Patent Description:
Electromagnetic devices, such as electrical transformers, can experience electrical inefficiencies and can generate significant heat in operation. Abating electrical inefficiencies and removing excess heat from such devices can conserve operational life, performance, and reduce the maintenance needs of the devices. Fluids, such as dielectric fluids, can be used as a cooling medium to remove heat from the devices and can provide an electrical insulation layer to suppress corona and arcing.

In operation, such cooling and/or insulating fluids can develop dissolved gases. Analysis of dissolved gases within the fluids of transformers can reveal useful information regarding the status of transformer operation.

<CIT>, on which the preamble of claim <NUM> is based, discloses an apparatus for detecting gas in a high-voltage device filled with an insulating medium. The apparatus comprises an inlet for introducing a carrier gas and an outlet for discharging a carrier gas; at least one gas sensor for detecting a gas; a first pump for conveying the carrier gas in the apparatus; a membrane which at least consists of at least one semipermeable material, is at least partially surrounded by the insulating medium and is at least partially subjected to a flow of the carrier gas; a second pump for conveying the carrier gas into the apparatus and for conveying the carrier gas out of the apparatus; wherein there is no valve which can be used to convey the carrier gas into or out of the apparatus.

<CIT> discloses an apparatus in which densities of water vapor can be detected and quantified at a high sampling rate for a gas. The gas can be contained within a sample chamber within or outside of an instrument enclosure. A first split beam passes through the enclosure and the sample chamber while a second split beam that passes only through the enclosure provides a reference that can be used to correct for ambient humidity in the instrument enclosure.

<CIT> discloses a sensor assembly for sensing a hydrogen and moisture content of insulation liquid of a liquid-filled electrical equipment based on radiation detection. The sensor assembly comprises an electromagnetic radiation source for emitting electromagnetic radiation; a water detection section arranged for receiving a water-containing component of the insulation liquid when the sensor assembly is in operational connection with the electrical equipment and for being illuminated by electromagnetic radiation from the electromagnetic radiation source; a first electromagnetic radiation detector configured for detecting electromagnetic radiation coming from the water detection section at a wavelength indicative of an amount of water present at the water detection section; a hydrogen detection section arranged for receiving at least a hydrogencontaining component of the insulation liquid when the sensor assembly is in operational connection with the electrical equipment and for being illuminated by electromagnetic radiation from the at least one electromagnetic radiation source; and a second electromagnetic radiation detector configured for detecting electromagnetic radiation coming from the hydrogen detection section at a wavelength indicative of an amount of hydrogen present at the hydrogen detection section.

According to an aspect of the invention, there is provided a transformer according to claim <NUM>.

The gas cell is arranged for determining characteristics of gas extracted from the fluid. In some embodiments, a transport conduit may be fluidly coupled with each of the extraction coil and the gas cell to transport gas received from the fluid to the gas cell for analysis. In some embodiments, the extraction coil may be formed as a conduit having an inner volume for receiving gas permeating through the gas-permeable material. In some embodiments, a gas species that is both within the inner volume and dissolved in the fluid may be in equilibrium.

In some embodiments, the gas-permeable material may include a fluoropolymer. In some embodiments, the gas-permeable material may include a fluoroplastic having at least one of: a yield strength within the range of about <NUM> MPa to about <NUM> MPa at about <NUM> °F, a yield strength within the range of about <NUM> MPa to about <NUM> MPa at about <NUM> °F, a yield strength within the range of about <NUM> MPa to about <NUM> MPa at about <NUM> °F, a tensile strength within the range of about <NUM> MPa to about <NUM> MPa at about <NUM> °F, a tensile strength within the range of about <NUM> MPa to about <NUM> MPa at about <NUM> °F, and a tensile strength within the range of about <NUM> MPa to about <NUM> MPa at about <NUM> °F. In some embodiments, the fluoropolymer may include a fluoroplastic having optical transmission percent of greater than <NUM>. In some embodiments, the fluoroplastic may include a fluoroplastic having gas permeability of at least one of H<NUM>O of about <NUM> Barrer, O<NUM> of about <NUM> Barrer, and N<NUM> of about <NUM> Barrer.

The concepts described in the present disclosure are illustrated by way of example and not by way of limitation in the accompanying figures. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference labels have been repeated among the figures to indicate corresponding or analogous elements.

While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives consistent with the present disclosure and the appended claims.

<FIG> shows an illustrative arrangement of an electrical transformer <NUM> including a gas analysis system <NUM> for determining characteristics of dissolved gases within fluid of the transformer <NUM>. The transformer <NUM> illustratively includes a housing <NUM> defining an interior <NUM> and electrical windings <NUM> arranged within the interior <NUM> of the housing <NUM>. The electrical windings <NUM> illustratively comprise windings of electrical wiring forming a series of turns about limbs of the transformer <NUM> to produce electromagnetic effect when current is passed through the wiring. The transformer <NUM> is illustratively embodied as a high- voltage, three-phase, core type transformer, but in some embodiments, may include any manner of electromagnetic device including but not limited to shell type and/or single or multi-phase.

In the illustrative embodiment as shown in <FIG>, the housing <NUM> contains fluid <NUM> for cooling and/or electrically insulating the components of the transformer <NUM>, such as the electrical windings <NUM>. As mentioned above, dissolved gases can develop within the fluid <NUM> as a result of operable use of the fluid <NUM> for cooling and/or insulation (for example, by fluid breakdown and/or faulty operational issues of the transformer <NUM>, generally, including leaks in the housing <NUM>) and/or the fluid <NUM> may carry gases generated from the degradation of other insulation materials in the transformer, such as paper. The gas analysis system <NUM> is illustratively arranged to extract dissolved gases from the fluid <NUM> for analysis.

