Irreversible dual-temperature heat indicator

Abstract

The invention relates to the field of irreversible heat indicating devices, and more particularly to irreversible dual-temperature heat indicators for assessing the state of and visually indicating critical defects in small pieces of operational equipment. The present irreversible dual-temperature heat indicator comprises a flexible base, a thermal sensitive element disposed on the front surface of said base and capable of undergoing an irreversible change in transparency when a threshold temperature is reached, and a protective layer. The invention provides for an increase in the operational reliability and safety of equipment by making it possible to assess the thermal state thereof during technical maintenance and repair and to detect critical defects in a timely fashion during visual inspection of operational equipment, and also prevents errors in the interpretation of heat indicator readings.

Description

[0001] An irreversible two-temperature thermal indicator for assessing the condition and identifying critical defects of small components of operating equipment

[0002] The field of technology to which the utility model belongs

[0003] The utility model relates to the field of irreversible temperature-indicating devices, namely, irreversible two-temperature temperature-indicating devices for assessing the condition and timely detection of critical defects in small units of operating equipment.

[0004] State of the art

[0005] An increase in temperature is one of the first and most common signs of developing defects in various equipment, such as increased contact resistance in electrical equipment contacts, interturn short circuits in electric motor windings, failure of chargers or batteries in household appliances, and bearing malfunctions. Early detection of such overheating allows for troubleshooting and the prevention of equipment failure, shutdowns, or fires. Technical and regulatory documents establish maximum permissible temperatures, heating above which should be considered a defect requiring the equipment to be taken out for repair (for example, RD 34.45-51.300-97, RD 153-34.0-20.363-99, GOST 8865-93, 8024-90, 10693-81, 2213-79, 10434-82, 16708-84, 2585-81, 32397-2020, 26346-84, 839-2019, GOST R 51321.1-2007, etc.).

[0006] Among the known methods of temperature monitoring, temperature-indicating monitoring has become widely used. This method relies on temperature indicators that visually detect the occurrence and / or past occurrence of heating above a threshold temperature. The threshold temperature is set during manufacturing of the temperature indicator and is determined by the nature (structure) of the material from which the temperature-sensitive element (TE) is made. Temperature indicators can be varnishes and paints, or devices containing temperature-sensitive components (e.g., stickers, clips, tips, etc.).

[0007] The advantages of using temperature-indicating devices over thermal paints and varnishes include the absence of direct contact between the surface of the test object and the temperature-sensitive component, the ability to use multiple components with different threshold temperatures in a single device, and the ability to display additional information on the device (e.g., response temperature, expiration date, markings, etc.). Furthermore, the accuracy of heat detection on temperature-indicating devices is higher than that of varnishes and paints, since the temperature-sensitive component is applied in the factory.

[0008] Thermal indicators can be reversible, that is, changing their appearance only when heated and returning to their original color upon cooling, or irreversible, changing their appearance after exceeding a given temperature and maintaining their changed appearance after cooling.

[0009] A special feature of reversible temperature indicators is that they only provide information about current overheating, that is, about exceeding the temperature threshold at the time of inspection.

[0010] Irreversible temperature indicators allow one to detect the fact that the threshold temperature has been exceeded during the entire period of operation, regardless of the heating temperature value at the time of inspection.

[0011] Irreversible temperature indicators are available in single-temperature and multi-temperature versions. Single-temperature indicators detect when a single threshold temperature is exceeded.

[0012] There are several threshold temperatures for heating equipment components, each corresponding to a specific state of the equipment (component): serviceability, emergency defect, critical defect, or fire hazard. Depending on the type of surface being monitored and the purpose of temperature monitoring, single-temperature temperature indicators can be selected to detect the occurrence of a defect, its progression, emergency heating, fire hazard heating, etc.

[0013] A single-temperature thermal indicator can detect the excess of a single set temperature, but it does not allow for condition assessment or monitoring of the heating (defect) dynamics. Thus, if only the threshold temperature exceeding the defect threshold is monitored, when the thermal indicator is triggered, it is impossible to assess the equipment's condition: whether it is operational but contains a defect, or whether it is already critical. Similarly, if the thermal indicator fails to trigger at a critical temperature, it is impossible to determine whether a defect exists.

