System and method for analyzing an insulating fluid with nmr

Abstract

A system (100) comprises an electrical apparatus (1) configured to comprise, in operation, an insulating liquid (2), wherein the NMR device (3) is configured to analyze gas (14) extracted from the insulating liquid (2) and / or gas (10) from a gas space (9) of the electrical apparatus (1), wherein the NMR device (3) is fluidically coupled to the electrical apparatus (1) for on-site analysis of the gas (10, 14).

Description

[0001] P2024,0583 WO E / P240013WO01 September5,2024 -1 - DescriptionSystem and method for analyzing an insulating fluidThe present disclosure relates to a system comprisi ng anelectrical apparatus comprising an insulating liqui d duringoperation and an NMR device for analyzing the insul atingliquid.US 2017 / 0168034 A1 discloses an apparatus for monit oringproperties of an insulating fluid of a power device bymicroelectronic, opto-electronic, micro- and / or nan o-scaleelectromechanical,electrochemicaland / ordetector componentsinstalled at a surface of a probe, which is in cont act withthe fluid through a valve in an open position. Samp les of thefluid may be drawn and subjected to laboratory anal ysis suchasgaschromatographyand NMR spectroscopy.Embodiments of the disclosure relate to an improved systemenabling analyzing an insulating liquid in an elect ricalapparatus.One objectto be achieved isto provide a system which contributesto a quickand reliable analysis ofan insulating liquid. According to a firstaspect,a system comprisesan electrical apparatusconfigured to comprise,in operation,an insulatingliquid. The system further comprises an NMR device configuredto analyze a sample of the insulating liquid and fu rtherconfigured to analyze gas extracted from the insula tingliquid and / or gas from a gas space of the electrica lapparatus. The NMR device is coupled to the electri calapparatusforon-site analysisofthe gas. P2024,0583 WO E / P240013WO01 September5,2024 -2 -The electrical apparatus may be a power or distribu tiontransformer,a reactor,a phase-shifteroranother devicewhere an insulating liquid is present in operation. Such anelectrical apparatus is subjected to degradation du e toregular usage, environmental stress or loading cond itions.Since such an apparatus can be an essential piece o fequipment for the backbone of the electrical system of anycountry, a relevant technological effort is applied to thedevelopment of condition-based maintenance and to t hecondition assessmentofsuch apparatuses.The degradation rate of such an electrical apparatu s can bemonitored by analyzing the insulating liquid used i n theapparatus.The apparatusmaycomprise a functional elementimmersed in a tank filled with an insulating fluid. It isalso possible that the insulating liquid circulates through aportion of the electrical apparatus during operatio n. Theinsulating liquid may be used for cooling and / or in sulatingpurposes. The insulating liquid is or comprises, fo r example,a mineral oil, a natural ester or a synthetic ester s liquid.The functional element may be a winding of a transf ormer, forexample. Generally, heat generating elements and / orelectrical current transporting elements of the ele ctricalapparatus may be surrounded by the insulating liqui d duringoperation. A gasspace in the electricalapparatusisa space above theinsulating liquid filled with gas. The gas space al lows forthe expansion and contraction of the insulating liq uid as itstemperature changes. The gas space may be filled wi thnitrogen or air, for example. The gas space may als o comprisecontaminants deriving from a degradation of the ele ctrical P2024,0583 WO E / P240013WO01 September5,2024 -3 -apparatus. This may also comprise volatile contamin ants fromthe insulating liquid. Itisalso possible thatthe transformercomprises anexpansion tank, apart from the main transformer tan k and aphysicalbarrier,forexample a rubberbag,maybe used toprevent the direct contact between the insulating l iquid andthe gas. Another possibility used in transformers i s to havemechanically expansible elements coupled to the mai n tank,not requiring a gas space above the insulating liqu id.The NMR device (“NMR”forNuclearMagneticResonance)comprises a magnet arrangement for producing a magn etic fieldin a sample region, radio frequency electronics for producingradio frequency signals and a coil for coupling the radiofrequency signal into the sample. The assembly of m agnetarrangement, sample region, transmitter coil and re ceivercoil can also be denoted as NMR probe. Moreover, th e NMRdevice may comprise electronics for measuring and / o ranalyzing the absorption of the radio frequency