Apparatus and method for non-invasively sensing internal temperature of a fluid contained in a housing

Abstract

This invention provides an apparatus and method for non-invasively determining the temperature of a fluid within a housing. First and second temperature sensors are positioned such that a temperature difference exists between them. This temperature difference between the first and second temperature sensors can be used to estimate the temperature of the fluid within the housing, and / or a zero-heat-flux method can be used to determine the temperature of the fluid within the housing.

Description

[Technical Field]

[0001] This application claims priority and interest in U.S. Provisional Patent Application No. 63 / 214695, filed June 24, 2021, the entire application of which is incorporated herein by reference for all purposes.

[0002] Some embodiments relate to apparatus for measuring temperature. Some embodiments relate to apparatus for non-invasively determining and / or estimating the temperature of a fluid contained within a housing. Some embodiments relate to methods for measuring temperature. Some embodiments relate to methods for non-invasively determining and / or estimating the temperature of a fluid contained within a housing. [Previous Technology]

[0003] Electronic equipment is a common component in modern society. Power distribution networks use various electronic devices, such as transformers, capacitors, reactors, and voltage regulators. For example, the electronic equipment of a transformer often includes components enclosed in a housing filled with a dielectric fluid such as mineral oil, natural or synthetic ester fluid, or silicone oil to maintain a stable operating temperature for the electronic equipment and to prevent or quickly suppress any discharge.

[0004] It is important to maintain the operating temperature of the electronic device, as reflected by the temperature of the dielectric fluid contained within the housing of the electronic device, within a desired range. For example, the expected lifespan of electronic equipment in a transformer decreases as the operating temperature of the electronic equipment increases. For instance, for some electronic equipment such as transformers, the expected lifespan of the equipment is reduced by about half for every approximately 5°C to 10°C increase in the continuous operating temperature experienced by the equipment.

[0005] If an electronic device operates periodically or consistently at a high temperature, the electronic device will permanently fail (i.e., before the end of its expected lifespan). If it operates periodically or consistently at a temperature higher than the desired operating temperature, it is prudent to replace the electronic device with one that has a larger load capacity.

[0006] For example, transformer lifespan reduction varies with time and temperature; therefore, the longer a transformer operates at an overload temperature, the greater the reduction in its expected lifespan. Unless at very extreme temperatures, a brief overload will not have a significant impact on expected lifespan; however, frequent overloads will have a significant impact on the transformer's expected lifespan. Therefore, if a transformer is slightly overloaded, utilities will monitor it further to determine whether this is a periodic event or an isolated incident. If these utilities determine it is a periodic event, they will replace the transformer with a larger transformer designed to handle higher loads. If the transformer is severely overloaded, it is a signal that significant lifespan reduction has occurred and that the transformer may be slightly overloaded on a normal basis.

[0007] Certain utilities have developed practices to optimize the lifespan of their equipment and the workload required to maintain it. These practices may include classifying overloaded equipment according to its operating temperature relative to a reference temperature and taking different actions based on that classification. For example, if a transformer is designed to operate at a reference temperature of 90°C, then a transformer operating at 110°C is classified as "overloaded" and a transformer operating at 120°C is classified as "extreme overloaded." An "overloaded" device is monitored more closely for a period of time, while an "extreme overloaded" device is replaced immediately.

[0008] A device is needed to sense and transmit temperature changes within electronic equipment to help determine whether the electronic equipment is operating under an "overload" or "extreme overload" condition. The faster the excessive temperature condition can be detected and the relevant power authority can be notified, the faster the situation can be resolved, thereby preventing premature or serious failure of the electronic equipment.

[0009] There is also a need for a device that can non-invasively and accurately sense and transmit temperature changes within an electronic device. US 9395252 by Frounfelker et al. teaches a system and method for estimating the temperature of a fluid contained within an electrical device without direct heat transfer to the fluid. The method includes: measuring a temperature of an outer wall of a housing of the electrical device; measuring an ambient temperature surrounding the housing; and using the measured wall temperature and the measured ambient temperature to estimate the temperature of a fluid within the housing. The method is also claimed to be able to adjust the estimated fluid temperature for ambient humidity conditions.

[0010] The aforementioned examples and related limitations in the related art are intended for illustrative purposes and are not the only ones. Other limitations of the related art can be understood by those skilled in the art upon reading the specification and studying the drawings. [Summary of the Invention]

[0011] The following embodiments and their variations are intended to illustrate and explain systems, tools, and methods in a manner that is not intended to limit their scope. In various embodiments, one or more of the aforementioned problems have been reduced or eliminated, while other embodiments relate to other improvements.

[0012] One embodiment provides an apparatus for non-invasively estimating a temperature within a housing. The apparatus includes: an environmental shield formed and configured to shield at least a portion of the housing from primary environmental conditions; a first temperature sensing element disposed within the environmental shield and positioned close to the housing when the apparatus is in use; and a second temperature sensing element separate from the environmental shield and positioned close to the housing when the apparatus is in use. In some embodiments, the second temperature sensing element is substantially exposed to primary environmental conditions, or is exposed to primary environmental conditions more extensively than the first temperature sensing element. In some embodiments, the apparatus includes a cartridge portion formed and configured for insertion into a cartridge housing extending within the housing, the cartridge portion containing the second temperature sensing element. In some embodiments, the apparatus includes a sensor for determining whether the cartridge portion has been inserted into the cartridge housing.