Referring to <FIG>, the gas analysis system <NUM> includes an extraction probe <NUM> for extracting gas from the fluid <NUM>. The extraction probe <NUM> is arranged in contact with the fluid <NUM> and is formed of a gas-permeable material to permit permeation of dissolved gases from the fluid <NUM>. The extraction probe <NUM> is illustratively embodied as a conduit defining an interior passage for receiving and communicating gas. The gas-permeable material illustratively permits dissolved gases to permeate into the interior passage while inhibiting ingress of liquids, for example, dielectric oils. Suitable gas-permeable materials may include one or more fluoropolymers. The extraction probe <NUM> is formed as an extraction coil having coil loops in contact with the fluid <NUM>. In other examples not forming part of the claimed invention, the extraction probe <NUM> may include any suitable shapes and/or forms.

As shown in <FIG>, the gas analysis system <NUM> includes a gas analysis module <NUM> for conducting analysis of gas. The gas analysis module <NUM> is fluidly connected with the extraction probe <NUM> and forms a gas circuit for circulation of gas between the extraction probe <NUM> and the gas analysis module <NUM>. An exemplary housing <NUM> of the gas analysis module <NUM> is shown in <FIG>. The gas analysis module <NUM> illustratively includes a gas cell <NUM> for receiving gas extracted from the fluid <NUM>. The gas cell <NUM> illustratively includes a cell body <NUM> defining a cavity <NUM> through which gas is passed for analysis. In the illustrative embodiment, the gas analysis system <NUM> conducts optical analysis of gas to determine gas characteristics. In the illustrative embodiment, portions of the gas circuit other than the extraction probe <NUM>, including the cavity <NUM>, are hermetically sealed to ambient air such that only the extraction probe <NUM> is arranged to allow permeation of gases into and out of the gas circuit, thereby allowing gas exchange with the transformer fluid <NUM>.

As shown in <FIG>, the gas analysis module <NUM> illustratively includes a gas analysis device <NUM> for conducting analysis of gas within the gas cell <NUM>. In the illustrative embodiment, the gas analysis device <NUM> is an optical device embodied as a light spectroscopy device, namely a Fourier transform infrared (FTIR) spectrometer. In some embodiments, the gas analysis module <NUM> may perform any manner of gas analysis techniques and may include any suitable configuration and/or components to perform such techniques, for example, but without limitation, ultra violet light spectroscopy, Raman spectroscopy, photoacoustic spectroscopy, tunable diode laser absorption spectroscopy (TDLAS).

The gas analysis device <NUM> illustratively performs light spectrum analysis of gas within the gas cell <NUM>. In some embodiments, the gas cell <NUM> may use optical path length enhancement techniques such as multi-pass cells or resonant cavities. Multi-pass cells may include White cell, Herriot cell, folded path cells, and/or other multi-pass cells. Resonant cavities may include Fabry-Perot cavities, cavities designed for cavity ring-down spectroscopy, integrated cavity output spectroscopy (ICOS), off-axis integrated cavity output spectroscopy (OA-ICOS), and/or other optical path length enhancement techniques.

As shown in <FIG>, the gas analysis device <NUM> illustratively includes a light source <NUM> and detectors <NUM>, <NUM> for receiving light from the light source <NUM>. As discussed in additional detail below, the light source <NUM> illustratively generates infrared (IR) light for propagation through gas for observation of the light absorption characteristics of the gas. The light directed through the gas is received by the detectors <NUM>, <NUM>. The detectors <NUM>, <NUM> are illustratively embodied as photodetectors that receive light propagated through gas (but that has not been absorbed by the gas) and that generate an electrical signal indicating the light received. The detectors <NUM>, <NUM> are illustratively embodied as analog detectors that generate an analog signal that is converted to a digital signal by an analog-to-digital converter. In some embodiments, the detectors <NUM>, <NUM> may include any suitable arrangement of signal generation for gas analysis.

The gas analysis device <NUM> illustratively determines characteristics of the gas based on the light received by the detectors <NUM>, <NUM>. In the illustrative embodiments, the gas analysis module <NUM> can determine characteristics of dissolved gas within the fluid <NUM> by analysis of gas extracted by the gas analysis system <NUM> from the transformer <NUM>. Relevant characteristics of dissolved gases within the fluid <NUM> of the transformer <NUM> include the presence and/or identification of such gases and their dissolved concentrations within the fluid <NUM>. A non- exhaustive list of gases of interest within the fluid <NUM> may include, for example, oxygen (O<NUM>), nitrogen (N<NUM>), hydrogen (H<NUM>), carbon dioxide (CO<NUM>), and/or hydrocarbons (e.g., methane, ethane, acetylene, and/or ethylene), among other gases. The gas analysis device <NUM> may also monitor water vapor (H<NUM>O) extracted from the moisture dissolved in transformer oil <NUM>.

Referring now to <FIG>, the transformer <NUM> is shown in partial cross-section for descriptive purposes. The housing <NUM> of the transformer <NUM> illustratively includes a sampling portal <NUM> defining a portion of the interior <NUM> containing fluid <NUM> as part of the housing <NUM>. The sampling portal <NUM> illustratively includes pipe extension <NUM> connected with a wall <NUM> of the transformer <NUM> and a shroud <NUM> secured with the pipe extension <NUM>. The extraction probe <NUM> is illustratively mounted within the shroud <NUM> in contact with fluid <NUM>. The extraction probe <NUM> is illustratively mounted within a fluid chamber <NUM> defined by the shroud <NUM> as a part of the interior <NUM>. The chamber <NUM> illustratively contains fluid <NUM> as part of the housing <NUM> and fluidly communicating through the pipe extension <NUM>. In the illustrative embodiment, the pipe extension <NUM> illustratively includes a valve <NUM> disposed fluidly between the wall <NUM> and the chamber <NUM> to permit isolation of the extraction probe <NUM>, but in some embodiments, the valve <NUM> may be excluded. In some embodiments, the extraction probe <NUM> may be arranged inside of the wall <NUM>.