sig nal by thesample. The magnet arrangement may be a permanent m agnetarrangementoran electricmagnetarrangement.For example,the permanent magnet arrangement is a Halbach arran gement.NMR technology allows an accurate identification an dquantification of compounds in a sample, also for t inyquantitiesofthe compounds. The NMR device isconfigured foron-site analysis. Thismeanson the one hand that the NMR device is small enough to beinstalled directly at or adjacent to the electricalapparatus. The NMR device may comprise a single, co mpactdevice or several separate, compact sub-devices. Th e NMRdevice or each of the sub-devices may be small enou gh to be P2024,0583 WO E / P240013WO01 September5,2024 -4 -installed inside a tank of the electrical apparatus . Forexample, the NMR device has dimensions which are sm aller than50 cm. Such an NMR device can be denoted as mini-NM R device.In the system, the NMR device may be installed outs ide thetransformer tank. As an example, the NMR device can beinstalled at the tank or separate from the tank. It is alsopossible that the NMR device is installed inside th e tank.A mini-NMR device or a portable NMR device, respect ively, is,forexample,described in the papersofDongwan Ha etal.“Scalable NMR spectroscopy with semiconductor chips ”, PNAS2014, Vol. 111, No. 33, pages 11955-11960; or in th e paper byKa-Meng Lei et al. “Portable NMR with Parallelism”, Anal.Chem.2020,92,2112-2120.FurtherNMR devicesare disclosed in US 11,506,810 B2 and US 10,295,636 B2.However, an NMR device for on-site operation has no t only tobe small enough but also has to comprise sufficient electricand magneticshielding foran operation atornear theelectrical apparatus such as a power transformer. A lso,sufficient mechanical robustness is required both f orstructural reasons and to avoid the NMR measurement devicebeing affected by the mechanical vibration generate d by thetransformers.By using an NMR device for on-site operation, the c ycle timesrequired to analyze a sample can be reduced. Shippi ng asample to a laboratory is not required. Furthermore , a samplecan be automatically taken from the insulating liqu id in acontinuousorintermittentmatter. P2024,0583 WO E / P240013WO01 September5,2024 -5 -Analyzing both the liquid and the gas extracted fro m theinsulating liquid orgasfrom the gasspace ofthe electricalapparatus has the advantage of allowing for a highe rsensitivity and accuracy in comparison to solely an alyzing asample ofthe insulating liquid.As examples, when analyzing gas, interactions occur ring in aliquid phase are reduced or absent and, thus, sharp er NMRpeakscan be achieved.Also interfering signalsof thesolvent can be avoided. Thus, artifacts and electri c noisecan be reduced when analyzing gas and a higher prec ision canbe achieved when combining the results of the gas a nalysisand the resultsofthe liquid analysis.The NMR device may be configured to analyze the sam ple of theinsulating liquid, extract gas from this sample and analyzethe extracted gas.Accordingly,the NMR device may be configured to analyze the sample ofthe insulating liquidused for gas extraction. This has the advantage tha t theresults from the gas analysis and the liquid analys is areobtained from the same sample and the accurateness ofthe overallresultforthe sample isincreased. The NMR device comprisesan NMR probe connected by a fluidicconnection to the electrical apparatus. “Fluidic co nnection”means thata sample ofthe insulating fluid orthe gasto be analyzed can flow from the electricalapparatusto the NMRdevice such that the sample can be automatically tr ansportedby the fluidic connection to the NMR device. Thereb y, acontinuous or intermittent automatic analysis is en abled. Thefluidic connection may be provided by one or more p ipes, forexample. The NMR probe can be configured for analyz ing boththe gas and the sample of the insulating liquid. It is also P2024,0583 WO E / P240013WO01 September5,2024 -6 -possible that the NMR probe is used for analyzing t he gas anda further NMR probe is present for analyzing the sa mple ofthe insulating liquid. The system maycomprise a gasextractorlocated in thefluidic connection for extracting gas from a sample of theinsulating liquid and for feeding the extracted gas to theNMR probe. This enables the NMR probe to analyze th eextracted gas supplied by a fluidic connection from theelectrical apparatus to the NMR probe via a gas ext ractor.The system may comprise a liquid outlet for feeding a sampleof the insulating liquid back to the electrical app aratusafter being analyzed and after gas extraction. Acco rdingly,the insulating liquid can be reused in the electric alapparatusand separate