[0014] Therefore, to assess the condition of equipment, it is necessary to monitor at least two temperatures: the first, which distinguishes the absence or presence of a defect in the monitored component, at which point the equipment may remain operational and usable, and the second, a critical temperature at which further operation poses a direct threat to personnel, and equipment operation must be immediately stopped. In other words:

[0015] - the absence of the fact of activation of two threshold temperatures of the thermal indicator indicates the absence of a defect and a serviceable condition; the activation of only one, low-temperature, thermal element of the thermal indicator indicates the presence of a defect that must be eliminated during repair, that is, a faulty, but operational condition;

[0016] - the activation of two thermal elements of the thermal indicator indicates a critical defect, the need for immediate equipment repair and its emergency condition.

[0017] For operational personnel responsible for inspecting equipment during operation, the most important task is identifying critical defects in equipment components (exceeding the second threshold temperature of the temperature indicator), while for maintenance personnel, it is identifying the presence of a defect (exceeding the first threshold temperature of the temperature indicator). Since the inspected element is kept at a safe distance from the inspection point during equipment inspection by operational personnel, and given the importance of correctly identifying critical temperatures for personnel safety, the critical temperature indication should be as visible as possible and distinct from other status indications.

[0018] For a more in-depth analysis of the condition of the monitored component, irreversible multi-temperature temperature indicators are used. Irreversible multi-temperature temperature indicators feature a temperature indicator scale consisting of several thermoelements whose appearance irreversibly changes at different temperatures. The temperature indicator scale allows for the maximum temperature reached by the monitored component during operation to be determined with a given accuracy. This allows for the tracking of defect development dynamics over time, the ability to compare the maximum heating temperatures of identical equipment components (assemblies), and the determination of excess temperature, defect rate, and stage of defect development. Examples of such temperature indicators include multi-temperature temperature indicator stickers (TIS), in which the thermoelements are applied to form a temperature indicator scale similar to a thermometer. These include irreversible temperature indicators such as "Testoterm," "Thermindex," "Brady," and "L-Mark."Multi-temperature melting temperature indicators are also known, in which TEs with different temperatures alternate (RU 2801907 C1, published 18.08.2023). However, placing a large number of TEs on a limited-size indicator reduces their size and, therefore, visibility.

[0019] This problem is particularly pronounced for inspecting small components or equipment components that can only be inspected from a distance, for example, due to occupational health and safety requirements. These include all contact connections of high-voltage equipment, bearing assemblies and gearboxes of rotating machines, fuses of high-temperature furnaces, autoclave valves, and other equipment.

[0020] Furthermore, the use of multi-temperature temperature indicators with three or more TEs complicates the defect detection process due to the need to analyze the indicators' response data using calculation methods. Ultimately, this leads to increased processing time, errors in interpreting the triggered indicators, and the need for specialized training for specialists inspecting such indicators.

[0021] One approach to simplifying the interpretation of the results of the operation of multi-temperature thermal indicators is the use of thermal indicators with different color transitions.

[0022] An example of the implementation of such an approach is the reversible temperature indicator “Traffic Light”, which has one TE, which, depending on the temperature, changes color from green to yellow and, with a further increase in temperature, to red, and upon cooling, the reverse color transition occurs.

[0023] (https: / / markerpro.ru / product / termoindikator-dlya-goryachih-poverhnostej-svetofor-hallcrest-traffic-light / ). A feature of this solution, which limits its use, particularly in the electric power industry, is its reversible operation, which prevents detection of overheating throughout the entire period of operation, but only provides information on the current temperature.

[0024] There are known thermo-indicating stickers containing three thermo-elements, when triggered the color of the base under the corresponding thermo-sensitive material is revealed, while the base under each material is painted in its own color (green, yellow, red or red, blue, burgundy)

[0025] (https: / / www.nichigi.co.jp / en / en_products / temperature_top / durable_en_samo / new3E.html). However, using a separate color for each TE does not allow for emphasizing a specific response temperature, and placing a large-area three-temperature indicator on equipment elements with a small surface area is not always possible. Separately, it is worth mentioning temperature indicator stickers that distinguish not the fact of exceeding the threshold temperature, but the duration of exposure to the threshold temperature. Thus, from US 2023196261 A1, 06 / 22 / 2023, a sensor label is known containing a plurality of reversible temperature-sensitive elements forming a temperature indicator scale, and a plurality of irreversible temperature-sensitive elements, also forming a temperature indicator scale. The label may also contain additional temperature-sensitive elements not included in the temperature indicator scale, designed to record the upper and / or lower temperature limit.This technical solution is designed to determine the duration of temperature exposure. Similar solutions have found application in the storage and transportation of food products, as well as pharmaceuticals and chemicals. However, this solution is not applicable in areas where it is important to record any excess of temperature thresholds, both long-term and short-term, such as monitoring electrical and electromechanical equipment and its components.