The gas analysis system <NUM> includes an extraction module <NUM> as shown in <FIG>, The extraction module <NUM> provides a packaging platform for mounting the extraction probe <NUM> within the housing <NUM> as shown in <FIG>. Referring to <FIG>, the extraction module <NUM> includes a mounting frame <NUM> and the extraction probe <NUM> secured with the mounting frame <NUM>. In the illustrative embodiment, a pump <NUM> is mounted to the frame <NUM> and is fluidly connected with the extraction probe <NUM> to provide a motive pressure source for circulation of gas within the gas circuit. Control valves and/or other flow distribution devices for operation of the gas circuit may be mounted to the mounting frame <NUM>.

As shown in <FIG>, the mounting frame <NUM> includes an engagement wall <NUM> and a probe arm <NUM> extending from the engagement wall <NUM>. The engagement wall <NUM> illustratively includes a face <NUM> that forms at least a portion of fluid boundary of the chamber <NUM>. The engagement wall <NUM> illustratively supports the probe arm <NUM> for extension within the chamber <NUM> for contact with fluid <NUM>.

In the illustrative embodiment as shown in <FIG>, and according to the invention, the probe arm <NUM> includes a spool <NUM> having the extraction probe <NUM> (which according to the invention is an extraction coil) looped around the spool <NUM>. In the illustrative embodiment, the extraction coil is looped around the spool <NUM> to form a number of coil turns having a successively stacked arrangement for exposure to fluid <NUM>. Increasing the number of coils may improve the effective exchange surface between oil and gas phase and may reduce the response time of the measurement. Gas circulated through the extraction probe <NUM> portion of the gas circuit illustratively flows successively through each of the coil turns and out for circulation to the gas analysis device <NUM>. In the illustrative embodiment, the extraction probe <NUM> is fluidly connected with the pump <NUM> for communication of extracted gas through the gas circuit.

As best shown in <FIG>, the spool <NUM> is illustratively cantilevered from the engagement wall <NUM> and provides structure for arranging the extraction probe <NUM> for contact with fluid <NUM>. In some embodiments, the extraction probe <NUM> may be secured to the mounting frame <NUM> in any suitable manner and/or arrangement. The spool <NUM> is illustratively formed as a structural frame defining an annular spool bed <NUM> for receiving the extraction probe <NUM> wrapped thereon and defining openings <NUM> extending through the spool bed <NUM> to permit fluid <NUM> to contact interior portions of the extraction probe <NUM> to increase the effective exchange surface between oil and gas phase. The spool <NUM> is illustratively shaped as a hollow cylinder to permit fluid <NUM> therein. The spool <NUM> illustratively includes a strut <NUM> bridging radially across the spool bed <NUM> to provide structural support and defining openings <NUM> to permit circulation of fluid <NUM> through the spool <NUM>.

Returning briefly to <FIG>, as previously mentioned, the extraction probe <NUM> and the gas analysis module <NUM> are fluidly connected to define a gas circuit for circulation of gas therebetween. In the illustrative embodiment, the extraction probe <NUM> and the gas analysis module <NUM> are fluidly connected by transport conduit <NUM> including conduit segments <NUM>, <NUM>. The segment <NUM> is illustratively embodied as a supply segment for providing gas from the extraction probe <NUM> to the gas analysis module <NUM> and the segment <NUM> is embodied as a return segment for providing gas from the gas analysis module <NUM> to the extraction probe <NUM>.

In the illustrative embodiment, the pump <NUM> is arranged fluidly along the supply segment <NUM> and provides a lower pressure level at the output of the extraction probe <NUM> (relative to the pressure of the gas cell <NUM>), which may assist with extraction of dissolved gases. In some embodiments, the gas circuit may be formed substantially or entirely by the extraction probe <NUM> and gas analysis module <NUM> being fluidly connected with each other by direct connection and/or with little or no transport conduit <NUM>. In some embodiments, the extraction probe <NUM> and gas analysis module <NUM> may be partly or wholly combined into a common module and/or arranged within a common housing for compact arrangement.

The gas circuit provides a circulation loop for communication of gas between the extraction probe <NUM> and the gas analysis module <NUM>. In the illustrative embodiment, the gas circuit encourages the gas extracted from the fluid <NUM> to reach and maintain equilibrium with dissolved gases within the fluid <NUM>. Such passive extraction and non-destructive analysis can avoid practical challenges with active sampling, such as fluid leaks, contamination, and waste materials, among others. Passive extraction does not rely on a precise determination of the extraction rate of the gas and thus reduces the need for factory calibration of each analyzer extraction rate. As mentioned above, the pump <NUM> illustratively assists circulation of the gas through the gas circuit and may assist extraction, but in some embodiments, circulation of the gas through the gas circuit may be provided by any suitable device(s), including but not limited to redundant pumps arrangements or arrangements without a pump such as convective and/or diffusive transport.

Referring now to <FIG>, a diagrammatic illustration of the gas analysis module <NUM> is shown. As mentioned above, the gas analysis module <NUM> illustratively includes the gas analysis device <NUM> arranged for conducting analysis of gas within the gas cell <NUM>. The light source <NUM> of the gas analysis device <NUM> illustratively includes a light generation source <NUM>. In the illustrative embodiment, the light generation source <NUM> includes an interferometer for modulating mid-IR light, for example, with a wavelength within a range of about <NUM> microns to about <NUM> microns (in some illustrative embodiments), about <NUM> microns to about <NUM> microns (in other illustrative embodiments), and about <NUM> to about <NUM> microns (in still other illustrative embodiments). The light generation source <NUM> also illustratively includes at least one light generator <NUM> for generating the mid-IR light and may include various relays, filters, and/or other conditioning devices (collectively indicated as <NUM>) for providing suitable light for gas analysis. A non-limiting example of a suitable light generator <NUM> may include a glow bar (globar). The light source <NUM> illustratively includes a relay mirror <NUM> arranged to receive a beam of light <NUM> from the light generation source <NUM> and a beam splitter <NUM> arranged to receive the beam <NUM> from the relay mirror <NUM>.