[0013] A method for using the above-described apparatus is provided, the method comprising the following steps: determining whether the cartridge portion has been inserted into the cartridge housing; if it is determined that the cartridge portion has been inserted into the cartridge housing, directly measuring the temperature of the fluid contained in the housing using a third thermal sensing element; or if it is determined that the cartridge portion has not been inserted into the cartridge housing, estimating the temperature of the fluid contained in the housing using the first and second thermal sensing elements.

[0014] A method for estimating the temperature of a fluid contained within a housing is provided, the method comprising the steps of: measuring a first temperature at a first external location on the housing, the first external location being shielded from environmental conditions; measuring a second temperature at a second external location on the housing, the second external location being exposed to environmental conditions or more exposed to environmental conditions than the first external location; and correlating a difference between the first temperature and the second temperature to estimate the temperature of the fluid contained within the housing.

[0015] One embodiment provides an apparatus for estimating the temperature of a fluid contained within a housing, the apparatus comprising: a first thermal sensing element; a second thermal sensing element; a heating element positioned outside both the first and second thermal sensing elements; and a thermal insulator positioned differently relative to the first and second thermal sensing elements.

[0016] A method for estimating the temperature of a fluid contained within a housing is provided, the method comprising the steps of: (i) measuring a first temperature at a first location near the housing; (ii) measuring a second temperature at a second location near the housing, a temperature difference initially appearing between the first and second locations; (iii) actuating a heating element positioned outside both the first and second locations if the first temperature is different from the second temperature; (iv) repeating steps (i) to (iii) until it is determined that the first and second temperatures are the same; and (v) determining that the temperature of the fluid contained within the housing is the same as the first and second temperatures.

[0017] One embodiment provides an apparatus for estimating the temperature of a fluid contained within a housing, the apparatus having: a first thermal sensing element; a second thermal sensing element; and a thermal insulator positioned between the housing and the second thermal sensing element when the apparatus is in use.

[0018] A method for estimating the temperature of a fluid contained within a housing, the method comprising the steps of: measuring a first temperature at a first location on the housing; measuring a second temperature at a second location, wherein a thermal insulator is positioned between the housing and the second location; and estimating the temperature of the fluid contained within the housing based on the relationship between the first temperature and the second temperature.

[0019] In addition to the above-described exemplary forms and embodiments, other forms and embodiments can be understood by referring to the drawings and by studying the following detailed description.

Implementation Method

[0033] Specific details are set forth throughout the following description in order to provide a more thorough understanding to those skilled in the art. However, known elements may not be shown or described in detail to avoid unnecessarily obscuring the disclosure. Therefore, the description and figures should be regarded as illustrative rather than restrictive.

[0034] As used herein, "environmental conditions" may include any external environmental parameter or any combination of such parameters that affects the internal temperature of a fluid contained within a housing. Examples of environmental conditions include primary ambient temperature, humidity, wind conditions, precipitation, and sunlight exposure, and include any combination of such conditions. For example, the housing and any fluid contained within it may be significantly cooled by a combination of cold and wind, rather than by cold or wind alone.

[0035] As used herein, “external” means the outer surface of a housing and “internal” means the inner surface or interior of the housing. “Outward” means a direction away from the interior of the housing.

[0036] The terms “adjacent” or “near” as used herein may mean direct contact or sufficient proximity through any intermediary element or space such that, for example, a temperature sensor can still measure an approximate value of the temperature of the surface that is “adjacent” or “near” it.

[0037] Please refer to Figure 1, which shows an exemplary electronic device of a transformer 100. The transformer 100 has a tank or housing 102 that encloses a fluid 104 within it. The fluid 104 is fluidly separated from an external environment 106 surrounding the housing 102 by means of the housing 102. That is, the fluid 104 is sealed within the housing 102 such that it is substantially not allowed to flow out of the housing 102. In some cases, fluid 104 may be harmful to the environment (e.g., fluid 104 may be a recognized greenhouse gas or may have toxic or harmful effects on various organisms). Therefore, it is important to keep fluid 104 substantially contained within housing 102. However, if the pressure inside transformer 100 accumulates above a certain value and actuates any pressure relief valves associated with transformer 100, some fluid 104 may be released. In some embodiments, depending on the design and rules applicable to a particular transformer 100, housing 102 may be opened to the external environment to a limited extent, for example, through a suction pipe, to allow pressure equalization. In some embodiments, the suction pipe may be plugged with rock wool or other material that allows air to pass through but restricts the passage of fluid 104.

[0038] Fluid 104 may be any electrically insulating or dielectric fluid suitable for electronic equipment, including mineral oil, natural or synthetic ester fluids, silicone oil or gas such as SF6.

[0039] The housing 102 can be any suitable slot or housing for an electronic device, such as a transformer like one of the transformers 100. In some embodiments, the housing 102 is made of carbon steel, stainless steel, or any other suitable material. Different types of housings 102 used for different transformers 100 can vary in many different design aspects, such as: the thickness of the housing, the material used to manufacture the housing, the thermal conductivity of the material used to manufacture the housing, the thickness of the protective coating (e.g., paint) applied to the housing, the size and dimensions of the housing (e.g., volume, height, length, width, and diameter), the shape of the housing (e.g., circular or rectangular), and the fluid circulation pattern of the fluid within the housing.

[0040] In the illustrated embodiment, a first portion of the housing 102, schematically shown as 108, is shielded from environmental conditions, while a second portion of the housing 102, schematically shown as 110, is exposed to environmental conditions.