refilling ofthe electrical apparatus isnotrequired.The electrical apparatus may comprise a tank housin g theinsulating liquid, wherein the tank comprises a gas spacelocated above the insulating liquid. A functional e lement ofthe electrical apparatus may be immersed in the ins ulatingfluid.The NMR device maybe fluidicallyconnected to the gasspace. In this case, a gas extractor is not require d.Thereby, the process of preparing the sample for an alysis canbe simplified. The NMR device or at least the NMR p robe canbe located in the gas space. Alternatively, the NMR probe islocated outside the tank and is connected by a flui dicconnection,e.g.,a pipe to the gasspace.The NMR device may comprise an NMR probe for analyz ing thegasand a furtherNMR probe foranalyzing a sample oftheinsulating liquid. Both the NMR probe and the furth er NMR P2024,0583 WO E / P240013WO01 September5,2024 -7 -probe can be fluidically connected to the electrica lapparatus. As an example, the NMR probe for analyzi ng the gascan be the NMR probe described in the following, ei therconnected to the insulating liquid via a gas extrac tor or toa gasspace ofthe electricalapparatus.The further NMR probe may be located in a fluidic c onnectionof the NMR probe with the electrical apparatus. The furtherNMR probe maybe configured to analyze a sample of an insulating fluid.Afterthat,gascan be extracted from the sample and provided to the NMR probe foranalysis. Thereby,the same sample can be analyzed in the liquid state and thegas state, leading to a higher precision of the res ults. Thesystem may comprise electronics for analyzing the s ignals.Asmentioned above,itisalso possible to analyze the gasand the insulating liquid by the same NMR probe. Th us, theNMR device comprises a single NMR probe for analyzi ng boththe gassample and the liquid sample.Accordingly, the NMRprobe for analyzing the gas sample is also provided foranalyzing the liquid sample. As an example, the liq uid samplemay be first analyzed by the NMR probe and, after t hat, gasis extracted from this liquid sample and analyzed b y the NMRprobe. Thereby, costs for the NMR device can be red uced.The NMR device may be simultaneously fluidically co upled orsimultaneously fluidically couplable to a plurality ofelectrical apparatuses. Particularly, when simultan eouslycoupled to a plurality of NMR devices, a fluidic co nnectionfrom the NMR device to each of the electrical appar atuses isestablished. In this way, a sample of the insulatin g liquidfrom each of the electrical apparatuses can flow in to thesample region ofthe NMR device. P2024,0583 WO E / P240013WO01 September5,2024 -8 -The NMR device may be configured to analyze the ins ulatingliquid ofthe pluralityofelectricalapparatusessimultaneously or one after the other. For example, the NMRdevice comprisesa separate sample region foreach oftheelectrical apparatuses to which it is simultaneousl yfluidically coupled, or samples of two or more elec tricalapparatuses are mixed in the sample region of the N MR device.Alternatively, when simultaneously fluidically coup led toseveral electrical apparatuses, samples from differ entelectrical apparatuses are transferred one after th e other tothe sample region in order to analyze them one afte r theother.A method for analyzing an insulating liquid of an e lectricalapparatus comprises the steps of providing a systemcomprising an electrical apparatus comprising an in sulatingliquid and an NMR device fluidically connected to t heelectrical apparatus for on-site analysis. The meth od furthercomprises the step of extracting gas from the insul atingliquid and / or gas from a gas space of the electrica lapparatusand analyzing the gasbythe NMR device. The systemmay comprise any functional and structural features of thesystem described in the foregoing.The method may further comprise the step of extract ing gasfrom the insulating liquid by a gas extractor. Furt hermore,the insulating liquid maybe additionallyanalyzed directlyby providing a further NMR probe for analyzing a sa mple ofthe insulating liquid in addition to an NMR probe f oranalysis of a sample of the gas. It is also possibl e that thesame NMR probe is used for analyzing the liquid sam ple andthe gassample. P2024,0583 WO E / P240013WO01 September5,2024 -9 -Furthermore, the gas used for analysis is extracted from thesample ofthe insulating liquid used foranalysis, whereinthe gas is analyzed first and the sample of the ins ulatingliquid is analyzed subsequently, wherein the result of theanalysisofthe gasisused in the analysisofthe sample ofthe insulating liquid. The gas analysis can provide the typeand content of a sub-group of contaminants which ar e presentin