thermo reversible.

During operation of the power component, the gel will be in semisolid or solid form. Accordingly, the thermo reversible gel will not be prone to leaking out which is advantageous from an environmental point of view. In case the temperature gets higher than the transition temperature the gel may go into a liquid form and the gel in liquid form will still work as an insulation medium. The gel could partly be in liquid form, such as in a portion close to a hot part.

Further, the thermo reversible gel may be in liquid form when filled into a power component for a switch gear assembly, thus facilitating assembly of the power component as will be explained in the below. After filling, when the temperature has been reduced, the thermo reversible gel will again be in semi solid or in solid form.

Further, the thermo reversible gel may have improved dielectric performance as compared to gas and compressed gas, as conventionally used in power components for switch gear assemblies. Also, the gel has elastic properties which may contribute to anti explosive properties of the gel. The thermo reversible gel may thus absorb energy, such as explosive force, which is advantageous for a power component for a switch gear assembly which is exposed to high voltage.

The thermo reversible gel may have a breakdown strength being relatively high as compared to gas and compressed gas. For example, the gel may be selected to be a thermo reversible gel having a breakdown strength over 20 kV/mm, for example 40 kV/mm. The relatively high breakdown strength implies that a lesser volume of gel is needed as compared to e.g. the volume of gas needed in prior art gas filled power components for switch gear assemblies. Accordingly, the volume of the power component may be reduced to the benefit of space saving. Optionally the thermo reversible gel may have a breakdown strength over 40 kV/mm.

Optionally the thermo reversible gel may have a relative permittivity in the range of 2 to 3. Further, when a thermo reversible gel is present in the housing, this implies that the pressure in the housing does not need to be as high as when gas is used. Accordingly, the thickness of the housing walls may be reduced. Less material will be needed, which will reduce cost. Further, the power component will have a relatively low weight which is also an advantage during e.g. transportation.

Optionally the power component comprises a second housing arranged inside said first housing, such that said first chamber volume extends between said second housing and said first housing, wherein the second housing encloses at least a portion of said one or more conductors, wherein a second chamber volume between said second housing and said one or more conductors comprises an insulation material insulating said conductors from said second housing. Hence, the power component comprises a second chamber volume and said first chamber volume, the first chamber volume being arranged outside of said second chamber volume.

Optionally, the second chamber volume and the first chamber volume may comprise the same insulation material. Optionally, the second chamber volume and the first chamber volume may comprise different insulation materials.

Optionally the insulation material of the first chamber volume and/or second chamber volume comprises a continuous volume of the thermo reversible gel.

Optionally the insulation material of the first chamber volume and/or second chamber volume comprises a permeable solid insulation material impregnated with said thermo- reversible gel.

Optionally the insulation material of said first chamber volume and/or second chamber volume comprises the thermo-reversible gel and a non-permeable solid insulation material. Such a non-permeable solid insulation material is not impregnated with the thermo reversible gel.

Non-permeable solid insulation materials, such as epoxy insulation materials, are nonporous and thus do not need to be impregnated with an insulation material.

Optionally at least one of the first chamber volumes and/or second chamber volume comprises a gas, such as SF₆ gas, air or fluoronitrile-based gas.

Optionally the insulation material of the first chamber volume and/or second chamber volume comprises a mixture of the thermo reversible gel and gas, such as SF₆, air, or fluoronitrile-based gas.

Optionally, when the power component comprises a second housing, the insulation material of said second chamber volume is free from thermo reversible gel. This allows for power components where the first chamber volume comprises thermo reversible gel, but where the second chamber volume comprises another insulator material.

In some power components it may be preferred to include an insulation material which is free from thermo reversible gel. For example, when a power component includes movable parts, it may be advantageous that the insulation material adjacent such movable parts is free from thermo reversible gel. When movable parts are worn against each other and possible arcs are created, particles may be formed, e.g. due to carbonisation. This may reduce the breakdown strength. To avoid this, another insulator material may be arranged adjacent the movable parts.

For example, the second chamber volume may be free from thermo reversible gel and comprise an insulating gas, such as SF₆, air or fluoronitrile-based gas.

Optionally the thermo reversible gel comprises an oil in amount of 50 to 99.9 wt% and a thickener in an amount of 0.0001 to 50 wt%, calculated on the total weight of the gel, the thermo reversible gel comprises iso-paraffinic oil, a mineral oil, a hydrocarbon based oil, a bio-based hydrocarbon oil, or a bio-based iso-paraffinic oil, or a mixture of any of the oils and the thickener comprises a styrene based copolymer.

The wt% are calculated on the total weight of the gel if nothing else is stated.

Optionally the thermo reversible gel comprises an oil in an amount of 80 to 99 wt% calculated on the total weight of the gel.

Optionally the thermo reversible gel comprises 0.1 to 30 wt% of the thickener, calculated on the total weight of the gel.

Optionally the thermo reversible gel comprises 0.001 to 30 wt% of the thickener, or preferably 0.01-10 wt%, 0.1-6 wt% calculated on the total weight of the gel.

The viscosity values of the gel may be chosen by controlling the content of thickeners. Optionally the thermo reversible gel comprises between 0.1 to 10 wt% of the thickener, calculated on the total weight of the gel.

Optionally the thermo reversible gel comprises a thickener in the amount of 1-10 wt%, calculated on the total weight of the gel.