[0041] Please refer to Figures 2A and 2B, which show another embodiment of a transformer 200 having a housing 202 with an inlet 250 therein housing a casing 252. The transformer 200 is otherwise similar to the transformer 100, and similar elements are indicated by similar symbols plus 100 and are not further described. These similar elements include fluid 204, external atmosphere 206, shielding portion 208 of the housing 202, and exposed portion 210. In the illustrated embodiment, the casing 252 is positioned such that it is hermetically joined to the housing 202 opposite the inlet 250 to prevent fluid 204 from flowing out of the space within the housing 202. The fluid level 212 of fluid 204 is shown by a dashed line in Figure 2B and may be referred to as the top oil level.

[0042] Please refer to Figure 3A, which provides an embodiment of a temperature sensor 300, which can be used to determine the temperature of fluid 104 or 204 inside transformer 100 or 200 using the following zero heat flow method. The zero heat flow method uses two temperature sensing elements to determine the heat flux or heat flow through housing 102 or 202 and uses an active electric heater to compensate for heat loss.

[0043] The temperature sensor 300 has a body 302, which is formed and assembled to be mounted on the housing of an electrical device, such as housing 102. The temperature sensor 300 has first and second temperature sensing elements 304 and 306 that are separated from each other and separated by a thermal insulation layer 308. Because the first temperature sensing element 304 is more directly exposed to the housing 102 while the temperature sensing element 306 is thermally shielded by the thermal insulation layer 308 and is not affected by heat leaving the housing 102, that is, because the thermal insulation layer 308 is positioned differently relative to the first and second temperature sensing elements when the temperature sensor 300 is in use, a temperature difference is generated between the first and second temperature sensing elements 304 and 306 when the temperature sensor 300 is in use.

[0044] Any suitable temperature sensor may be used for the first and second temperature sensing elements 304, 306, such as a thermocouple, a resistive thermal device (RTD) sensor, a thermistor, or a semiconductor-based integrated circuit. Any suitable material may be used to provide the thermal insulation 308, such as a foam, an air-tight material, or a material forming a portion or component of the temperature sensor 300. The insulation value provided by the thermal insulation 308 should remain constant throughout the use of the temperature sensor 300, such that the calibration of the temperature sensor 300 as described below can be used to determine the temperature of the fluid 104 or 204 within the housing 102 or 202 as described herein. For example, components forming a portion of the thermal insulation 308 should not be removed or modified in a manner that could alter the insulation value provided by the thermal insulation 308.

[0045] A heating element 310 is disposed outside the second temperature sensing element 306. The temperature sensor 300 is configured such that the first temperature sensing element 304 can be placed or brought into thermal contact with the housing 102. A thermal insulator 308 is positioned outside the first temperature sensing element 304 such that heat moving outward along the heat flow path (arrow 312) must pass through the thermal insulator 308 to reach the second temperature sensing element 306 positioned outward on the body 302 by the thermal insulator 308. Finally, any heat passing through the second temperature sensing element 306 along the heat flow path 312 can reach the heating element 310. Due to this configuration, there may be a temperature difference between the temperature sensing elements measured by the first temperature sensing element 304 and the second temperature sensing element 306, which reflects a portion of the temperature gradient from the fluid 104 to the external environment 106.

[0046] The surface area of ​​the housing 102 covered by the temperature sensor 300 should be large enough that a significant amount of heat is not lost along a path other than the heat flow path 312. That is, if the surface area of ​​the housing 102 covered by the temperature sensor 300 is too small, heat will not only move along the heat flow path 312 but also in a direction perpendicular to it. This means that the temperature measured by the second temperature sensing element 306 is lower than if heat only flowed along the heat flow path 312. Similarly, the surface area covered by the thermal insulation 308 and the heating element 310 should be large enough to ensure that a significant amount of heat is not lost along a path other than the heat flow path 312.

[0047] In use, heating element 310 is used to apply heat to the system until there is no temperature gradient between the first and second temperature sensing elements 304, 306. This indicates that heat has stopped flowing along the heat flow path 312, such that the first and second temperature sensing elements 304, 306 and the thermal insulation 308 are all at the same temperature as the fluid 104 within the housing 102. During this stage, the readings of temperature sensors 304, 306 correspond to the temperature of the fluid 104.

[0048] Other configurations can be used to determine the temperature of the fluid 104 or 204 inside the transformer 100 or 200 using a zero heat flow method, as long as the initial temperatures measured by the first and second temperature sensing elements 304, 306 are different due to the different insulation between each temperature sensing element of the first and second temperature sensing elements 304, 306 and the housing 102 or heating element 310 (i.e., a temperature difference is generated between the first and second temperature sensing elements 304, 306 due to the different positioning of the thermal insulator 308 relative to the first and second temperature sensing elements 304, 306).

[0049] For example, please refer to FIG3B, which shows another embodiment of a temperature sensor 300', wherein the first and second temperature sensing elements 304', 306' are laterally separated from each other. In the illustrated embodiment, the first temperature sensing element 304' is close to the housing 102' of the transformer and is within the body 302' without any obvious insulating material between the first temperature sensing element 304' and the housing 102', such that the temperature measured by the first temperature sensing element 304' reflects or is an approximation of the temperature of the housing 102'. The second temperature sensing element 306' is separated from the housing 102' by a thermal insulation 308', such that a temperature difference is generated between the first temperature sensing element 304' and the second temperature sensing element 306' due to the different positioning of the thermal insulation 308' (i.e., the first temperature sensing element 304' is more affected by the temperature changes of the internal fluid 104 than the second temperature sensing element 306'). Similar to thermal insulation 308, any suitable material can be used to provide thermal insulation 308', such as foam, air trapping material, or material forming part or component of temperature sensor 300'.