the sample of the insulating liquid. The analysi s of thesub-group can facilitate the analysisofthe othercontaminants in the insulating liquid and improve t heaccuracy of the liquid phase measurements, both for the sub-group and the othercontaminants.The present disclosure comprises several aspects an dembodiments. Every feature described with respect t o one ofthe aspects and embodiments is also disclosed herei n withrespectto the otheraspectsand embodiments,even iftherespective feature is not explicitly mentioned in t hiscontext.Further features, refinements and expediencies beco meapparent from the following description of the exem plaryembodimentsin connection with the figures.In the figures,elements of the same structure and / or functionality may bereferenced by the same reference signs. It is to beunderstood that the embodiments shown in the figure s areillustrative representations and are not necessaril y drawn toscale.Figure 1 shows an embodiment of a system in a schem atic view, P2024,0583 WO E / P240013WO01 September5,2024 -10 -Figure 2 shows a part of an embodiment of an NMR de vice foranalyzing gas in the system of Fig. 1 in a schemati c view,Figure 3 shows an embodiment of an NMR device in th e systemofFig.1 in a schematicview,Figure 4 shows a further embodiment of an NMR devic e in thesystem ofFig.1 in a schematicview,Figure 5 to 8 show further embodiments of systems i nschematicviews.Fig. 1 shows an embodiment of a system 100 comprisi ng anelectrical apparatus 1 configured to be operated wi th aninsulating liquid 2. The system 100 further compris es an NMRdevice 3 configured to analyze gas extracted from t heinsulating liquid 2 ofthe electricalapparatus1. The NMRdevice 3 is on-site, e.g., directly installed at th eelectricalapparatus2. The system 100 furthercomprisesa processor5 and a userinterface 4, namely a display. The processor 5 and / or theuserinterface 4 maybe on-site atthe location of theelectrical apparatus 1 or may be remote from the el ectricalapparatus,e.g.,in a controlcenter.The electrical apparatus 1 can be a transformer, e. g., a highvoltage transformer or power transformer, a reactor oranother device where a functional element 7 is plac ed in atank 8 filled with an insulating liquid 2. The insu latingliquid 2 may be a mineral oil, for example, or a na tural or asynthetic ester fluid. P2024,0583 WO E / P240013WO01 September5,2024 -11 -The electrical apparatus 1 is subject to degradatio n, whereinthe degree ofdegradation can be determined bythe contentofspecific gases in the insulating liquid 2. For prov idingcontinuous and accurate monitoring of the health st atus ofthe electrical apparatus 1, the NMR device 3 is cou pled by afluidic connection 6 to the insulating liquid 2. Th ereby, asample of the insulating liquid 2 can be continuous ly orintermittentlydrawn from the electricalapparatus 1 duringoperation of the electrical apparatus 1. The system 100 maybe configured to analyze the sample automatically a t a pre-selected frequency, e.g., every 15 minutes. The ana lysis iscarried out on-site such that a transport of the sa mple to alaboratory is not required. Furthermore, the analys is iscarried out online, during operation of the electri calapparatus1.It is also possible that the NMR device 3 is additi onallycoupled bythe fluidicconnection 6 to a gasspace 9 ofthe electricalapparatus1,wherein the gasspace 9 is a space inthe tank 8 filled with gas 10, which is located abo ve theinsulating liquid 2. The gas space 9 allows for the expansionand contraction of the insulating oil as its temper aturechanges. The gas space 9 may be filled with nitroge n or air,for example, and gases deriving from the insulating liquidwhich may result from a degradation of the electric alapparatus 1. It is also possible that the NMR devic e 3 ispositioned inside the electrical apparatus 1, e.g., in thegasspace 9 orin the insulating liquid 2.The fluidic connection 6 extends from the tank 8 to the NMRdevice 3 and from there backinto the tank8.This allows refeeding the sample ofthe insulating liquid 2 to the tank8. Thereby, separate refilling of the insulating li quid 2 can P2024,0583 WO E / P240013WO01 September5,2024 -12 -be avoided. Accordingly, the insulating liquid 2 ci rculatesin the fluidicconnection 6.It is also possible that the fluidic connection 6 d oes notextend back into the tank 8. This may require refil linginsulating liquid 2 from time to time. The NMR device 3 isconfigured to analyze a sample oftheinsulating liquid 2. Additionally, the NMR device 3 isconfigured to analyze a sample of gas extracted fro m theinsulating liquid 2 and / or a sample of gas directly providedfrom the gas space 9. When the