Optionally the thermo reversible gel comprises a thickener in the amount of 2-10 wt%, or more preferably in the amount of 2-6 wt%, calculated on the total weight of the gel. Optionally the thermo reversible gel may comprise a thickener in the amount of 5-10 wt%, calculated on the total weight of the gel. A higher amount of thickener may make the thermo reversible gel more solid or in a thicker state. This may improve the dielectric properties of the thermo reversible gel. The thickener may for example increase the permittivity of the thermo reversible gel. Further, the dielectric strength may increase. A relative permittivity value of about 2.2 may be more desirable than for example the relative permittivity of SF₆ gas. It may for example alter electric field distribution in AC switch gear components e.g. around conductors, as compared to SF₆ isolated switch gear components. However, one may not want to increase the permittivity value too much as that could increase dielectric losses. Similarly, dielectric strength can be increased by increasing the thickener concentration which may enable e.g. reducing the size of the switch gear components. However, a too high amount of the thickener may increase losses and also provide a gel being more difficult to fill into the switch gear components.

Optionally the density of the thermo reversible gel is typically 0.7 to 1.0 kg/dm³ (at 20°C).

Optionally the styrene based copolymer comprises a tri-block copolymer which consists of any of polystyrene-block-poly(ethylene-ethylene/propylene)-block-polystyrene (SEEPS), polystyrene-block-poly(ethylene/butylene)-block-polystyrene (SEBS), polystyrene-block- poly(ethylene/propylene)-block-polystyrene (SEPS), enhanced rubber segments (ERS) polymers, S-EB/S-S, alone or combination.

Optionally the styrene based copolymer comprises a di-block copolymer which consists of any of polystyrene-block-poly(ethylene/propylene) and SEP, alone or in combination.

Optionally the styrene based copolymer consists of said tri-block copolymer and said diblock copolymer.

Optionally the thermo reversible gel comprises 0 to 50 wt%, preferably 0 to 30 wt%, more preferred 0 to 10 wt%, of an additive for improvement of thermal and dielectric performance, calculated on the total weight of the gel.

Optionally the additive for improvement of thermal and dielectric performance comprises particles of one or more of the following, alone or in combination: Boron nitride (BN), hexagonal boron nitride (h-BN), Fe304, Fe203, ZnO, AI2O3, S1O2, Ce02, T1O2, MgO, BaTi03, CaCu3TUOi2 (CCTO), and Bao.85Cao.15Zro.1Tio.9O3 (BCZT). Optionally, the oil is chosen from bio-based hydrocarbon oil, or a bio-based iso-paraffinic oil, or a mineral oil, or a hydrocarbon based oil, or an iso-paraffinic oil, or any combination of them.

Optionally the power component is configured for conducting a flow of power. For example, the power component may be one out of a bushing and a connector.

Optionally the power component is a power conducting component configured for conducting and/or interrupting a flow of power.

Optionally the power component is a component configured for conducting or interrupting a flow of power, and comprises at least two contact elements being movable between a contact position for conducting a flow of power, and a spaced position for interrupting a flow of power.

Optionally the power component is one out of a breaker and an interrupting chamber, or one out of disconnector and earthing switch components. Optionally the power component is a breaker, or a disconnector, or an earthing switch.

Optionally the power component is a control system component, for example an instrument transformer such as a current transformer or a voltage transformer, or a combined transformer.

In a second aspect there is provided a switchgear assembly comprising one or more power components in accordance with the first aspect.

Optionally at least two out of said one or more power components comprised in the switchgear assembly are in accordance with the first aspect.

Optionally a majority of said one or more power components comprised in the switchgear assembly are in accordance with the first aspect. Optionally all of said one or more power components comprised in the switchgear assembly are in accordance with the first aspect. Optionally at least one of the one or more power components comprises an insulation material comprising a gas, such as SF₆, air orfluoronitrile-based gas. When less than all out of the one or power components of the switchgear assembly are in accordance with the first aspect, at least one of the remaining power components of the switch gear assembly may be free from thermo reversible gel. For example, at least one of the remaining power components of the switch gear assembly may be free from thermo reversible gel and comprise a gas, such as SF₆, air or fluoronitrile-based gas. For example, as an option gas may be used in some power components of the switch gear assembly where less weight is required.

Thus, it may be preferred to use gas in one or more power components and thermo reversible gel in another one or more power components in the same switch gear assembly. In such a switch gear assembly the content of gas such as SF₆ gas will still be reduced compared to a conventional gas insulated switch gear. Hence, a more environmentally friendly switch gear assembly will be obtained, as compared to the conventional gas insulated switch gear, and the advantages in terms of space saving, costs and reduced risk of leakage may at least partly be achieved.

Optionally, when the switchgear assembly comprises one or more power components comprising thermo reversible gel and one or more power components being free from thermo reversible gel, such as comprising gas, thermo reversible gel may be applied in power components to be arranged in vertically lower parts of the switch gear assembly. This may be advantageous since the thermo reversible gel is generally heavier than e.g. gas. Thus, the resulting switch gear assembly may be more stable.

Optionally at least one of the one or more power components comprises movable parts. The insulation material of said power component comprising movable parts may comprise a gas, such as SF₆, air or fluoronitrile-based gas.

Optionally the switchgear assembly comprises two or more power components, wherein said first housings of said at least two components are interconnected to form a common switch gear assembly housing for said at least two power components. Optionally, the first chamber volumes of said at least two power components are in fluid communication. Thus, when assembling the switch gear assembly as will be described in the below, the thermo reversible gel in liquid form may be filled into the respective first chamber volumes of the two power components in the same filling step.