[0050] Although in the illustrated embodiment the second temperature sensing element 306' is shown to be positioned further outward from the housing 102' than the first temperature sensing element 304', in other embodiments the first and second temperature sensing elements may be positioned at the same distance outward from the housing 102', or the second temperature sensing element 306' may actually be positioned closer to the housing 102', as long as the thermal insulation value of the material between the second temperature sensing element 306' and the housing 102' is greater than the thermal insulation value of the material between the first temperature sensing element 304' and the housing 102', so as to provide a temperature difference between the first and second temperature sensing elements 304', 306'.

[0051] Similarly, although in the illustrated embodiment the thermal insulation 308' is shown positioned between the second temperature sensing element 306' and the housing 102' to provide different positioning of the thermal insulation 308' relative to the first and second temperature sensing elements 304', 306', in other embodiments the temperature difference between the first and second temperature sensing elements 304', 306' can be generated by positioning the thermal insulation 308' between the first temperature sensor 304' and the heating element 310'.

[0052] In another embodiment, it can be deduced that when the different positioning is provided by positioning the thermal insulator in different orientations around the sensors, for example by shielding the first temperature sensing element 304' from the heat flow by a relative lateral heat flow to a degree greater than that of the second temperature sensing element 306', a temperature difference is generated between the sensing elements 304' and 306'.

[0053] In the case of temperature sensor 300', heat flows out of housing 102' and along a first heat flow path 312A through the first temperature sensing element 304', while heat flows out of housing 102' through thermal insulation 308' and then along a second heat flow path 312B through the second temperature sensing element 306'. Furthermore, the temperature difference measured by each temperature sensing element of the first temperature sensing element 304' and the second temperature sensing element 306' reflects a portion of the temperature gradient from fluid 104 to the external environment 106, and can be similarly used in conjunction with heat applied by heating element 310' until there is no temperature gradient between the first and second temperature sensing elements 304', 306'. When this condition is reached, it indicates that heat has stopped flowing along both the first heat flow path 312A and the second heat flow path 312B, such that the first and second temperature sensing elements 304', 306' and thermal insulation 308' are all at the same temperature as the fluid 104 within housing 102'. Furthermore, at this time, the readings of temperature sensors 304' and 306' correspond to the temperature of fluid 104.

[0054] In another embodiment, the shape and temperature of the heating element 310 or 310' may differ. For example, in some embodiments, the heating element 310 or 310' may be circular or elliptical and optionally have a hole through its center (e.g., an annular hole) to reduce heat passing laterally away from the heat flow path 312 (or 312A / 312B). In other embodiments, both the first and second temperature sensing elements may be separated by the housing by the same or substantially the same distance, but thermal insulation may be positioned only between the second temperature sensing element and the housing (i.e., not between the first temperature sensing element and the housing) or only between the first temperature sensing element and the heating element (i.e., not between the second temperature sensing element and the heating element) to provide a temperature difference between the two temperature sensing elements.

[0055] Temperature sensors 300 or 300' can be used in a method 3000 shown in FIG. 4 for estimating the temperature of a fluid within a housing using a zero-heat-flow method. Initially, in step 3002, heat flows outward from the fluid 104 along heat flow path 312 (or 312A / 312B) across the housing 102 toward the external environment 106. Because of the presence of thermal insulation 308 or 308', less heat reaches the second temperature sensing element 306 or 306' than the heat reaches the first temperature sensing element 304 or 304', and the temperature T2 measured by the second temperature sensing element 306 or 306' is lower than the temperature T1 measured by the first temperature sensing element 304 or 304'.

[0056] In step 3004, if it is determined that T1 is greater than T2, then in step 3006, the heating element 308 is activated to supply heat. Steps 3004 and 3006 can be repeated until it is determined in step 3004 that T1 and T2 are the same. At this time, it can be determined in step 3008 that the temperature of the fluid 104 in the housing 102 is the same as both T1 and T2. In the case where it is determined in step 3004 that T2 is greater than T1, the heating element 308 can stop applying heat and step 3004 can be repeated until it is determined in step 3004 that T1 is greater than T2 again (when step 3006 can be repeated) or until it is determined in step 3004 that T1 is equal to T2. At this time, it can be determined in step 3008 that the temperature of the fluid 104 in the housing 102 is the same as both T1 and T2.

[0057] Please refer to Figures 5A, 5B, and 5C, which show an embodiment of a temperature sensor 400 that can be used to estimate the temperature of fluid 104 within housing 102 using a temperature difference or differential T method. The sensor 400 has a body 402 having a first portion or head 404 and a second portion, a handle 406. In the illustrated embodiment, the head 404 is vertically positioned above the handle 406, but it is understood that the relative positions of these components may vary depending on the orientation of the sensor 400.

[0058] Sensor 400 has a first or head temperature sensing element 408 positioned in head 404 such that head temperature sensing element 408 can be positioned to make thermal contact with housing 102 when sensor 400 is in a mounting configuration, as shown in FIG5A. Sensor 400 also has a second or handle temperature sensing element 410 positioned in handle 406 such that handle temperature sensing element 410 can be positioned to make thermal contact with housing 102 when sensor 400 is in this mounting configuration. Any suitable temperature sensor can be used for the first and second temperature sensing elements 408, 410, such as a thermocouple, a resistive thermal device (RTD) sensor, a thermistor, or a semiconductor-based integrated circuit, etc.