NMR device 3 is conf igured toanalyze a sample of gas extracted from the insulati ng liquid2, the NMR device 3 may comprise a gas extractor (s ee Fig.2).For directly analyzing a sample of the insulating l iquid 2,the sample can be analyzed before gasisextracted from thesample. It is also possible that a different sample of theinsulating liquid 2 is analyzed than used for extra cting gas.In this case, the insulating liquid 2 may be provid ed to theNMR device 3 by the fluidic connection 6 or by a fu rtherfluidicconnection.The NMR device 3 is configured to analyze the gas f or one ormore specific compounds. Analyzing the gas in addit ion toanalyzing the liquid has the advantage that the sen sitivityand accuracy of detection can be increased in compa rison toonly analyzing a sample of the insulating liquid 2. As anexample, interactions occurring in a liquid phase a re reducedor absent and, thus, sharper NMR peaks can be achie ved. Alsointerfering signalsofthe solventcan be avoided.Furthermore, a higher relative and / or absolute conc entration P2024,0583 WO E / P240013WO01 September5,2024 -13 -of specific gases can be analyzed in a sample. As a n example,NMR analysis enables identifying and quantifying sp ecificcarbonyls and hydrogen bonds in the molecular struc ture.Thereby, contaminants such as acids and oxid byprod ucts canbe identified and properties of the insulating liqu id 2estimated. The properties will change with operatio n of theelectrical apparatus 1 and the circulation of the i nsulatingliquid 2.The specific compounds can be, for example, dissolv ed gasesand volatile compounds. Further compounds can be, f orexample, free gases, combustible gases, non-combust iblegases.Othercompoundssuch assolid and / orliquid insulation aging markers,contaminants,water,soluble acids, aldehydes,alcohols, oxidation byproducts, peroxides, oxidatio ninhibitors and additives, sludge, particulate matte r can bedetected in the liquid phase.By analyzing the gas phase volatile contaminants an d gasespreviously dissolved in the liquid are detected. Du e to theabsence of the insulating liquid and all non-volati lesubstances, the content of the contaminants investi gated inthe gas phase can be magnified. The well-known corr elationsbetween contents of substances in the gas phase and dissolvedin the liquid, e.g. as described by the Ostwald coe fficients,allows using the results from the gas-phase analysi s toidentifythe remaining contaminantsin the liquid, afterthedissolved gases and volatile contaminants have been measuredin the gas phase. Thus, the type and content of a s ub-groupof the contaminants in the liquid can be identified byanalyzing the gas phase and by converting the resul ts for theliquid phase.Accordingly,the type and contentof a sub-group of the contaminants in the liquid-phase is “p re- P2024,0583 WO E / P240013WO01 September5,2024 -14 -calculated”, thereby facilitating identification of the othercontaminants in the liquid and improving the accura cy of theliquid phase measurements.The NMR device 3 is connected by a signal connectio n 11 tothe processor5.The signalconnection 11 can be a wired or wirelessconnection.The processor5 isconfigured todetermine operating parameters of the gas depending on thecompoundsanalyzed with the help ofthe NMR device 3.Forexample, depending on the information provided by t he NMRdevice 3, for example the measured absorption spect rum, theprocessor 5 can determine the amount of important g ases suchashydrogen,methane,acetylene,ethylene,ethane, carbonmonoxide, carbon dioxide, oxygen, and other volatil esubstances,such aslow-molecular-weightacids.The processor 5 is connected by a further signal co nnection12 to the user interface 4 so that the operating pa rameterscan be shown ata display,forexample.Itisalso possiblethat an alarm is provided when the analysis shows a criticalcondition ofthe electricalapparatus1.Fig. 2 shows a detailed, partial view of an exempla ryembodiment of an NMR device 3 comprising a gas extr actor 13and an NMR probe 38 for analyzing a sample of the g as. TheNMR device 3 can be used in the system 100 of Fig. 1. TheNMR device 3 is also configured for analyzing a sam ple of theinsulating liquid 2, as shown in the further Figure s.The NMR device 3 is a mini-NMR device or portable N MR device.The dimensions of the whole NMR device 3 do not, fo r example,exceed 50 cm in each spatialdirection. P2024,0583 WO E / P240013WO01 September5,2024 -15 - The NMR device 3 maycomprise sub-devices,wherein one ofthesub-devices comprises an NMR probe 38 for analyzing the gasand a further one of the sub-devices may comprise a furtherNMR probe for analyzing the insulating liquid. It i s alsopossible