[0026] Existing solutions offer either single-temperature temperature indicators, which can be installed on surfaces of any size but offer limited information, or multi-temperature temperature indicators, which allow for retrospective assessment of the maximum heating temperature range of a monitored object but are not visible from a safe distance on small monitored components, or whose response is dependent on the time of temperature exposure. Therefore, a practical challenge is to combine in a single temperature indicator one extremely large and externally visible temperature element, responsible for the critical temperature, and another, smaller, additional temperature indicator element, visible only from close range during repair work.In other words, the task boils down to creating a dual-temperature thermometer with differently sized thermocouples: the high-temperature thermocouple is clearly visible from a safe distance during inspections, while the low-temperature thermocouple is easily visible from a close distance during repairs. This thermometer will ensure informative and unambiguous interpretation of its operation results.

[0027] A prior art thermal indicator is designed to monitor the temperature regime during the transportation and storage of pharmaceuticals, medical products, and food products, as well as certain industrial products, wherein temperature-sensitive elements are applied in layers or distributed one within the other (US 10031086 B2, May 11, 2012). This thermal indicator detects two threshold temperatures—the cumulative and peak thermal effects—by irreversibly optically changing the appearance of thermal indicator compositions with different response temperatures. The composition detecting the cumulative effect has a lower response temperature than the composition configured for the peak effect. Upon reaching the peak temperature, the corresponding composition changes color or transparency due to the melting of a fusible solid included in the corresponding composition.The temperature-sensitive compounds are applied to the substrate in such a way that the cumulative exposure indicator has a small area in the central portion of the viewing window, while the peak exposure indicator has an area larger than the cumulative exposure indicator and completely overlaps it. As a result, the visual output of the cumulative and peak exposure indicator zones is integrated into a single overlapping viewing window.

[0028] The main technical difference of the solution proposed in US 10031086 B2 is the layered arrangement of temperature-sensitive elements. This arrangement allows for efficient use of the entire surface area of ​​the temperature indicator. However, layered application has several drawbacks, particularly when using such temperature indicators for thermal monitoring of moving components of operating equipment. Key among these is the risk of false activation of the high-temperature element after the low-temperature element has been triggered due to the destruction of the separating film or melt spreading.

[0029] Based on the logic of operation, when using a release film, the top layer of the temperature indicator proposed in US 10031086 B2 is low-temperature, since if the low-temperature composition is applied under the high-temperature layer and separated from it by a release film, the fact that only the low-temperature composition is activated will not be visually noticeable.

[0030] If a high-temperature compound is located beneath a low-temperature compound, mechanical or vibrational impacts may cause the melt of the low-temperature compound to flow into the lower high-temperature layer. Wetting of a failed high-temperature compound by the melt of a triggered temperature-sensitive material will change the device's appearance and cause incorrect interpretation of the temperature indicator's activation. Furthermore, mixing substances with different melting points will change the activation temperature of the resulting mixture relative to the original values, leading to false activation.Furthermore, layer-by-layer application of thermal compounds increases the overall thickness of the temperature indicator in the layered area, which reduces the speed and accuracy of detecting threshold temperature exceedances. Short-term heating only heats the lower, high-temperature layers of the temperature indicator, located closer to the heating source, while the upper layers do not have time to warm up and, consequently, undergo processes that change their appearance. Separating the layers with an inert insulating material further increases the thickness of the temperature indicator, distancing the upper layer from the heat source and reducing the accuracy and speed of detecting exceedances of preset temperatures. Therefore, such solutions cannot be used to detect short-term heating events caused, for example, by inrush currents or short-circuit currents, cold running, switching, or other processes.

[0031] Layering one composition directly on top of another without using a separating insulating film will, on the one hand, reduce the overall thickness of the temperature indicator, allowing for faster heating of the top layer. However, in this case, after melting one component, the second will be uniformly distributed within it, affecting both the appearance of the temperature indicator and the response temperature of the second component. As a result, temperature control readings will be unreliable. Furthermore, with prolonged exposure, especially at temperatures close to threshold, partial spreading or "slippage" of the melt may occur, accompanied by the dissolution of one composition in the other, forming solid eutectic systems (Eutectics. "Brief Chemical Encyclopedia", Moscow: Soviet Encyclopedia, 1967, Vol. 5, p. 457). This effect is especially noticeable during the formation of solid eutectics for substances with high melting points (100°C and above).