Optionally, the first housings of at least a majority of the power components of the switch gear assembly are interconnected to form a common switch gear assembly housing for said at least a majority of the power components. Optionally, the first chamber volumes of at least a majority of the power components of the switchgear assembly are in fluid communication. Thus, when assembling the switch gear assembly as will be described in the below, the thermo reversible gel in liquid form may be filled into the respective first chamber volumes of the majority of the power components in the same filling step.

Optionally, the first housings of all of the power components of the switch gear assembly are interconnected to form a common switch gear assembly housing for all of the power components of the switch gear assembly. Optionally, the first chamber volumes of all of the power components of the switchgear assembly are in fluid communication. Thus, when assembling the switch gear assembly as will be described in the below, the thermo reversible gel in liquid form may be filled into the respective first chamber volumes of all of the power components in the same filling step.

In a third aspect there is provided a power station comprising one or more switchgear assemblies according to the second aspect.

Optionally the power station further comprises at least one of one or more switch gear assemblies, one or more transformers, one or more converters, and/or one or more generators.

In a fourth aspect the invention comprises a method for assembling a power component as disclosed herein, comprising the steps of: filling the first chamber volume of the power component with said thermo reversible gel in liquid form or in semi-solid form.

Optionally the first chamber volume of the power component is filled under vacuum. Optionally, where the power component comprises a second chamber volume, the method comprises filling a second chamber volume of the power component with an insulation material free from thermo-reversible gel, such as with a gas, such as air, fluoronitrile-based gas, or SF₆ gas. Optionally the method comprises filling the first chamber volume of the power component with a mixture of the thermo reversible gel and a gas, such as air, fluoronitrile-based gas or SFe gas, wherein the filling is performed under pressure.

Optionally the method comprises one or more of the following steps performed before the step of filling the first chamber volume, degassing the oil, adding the thickener to the oil and mix the oil and the thickener, heating the mixture of oil and thickener, reducing the temperature of the mixture to a temperature higher than the transition temperature of the gel and/or setting vacuum at the first chamber to be filled with the thermo reversible gel.

Optionally, the method comprises assembling a power component in a switchgear assembly.

Optionally, the method comprises assembling at least two power components of a switch gear assembly, wherein the first housings of the at least two power components form a common housing and the first chamber volumes of the at least two power components are in fluid communication, wherein said first chamber volumes of the two power components are filled with thermo reversible gel in the same filling step.

Features and advantages as described in relation to one of the aspects of the disclosure are equally applicable to the other aspects of the disclosure. Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described more fully hereinafter with reference to the accompanying drawings showing variants of the invention.

Fig. 1 shows a cross-section of a schematically illustrated switch gear assembly according to a variant of the invention.

Fig. 2 shows a cross-section of a schematically illustrated power component in the form of an interrupter chamber.

Fig. 3 shows a cross-section of a schematically illustrated power component in the form of a bushing.

Fig. 4 shows a cross-section of a schematically illustrated power component in the form of a voltage transformer.

Fig. 5 shows a cross-section of a schematically illustrated power component in the form of an L-element.

Fig. 6 shows a schematic graph showing the complex viscosity at different temperatures for an oil based thermo reversible gel with a thickener.

Similar reference numbers indicate similar feature throughout the drawings, unless otherwise indicated.

DETAILED DESCRIPTION

The present disclosure relates to a switch gear assembly and it relates to power components for a switch gear assembly. Switch gear assemblies comprise power components which may be used to protect and isolate electrical equipment. The switch gear assembly may comprise conducting components, such as pair of electrical contacts in breakers that conduct or interrupt flow of electrical power. Further the switch gear assembly may comprise components which are measurement system or control system components, such as an instrument transformer.

Commonly used switch gear assemblies are insulated with gas or oil. Gas-insulated switch gear assemblies may contain SF₆ as insulating gas. The inventor has now found that it is possible to reduce the amount of e.g. SF₆ gas which for example may reduce the negative impact on environment and/or improve the dielectric performance.

A schematic cross section of an example of a switch gear assembly is shown in Fig. 1. A switch gear assembly 100 comprises one or more power components. The example of a switch gear assembly 100 in Fig. 1 includes for example a breaker 101, a current transformer 102, straight connecting elements 103, 104, an earthing switch 105, a voltage transformer 106, a cable connection 107 and a disconnector 119.

The power components 101-107, 119 exemplified in Fig. 1 are hence examples of the power component disclosed herein, i.e. a power component being configured for use at voltages of at least 36 kV, the power component comprising at least a first housing 108, and comprising one or more conductors 109 for conducting power being arranged in said first housing 108, wherein a first chamber volume 110 between said first housing 108 and said one or more conductors 109 comprises an insulation material 111 insulating said conductors 109 from said housing 108, wherein the insulation material 111 comprises a thermo reversible gel.

Figure 1 shows several power components 101-107, 119. The power components 101- 107 comprises first housings 108 for each power component 101-107, 119 respectively. The first housings 108 of the respective power components 101-107, 119 may together form a common housing 108. The first housing 108 may comprise thermo reversible gel.

The thermo reversible gel has by the inventor been found to be useful in switch gear assemblies. The thermo reversible gel has a breakdown strength over 20 kV/mm, for example 40 kV/mm and thus has high dielectric performance, which is important for the components used in switch gear assemblies used at high voltages where there may be risks for overload, electric failures and breakdown. The thermo reversible gel may have a dielectric strength above 40 kV/mm.