that both NMR probes 38, 39 are positioned in asingle compactdevice.Furthermore,itispossible thatthegas and the insulating liquid are analyzed in a sin gle NMRprobe.As an example, the NMR device 3 may have a structur e asdescribed in US 11,506,810 B2 and US 10,295,636 B2 orin thepapers of Dongwan Ha et al. “Scalable NMR spectrosc opy withsemiconductorchips”,PNAS 2014,Vol.111,No.33, pages 11955-11960;orin the paperbyKa-Meng Leietal. “PortableNMR with Parallelism”, Anal. Chem. 2020, 92, 2112-2 120 or inthe disclosure in.However, the NMR device 3 is configured to be robus t andelectrically shielded to be installed on-site at th e locationof the electrical apparatus 1. As an example, the N MR device3 may be directly installed at the electrical appar atus 1,e.g., at the wall of the tank 8. The NMR device 3 m ay beinstalled atan outerside ofthe wallofthe tank 8.In someembodiments, the NMR device 3 may be also installed insidethe tank 8. Furthermore, in contrast to the known m ini-NMRdevices,the NMR device 3 isconfigured to analyze circulating gases.The NMR device 3 comprises a gas extractor 13 for e xtractinggasfrom the insulating liquid 2 being provided by the fluidicconnection 6.Itisalso possible thatthe gasextractor 13 is a component separate from the NMR d evice 3. P2024,0583 WO E / P240013WO01 September5,2024 -16 -The insulating liquid 2 flows through a liquid inle t 6a tothe gasextractor13,where a calibrated volume of gas14 isextracted from the insulating liquid 2. Gas extract ion may beperformed byvacuum extraction orbyexpanding the volume ofa vial containing a sample of the insulating liquid 2, forexample.The extracted gas 14 flows from the gas extractor 1 3 via agasconnection 6b to a sample region 34 ofthe NMR device 3, where the analysisisperformed.The sample region 34 maybe a capillarytube.The sample of the insulating liquid 2 flows back vi a a liquidoutlet 6d to the electrical apparatus 1, in particu lar backinto the tank 8. This avoids the necessity of separ atelyrefilling insulating liquid 2 into the tank8.The NMR device 3 comprises a magnet arrangement 35, forexample a Halbach arrangement of permanent magnets. Thereby,a uniform and, thus, high-quality magnetic field ca n begenerated.The magnetarrangement35 surroundsthe sampleregion 34 into which the sample of the gas is guide d via thegas connection 6b. The magnet arrangement generates amagneticfield B.A transmitter coil and a receiver coil surround the sampleregion 34 and are connected to an integrated circui t chip 30,also referred to as IC chip. The IC chip 30 include s atransmitter 31 and a receiver 32 as well as electro nics 33for producing radiofrequency signals and for analyz ing thesignal received with the help of the receiver 32. T heanalysis of the signal can be also done by the proc essor 5shown in Fig. 1. Such an analysis is indicated in t he diagram P2024,0583 WO E / P240013WO01 September5,2024 -17 -of Fig. 2, showing a peak in the absorption spectru m of theradiofrequency signals indicating the presence of a certaincompound in the sample ofthe gas14.The assembly ofmagnet arrangement35,sample region 34,transmittercoil and receivercoilcan also be denoted asNMR probe 38.After analysis, the gas 14 is released via a gas ou tlet 6c tothe ambient.Fig. 3 shows a detailed view of an embodiment of an NMRdevice 3 which can be used in the system 100 of Fig . 1. Thepart of the NMR device 3 shown in Fig. 2 is the par t at therightside ofthe NMR device 3 shown here.In thisembodiment, the NMR device 3 comprises a further NM R probe 39in addition to the NMR probe 38 as described in Fig . 2. Thefurther NMR probe 39 comprises a further magnet arr angement37,a furthersample region 36,a furtherreceiver coiland furthera transmittercoil.The further NMR probe 39 is configured to analyze t heinsulating liquid 2 directly in its liquid phase. T he furtherNMR probe 39 is located upstream in relation to the NMR probe38.The insulating liquid 2 flows from the electrical a pparatus 1via a liquid inlet6a to the furthersample region 36 wherean analysis is carried out in the liquid state. Theinsulating liquid 2 then flows through a liquid con nection 6eto the gasextractor13 where gas14 isextracted. The gas14flows via the gas connection 6b to the magnet arran gement 35where an analysisin the gasstate iscarried out. Theinsulating liquid 2 flows from the gas extractor 13 back via P2024,0583 WO E / P240013WO01 September5,2024 -18 -the liquid outlet 6d to the electrical apparatus 1, inparticularbackinto the tank8.The analysis and processing of the insulating liqui d 2 whenentering the gasextractor13 and ofthe extracted gas14 isthe same as described in connection with Fig. 2. Af