[0032] Furthermore, the presented solution selects threshold temperatures from a range of 30-60°C, limiting the thermal indicator's application to temperature monitoring in logistics. It also precludes the proposed solution from being used for assessing the condition and detecting defects in electrical equipment components, which may have operating temperatures of 60-80°C and critical temperatures of 90-140°C and higher. Consequently, the materials used in this solution may also not have the necessary characteristics for use in thermal monitoring of operating equipment components.

[0033] Summarizing the above arguments, it can be concluded that the solution proposed in US 10031086 B2 cannot be used to assess the condition and promptly identify critical defects in small components of operating equipment, nor can it be adapted for this task using known methods and approaches. To improve the reliability and safety of equipment operation, it is necessary that the low-temperature and high-temperature thermal zones be separated on the surface and reliably isolated from each other both before and after activation, and that the thermal indicator be clearly visible during inspection after activation of the high-temperature temperature-sensitive element.

[0034] It is known that the visibility of a temperature indicator can be ensured by the large area of ​​both the device itself and the proportion of the area occupied by the temperature-sensitive component relative to the total area of ​​the device (RU 213931 C1, publication date 06.10.2022). The presented device has a heat-activated zone area of ​​at least 100 mm. 2, and its proportion relative to the device's front surface area is at least 50%, preferably at least 70%. This makes overheating visible from a safe viewing distance, as a large triggered indicator surface is more visible than a small one. Coating the device with a protective varnish or polymer film protects it from external environmental influences, humidity, UV radiation, and mechanical damage, extends the device's service life, and prevents the heat-activated compound from flowing during the phase transition. The device also has a flexible base no more than 1 mm thick, ensuring a response time of no more than 5 seconds and enabling detection of even short-term overheating under peak loads of monitored components. However, this device contains a heat-sensitive compound with only one response temperature, so it cannot be used to assess the condition of equipment.At the same time, as was said above, on small-sized elements it is not always possible to install two temperature indicators of different sizes with different response temperatures.

[0035] Thus, the current state of the art does not yet include temperature indicators capable of assessing the condition of small surfaces of electrical equipment components (e.g., cable lugs, contact jaws, and plug-in contacts) that have two temperature-sensitive elements located separately on a base. The high-temperature element occupies a large area of ​​the indicator, amounting to at least 50% of the total area of ​​the temperature indicator, and is significantly different from the second, low-temperature temperature-sensitive element. Compared to a single-temperature indicator, the addition of a small second element will barely increase the area of ​​the indicator, allowing it to be placed on small equipment components or those located remote from inspection points. This, in turn, will allow such a temperature indicator to be used for assessing the condition of equipment.Placing the thermocouples in isolation from one another, rather than in layers, prevents false alarms of the temperature indicator caused by melt from one component flowing into the zone of another thermal composition, the formation of solid eutectic systems, etc., and also allows for the production of thin devices and the detection of short-term heating.

[0036] The operating principle of this dual-temperature thermal indicator is based on its installation on the monitored equipment element and regular inspection. The TE temperatures are selected as follows. Activation of the high-temperature element indicates a defect requiring immediate equipment repair. For this purpose, the high-temperature element (HTE) is large, ensuring its visibility on operating equipment from a safe distance, which typically ranges from 1 to 10 meters, depending on the voltage class, temperature, or pressure inside the monitored equipment. The activation temperature of the low-temperature element (LTE) is selected to indicate the presence of a defect that requires correction during repairs or maintenance of the electrical installation, with the power removed.Therefore, the size of the NTE is selected in such a way as to ensure its visibility from a close distance, save space for the VTE and prevent errors in interpreting the results of the operation.

[0037] Since there are currently no known prior art examples of the use of such an approach, the claimed utility model addresses the problem of creating an irreversible temperature indicator, comprising two temperature-sensitive elements with significantly different areas and different response temperatures, for assessing the thermal state during maintenance and repair, and for the timely detection of critical defects during inspection of operating equipment.

[0038] Terms, definitions and abbreviations used in the description of this utility model

[0039] The following terms, definitions, and abbreviations used in the description of this utility model are intended to provide a better and more precise understanding of this utility model, but do not limit this utility model to the stated wording. The term "thermal indicator" is a device that changes its appearance (in particular, color) when heated above one or more threshold temperatures. Typically, a thermal indicator consists of a base intended for attaching the thermal indicator to the monitored surface, and one or more temperature-sensitive elements (TE) located on the front side of the base that change appearance when heated.

[0040] Single-temperature temperature indicators include temperature indicators that have one or several heating elements that are triggered when one threshold temperature is reached.