[0059] As schematically shown in Figure 5, a thermal insulation and environmental shielding barrier, designated 412, is disposed in the head 404 to protect the head temperature sensing element 408 and the corresponding shielding portion 414 of the housing 102 of the fixed head 404 from external environmental influences when the sensor 400 is in this mounting configuration. Therefore, when the sensor 400 is in this mounting configuration, the head temperature sensing element 408 and the corresponding shielding portion 414 of the housing 102 of the fixed head 404 are protected from external environmental influences.

[0060] Conversely, no thermal insulation or environmental shielding barrier is provided on the handle 406. In addition, the surface area of ​​the handle 406 that contacts the housing 102 is relatively small, so that the portion 416 of the housing 102 that is in contact with the handle temperature sensing element 410 is more exposed to the external environment.

[0061] Please refer further to Figures 5B and 5C for a more detailed illustration of an embodiment of a thermal insulator and environmental shield as a solid barrier. In the illustrated embodiment, the head temperature sensing element 408 is circumferentially surrounded by an inner circumferential washer 420. Similarly, the outer periphery of the portion of the head 404 that contacts the housing 102 is circumferentially surrounded by an outer circumferential washer 421. These inner and outer circumferential washers 420, 421 help to prevent or minimize the effects of environmental conditions by substantially preventing and / or reducing the entry of certain environmental factors, such as wind, rain, and sunlight, into the head temperature sensing element 408 and the portion 414 of the housing 102 that holds the head 404. This minimizes the impact of these environmental factors on the temperature of the portion 414 of the housing 102 and also minimizes the impact of these environmental factors on the head temperature sensing element 408.

[0062] The inner and outer circumferential gaskets 420, 421 do not need to achieve a 100% seal on the outer surface of the housing 102 to achieve this minimization. The material of the body 402 of the head 404 and its contained components (e.g., air 430, circuit board 432, and inner gasket 422, etc.) alone is sufficient to prevent wind, rain, and sunlight from penetrating the portion 414 of the outer surface of the housing 102 that holds the head 404. Additional inner and / or outer circumferential gaskets can further enhance the protection against these environmental factors provided by the head 404, but in some embodiments, one or both of the inner and / or outer circumferential gaskets may be removed. The head 404 should be designed to cover a sufficient amount of surface area 414 to shield a sufficiently large surface area of ​​the housing 102 to ensure that the head temperature sensing element 408 senses a shielding temperature. Therefore, the heat flow laterally through the wall of the housing 102 from the shielding portion 414 should be sufficiently low to allow for proper determination of the shielding temperature.

[0063] The head temperature sensing element 408 is also thermally shielded from the external environment. In the illustrated embodiment, the materials of the body 402 of the head 404 and its contained components (e.g., air 430, circuit board 432, inner gasket 422, walls of the body 402, and inner and outer peripheral gaskets 420 and 421, etc.) prevent wind, rain, and sunlight from penetrating the portion 414 of the outer surface of the housing 102 that holds the head 404, and together they act as thermal insulators to thermally shield the head temperature sensing element 408 from the external environment. This collective shielding of the head temperature sensing element 408 and the corresponding shielding portion 414 of the housing 102 from the influence of ambient temperature and environmental conditions.

[0064] Unlike the head temperature sensing element 408, the handle temperature sensing element 410 is not shielded from the external environment, and any shielding provided by the handle 406, for example by the handle 406 having a relatively narrow width and small size compared to the head 404, is minimized.

[0065] Referring to Figure 6, a method 4000 is shown for estimating the internal temperature of fluid 104 using a temperature difference or differential T method. A sensor 400 may be used to implement certain embodiments of method 4000. In step 4002, the head temperature sensing element 408 measures the temperature T3 of the shielded portion 414 of the housing 102. In step 4004, the handle temperature sensing element 410 measures the temperature T4 of the exposed portion 416 of the housing 102.

[0066] Because T3 is measured on the shielded portion 414 and T4 is measured on the exposed portion 416, these temperatures are different. The difference between these temperatures, or the difference T, changes with, for example, the temperature of the fluid 104 and the influence of the external environment 106 on the cooling transformer 100. The head temperature sensing element 408 and the handle temperature sensing element 410 can be calibrated using a reference transformer that operates at a known temperature of the fluid 104. Using these known reference measurements, the correlation between T3 and T4 can be used to derive a relationship between these two measurements and the internal temperature of the fluid 104, so that the difference between T3 and T4 can be used in-situ in step 4006 to predict the temperature of the fluid 104.

[0067] In some embodiments, the internal oil temperature system is estimated using a transfer function, which can take various mathematical forms such as exponentiation, linearity, etc. If an exponentiation equation is used, it can look like the following equation (1): (1) where T is the estimated oil temperature, TS is the shielded tank temperature, TE is the exposed tank temperature, and A and B are experimentally derived coefficients. If a linear function is used, it can take the form of the following equation (2): (2) where T is the estimated oil temperature, TS is the shielded tank temperature, TE is the exposed tank temperature, and A, B, and C are experimentally derived coefficients.