teranalysis, the gas 14 is released via a gas outlet 6 c to theenvironment.The transmitter coils and receiver coils of the fur thermagnet arrangement 37 and of the magnet arrangement 35surrounding the further sample region 36 and the sa mpleregion 34, respectively, can be connected to the sa me siliconchip 30 comprising a transmitter31 and a receiver 32.Itisalso possible to connect the magnet arrangements 35 , 37 todifferent silicon chips and / or to different transmi tters andreceivers.The signals from the NMR probe 38 and the further N MR probe39 are processed byelectronics33.The processing can alsobe done by the processor 5 shown in Fig. 1, for exa mple. Bycomparing the signals derived from the liquid state and thegas state, a higher precision can be achieved. Also ,artifactsand electricnoise can be reduced.Fig. 4 shows a detailed view of a further embodimen t of anNMR device 3 which can be used in the system 100 of Fig. 1.In this embodiment, the same NMR probe 38 is used f oranalyzing a sample of the insulating liquid and a g as sample.After gas extraction, the extracted gas 14 is provi ded via agas connection 6b to the NMR probe 38 which is also used foranalyzing the liquid 2. As an example, in a first s tep, the P2024,0583 WO E / P240013WO01 September5,2024 -19 -insulating liquid 2 and in a subsequent step, the g as sample14 can be analyzed.The fluidic connection 6 can be provided with one o r morevents such that the insulating liquid 2 and the gas 14 is notsimultaneouslyin the sample region 34.Itisalso possible to configure the fluidicconnection 6 with movable regions such thatthe partproviding the insulating liquid 2 to the NMR probe 38 ismoved outofthe NMR probe 38 when the gas14is provided to the NMR probe 38 and vice versa. How ever, itis also possible to analyze the gas 14 and the insu latingliquid 2 simultaneouslyin the same NMR probe 38. In the same way,gasextracted from the head space and theinsulating liquid may be analyzed in the same NMR p robe 38.Fig. 5 shows a further embodiment of a system 100 w here thefluidic connection 6 connects the gas space 9 of th eelectrical apparatus 1 with the NMR device 3. In th is case, agasextractorisnotrequired.The gas10 from the gasspacecan be directly analyzed by the NMR device 3. A sam ple of theinsulating liquid 2 obtained by a fluidic connectio n to theinsulating liquid in the tank can be analyzed by th e same NMRdevice 3 or a further NMR device. The fluidic conne ction tothe insulating liquid in the tank is not shown in F ig. 5 butcan be asdisclosed in the foregoing Figures.Fig. 6 shows a further embodiment of a system 100 w here anNMR device 3 is positioned in the gas space 9. It i s alsopossible that only the NMR probe 38 is positioned i n the gasspace 9 while the further components of the NMR dev ice 3 suchaschip and electronicsare positioned outside the tank8.Also in this embodiment a gas extractor is not requ ired. A P2024,0583 WO E / P240013WO01 September5,2024 -20 -sample of the insulating liquid 2 obtained by a flu idicconnection to the insulating liquid in the tank can beanalyzed bythe same NMR device 3 ora furtherNMR device. The fluidicconnection to the insulating liquid in the tankis not shown in Fig. 6 but can be as disclosed in t heforegoing Figures.Apart from the non-presence of the gas extractor, t hestructure and processing of the systems 100 shown i n Figs. 5and 6 can be the same or similar as in the foregoin g figures.In the embodiments of Figs. 5 and 6, the differenc es betweenthe gas sample and the liquid sample have to be con sidered inthe analysis, as the gas phase and the liquid phase are nottaken from the same sample.Fig. 7 shows a system 100 comprising three electric alapparatuses1,each realized asa transformer.The NMR device3 is reversibly fluidically couplable to each of th eapparatuses 1. In this way, one NMR device 3 can be coupledto several transformers 1, one after the other, and can beused to analyze gas extracted from the insulating l iquid 2 ofeach ofthe transformers1.Fig. 8 shows a system 100 comprising a plurality ofelectrical apparatuses 1, each realized as a transf ormer 1.Compared to Fig. 4, however, the NMR device 3 is no wsimultaneously fluidically coupled to each of the e lectricalapparatuses1 bya fluidicconnection 6.Thus,the NMR device3 can be used to analyze gas extracted from the ins ulatingliquids 2 of the electrical apparatuses 1 simultane ously orone afterthe other. P2024,0583 WO E / P240013WO01 September5,2024 -21 -Also, the embodiments of Figs. 7 and 8, can be adju sted suchthatgasisdirectlytaken from head spacesofthe electricalapparatuses 1. Furthermore, a combination with a fu rther NMRprobe 39 can be provided.