Fig. 1 illustrates an example of a switch gear assembly 100. As such, a switch gear assembly 100 may comprise several power components 101-107, 119. Each power component 101-107, 119 comprises conductor elements 109 enclosed by a housing 108, such that a first chamber volume 110 may be fined between said conductor elements 109 and housing 108. The first chamber volume 110 comprises an insulation material 111. In the Figures, the same reference numbers are used for the housing 108, the conductors 109, the first chamber volume 110 and the insulation material 111 for all of the illustrated power components 101-107, 119. The same reference number indicate similar features throughout the Figures. To the benefit of clarity of the figures, all reference numbers are not repeated in all figures.

In accordance with a switch gear assembly 100 as proposed herein, at least one out of the power components 101-107, 119 comprises a thermo-reversible gel.

For example, all first chamber volumes 110 of the first housings 108 of power components 101-107, 119 of the switch gear assembly 100 may comprise thermo reversible gel.

Alternatively, at least two of the first chamber volumes 110 of the first housings 108 of power components 101-107, 119 of the switch gear assembly may comprise thermo reversible gel.

The thermo reversible gel may continuously fill the first chamber volume 110 of the power components 101-107, 119. In other options, the thermo reversible gel may be mixed e.g. with a gas in the first chamber volume 110 of one or more of the power components 101- 107, 119.

Alternatively, at least one of the first chamber volumes 110 of the first housings 108 of the power components 101-107, 119 of the switch gear assembly 100 comprises thermo reversible gel and at least one first chamber volume 110 of the housings 108 of the power components 101-107, 119 is free from thermo reversible gel. Optionally, the at least one first chamber volume 110 being free from thermo reversible gel comprises a gas, such as SFe gas, air or fluoronitrile-based gas. For example, a switch gear assembly may comprise one or more power components being control system components, such as an instrument transformer, for example a current transformer 102 or a voltage transformer 106, as exemplified in Fig. 1, or a combined transformer. In a variant of such a switch gear assembly, the first chamber volumes 110 of the control system components may comprises thermo reversible gel and the first chamber volumes 110 of the remaining power components in the switchgear assembly may be free from thermo reversible gel, and instead comprise gas.

In another variant, the control system component components may be free from thermo reversible gel, e.g comprising gas, and the remaining power components may comprise thermo reversible gel.

In another example of switch gear assembly, wherein the first chamber volume 110 of a first housing 108 of a bushing 115 comprises thermo reversible gel and the other first chamber volumes 110 of the first housings 108 of the power components are free from thermo reversible gel, e.g. comprising gas. In another example the bushing may be free from thermo reversible gel, e.g. comprising gas, and the remaining power components may comprise the thermo reversible gel.

The first chambers 110 of the power components 101-107, 119 may comprise the same or different insulation materials as mentioned above. For example, a power component, such as a voltage transformer 106, may comprise thermo reversible gel, while the cable connection 107 may comprise gas, such as SF₆ gas.

The switch gear assembly may comprise at least two power components wherein the two first housings of the two power components are interconnected to form a common switch gear assembly housing for the at least two power components. For example, in Fig. 1 , the first housings 108 of all of the power components 101-107, 119 are interconnected to form a common housing. As mentioned in the above, the first chamber volumes 110 of the different power components 101-107, 119 may comprise the same insulation material or they may comprise different insulation materials.

When the respective first chamber volumes 110 of adjacent components in a switchgear assembly comprise different insulation materials, a barrier 120 may be needed between the adjacent components, such as between the voltage transformer 106 and the cable connection 107 as exemplified in Fig. 1. The barrier 120 may need to be liquid or gel tight e.g. in order to hinder gel to leak out from housing 108 of the voltage transformer 106 to the housing 108 of the cable connection 107. Further, the barrier 120 may need to be electrically insulating. In some cases, the barrier 120 may need to be gas tight. The barrier 120 may be a partition insulator. The conductor 109 may penetrate through the barrier 120. Barriers may be arranged in several places in a switchgear assembly but are only numbered in one place in Fig. 1. When the same insulation material 111 is used in the first chamber volumes 110 of adjacent components, gel tight barriers are not needed between the first chamber volumes 110. However, support structures allowing for gel/liquid/gas passage may be arranged for the purpose of supporting the conductors mechanically.

When the respective first chamber volumes 110 of adjacent components in a switchgear assembly comprises the same insulation materials, the first chamber volumes 110 may be in fluid communication.

Sealings (not shown) may be arranged between adjacent first housings 108. When the insulation material is thermo reversible gel, the sealing pressure handling requirement on the housings and any sealings may be relatively lower as compared to when a gas, arranged under a relatively higher pressure, is used as the insulating medium in the housings.

In accordance with the present disclosure, and as exemplified in claim 1, a power component 101-107, 119 for a switch gear assembly 100 is proposed. The power component 101-107, 119 is configured for use at voltages of at least 36 kV, and comprises at least a first housing 108, and comprising one or more conductors 109 for conducting power being arranged in said first housing 108, wherein a first chamber volume 110 between said first housing 108 and said one or more conductors 109 comprises an insulation material 111 insulating said conductors 109 from said housing 108. Said insulation material 111 comprises a thermo reversible gel.

The insulation material 111 may comprise a continuous volume of the thermo reversible gel. The thermo reversible gel may substantially fill the first chamber volume 110 for insulating the conductors 109 from the first housing 108.

The insulation material 111 of the first chamber volume 110 may comprise a permeable solid insulation material impregnated with said thermo-reversible gel. A solid insulation material may be used for example in the cable connection 107. The solid insulation 118 is enclosing the conductor in a conical form in this example.