[0068] The aforementioned equation used to estimate the internal oil temperature is merely an example. Those skilled in the art will determine that other transport equations of a form other than exponential or linear can produce similar effective results if the same inputs TS and TE (corresponding to T3 and T4 above) are provided.

[0069] In some embodiments, the handle 406 of the temperature sensor 400 is formed and assembled to be inserted into the cartridge housing 252. In these embodiments, the temperature sensor 400 can be inserted into the cartridge housing 252 when the transformer 200 is equipped with it. In these configurations, the handle temperature sensing element 410 is positioned inside the housing 202 during use and can directly or almost directly measure the temperature of the fluid 204 inside the housing 202. Therefore, the true temperature of the fluid 204 inside the housing 202 can be measured.

[0070] In one embodiment, the temperature sensor 400 can be used in a method for deriving calibration coefficients for estimating the internal temperature of a fluid within a transformer, such as transformer 100, which does not contain any holes or openings for determining an internal temperature. For example, when the sensor 400 is externally mounted on housing 102 or 202, the calibration of a particular transformer 100 relative to the differences T3 and T4 measured by the head temperature sensing element 408 and the handle temperature sensing element 410 may depend on various parameters associated with the transformer 100 or housing 102, including the thickness of the walls of housing 102, the applied paint coating, and the type of metal used to manufacture housing 102. Because these parameters differ, each transformer 100 should be calibrated separately, but calibration performed on one transformer 100 having one set of specific parameters (i.e., on a particular type of transformer) may be effective on other transformers 100 sharing the same set of parameters. The same principle can be applied to deriving calibration coefficients for determining the internal temperature of a fluid contained in other electronic devices or apparatuses.

[0071] The sensor 400 can be used to perform the calibration by inserting the handle 406 of a first sensor 400 into the casing 252 of a transformer 200 and externally mounting a second sensor 400 onto the casing 202. The transformer 200 can be subjected to a plurality of different temperatures and environmental conditions to determine the different values ​​of T3 and T4 measured by the head and handle temperature sensing elements 408, 410 of the second sensor 400 at a plurality of different temperatures or under different environmental conditions, and compare the values ​​of T3 and T4 from the second sensor with the measured value of the temperature of the fluid 204 inside the casing 202 measured by the handle temperature sensing element 410 of the first sensor as a third temperature sensor (or by directly measuring the internal temperature of the fluid 204 inside the casing 202 in any other way). Using these measurement data, the coefficients of the equations used to model the internal temperature of the tank with respect to T3 and T4 can be determined.

[0072] In one embodiment, the temperature sensor 400 further includes a position sensor, such as a gyroscope or contact sensor, schematically shown as sensor 440. Examples of sensors that can be used with sensor 440 include: a tilt switch for determining whether sensor 400 is vertically mounted (indicating external mounting) or horizontally mounted (indicating mounting within the cartridge housing 252); a reed switch with a magnet; a logic rule based on the measured temperature, for example, if the handle sensor is at a higher temperature than the head sensor, sensor 400 may be mounted within the cartridge housing 252, while an inverted temperature condition indicates external mounting; an accelerometer; a physical switch that toggles when sensor 400 is mounted in a specific configuration; and a shutter or other digital switch that triggers in one mounting position but not in another, etc.

[0073] The orientation sensor 440 can be used to determine whether the temperature sensor 400 is installed outside a housing or whether the temperature sensor 400 is inserted into the cartridge housing 252. If the orientation sensor 440 determines that the temperature sensor 400 is inserted into the cartridge housing 252, the handle temperature sensing element 410 can be used to directly measure the internal temperature of the housing and, if calibration is performed for a specific transformer 200, can be further used as the third sensor. If the orientation sensor 440 determines that the temperature sensor 400 is installed outside a housing, the temperature sensing elements 408 and 410 are used, for example, by implementing method 4000 to estimate the internal temperature of the fluid inside the housing.

[0074] For example, referring to FIG7, method 700 can be used to determine how a temperature sensor, such as temperature sensor 400, is installed and thus determine the temperature of a fluid contained within a housing. In step 702, it is determined whether the handle 406 of temperature sensor 400 has been inserted into a cartridge housing within the electrical device. In step 704, if it is determined that the handle 406 of temperature sensor 400 has been inserted into the cartridge housing 252, the temperature of the fluid contained within the housing is directly determined using the handle temperature sensing element 410. In step 706, if it is determined that the handle 406 of temperature sensor 400 has not been inserted into the cartridge housing 252, the thermal sensing elements 410 and 412, separated by thermal insulation 414, are used, for example, by implementing method 4000 to estimate the internal temperature of the fluid within the housing.

[0075] In some embodiments, a method is provided for estimating the temperature of fluid 104 using a temperature difference or differential T method, which incorporates an additional compensation factor based on the ambient temperature. An example of method 5000 is shown in FIG8. Method 5000 may use any suitable means (e.g., temperature sensor 400) for determining the temperature of housing 102 at a shielded location 108 and an exposed location 110, and any suitable means for determining the ambient temperature, such as a thermocouple, a resistive thermal device (RTD) sensor, a thermistor, or a semiconductor-based integrated circuit. For example, by including the ambient temperature in similar equations (1) and (2) and using the aforementioned known reference measurements for referring to the temperature difference or differential T method described in method 4000, a correlation between T3, T4, and the ambient temperature and the temperature of fluid 104 may be derived, the ambient temperature may be used as another variable in method 5000 to correlate the three measured temperatures with the temperature of fluid 104.