[0041] Multi-temperature temperature indicators include temperature indicators that have several heating elements that differ in their response temperature (threshold temperature).

[0042] The term "irreversible" defines thermal indicators that, after heating to the operating temperature, visually change their appearance, in particular their color, in such a way that after cooling below the operating temperature, their appearance does not return to a form that is visually indistinguishable from the original.

[0043] The term "temperature-sensitive element (TSE)" refers to a temperature indicator element that changes its appearance when a threshold temperature is reached. The TSE may contain one or more substances. Upon reaching the threshold temperature, the TSE may change color or transparency. In the latter case, the visual effect of the temperature indicator's activation is determined by the color of the base located beneath the TSE. The change in color or transparency of the TSE upon reaching the threshold temperature may occur due to a chemical reaction, the melting of one or more substances, other phase transitions, or more complex processes. The TSE may also additionally include solid or gaseous inclusions located within the volume of the temperature-sensitive component; support elements; and an absorbent material onto which the temperature-sensitive component is applied.

[0044] This utility model prefers the use of fuel cells whose operation is based on a change in appearance upon melting, specifically a change in transparency. However, the utility model is not limited to the use of such components, and fuel cells can be constructed using components operating on different principles.

[0045] The TE may be a single element or comprise several spatially separated elements with the same response temperature and the same composition of substances that ensure the response temperature. The terms "high-temperature thermosensitive element (HTE)" and "low-temperature thermosensitive element (LTE)" are relative and are defined by the threshold temperature of the TE in a specific temperature indicator. For the purposes of this utility model, the HTE response temperature is at least 10°C higher than the LTE response temperature. To achieve the technical result claimed in this utility model, the area of ​​the HTE must be at least three times larger than the area of ​​the LTE, and the area occupied by the HTE constitutes at least 40% of the total surface area of ​​the base.Heat-sensitive elements (HSEs) and low-temperature elements (LTEs) typically use the same operating principle. However, heat-sensitive elements based on different operating principles may be used if required to ensure the required technical characteristics. The initial color and color transition, as well as the shape of the heat-sensitive HSEs and low-temperature elements, may be the same or different, depending on the intended purpose of the temperature indicator.

[0046] Threshold temperature is the minimum value of the heating temperature of a thermal indicator during the time required to achieve an equilibrium (unchanging over time) state, at which the appearance of the TE of a given thermal indicator changes.

[0047] The "color transition of a temperature-sensitive element" refers to the change in color of the temperature indicator upon activation of the TE. When describing the color transition, the color before activation is first indicated, followed by the color after activation. For example, a TE that is initially white (opaque) and after activation becomes transparent, revealing the color of the underlying black base, is said to have a white-to-black color transition. In some cases, either the TE or the base beneath it may bear inscriptions indicating, for example, the numerical value of the TE's threshold temperature, or signal symbols. In this case, the color of the TE before or after activation refers to the color of the background on which such inscriptions or symbols are applied, or the color transition of the main surface of the TE.

[0048] A change in the appearance of a temperature indicator or TE that occurs solely as a result of heating to any of the possible temperature thresholds is called "activation." In the context of the description of this utility model, activation of a temperature indicator is preferably associated with an increase in transparency achieved by melting a substance or group of substances comprising the TE.

[0049] A change in the appearance of a temperature indicator, in particular the color and / or transparency of the TE, that occurs as a result of an external influence other than heating the temperature indicator above the corresponding temperature threshold values, is called a “false triggering of the temperature indicator.”

[0050] A "Thermal Indicator Sticker (TIS)" is a device that acts as a temperature indicator and can be adhered to a test object using an adhesive layer applied to the back of the base during the manufacturing process. The TIS comprises a flexible elastic base, the back of which is coated with an adhesive layer protected by a release agent prior to installation on the test object, and the front of which contains areas with a thermal element, which, in turn, can be coated with a protective layer.

[0051] The term "visible light" defines a narrow region in the electromagnetic spectrum in the frequency range of 3.8 - 10 14 - 7.9 - 10 14 Hz, which corresponds to wavelengths in a vacuum from ~400 to ~760 nm, which can be distinguished by the human eye.

[0052] The term "opaque to at least part of the visible light spectrum" means a material that does not transmit all or part of the visible light spectrum.

[0053] The term "transparent to at least part of the visible light spectrum" means a material that allows all or part of the visible light spectrum to pass through.