As shown in <FIG>, the gas analysis device <NUM> illustratively includes two optical channels as explained herein. The beam splitter <NUM> illustratively divides the beam <NUM> into two beams of light <NUM>, <NUM> for spectrum analysis. The beam splitter <NUM> is illustratively embodied to have a beam- splitting ratio of <NUM>:<NUM> (<NUM>/<NUM> splitter) dividing the beam <NUM> evenly into the two beams <NUM>, <NUM>, but in some embodiments, the beam splitter <NUM> may have other suitable beam-splitting ratios. In some embodiments, any suitable arrangement of relays, filters, splitters, and/or other conditioning devices may be employed to propagate light accordingly for gas analysis. Beams <NUM>, <NUM> propagate through respective defined spaces for collection by detectors <NUM>, <NUM>.

In the illustrative embodiment as shown in <FIG>, analysis of the beams <NUM>, <NUM> propagated through respective defined spaces can determine characteristics of the gas extracted from the fluid <NUM>. The beam <NUM> illustratively propagates through the gas cell <NUM> for reception by detector <NUM>. The beam <NUM> illustratively enters the gas cell <NUM> through a window <NUM>, propagates through the cavity <NUM> for interaction with gas therein, and exits the gas cell <NUM> through another window <NUM>. Light from the beam <NUM> exiting the gas cell <NUM> is received by the detector <NUM> for analysis. The gas within the cavity <NUM> affects the beam <NUM> in a manner such that the affected light received by detector <NUM> can indicate characteristics of the gas within the cavity <NUM>. As explained below, the detector <NUM> can generate a signal related to the absorption spectrum of the gas within the cavity <NUM> based on the light received from beam <NUM>.

In the illustrative embodiment, the gas within the cavity <NUM> absorbs energy from the beam <NUM> in the form of electromagnetic radiation. The remaining energy of beam <NUM> passes through the gas and is received by the detector <NUM> to generate a signal related to an absorption spectrum in the illustrative embodiment. The absorption spectrum of the relevant gas can include the fraction of incident radiation absorbed by the gas sample (in this instance, the gas within the cavity <NUM>) over a range of wavelengths and/or frequencies of propagated light. By analysis of the light received by the detector <NUM> (for example, but without limitation, the wavelength and/or frequency thereof), the characteristics of the gas within the cavity <NUM> can be reliably determined. Moreover, characteristics of the dissolved gases within fluid <NUM> can be determined based on the characteristics of the gas within the cavity <NUM>. In some embodiments, other analytical techniques and/or equipment may be used to determine gas characteristics. In some embodiments, additional gas analysis devices may be included in the gas cell to detect certain gases, such as hydrogen (H<NUM>), oxygen (O<NUM>), and/or nitrogen (N<NUM>), and some of those additional gas analysis devices may use non-optical measurement principals that do not require gas interaction with light, such as resistive, capacitive, and/or thermo-conductive sensors, by way of example.

Accurate determination of the characteristics of gas within the cavity <NUM> (and ultimately the dissolved gases within fluid <NUM>) should account for contaminants and/or artifacts. Common sources of artifacts includes constituents within the air contained in the gas analysis module <NUM> and/or constituents within the air in the vicinity of the transformer <NUM> that may enter the gas analysis module <NUM>. For example, ambient air within the gas analysis module <NUM> can reduce the light received by the detector <NUM> even though it cannot enter into the cavity <NUM>. Accordingly, reference information regarding the ambient environment can be useful in interpreting the light received by the detector <NUM>. In the present disclosure, the terms "air" and "ambient air" are not intended to limit the gas constituents which can be considered, but may include any gas constituent, including constituents of the same species as the dissolved gases of interest in the fluid <NUM>. By considering such reference information of ambient air, the characteristics of the gas within the cavity <NUM> (and by correspondence, the characteristics of the dissolved gases within the fluid <NUM>) can be accurately determined by correction and/or calibration of the light received by the detector <NUM> (absorption spectrum). Such corrective approaches can reduce the need for purging, scrubbing, desiccants, relay adjustment, and/or other resource-laden or mechanically demanding techniques to achieve accurate results.

As shown in <FIG>, the beam <NUM> (split from the beam <NUM>) illustratively propagates through a reference space <NUM> to provide characteristics of ambient air as reference information. The reference space <NUM> illustratively contains ambient gas (illustratively embodied as ambient air) which affects the beam <NUM> in a manner such that the affected light received by detector <NUM> can indicate characteristics of the ambient gas. The characteristics of the ambient gas can be used in interpreting the light received by detector <NUM>. Analysis of the light received by the detector <NUM> in combination with the light received by the detector <NUM> can allow determination of characteristics of the gas within the cavity <NUM> (and, hence, the characteristics of the dissolved gases within the fluid <NUM>) by reducing artifacts from the light absorbed by the ambient gas. Reduction of artifacts from the light absorbed by the ambient gas is illustratively achieved by consideration of the corresponding absorption spectra perceived by detectors <NUM>, <NUM>. In some embodiments, reference information may be obtained by any suitable technique and/or equipment.