[0076] In method 5000, in step 5002, the temperature of the shielded location 108 is determined (corresponding to T3 as described in method 4000). In step 5004, the temperature of the exposed location 110 is determined (corresponding to T4 as described in method 4000). In step 5006, the ambient temperature is determined. In step 5008, the internal temperature of the fluid 104 is estimated based on the measured values ​​of T3, T4, and the ambient temperature.

[0077] Please refer to Figure 9, which shows one embodiment of a temperature sensor 600 that can be used to estimate the internal temperature of fluid 104 using a hybrid zero-heat-flow temperature difference method. The temperature sensor 600 has a body 602 and is configured to be mounted on the outer surface of the housing 102. A first temperature sensing element 604 is positioned to be mounted adjacent to the outer surface of the housing 102, and similar to temperature sensor 300, a thermal insulation layer 608 is positioned outward from the first temperature sensing element 604, and then a second temperature sensing element 606 is positioned outward from the thermal insulation layer 608. Therefore, heat flows outward from the housing 102 along the heat flow path indicated by arrow 612.

[0078] The temperature sensor 600 differs from the temperature sensor 300 in that a heating element is omitted. Therefore, instead of using heat applied by a heating element to calculate the internal temperature of the fluid 104 using a zero-heat-flow method, the temperature sensor 600 derives an equation that can be used to model and predict the temperature of the fluid 104 based on the temperature difference between the first and second temperature sensing elements 604 and 606 under a series of known internal temperature conditions.

[0079] In some embodiments, a method is provided for estimating the temperature of fluid 104 using a hybrid zero heat flux and temperature difference or differential T method. In some embodiments, the method may, similar to method 5000, incorporate an additional compensation factor based on the ambient temperature. An example of method 6000 is shown in FIG10. Method 6000 may be implemented using a temperature sensor 600. In some embodiments, if the internal temperature of fluid 104 is estimated using the ambient temperature, any suitable device for determining the ambient temperature may also be used, such as a thermocouple, a resistive thermal device (RTD) sensor, a thermistor, or a semiconductor-based integrated circuit.

[0080] In step 6002, the temperature T5 of the first temperature sensing element 604, which is located closest to the housing 102, is determined. In step 6004, the temperature T6 of the second temperature sensing element 606, which is located further away from the housing 102, is determined. In step 6006, the ambient temperature is selectively determined. In step 6008, the internal temperature of the fluid 104 is estimated based on the measured values ​​of T5 and T6, according to previously derived coefficients for the electronic device. In some embodiments, if the ambient temperature is measured in step 6006, the internal temperature of the fluid 104 is estimated in step 6008 based on all of T5, T6, and the measured ambient temperature.

[0081] In some embodiments, the temperature sensor 300 or 400 may be equipped with a light schematically displayed as one of 320 / 320' / 420, or other visual indicator that the external temperature of a housing has exceeded a temperature exceeding a predetermined temperature threshold, such as a threshold that would make it unsafe for a person to touch the outer surface of the housing.

[0082] In some embodiments, as shown with respect to the temperature sensor 800 displayed in FIG11, any of the temperature sensors described herein may also have a wired connection 806 to allow connection, for example, to a digital sensor bus or other processor or communication module. The temperature sensor 800 has a head 802 and a handle 804. The wired connection 806 allows the temperature sensor 800 to relay information about the sensed temperature to a controller or other processor. In other embodiments, a wireless communication module may allow the temperature sensor 800 to relay information about the sensed temperature to a controller or other processor equipped with a parallel wireless communication module. In some embodiments, the wired connection 806 may be omitted. Example

[0083] Certain embodiments are further illustrated by the following examples, which are intended to be illustrative and not limiting in nature. Example 1.0 Comparison of estimated and actual internal temperatures

[0084] The inventors used one embodiment of the temperature sensor 400 to conduct a test to estimate the internal temperature of a fluid within a housing using method 4000. A controlled measurement of the actual internal temperature of the fluid within the housing was performed to evaluate the accuracy of the estimated temperature. In the experimental setup, the oil temperature and environmental conditions, such as ambient temperature and wind speed, could be independently controlled. Environmental conditions, including the ambient temperature, changed at each time point T1 and T2, but the actual internal oil temperature remained unchanged throughout the entire period of the change between T1 and T2.

[0085] The results are shown in Figure 12. The measured temperature of the fluid inside the housing (actual oil T) represents a known temperature value. The temperature of the shielded portion of the housing of the tank (shielding sensor T) and the temperature of the exposed portion of the housing of the tank (exposed sensor T) are measured and used to estimate the internal temperature of the fluid inside the housing (estimated oil T) using a transfer function as described above.

[0086] It can be seen that, particularly after any change in environmental conditions (i.e., shortly after the ambient temperature changes at each T1 and T2) reaches a stable state, the estimated temperature closely tracks the measured temperature (obtained independently using a separate temperature sensor located within the housing). Conversely, neither the shielded sensor T nor the exposed sensor T is particularly close to the actual oil T, indicating the need for another method to determine the internal oil temperature.

[0087] Although several exemplary embodiments and examples have been described above, those skilled in the art will recognize certain modifications, substitutions, additions, and sub-combinations. Therefore, it is intended that the following appended claims and subsequently added claims be interpreted as including all such modifications, substitutions, additions, and sub-combinations, since they substantially conform to the broadest interpretation of the specification. [Simplified Explanation of the Diagram]

[0020] Exemplary embodiments are shown in the reference figures of the drawings. The embodiments and drawings disclosed herein are to be regarded as illustrative and not limiting.