[0054] "Response speed" is the maximum time required for a temperature indicator or TE to transition from its initial state to its activated state after the TE has heated up to the response temperature, taking into account the specified accuracy of registering when the threshold temperature is exceeded. For the purposes of this utility model, the response speed of a temperature indicator is no more than 10 seconds, and typically no more than 5 seconds.

[0055] For the purposes of the claimed utility model, the term “threshold temperature” means the temperature value at which the appearance of the TE changes (its operation), determined with a given accuracy.

[0056] The term “accuracy of recording the excess of the threshold temperature” refers to the boundaries of the range of temperature values ​​that meet the following conditions (1) - (3):

[0057] (1) until the threshold temperature is reached minus the specified accuracy value, the corresponding TE does not change its appearance (in particular, it remains opaque to at least part of the visible light), and the temperature indicator in this area does not change its appearance;

[0058] (2) when the threshold temperature is exceeded, taking into account the specified accuracy, the corresponding TE is triggered, in particular, with an increase in transparency achieved by melting one substance or a group of substances included in the TE, and the thermal indicators in this area acquire an appearance different from the original;

[0059] (3) In the case of using a TE in which the change in appearance upon reaching a threshold temperature is associated with an increase in transparency achieved by melting one substance or a group of substances included in the TE, the exact value of the phase transition temperature of the melting of the substance is within a specified range and is not further established. The accuracy of recording the excess of the threshold temperature defined by this utility model is preferably no more than 5 °C, most preferably no more than 2 °C.

[0060] The term "gas-filled hot-melt material" (GFTM) defines a material comprising a solid phase or phases, as well as a gas phase contained within the cavities of the solid phase. At least one of the GFTM solid phases, referred to as the "hot-melt phase," is capable of melting when heated to a threshold temperature. The gas phase is predominantly distributed uniformly throughout the GFTM, with most of the pores interconnected, allowing for the unimpeded distribution and release of gas during heating and / or melting of the material. The gas pressure within the pores may be less than atmospheric pressure, equal to atmospheric pressure, or greater than atmospheric pressure.

[0061] The solid phase of the thermal-sintering material may additionally include particles of a solid substance with a melting point above the threshold, the strength of which predominantly exceeds that of the thermal-sintering phase, polymers that completely or partially coat the thermal-sintering phase, and other inclusions. Such substances or inclusions are used to increase the mechanical strength of the thermal-sintering material.

[0062] The hot-melt phase contains the "active (main) substance of the HTPM"—a substance, specifically an organic compound, that determines the melting point of the HTPM (the threshold temperature for the FC to operate). The mass content of the active substance in the HTPM structure generally exceeds the content of other HTPM components. The term also refers to a mixture of such substances.

[0063] The term "organic substances" restricts the class of chemical substances that contain carbon atoms bonded to atoms of other chemical elements, excluding metal carbides, metal and ammonium carbonates, and carbon oxides.

[0064] The term "gas phase" by default refers to the gas-filled pores within the gas-filled thermocouple. The gas phase can be air, nitrogen, inert gases, or other substances in the gaseous state under the operating conditions of the thermocouple.

[0065] The term "gas phase fraction in a gas-filled slurry mixture" refers to the ratio of the pore volume within the gas-filled slurry mixture to the total volume of the gas-filled slurry mixture, or the ratio of the area of ​​gas-filled sections to the total area of ​​the gas-filled slurry mixture section in one of its cross-sections. For the purposes of this utility model, the gas phase fraction may be determined by one of the following methods.

[0066] The first method involves scanning electron microscopy of the surface of a section of the gas-filled slurry using software that calculates the total external surface area of ​​the sample's solid particles and their agglomerates in the section. The area of ​​gas-filled regions is calculated by subtracting the total surface area of ​​the solid particles and their agglomerates from the area of ​​the analyzed region. To determine the proportion of the gas phase, the resulting value for the area of ​​gas-filled regions is divided by the area of ​​the analyzed region. Measurements are performed on 5-7 sections of the gas-filled slurry, and the average value is calculated.

[0067] The second method is based on X-ray microtomography. Sample preparation is similar to the first method. A section of the gas-phase material of known volume is analyzed using a laboratory digital X-ray tomograph with software capable of calculating the percentage of gas in a given sample volume. Measurements are taken from 5-7 sections of the material, obtaining an average value for the gas phase content, expressed as a percentage.

[0068] Any method for determining the gas phase fraction can be applied to finished products containing gas-phase materials, such as temperature indicators. During sample preparation, a uniform section of the product is cut out and the protective layer is removed to ensure the integrity of the gas-phase material.