In other examples, the insulation material 111 of said first chamber volume 110 may comprise the thermo-reversible gel and a non-permeable solid insulation material.

In other examples, the insulation material 111 of the first chamber volume 110 may comprise a mixture of the thermo reversible gel and gas, such as SF₆, air or fluoronitrile- based gas.

The power component may be any type of power component suitable for use in a switchgear assembly.

For example, the power component may be configured for conducting a flow of power. Such a power component may e.g. be one out of a bushing and a connector.

In another example, power component 101-107, 119 may be a control system component, preferably an instrument transformer such as a current transformer 102 or a voltage transformer 106, or a combined transformer. A control system component may be a component used for measuring. In the example of a switch gear assembly 100 in Fig. 1, one voltage transformer 106 is arranged in the switch gear assembly 100 and one current transformer 102 is arranged in the switch gear assembly 100.

The power component may be a power conducting component configured for conducting and/or interrupting a flow of power.

The power component may be a component configured for conducting or interrupting a flow of power, and comprises at least two contact elements being movable between a contact position for conducting a flow of power, and a spaced position for interrupting a flow of power.

The power component may be one out of a breaker and an interrupting chamber, or one out of disconnector and earthing switch components. Some power components, such as breakers, may comprise movable parts. In some examples, power components comprising movable parts may comprise a thermo- reversible gel adjacent said movable parts. However, in some applications, particles may be formed in the thermo-reversible gel when movable parts are worn against each other and possible arcs are created. In such applications, it may be advantageous if the insulation material adjacent said movable parts is free from thermo reversible gel.

Fig. 2 illustrates an example of a power component comprising movable parts, in the form of a breaker 101. The movable parts are in this example in the form of connectors being movable between an open position, interrupting a flow of power between the connectors, and a closed position, allowing a flow of power between the connectors. The power component 101 comprises a second housing 112 arranged inside said first housing 108, such that said first chamber volume 110 extends between said second housing 112 and said first housing 108. The second housing 112 encloses at least a portion of the one or more conductors 109, forming a second chamber volume 113 between said second housing 112 and said one or more conductors 109 (not shown in the second housing in the figure). The inner housing comprises an insulation material 114 insulating said conductors from said second housing 112. The movable parts are arranged inside the second housing 112.

When the power component comprises a second housing 112 forming a second chamber volume 113, the insulation material 114 in said second chamber volume 113 may be the same or it may be different from the insulation material 111 in the first chamber volume 110.

According to an alternative the second chamber volume 113 may comprise a gas as insulation material 114 and the first chamber volume 110 may comprise thermo reversible gel as insulation material 111.

When a second housing 112 is arranged inside the first housing 108, and thus two chambers are arranged in a housing 108, other configurations for the insulation material 111 and 114 can be applied. For example, the second chamber 113 may comprise thermo reversible gel. As an alternative, the second chamber volume 113 may comprise a gas as insulation material 114 and the first chamber volume 110 may comprise a thermo reversible gel as insulation material 111.

Fig. 3 illustrates a power component having a first housing 108 and a conductor 109. The power component illustrated in Fig. 3 is for a switch gear assembly 100, being a bushing 115. Such a bushing 115 could be used in a switch gear assembly, for example it could be a component in a variant of a switch gear assembly as outlined in Fig. 1.

The first housing 108 of the bushing 115 includes a first chamber volume 110 which may comprise insulation material 111 comprising thermo reversible gel.

Another example of a power component as disclosed herein may be a voltage transformer. Fig. 4 illustrates a power component having a first housing 108 and a conductor 109. A voltage transformer 106 is shown in Fig. 4. The first housing 108 of the voltage transformer 106 includes a first chamber volume 110 comprising an insulating material 111.

Barriers and/or support structures are shown also in other Figures but not numbered.

In another example, the power component may be a power component comprising a connector. There are power components which are used to connect the different parts of the switch gear assembly. For example a straight connector 104 is shown in Fig. 1. Another example of a power component in the form of a connector is an L-element forming a connector. An L-connector 117 is shown in Fig. 5, the L-connector having a first housing 108 and a conductor 109. The L-element has a first housing 108, a first chamber volume 110 and an insulation material 111 in the same manner as other power components. There are more examples of connectors, such as straight connectors, T- connectors and cross-shaped connectors.

The power components may comprise openings for filling the power components or connecting to further elements for example. Openings may be closed with lids and sealings and connection to further elements may comprise sealings. Further, there may be sealings arranged between power components. When first chamber volumes of first housings of the power components comprises gel, the pressure in the housings are not so high and the pressure handling requirement on the housings and sealings may be lower compared to when higher pressure gas is used as the insulating medium in the housings. The thermo reversible gel may not give high pressure on the first housing of the power component compared to if gas has been applied in a housing of a power component. Cost may then be reduced since there is not so high requirement on the sealings.

If thermo reversible gel would leak, it is not so devastating since the gel will not diffuse in the environment. In addition, if the thermo reversible gel would leak in liquid form, it will quite soon form a gel and will thus not diffuse in the environment.

The present disclosure relates in another aspect to a power station which may comprise one or more switchgear assemblies as disclosed herein.

The power station may further comprise at least one of one or more switch gear assemblies, one or more transformers, one or more converters, and/or one or more generators.

The thermo reversible gel may comprise 0.1 to 30 wt% of the thickener, calculated on the total weight of the gel. The viscosity of the thermo reversible gel may be adjusted by amending the content of the thickener.