[0002] P2024,0583 WO E / P240013WO01 September5,2024 -22 -Reference Signs1 electricalapparatus 2 insulating liquid 3 NMR device 4 userinterface 5 processor 6 fluidicconnection 6a liquid inlet 6b gasconnection 6c gasoutlet 6d liquid outlet 6e liquid connection 7 functionalelement 8 tank 9 gas space 10 gasfrom gasspace 11 signalconnection 12 furthersignalconnection 13 gasextractor 14 extracted gas 30 silicon chip 31 transmitter 32 receiver 33 electronics 34 sample region / sample volume 35 magnetarrangement 36 furthersample region 37 furthermagnetarrangement 38 NMR probe 39 furtherNMR probe 100 system

Claims

P2024,0583 WO E / P240013WO01 September5,2024 -23 - Claims 1.A system (100)comprisingan electrical apparatus (1) configured to comprise, inoperation, an insulating liquid (2), and an NMR dev ice (3),wherein the NMR device (3) is configured to analyze a sampleofthe insulating liquid (2),wherein the NMR device (3) is further configured to analyzegas (14) extracted from the insulating liquid (2) a nd / or gas(10) from a gas space (9) of the electrical apparat us (1),wherein the NMR device (3) is fluidically connected to theelectrical apparatus (1) for on-site analysis of th e gas (10,14). 2.The system (100)ofclaim 1,wherein the NMR device (3) comprises an NMR probe ( 38)connected by a fluidic connection (6) to the electr icalapparatus (1), wherein the system (100) comprises a gasextractor (13) located in the fluidic connection (6 ) forextracting gas (14) from a sample of the insulating liquid(2) and feeding the extracted gas (14) to the NMR p robe (38).3.The system (100)ofclaim 2,wherein the NMR device (3) is configured to analyze thesample of the insulating liquid (2) used for gas ex traction.

4. The system (100) of any of the preceding claims,comprising a liquid outlet (6d) for feeding a sampl e of theinsulating liquid (2) back to the electrical appara tus (1)aftergasextraction.

5. The system (100) of any of the preceding claims,comprisingP2024,0583 WO E / P240013WO01 September5,2024 -24 -a tank (8) housing the insulating liquid (2), where in thetank (8) comprises a gas space (9) located above th einsulating liquid (2), wherein the NMR device (3) i sfluidicallyconnected to the gasspace (9).

6. The system (100) of any of the preceding claims,wherein the NMR device (3) comprises an NMR probe ( 38) foranalyzing the gas(10,14)and a furtherNMR probe (39)for analyzing the sample ofthe insulating liquid (2), whereinthe NMR probe (38) and the further NMR probe (38) i sfluidically connected to the electrical apparatus ( 1).7.The system (100)ofclaim 6, wherein the furtherNMR probe (39)islocated in a fluidicconnection (6) of the NMR probe (38) with the elect ricalapparatus(1). 8.The system (100)ofanyofclaims1 to 5,wherein the NMR probe (38) is configured for analyz ing boththe gas (10, 14) and the sample of the insulating l iquid (2).

9. The system (100) of any of the preceding claims,wherein the electrical apparatus (1) is an electric altransformer or an autotransformer or a reactor or a phaseshifterora HVDC device.

10. The system (100) of any of the preceding claims ,wherein the NMR device (3) is a mini-NMR device (3) withdimensionssmallerthan 50 cm.

11. The system (100) of any of the preceding claims ,being configured for online analysis of the gas (10 , 14).P2024,0583 WO E / P240013WO01 September5,2024 -25 -12. The system (100) of any of the preceding claims ,wherein the NMR-device (3) is reversibly fluidicall ycouplable to the electricalapparatus(1)in order to enablethe NMR-device (3) to be fluidically coupled to two or moreelectrical apparatuses (1), one after the other, an d toanalyze the insulating liquid (2) of the electricalapparatuses(1).

13. The system (100) of any of the preceding claims ,wherein the NMR-device (3) is simultaneously fluidi callycoupled orsimultaneouslyfluidicallycouplable to aplurality of electrical apparatuses (1), the NMR-de vice (3)isconfigured to analyze the insulating liquid (2) oftheplurality of electrical apparatuses (1) simultaneou sly or oneafterthe other.

14. The system (100) of any of the preceding claims ,wherein the electrical apparatus (1) comprises a ta nk (8) forhousing the insulating liquid (2),wherein the NMR device (3) isinstalled outside the tank(8).

15. The system (100) of any of the preceding claims ,wherein the electrical apparatus (1) comprises a ta nk (8) forhousing the insulating liquid (2),wherein the NMR device (3) isinstalled inside the tank(8).

16. A method for analyzing an insulating liquid (2) of anelectrical apparatus (1), the method comprising the steps ofproviding an electrical apparatus (1) comprising aninsulating liquid (2) and an NMR device (3) fluidic allyconnected to the electrical apparatus (1) for on-si teanalysis,P2024,0583 WO E / P240013WO01 September5,2024 -26 -analyzing a sample of the insulating liquid (2) and analyzingthe gas (14) extracted from the insulating liquid o r gas (10)from a gas space (9) of the electrical apparatus (1 ) by theNMR device (3). 17.The method ofclaim 16,comprising the step of extracting gas (14) from theinsulating liquid (2)bya gasextractor(13). 18.The method ofclaims16 or17,wherein the gas (14) which is analyzed is extracted from thesample of the insulating liquid (2) which is analyz ed whereinthe gas (14) is analyzed first and the sample of th einsulating liquid (2) is analyzed subsequently, whe rein theresult of the analysis of the gas (14) is used in t heanalysis of the sample of the insulating liquid (2) .

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