[0069] In the context of describing a gas-phase flow system, a "phase" refers to the homogeneous portion of the gas-phase flow system, separated from the remaining portions by a visible interface where some phase characteristics, such as density, composition, or optical properties, abruptly change. The collection of individual homogeneous portions of the system, each possessing identical properties, is considered a single phase.

[0070] The composition of the thermal melting material may additionally include particles of a solid substance with a melting point above the threshold, the strength of which predominantly exceeds the strength of the thermal melting phase, as well as other inclusions.

[0071] The term "GTPM structure" defines the spatial arrangement of solid particles and gas-filled pores in a GTPM sample. The GTPM structure determines its physical, optical, and mechanical properties. Upon reaching a threshold temperature, melting of at least one of the solid phases of the GTPM occurs. During the melting process, the GTPM structure changes, that is, the spatial arrangement of particles and / or volumes of individual phases of the material, their size, and shape. Destruction of the structure may include the following stages: melting of the GTPM particle surface, their compaction, reduction of the pore size within the GTPM and the gas-solid interface area, and particle fusion up to their complete fusion and the formation of a monolithic layer (melt) or a single phase. The process of GTPM structure destruction is accompanied by an irreversible decrease in the volume fraction of the gas phase within the GTPM. The proportion of the gas phase in the material obtained after the activation of the temperature indicator is less than in the initial state of the GTPM.

[0072] When describing a thermoplastic composite with a thermal-melting phase, the term "binder" refers to a material or substance, preferably a high-molecular-weight organic compound, that enables the adhesion of solid particles relative to one another. A solid thermal-melting phase binder, in particular, increases the strength of the thermal-melting phase and reduces its abrasion, and can also ensure the adhesion of the thermal-melting phase to the base or absorbent material.

[0073] By "hermetic protective layer" is meant a protective layer that is impermeable to air and water at atmospheric pressure and in the absence of mechanical impact, made without gaps or holes, and tightly connected to the base by welding or gluing in such a way that the joint is also impermeable to air and water at atmospheric pressure and in the absence of mechanical impact.

[0074] The term "absorbent material" refers to a material capable of receiving and retaining, by any means, a molten, hot-melt material, such as a molten active substance or a hot-melt phase. Retention may occur through wetting, adsorption, absorption, or penetration of the melt into pores or other internal cavities of the absorbent material. A special case of an absorbent material is a "sorbent material." Within the framework of this utility model, the absorbent material may be a "porous material," which is a solid material containing free space in the form of cavities, channels, or pores and characterized by a developed surface area. The main parameters of porous materials are porosity, pore size, pore size distribution, and specific surface area. For the purposes of the claimed utility model, the use of "microporous materials" containing pores with a diameter of less than 2 μm is preferred.The term "sorption" should be understood in its most general sense as the absorption of various substances by a solid body. The absorbed substance is called a "sorbate," and the absorbing solid or liquid is called a "sorbent." Within the framework of this utility model, when describing a fuel cell with a thermal-steel-based material (TSM), the sorbate is the melted thermal-steel-based material, i.e., a liquid, and the sorbent is various solid absorbent materials. "Absorption" is preferred as a special case of sorption, resulting in the absorption of the sorbate by the entire volume of the sorbent, increasing the sorbent's mass with a slight increase in its volume and changes in its physical properties, particularly its strength.

[0075] The term “support element” or “support element (SE)”, when describing a TE with a GTPM, defines an arbitrary element located in the region of the GTPM, which has a melting temperature greater than the operating temperature of the given GTPM, and which can take on most of the mechanical stress acting on the GTPM in the transverse direction, thereby preventing significant destruction of the GTPM structure.

[0076] The term “defect” indicates the non-compliance of the control object with the requirements established by the documentation, at least for one indicator.

[0077] The "defectivity factor" is the ratio of the measured temperature rise of the contact connection to the temperature rise measured on the entire section of the busbar or wire, located at a distance of at least 1 m from the contact connection.

[0078] The “brightness coefficient” is defined according to GOST 8784-75 as the ratio of the brightness of the coating to the brightness of the standard, measured under the same lighting conditions with a light incidence angle of 45°.

[0079] "Excess temperature" is the excess of the measured temperature of the controlled object over the temperature of similar units of other phases located in the same conditions.

[0080] The term "fire-hazardous heating" refers to the heating of an element of an electrical installation to a temperature at which there is a risk of ignition of one or more materials from which the element is made.

[0081] The term "flexible" refers to materials that have the ability to change shape under external influences so that their functional properties remain unchanged after returning to their original form. The term "elasticity" refers to the ability of a material or product to conform to its shape when bent around a cylindrical surface without losing its functional properties.