[0021] Figure 1 shows an electronic device, namely a transformer, in one exemplary embodiment.

[0022] Figure 2A shows a second exemplary embodiment of an electronic device, namely a transformer, in which a recessed hole is formed. Figure 2B is a cross-sectional view taken along line 2B-2B.

[0023] Figure 3A shows a cross-sectional view of one exemplary embodiment of a temperature sensor, which can be used to estimate the temperature of a fluid inside a housing using a zero-heat-fluidity method. Figure 3B shows a cross-sectional view of a second exemplary embodiment of a temperature sensor, which can be used to estimate the temperature of a fluid inside a housing using a zero-heat-fluidity method.

[0024] Figure 4 shows an exemplary embodiment of a method for estimating the temperature of a fluid inside a shell using a zero heat flux method.

[0025] FIG5A shows a cross-sectional view of an exemplary embodiment of a temperature sensor that can be used to estimate the temperature of a fluid inside a housing using a temperature difference or differential T method, FIG5B shows an enlarged cross-sectional view of the exemplary embodiment, and FIG5C shows a partial perspective view of the exemplary embodiment.

[0026] Figure 6 shows an exemplary embodiment of a method for estimating the temperature of a fluid inside a shell using a temperature difference or differential T method.

[0027] Figure 7 shows an embodiment of determining whether a temperature sensor has been installed to directly measure or estimate the temperature of one of the fluids contained in a housing.

[0028] Figure 8 shows an embodiment of a method for estimating the temperature of a fluid inside a shell using a temperature difference or differential T method, wherein a compensation factor for the ambient temperature is incorporated.

[0029] Figure 9 shows an embodiment of a temperature sensor that can be used to estimate the temperature of a fluid inside a housing using a modified zero heat flow method.

[0030] Figure 10 shows an embodiment of a method for estimating the temperature of a fluid inside a shell using a mixed zero heat flux and a temperature difference or differential T method.

[0031] Figure 11 shows an embodiment of a temperature sensor having a wired connection.

[0032] Figure 12 shows a test example illustrating the correlation between the estimated internal temperature of a housing and the measured temperature.

Claims

1. A device for non-invasively estimating the temperature inside a housing, the device comprising: an environmental shielding portion formed and assembled to shield at least a portion of the housing from major environmental conditions to provide an environmentally shielded portion of the housing; a first temperature sensing element disposed within the environmental shielding portion and positioned to be in thermal contact with the housing within the environmentally shielded portion of the housing when the device is in use; and a second temperature sensing element separated from the environmental shielding portion and positioned to be in thermal contact with the housing outside the environmentally shielded portion of the housing when the device is in use.

2. The apparatus of claim 1, wherein the second temperature sensing element is substantially exposed to the primary environmental conditions, or is exposed to the primary environmental conditions in greater quantities than the first temperature sensing element.

3. The device of claim 1, wherein the first temperature sensing element and / or the second temperature sensing element are configured to be positioned adjacent to the housing when the device is in use.

4. The device of claim 1, wherein the first temperature sensing element and / or the second temperature sensing element are configured to be positioned against the housing when the device is in use.

5. The device of claim 1 further includes a cartridge portion formed and assembled for insertion into a cartridge housing extending within the housing, the cartridge portion including the second temperature sensing element.

6. The device of claim 5 further includes a sensor for determining that the cartridge portion has been inserted into the cartridge housing.

7. The apparatus of claim 1 further includes a sensor for measuring the ambient temperature of the environment outside the housing.

8. The apparatus of claim 1 further includes a visual indicator for providing an indication that the external temperature of one of the housings exceeds a predetermined critical value.

9. The device of claim 1, wherein the housing comprises the housing of an electronic device.

10. A method of using the apparatus of claim 6, the method comprising the steps of: determining whether the cartridge portion has been inserted into the cartridge housing; if the cartridge portion has been inserted into the cartridge housing, directly measuring the temperature of the fluid contained in the housing using a third thermal sensing element; or if the cartridge portion has not been inserted into the cartridge housing, estimating the temperature of the fluid contained in the housing using the first and second thermal sensing elements.

11. The method of claim 10, wherein the second thermal sensing element and the third thermal sensing element are the same thermal sensing element.

12. The method of claim 10, wherein the housing comprises the housing of an electronic device.

13. A method for estimating the temperature of a fluid contained within a housing, the method comprising the steps of: measuring a first temperature at a first external location on the housing, the first external location being shielded from environmental conditions; measuring a second temperature at a second external location on the housing, the second external location being exposed to environmental conditions or more extensively than the first external location; and correlating a difference between the first temperature and the second temperature to estimate the temperature of the fluid contained within the housing.

14. The method of claim 13, further comprising the steps of: measuring an ambient temperature of the environment outside the housing; and using the measured ambient temperature as another parameter to estimate the temperature of the fluid contained within the housing based on the relationship between the first temperature and the second temperature.

15. A method for deriving a calibration coefficient for a particular type of housing using the apparatus of claim 1, the method comprising the steps of: measuring an internal temperature of a first housing representing a particular type of housing; measuring temperatures recorded by temperature sensing elements of the first temperature sensing element and the second temperature sensing element to provide first and second temperatures; and deriving a mathematical relationship between the first and second temperatures to generate the calibration coefficient.

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