In the illustrative embodiment as shown in <FIG>, the beam splitter <NUM> effectively provides a reference source point <NUM> for propagation of light through the defined spaces <NUM>, <NUM>. The reference source point <NUM> is illustratively represented as a single point on the beam splitter <NUM> for descriptive purposes. As shown in <FIG>, a propagation distance di is illustratively defined between the reference source point <NUM> and each of the detectors <NUM>, <NUM>. A first propagation distance, referred to as a cell distance dcell, is illustratively defined between the reference source point <NUM> and the detector <NUM>. The cell distance dcell illustratively corresponds to the propagation of the beam <NUM>. A second propagation distance, referred to as a reference distance dRef is illustratively defined between the reference source point <NUM> and the detector <NUM>. The reference distance dRef illustratively corresponds to the propagation of the beam <NUM>. A third propagation distance, referred to as the cell body distance L, is illustratively defined between the first window <NUM> and the second window <NUM> delimiting the cavity <NUM> of the gas cell <NUM>. In the illustrative embodiment, the distance (span) resulting from the subtraction of the cell body distance L from the cell distance dcell (e.g., the span may include the sum of the distance between the reference source point <NUM> and the cavity <NUM>, S<NUM>, and the distance between the detector <NUM> and the cavity <NUM>, S<NUM>, as indicated in <FIG>, either or both of which may contain ambient gas) is substantially equal to the reference distance dRef in such a way that the propagation distances in ambient air between the reference source point <NUM> and each of the detectors <NUM>, <NUM> are substantially equal. In other embodiments, however, the propagation distances in ambient air between the reference source point <NUM> and each of the detectors <NUM>, <NUM> may be different from each other and a correlation can be applied to equate their corresponding absorption spectra.

In some embodiments, the cell distance dcell may be substantially equal to the sum of the reference distance dRef and the cell body distance L. In some embodiments, the propagation distances between the reference source point <NUM> and each of the detectors <NUM>, <NUM> may be substantially equal. In some embodiments, the propagation distances may be different from each other and a correlation can be applied to equate their corresponding absorption spectra.

In the illustrative embodiment, the light source <NUM> provides the beam of light <NUM> for division into beams <NUM>, <NUM> for respective propagation through each of the cavity <NUM> and reference space <NUM>. Thus, the light source <NUM> illustratively provides each of beams <NUM>, <NUM> simultaneously from the same source for use in two optical channels; one channel analyzing light propagated through the gas cell <NUM>, and another channel analyzing light propagated through the reference space <NUM>. The dual channel arrangement using the same source of light can promote uniformity between the spectral characteristics of the channels and decrease adjustable parameters (e.g., moving optics, pressure/temperature modulation of gas samples) and/or the use of commodities (e.g., purge gas, desiccants, scrubbers) in obtaining reliable readings.

Devices, systems, and methods of the present disclosure can be advantageous for remote operation where commodities and/or maintenance availability is of concern. Moreover, arrangements of the present disclosure can account for unexpected and/or unknown contaminants, even without identifying the exact contaminant. In some embodiments, the reference information of the ambient gas may not identify one or more of the substances in the gas analysis module <NUM> and/or located between the light generator <NUM> and detectors <NUM>, <NUM>. However, the reference information of the unidentified substance can still be considered in accurately determining the characteristics of the gas within the cavity <NUM>.

Referring now to <FIG>, an illustrative embodiment of the gas cell <NUM> is shown. The gas cell <NUM> illustratively includes a housing <NUM>, which is shown partially cutaway (and semi- transparent) to reveal a cell body <NUM> that defines the cavity <NUM> therein (the cell body <NUM> being an illustrative embodiment of the cell body <NUM> of <FIG>). The cell body <NUM> illustratively includes openings <NUM> penetrating through the cell body <NUM> on opposite ends <NUM>, <NUM> to connect with the cavity <NUM>. Each opening <NUM> is enclosed by a respective one of the windows <NUM>, <NUM>. The cell body <NUM> illustratively includes gas ports <NUM>, <NUM> that each penetrate through the housing <NUM> and fluidly connect with the cavity <NUM> to form a portion of the gas circuit to communicate gas with the extraction probe <NUM>.

The gas port <NUM> is illustratively embodied as an inlet port (relative to the gas cell <NUM>) for receiving gas from the extraction probe <NUM> and the gas port <NUM> is embodied as an outlet port for sending gas to the extraction probe <NUM>. The cell body <NUM> illustratively includes pressure and temperature sensor ports <NUM> for insertion of pressure and temperature sensors <NUM>, <NUM> (shown in <FIG>) to monitor the conditions within the cavity <NUM>. A cell heater <NUM> including electrical leads <NUM> is illustratively connected with the cell body <NUM> within the housing <NUM> to provide temperature control of the cavity <NUM>.

Referring to <FIG>, an illustrative flow diagram is shown. A process <NUM> for determining characteristics of gases is described relative to boxes <NUM>-<NUM>. In box <NUM>, dissolved gases are illustratively extracted from fluid <NUM> of the transformer <NUM>. In the illustrative embodiment, the dissolved gases are extracted by permeation into the extraction probe <NUM> to enter the gas circuit. The process illustratively proceeds from box <NUM> to box <NUM>.

In box <NUM>, extracted gas illustratively enters a detection field. In the illustrative embodiment, the extracted gas enters the detection field as it circulates through the gas cell <NUM> and light is propagated through the extracted gas for reception by the detector <NUM>. In embodiments in which reference information is used for correction, in box <NUM>, the characteristics of ambient gases are detected. In the illustrative embodiment, the second channel of the gas analysis module <NUM> propagates light through the reference space <NUM> and the ambient gas therein for reception by the detector <NUM>. The process proceeds from box <NUM> to box <NUM>.

In box <NUM>, gas within the detection field circulates out of the detection field. In the illustrative embodiment, gas within the gas cell <NUM> is circulated through the gas circuit to return to the extraction probe <NUM>. The circulation of the gas within the gas circuit promotes nondestructive testing and enables equilibrium between gas in the gas circuit and dissolved gas within the fluid <NUM>.

Returning briefly to <FIG>, operation of the gas analysis system <NUM> and the various methods and functions described herein is illustratively governed by a control system <NUM>. The control system <NUM> illustratively includes a processor <NUM>, memory device <NUM>, and communications circuitry <NUM> in communication with each other. The memory device <NUM> stores instructions for execution by the processor <NUM> to conduct operations of the gas analysis system <NUM>. In the illustrative embodiment, the instructions include at least one algorithm for conducting the disclosed operations, but in some embodiments, the instructions may include any of look up tables, charts, and/or other reference material. The communications circuitry <NUM> illustratively includes various circuitry arranged to send and receive communication signals between the control system <NUM> and various components as directed by the processor <NUM>. It will be appreciated that the communications circuitry <NUM> also allows the control system <NUM> to communicate with other devices, including remote devices, and along various communications networks, such that the gas analysis system <NUM> (as well as the transformer <NUM>) can be connected to and form part of the Internet of Things. As a result, various components of the gas analysis system <NUM> may be sensed and/or controlled remotely across existing network infrastructure.