The oil may be an iso-paraffinic oil, a mineral oil, a hydrocarbon based oil, a bio-based hydrocarbon oil, or a bio-based iso-paraffinic oil, or a mixture of any of the oils.

The styrene based copolymer may comprises a tri-block copolymer which consists of any of polystyrene-block-poly(ethylene-ethylene/propylene)-block-polystyrene (SEEPS), polystyrene-block-poly(ethylene/butylene)-block-polystyrene (SEBS), polystyrene-block- poly(ethylene/propylene)-block-polystyrene (SEPS), enhanced rubber segments (ERS) polymers, S-EB/S-S, alone or combination.

The styrene based copolymer may comprise a di-block copolymer which consists of any of polystyrene-block-poly(ethylene/propylene) and SEP, alone or in combination.

The styrene based copolymer may consist of the tri-block copolymer and the di-block copolymer. The thermo reversible gel may comprise 0 to 50 wt%, preferably 0 to 30 wt%, more preferred 0 to 10 wt%, of an additive for improvement of thermal and dielectric performance, calculated on the total weight of the gel.

The additive for improvement of thermal and dielectric performance may comprise particles of one or more of the following, alone or in combination: Boron nitride (BN), hexagonal boron nitride (h-BN), FesCU, Fe2C>3, ZnO, AI2O3, S1O2, CeC>2, T1O2, MgO, BaTiCh, CaCu3TUOi2 (CCTO), and Bao.85Cao.15Zro.1Tio.9O3 (BCZT).

The thermo reversible gel is a two-phase material. At a higher temperature, i.e. a temperature higher than the transition temperature, which is defined as the temperature where the tangent value of viscosity shows the maximum value, the gel is a liquid. With the temperature reduced to a temperature lower than the transition temperature the gel is a semisolid material. The gel can work both in the liquid phase and in the semisolid phase dependent on the service temperature. The thermo reversible gel, consists of two parts: an oil and a thickener. Both the selected oil and the thickener are insulating materials and the thermo reversible gel is a dielectric gel with high dielectric performance. The typical breakdown strength of the thermo reversible gel is over 20 kV/mm for example 40 kV/mm which is higher than that of SF₆ gas. The breakdown strength may be above 40 kV/mm. The breakdown phenomena in the thermo reversible gel are self-healable. Furthermore, the thermo reversible gel may be anti-explosive due to its excellent elastic properties, may be environmentally friendly with less leakage issue and may reduce or avoid contamination to the air and to the earth soil.

Table 1 shows the examples of components for gel formulation. The gel consists of insulating oils, such as mineral oils, iso-paraffinic oils, hydrocarbon based oils, or a mixture of them, the thickener of styrenic block copolymers, and optional other additives, such as, antioxidants, for example, DBPC (C₁₅H₂₄O) or octadecyl 3-(3,5-di-tert-butyl-4- hydroxyphenyl) propionate (C₃₅H₆₂O₃) and the additives to increase the thermal & dielectric performances of gel, such as, boron nitride (BN), hexagonal boron nitride (h- BN), the nano structures of FesCU, Fe2C>3, ZnO, AI2O3, S1O2, Ce02, T1O2, MgO, BaTi03, CaCu3TUOi2 (CCTO), and Bao.85Cao.15Zro.1Tio.9O3 (BCZT). Wth the use of fire-resistant fluid in formulation, such as the beta fluid in Table 1 , the gel will have a relative high fire point (~ 308 °C), is less flammable and is self-extinguishable when the source of a fire is removed. With the use of bio liquid in the gel, such as bio-based hydrocarbon or bio-based iso- paraffinic oil in Table 1, the gel will have a sustainable feature and thus the switchgear is a renewable product.

The gel is a mixture of insulating oil with the thickener. The fabrication of gel is exampled as follows: Preheat the insulating oil to a reference temperature such as at 100 °C. Add the thickener into the preheated oil, and raise the oil temperature to a higher value such as over 120 °C. A stirring system, such as a heating plate with the function of magnetic stirring, is introduced in order to shorten the time of mixing. A vacuum environment is good for degassing the oil, but it is not a necessary step in obtaining a gel. As a successful result, the thickener is fully dissolved in the oil during the mixture, and then a clear and transparent gel is obtained after the temperature is reduced to below the transition temperature of some gels as can be seen in Fig. 6. Further, curves for two oils are also disclosed. The gels and oils are

1. A mineral oil, 2. A hydrocarbon oil,

3. A gel: a mineral oil + 1.0 wt% a tri-block copolymer, calculated on the total weight of the gel.

4. A gel: another hydrocarbon oil + 0.8 wt% a tri-block copolymer + 1.6 wt% a di block copolymer + 0.3 wt% antioxidant, calculated on the total weight of the gel. 5. A gel: another mineral oil + 1.0 wt% a tri-block copolymer, calculated on the total weight of the gel.

6. A gel: a hydrocarbon oil + 1.5 wt% a tri-block copolymer, calculated on the total weight of the gel. The wt% are calculated on the total weight of the gel if nothing else is stated. In Fig. 6 the complex viscosity is shown against the temperature. The transition temperature can be seen as indicated by an arrow for the curve for gel 3. The transition temperature is also sometimes called the knee temperature. At a temperature higher than the transition temperature the gel is a liquid and at a temperature lower than the transition temperature the gel is semisolid. The viscosity values of gel are controllable by controlling the content of thickeners, such as, between 0.001 wt% and 50 wt%, preferable between 0.1 wt% and 10 wt%, calculated on the total weight of the gel. The content of antioxidants can be less than 10 wt%, preferable less than 1 wt%, more-preferable less than 0.5 wt%, calculated on the total weight of the gel. The content of the additives for the improvement of thermal & dielectric performances are between 0 and 50 wt%, preferable less than 30 wt%, more- preferable less than 10 wt%, calculated on the total weight of the gel. The transition temperature of gel is also adjustable with the use of different oils, alternatively the use of thickeners with different molecular weight. The higher the molecular weight of thickener, the higher the transition temperature is.

Since SF₆ is used at different locations in the application of switchgear, those are the locations in which the SF₆ could be replaced by the thermo reversible gel totally or partially.

Table 1. Formulation of invented gels for the application in gel-insulated switchgear.

A method for assembling a power component is disclosed herein comprising the steps of: filling the first chamber volume of the power component with the thermo reversible gel in liquid form or in semi-solid form.

The first chamber volume of the power component may be filled under vacuum.

The method may comprise filling a first chamber volume of the power component as disclosed herein. The method may comprise filling the first chamber volume of the power component with a gas, such as air, fluoronitrile-based gas, or SF₆ gas.

The method may comprise filling the first chamber volume of the power component with a mixture of the thermo reversible gel and a gas, such as air, fluoronitrile-based gas or SF₆ gas, wherein the filling is performed under pressure.

The method may comprise filling the second chamber volume of the power component with the thermo reversible gel in liquid form or in semi-solid form.

The method may comprise one or more of the following steps performed before the step of filling the first chamber volume, degassing the oil, adding the thickener to the oil and mix the oil and the thickener, heating the mixture of oil and thickener, reducing the temperature of the mixture to a temperature higher than the transition temperature of the gel and/or setting vacuum at the first chamber volume to be filled with the thermo reversible gel. Further, the method may comprise one or more of the following steps before filling the first chamber volume, degas the oil in vacuum condition, such as around 1 mBar, at a preheated temperature, such as between 50 and 80 °C, add the thickeners, and optional the additives, into the degassed oil and raise the temperature to over 120 °C, such as between 130 °C and 200 °C. The temperature is dependent on which oil is used.

The degas step may eliminate moisture and gas bubbles inside the oil.

The thickeners are dissolved in the oil by a mixture process. A stirring system, such as a mechanical or magnetic stirring system, may be used for shortening the time of mixing until a clear oil phase of gel is obtained.

The method comprises to reduce the temperature to a temperature higher than the transition temperature of gel. Then the liquid gel phase of gel is ready for the filling. The method for filling the first chamber volume with thermo reversible gel may further comprise one or more of the following steps setting vacuum and elevated temperature conditions inside the first housings of the power components of switchgear that are to be filled with the gel, turning off the vacuum and let dry air or nitrogen gas, such as at the atmospheric pressure, go into the mixture tank that contains the liquid phase of gel, filling the oil phase of gel into the components of switchgear through opening the filling tubes that conduct the gel mixture tank and the components. Thus, the liquid phase of gel will be filled into the components due to the inside pressure difference between the gel mixture tank and the switchgear components.

Further, the method may comprise ending the filling when the gel was filled in each wished housing inside the switchgear assembly.

The present disclosure is not limited to the examples of variants described herein, but other options and alternatives will be available to the person skilled in the art.

Claims

1. A power component (101-107, 119), for a switch gear assembly (100), the power component (101-107, 119) being configured for use at voltages of at least 36 kV, the power component comprising at least a first housing (108), and comprising one or more conductors (109) for conducting power being arranged in said first housing (108), wherein a first chamber volume (110) between said first housing (108) and said one or more conductors (109) comprises an insulation material (111) insulating said conductors (109) from said housing (108) characterized in that the insulation material (111) comprises a thermo reversible gel.

2. The power component according to claim 1 , wherein the power component (101- 107, 119) comprises a second housing (112) arranged inside said first housing (108), such that said first chamber volume (110) extends between said second housing (112) and said first housing (108), wherein the second housing (112) encloses at least a portion of said one or more conductors, wherein a second chamber volume (113) between said second housing (112) and said one or more conductors comprises an insulation material (114) insulating said conductors from said second housing (112).

3. The power component according to claim 1 or 2, wherein said insulation material

(111, 114) of said first chamber volume (110) and/or second chamber volume (113) comprises a continuous volume of the thermo reversible gel.

4. The power component according to any of claims 1 to 3, wherein said insulation material (111, 114) of said first chamber volume (110) and/or second chamber volume (113) comprises a permeable solid insulation material impregnated with said thermo-reversible gel.

5. The power component according to any of claims 1 to 4, wherein said insulation material (111, 114) of said first chamber volume (110) and/or second chamber volume (113) comprises the said thermo-reversible gel and a non-permeable solid insulation material.

6. The power component according to any of the claims 1-5, wherein said insulation material of the first chamber volume (110) and/or second chamber volume (113) comprises a mixture of the thermo reversible gel and gas, such as SF₆, air or fluoronitrile-based gas.

7. The power component according to claim 2 alone or in combination with any one of the claims 3 to 6, wherein said insulation material (114) of said second chamber volume (113) is free from thermo-reversible gel and comprises an insulating gas, such as SF₆, air orfluoronitrile-based gas.