The control system <NUM> is illustratively arranged in communication with the gas analysis module <NUM> and the pump <NUM> through communication links <NUM> to communicate signals to govern their operation. Communication links <NUM> illustratively include hardwired connections, but in some embodiments may include any of hardwired and wireless connections, and/or combinations thereof. In the illustrative embodiment, the control system <NUM> is in communication with each of the light source <NUM>, the detectors <NUM>, <NUM>, gas cell temperature and pressure sensors <NUM>, <NUM> through individual links <NUM>, but in some embodiments, the control system <NUM> may be in communication with components of the gas analysis module <NUM> by one or more shared links <NUM>. The control system <NUM> illustratively performs spectrum analysis of the light received by the detectors <NUM>, <NUM> and determines the characteristics of the gas within the cavity <NUM> and the corresponding characteristics of the dissolved gas within the fluid <NUM>.

As shown in <FIG>, the transformer <NUM> illustratively includes a pump <NUM> arranged to circulate fluid <NUM> within the housing <NUM>. Circulating the fluid <NUM> can assist in providing uniform distribution of dissolved gases and can assist in extracted gases reaching accurate equilibrium faster than with stagnant fluid conditions. In the illustrative embodiment, the pump <NUM> is a thermal pump circulating the fluid <NUM> by convective movement. In other embodiments, any suitable device for circulating the fluid <NUM> may be used, including, for example, a displacement pump and/or an agitator. In the illustrative embodiment, the control system <NUM> is in communication with the pump <NUM> to govern operation of the pump <NUM>.

In the illustrative embodiment, the control system <NUM> is embodied to govern operations of all components of the gas analysis system <NUM>. In some embodiments, the control system <NUM> may govern operation of other systems of the transformer <NUM>. In some embodiments, the control system <NUM> may include multiple processors, memory devices, and/or communications circuitry that may have any suitable arrangement including but not limited to dedicated and partly or wholly shared arrangements. In some embodiments, another control system <NUM> may be dedicated to govern operation of the gas analysis module <NUM> and the remainder of the gas analysis system <NUM> may be governed by the control system <NUM>.

As mentioned above, the extraction probe <NUM> may include a suitable permeable material, for example, fluoropolymers. Suitable gas-permeable materials may include, for example, but without limitation, amorphous fluoroplastics. such as Teflon® AF and/or Chemours® AF, as marketed by Professional Plastics, Inc. (under affiliation and/or with permission from DuPont®), with typical properties as shown in the table below:.

Non-limiting examples may include Teflon® AF <NUM> and/or Teflon® AF <NUM> (and/or Chemours® AF <NUM> and/or AF <NUM>) having typical properties as described within the table below:.

In some embodiments, any suitable materials for gas-permeable, liquid-resistant extraction of dissolved gases from transformer fluid may be applied.

The present disclosure includes devices, systems, and methods for oil and gas management for dissolved gas analyzers for use in transformer monitoring. The devices, systems, and methods of the present disclosure may include detecting dissolved gases in insulating oil of electrical equipment using gas equilibrium theory. Equilibrium can be achieved relative to the solubility of a gas in a transformer fluid <NUM>, such as mineral oils, ester-based oils, or other insulation fluids, at a given temperature and for a given partial vapor pressure of a gas. Gas solubility can be described with quantities such as Ostwald coefficients of gas solubility that are specific to the type of fluid and to each gas constituent and may have temperature dependency. Gas solubility coefficients can be used to relate the partial pressure of gas in the gas cell with the concentration of dissolved gas in oil. The extracted gases being in equilibrium with the dissolved gases in oil may provide more accurate readings without requiring precise knowledge of extraction rates. In some embodiments, the extraction probe <NUM> of the present disclosure may comprise at least one ring of highly gas permeable tubing that is not permeable to liquid. In some embodiments, the extraction probe <NUM> may be connected to a closed-circulation system. The closed-circulation system may include one or more pumps for gas circulation and a gas cell, for example, gas cell <NUM>, for analytical measurement of the gas.

The present disclosure includes devices, systems, and methods adapted to monitor the health of a transformer by measuring dissolved gases within insulating oil of the transformer. For example, the concentration of specific gases can give indications of specific aspects of the operation of the transformer. Direct oil sampling and analysis of dissolved gases contained in transformer oil use active extraction of the gases and active measurement technics that consume the gases through the analyses. They are often implemented by circulating and/or conditioning oil samples outside the transformer in an oil circuit and may present a risk of oil leakage in case of breakage of the oil circuit. By contrast, embodiments of the devices, systems, and methods of the present disclosure permit online measurement with high accuracy and without active extraction. In some of the disclosed embodiments, oil containing the dissolved gases is circulating around highly permeable material tube within a fluid chamber <NUM> communicating fluidly with the transformer <NUM> through the pipe extension <NUM>. In some embodiments, the oil circulation around the permeable tube may be generated by pump, propeller and/or other mechanical systems and/or using thermally induced convection. Gases contained in oil can pass through permeable material to reach the gas phase loop. The permeable material properties can assist in obtaining equilibrium between gases in the liquid and gases in the gas phase loop. The gas loop may include a gas cell with optical inlet and outlet allowing examination of the gases by optical analyzer.

Devices, systems, and methods of the present disclosure may include highly permeable fluoropolymer tubing, such as Teflon AF family of amorphous fluoroplastics, by way of example. Highly gas permeable material can promote gas equilibrium and can improve measurement response time. The tubing may be rolled to form one or more turns of a coil. Devices, systems, and methods of the present disclosure may include circulation of the transformer fluid (e.g., oil) around this coil. A structural ring may support the tubing. According to the present disclosure, the fluoropolymer tubing may be connected to a gas circulating loop. The gas circulating loop may include one or more pumps to enhance reliability. In some embodiments, stainless steel tubing may transport gas to a gas cell for analysis. In some embodiments, a spectrometer may perform analysis of the gases. In some embodiments, in-oil sensors may be used for H<NUM> and/or H<NUM>O measurement. Devices, systems, and methods of the present disclosure may include passive extraction of dissolved gases and measurement, in lieu of active principles for gas separation and measurement. In some embodiments, the present disclosure may include transport of extracted gases without a carrier medium (e.g., a carrier gas). In some embodiments, a lower pressure may be formed within the extraction probe <NUM>, relative to the pressure within the gas cell <NUM> to assist with extraction of dissolved gases.

Devices, systems, and methods of the present disclosure can be used in transformer monitoring and/or specifically in monitoring of dissolved gases analysis in transformer fluid such as oil. For gas phase analysis, gases can be extracted from the transformer oil. Measurement of the gases can require a complex system for analysis, and in some embodiments, the gas sample can be transported to a gas analyzer. The devices, systems, and methods of the present disclosure can be helpful in avoiding transporting the transformer oil itself to an analyzer, which can present a risk of oil leakage in case of tubing breakage.

Use of passive measurement and passive extraction of the gases can simplify the calibration and installation of gas analysis systems. Use of high porosity and/or highly permeability material can help to reach equilibrium between gases in oil and gases in the sample gas phase. Using gases equilibrium, without requiring new gases to be sampled, can reduce risk of contamination of the oil. Use of a lower pressure (relative to the pressure within the gas cell) in the gas sampling probe can reduce the response time of the systems. The use of multiple transport pumps can help to reduce risk of failure. In some embodiments, measurement of H<NUM> may be conducted in gas phase to reduce the cost. In some embodiments, measurement of O<NUM>, H<NUM>, and/or N<NUM> may be performed optically and/or with non-optical sensors. In some embodiments, O<NUM> can be measured by paramagnetic analyzer. In some embodiments, gas leak detection may be performed by monitoring the presence of CO<NUM> or H<NUM>O with the gas cell, whether by direct and/or indirect sampling. The present disclosed devices, systems, and methods may involve advanced analyses and identification of interferent and outlier.

The present disclosure includes devices, systems, and methods for dual channel optical gas analyzers for compensation of ambient air constituents. Spectrometers can be used to measure light absorption spectra of gases. When gases of interest in a sample under observation are also present in ambient air (e.g., air either in the analyzer and/or around the sampling system) or when other gases in ambient air might interfere with the measurement of the gases of interest, spectrometers often must be purged, for example, with a purified gas to determine the contribution due to the absorption of only the gases of interest in the gas sample. The present disclosure includes devices, systems, and methods to reduce and/or remove the need for conditioning of the air in the analyzer or around the sampling system. The present disclosure includes spectrometers with two measurement channels. One channel can receive light propagating through ambient air and through a sampling gas cell. The transmitted light is then detected by a photodetector which generates an electrical signal that is digitized using an analog to digital converter. Another channel receives light propagating through ambient air only. Unlike in the first channel, the light of this second channel is not propagating through the sampling gas cell. The gas absorption contribution to the transmitted light in this second channel is related to ambient air constituents. The transmitted light of this second channel is detected by a second photodetector which generates an electrical signal that is digitized using a second analog to digital converter.

Devices, systems, and methods within the present disclosure may include light sources that split the light (e.g., by beam splitter, light divider, and/or any other suitable light splitting technique), a gas cell that may contain one or many gases of interest, components to insert gases into the gas cell, a first detector measuring the light transmitted through the gas cell and through ambient air, a second detector measuring the light transmitted only through ambient air, a processor to determine the concentration of one or more gases present in the sampling gas cell from the first channel signal, and remove interferences and/or contribution of gases in ambient air of the first channel based on the ambient air signal recorded from the second channel.

In some embodiments, a light source may be modulated by an interferometer. The light source may be divided in two different beams by a <NUM>/<NUM> Wedged ZnSe Beamsplitter. One of the beams may propagate through the gas cell and may reach the gas cell detector. The other beam may be directed towards a reference detector, to sense the ambient air composition only. The propagation distance in ambient air can be adjusted for both beams. The adjustment can be performed in a manner such that both the light transmitted by the gas cell and reaching the first detector and the light reaching the reference detector of the second channel propagate through similar distances in ambient air. In some embodiments, it may be assumed that ambient air composition in the instrument is homogeneous, and the light absorption due to the gases from ambient air should be the proportional to the gases concentration as well as to the respective propagation distance of both channels.

In some embodiments, the gas cell may be a closed container with one inlet and one outlet to fluidly connect to form a gas circulation loop. The light from the interferometer can enter the gas cell from one side and exit through the other side to the gas cell detector. The gas cell can be temperature controlled by a cartridge heater. The pressure and temperature of the gases in the gas cell can be measured and used as input parameters to the calculation of gases concentrations.

The present disclosure includes devices, systems, and methods in which the need for a purging system can be reduced and/or removed. Reducing and/or removing the need for a purging system can be an advantage when an analyzer is located in remote areas and purging systems are not available and/or are costly to install and operate. Concentration of gases in the gas cell that may also be present ambient air can be determined without purge, scrubber, desiccant and/or analyzer sealing. Other ambient air gases which have absorption signatures that may interfere with the determination of the gases concentration in the gas cell may also be compensated without purge, scrubber, desiccant and/or sealing. With the teachings of the present disclosure, the gases in ambient air can be measured simultaneously with the gases in the gas cell if desired, as opposed to calibration methods where only one channel can be used. Single channel calibration may perform reference background measurement taken apart from and/or without the gases of interest in the gas cell. The devices, systems, and methods of the present disclosure can provide an advantage when ambient air composition varies over time. The devices, systems, and methods of the present disclosure can include calibration for spectral intensity of the source, and calibration for the spectral characteristics of optical components that are common to both the first and second channels.