8. The power component according to any of the preceding claims, the thermo reversible gel comprising an oil in amount of 50 to 99.9 wt% and a thickener in an amount of 0.0001 to 50 wt%, calculated on the total weight of the gel, the thermo reversible gel comprises iso-paraffinic oil, a mineral oil, a hydrocarbon based oil, a bio-based hydrocarbon oil, or a bio-based iso-paraffinic oil, or a mixture of any of the oils and the thickener comprises a styrene based copolymer.

9. The power component according to any of the preceding claims, wherein the thermo reversible gel comprises 0.001 to 30 wt% of the thickener, or preferably 0.01-10 wt%, 0.1-6 wt% calculated on the total weight of the gel.

10. The power component according to any of the preceding claims, wherein the styrene based copolymer comprises a tri-block copolymer which consists of any of polystyrene-block-poly(ethylene-ethylene/propylene)-block-polystyrene (SEEPS), polystyrene-block-poly(ethylene/butylene)-block-polystyrene (SEBS), polystyrene-block-poly(ethylene/propylene)-block-polystyrene (SEPS), enhanced rubber segments (ERS) polymers, S-EB/S-S, alone or combination.

11. The power component according to any of the preceding claims, wherein the styrene based copolymer comprises a di-block copolymer which consists of any of polystyrene-block-poly(ethylene/propylene) and SEP, alone or in combination.

12. The power component according to claims 10 and 11, wherein the styrene based copolymer consists of said tri-block copolymer and said di-block copolymer.

13. The power component according to any of the preceding claims, wherein the thermo reversible gel comprises 0 to 50 wt%, preferably 0 to 30 wt%, more preferred 0 to 10 wt%, of an additive for improvement of thermal and dielectric performance, calculated on the total weight of the gel.

14. The power component according to claim 13, wherein the additive for improvement of thermal and dielectric performance comprises particles of one or more of the following, alone or in combination: Boron nitride (BN), hexagonal boron nitride (h-BN), Fe₃C>4, Fe₂C>3, ZnO, AI2O3, Si0₂, Ce0₂, T1O2, MgO, BaTiCh, CaCu3TUOi2 (CCTO), and Bao.85Cao.15Zro.1Tio.9O3 (BCZT).

15. The power component according to any of the preceding claims, wherein said power component is configured for conducting a flow of power, preferably said power component is one out of a bushing (115) and a connector (103, 104).

16. The power component according to claim any of claims 1-14, wherein said power component is a power conducting component configured for conducting and/or interrupting a flow of power.

17. The power component according to claim any of claims 1-14 or 16, wherein said power component is a component configured for conducting or interrupting a flow of power, and comprises at least two contact elements being movable between a contact position for conducting a flow of power, and a spaced position for interrupting a flow of power.

18. The power component according to claim 17, wherein said power component is one out of a breaker (101) and an interrupting chamber, or one out of disconnector (119) and earthing switch components.

19. The power component according to claim 18, wherein said power component is a breaker (101), or a disconnector (119), or an earthing switch.

20. The power component according to any one of the claims 1 to 14, wherein the power component is a control system component, preferably an instrument transformer such as a current transformer (102) or a voltage transformer (106), or a combined transformer.

21. A switchgear assembly (100) comprising one or more power components (101- 107, 119) according to any one of the preceding claims.

22. The switchgear assembly according to claim 21 , wherein at least two, preferably a majority of, most preferred all out of said one or more power components comprised in the switchgear assembly (100) are according to any one of the claims 1 to 20.

23. The switchgear assembly according claim 21 or 22, wherein at least one of the one or more power components comprises an insulation material comprising a gas, such as SF₆, air or fluoronitrile-based gas.

24. The switchgear assembly according to claim 23, wherein at least one of the one or more power components comprise an insulation material free from said thermo-reversible gel, for example comprising an insulation material comprising a gas, such as SF₆, air or fluoronitrile-based gas.

25. The switchgear assembly according to claim 24, wherein at least one of the one or more power components comprises movable parts and wherein the said insulation material of said power component comprising movable parts comprises a gas, such as SF₆, air or fluoronitrile-based gas.

26. The switchgear assembly according to any one of the claims 21 to 25, comprising two or more power components, wherein said first housings of said at least two components are interconnected to form a common switch gear assembly housing for said at least two power components.

27. A power station comprising one or more switchgear assemblies according to any one of the claims 21 to 26.

28. The power station according to claim 27, wherein the power station further comprises at least one of one or more switch gear assemblies, one or more transformers, one or more converters, and/or one or more generators.

29. A method for assembling a power component according to any one of the claims 1 to 20 comprising the steps of: filling the first chamber volume of the power component with the thermo reversible gel in liquid form or in semi-solid form.

30. The method according to claim 29, wherein the first chamber volume of the power component is filled under vacuum.

31. The method according to any of claims 29-30, wherein the power component comprises a second chamber volume, the method comprises filling a second chamber volume of the power component with a gas, such as air, fluoronitrile- based gas, or SF₆ gas.

32. The method according to any of claims 29-31 , wherein the method comprises filling the first chamber volume of the power component with a mixture of the thermo reversible gel and a gas, such as air, fluoronitrile-based gas or SF₆ gas, wherein the filling is performed under pressure.

33. The method according to any of claims 29-32, wherein the method comprises one or more of the following steps performed before the step of filling the first chamber volume, degassing the oil, adding the thickener to the oil and mix the oil and the thickener, heating the mixture of oil and thickener, reducing the temperature of the mixture to a temperature higher than the transition temperature of the gel and/or setting vacuum at the first chamber volume to be filled with the thermo reversible gel.