The present disclosure is used in the field of transformer monitoring by analysis of dissolved gases. The teachings of the present disclosure are generally applicable to other fields where optical methods require purge, scrubber, desiccant and/or sealing in order to calibrate, remove, and/or correct for ambient air constituents, but this does not form part of the claimed invention.

The devices, systems, and methods of the present disclosure can provide an alternative to systems taking reference measurements using only one detector, by removing the gases of interests from the gas cell and/or bypassing the gas cell.

Measuring low concentration gases by spectroscopy with accuracy can be challenging, particularly when the same gases or other interfering gases are present in ambient air, either in the analyzer or around the sampling system. Concentration of these gases in ambient air and/or the relative propagation distance of the light in ambient air could be non- negligible compared to the concentration of the gases in the gas cell and the propagation distance in the gas cell. Furthermore, the concentration of these gases in ambient air may vary with time, and unexpected gases can appear in ambient air in some sites. Pressure and temperature of the ambient air may differ from the pressure and temperature of the gas sample in the gas cell.

To remove the contribution of ambient air gases, analyzers are often purged with purified gases (by way of example, the MB3000 spectrometer marketed by ABB Inc. , includes a purging option). Purging can require bottles of purified gases, like Nitrogen, and/or a purified gas generator. Purge air is often dried to remove humidity, which can be a significant interferent in some instances, and CO<NUM> is often removed as well with a scrubber. In other systems where a purge is not possible and/or desirable, desiccants and/or scrubbers are used to remove humidity and/or other gases, but must be replaced or regenerated after some time. Other exemplary techniques can include moving relay mirrors to the gas cell in and out of the first channel in order to bypass the gas cell and direct the light to the detector to take background measurement. The relay optics can be designed such that the propagating distance in air with and without the relay optics is the same. Still other exemplary techniques can include using a scrubber to remove the gas component of interest from the gas cell after measuring the gas sample with the gas component of interest and inferring its concentration by the comparison of those two alternate measurements. Still other techniques may vary the pressure and/or the temperature of the gas sample to discriminate its composition over ambient air composition. In cases where the purge gas is supplied from an exhaustible source, such as a bottle, the exhaustible source will need to be refilled and/or changed at periodic maintenance intervals. Purge generators can be costly equipment that can require maintenance as well. Scrubbers and desiccants also require maintenance. Thus, the purge-based systems can increase the cost of operating spectrometers.

As mentioned above, the present disclosure can include reducing and/or removing the need for a purging system, desiccants, scrubbers and/or instrument sealing. Accordingly, the devices, systems, and methods of the present disclosure can reduce installation and/or maintenance costs related to the spectrometer, and can enable solutions for remote sites where purging systems are not available and/or maintenance cannot be performed frequently due to cost and/or safety issues. In some embodiments, the devices, systems, and methods of the present disclosure do not require moving optics and/or sample gas pressure modulation, and the ambient air constituents can be measured simultaneously with the gas cell constituents.

Since spectrometers using certain teachings of the present disclosure can measure spectra of ambient air, they may also detect and/or compensate for unexpected gases present in the ambient air, as opposed to scrubbers that are designed for specific constituents. Devices, systems, and methods of the present disclosure may be used to detect other defects around the transformer, for example but without limitation, detection of insulation gas leaks, such as SF<NUM>. By measuring and removing ambient air absorption, the devices, systems, and methods of the present disclosure can reduce sensitivity to ambient air compositions. The composition of the air inside the optical analyzer and/or around the sampling system may not need to be controlled by use of purge system, desiccants, scrubbers and/or instrument sealing.

In some embodiments, the devices, systems, and methods of the present disclosure may use factory calibration to characterize the difference of light propagating distances in air between first and second channels. In some embodiments, the devices, systems, and methods of the present disclosure may use factory calibration of the system to measure the spectral response of the first and second detectors as well as spectral response of optical components not common to first and second channel. In some embodiments, the devices, systems, and methods of the present disclosure may use factory calibration to characterize the spectral response and/or instrument line shape of the first and second channels in order to improve the compensation of air constituents in the first channel using the second channel. Factory calibration may include purge of the analyzer. The present disclosure include techniques developed to adjust the position of system components (mirrors, lenses, detectors, etc.) to minimize the difference of light propagating distance in air between first and second channel. In some embodiments, one or more algorithms may be used to compensate for the ambient constituents of the first channel using the second channel signal.

Claim 1:
A transformer (<NUM>), comprising:
at least one electrical winding (<NUM>);
a fluid system including fluid (<NUM>) for insulating the at least one electrical winding (<NUM>); and
a gas analysis system (<NUM>) for determining characteristics of gas dissolved in the fluid (<NUM>) of the fluid system, the gas analysis system (<NUM>) including an extraction coil (<NUM>) and a gas cell (<NUM>) for analysis of gas, the extraction coil (<NUM>) arranged in contact with the fluid (<NUM>) and including a gas-permeable material for receiving dissolved gas from the fluid (<NUM>), the extraction coil (<NUM>) and the gas cell (<NUM>) fluidly communicating to form a gas circulation loop for circulating gas,
wherein the gas cell (<NUM>) is arranged for determining characteristics of gas extracted from the fluid (<NUM>),
characterized in that the gas analysis system (<NUM>) includes an extraction module (<NUM>) for mounting the extraction coil (<NUM>) within a housing (<NUM>) of the transformer (<NUM>), the extraction module (<NUM>) comprising:
a mounting frame (<NUM>) including an engagement wall (<NUM>) and a probe arm (<NUM>) extending from the engagement wall, wherein the probe arm (<NUM>) includes a spool (<NUM>) having the extraction coil (<NUM>) looped around the spool (<NUM>).