[0082] The terms "elastic base" and "elastic protective layer" characterize the base or protective layer material, which is capable of changing its shape without breaking under external influence.

[0083] The essence of the utility model

[0084] The objective of the claimed utility model is to create an irreversible temperature indicator with two temperature-sensitive elements - high-temperature and low-temperature, which have different areas and are separated from each other on the surface of the base, intended, for example, to assess the thermal state of equipment during maintenance and repair, as well as the timely detection of critical defects during inspection of operating equipment.

[0085] The technical result of the claimed utility model consists in increasing the reliability and safety of operation of equipment, small units of which are equipped with thermal indicators according to this utility model, due to the possibility of assessing the thermal state of the equipment during maintenance and repair, and the timely detection of critical defects during inspection of operating equipment, as well as the elimination of errors in the interpretation of the results of thermal indicator control.

[0086] According to the utility model, the technical result is achieved by an irreversible two-temperature thermal indicator (TI) comprising a flexible base; a high-temperature heat-sensitive element (HTE) located on the front surface of the base, configured to irreversibly change transparency upon reaching a threshold temperature (TtSE), wherein the area occupied by the HTE is at least 40% of the total area of ​​the front surface of the base; a low-temperature heat-sensitive element (LTE) located on the front surface of the base, isolated from the LTE, and configured to irreversibly change transparency upon reaching a threshold temperature (TntSE); a protective layer covering the LTE, the LTE, and at least a portion of the base free of heat-sensitive elements (TE); characterized in that the area of ​​the HTE is at least 3 times greater than the area of ​​the LTE, and TtSE is greater than TntSE by at least 10 °C (Fig. 1).The need to use irreversible temperature indicators stems from the need to detect instances of the monitored element heating above threshold temperatures throughout its entire operating life, regardless of the load and equipment temperature at the time of inspection. The change in transparency of the TE when threshold temperatures are reached ensures high contrast and a visible color transition (e.g., white to black) due to the ability to use any color base, particularly black, and to apply any sign or symbol (e.g., a flame, exclamation point, etc.) to the base. This sign appears upon activation and simplifies equipment condition assessment during inspections.

[0087] The placement of two TEs with two different response temperatures on a temperature indicator allows the use of such temperature indicators to assess the condition (e.g., serviceable / faulty / emergency) of small-sized elements (e.g., cable lugs, contact jaws, plug-in contacts), on which it is physically impossible to install two separate temperature indicators: both high-temperature and low-temperature.

[0088] In the temperature indicator of this utility model, the high-temperature elements (HTE) and low-temperature elements (LTE) are not layered on top of each other, but are applied directly to the base and separated from each other, preventing their contact before and after activation, which would result in the formation of solid eutectic systems. The proposed arrangement of the high-temperature elements (HTE) and low-temperature elements (LTE) increases the reliability of the temperature indicator, the reliability of its operation, and reduces the likelihood of false alarms, since the possibility of the activated low-temperature element (LTE) melt penetrating the unactivated high-temperature element (HTE) is eliminated.

[0089] Exceeding the low-voltage element's (NLE) threshold temperature may indicate one of several equipment conditions: equipment commissioning, the occurrence of a defect that requires correction during routine repair or maintenance of the electrical installation with the voltage removed, or reaching the operating temperature of the facility. The low-voltage element has a smaller area than the high-voltage element, and differs by at least a factor of three, reducing the risk of misinterpreting temperature indicator monitoring results.

[0090] The significant difference in the areas of the VTE and LTTE increases the visibility of the VTE activation during visual inspection of operating equipment from a safe distance. This is especially important when using temperature indicators in the electric power industry, where occupational safety regulations stipulate a minimum distance of 1-10 meters between a person and the operating equipment, depending on the voltage class. Furthermore, the activation of the VTE may indicate a critical defect requiring immediate shutdown and repair of the equipment. To ensure the visibility of the VTE activation, it must occupy as large a surface area as possible on the temperature indicator. Therefore, in the specified temperature indicator, the area occupied by the VTE must be at least 40% of the total surface area of ​​the indicator base.

[0091] The difference between the threshold temperatures of the low-voltage element (LVE) and the low-voltage element (LTE) is at least 10°C. This enables the equipment condition to be assessed and the absence (LVE and VTE in their initial state) or presence (LVE triggered, VTE in its initial state) of a defect in the monitored component can be detected, as well as the excess of a critical temperature (both LVE and VTE triggered). At this temperature, further operation poses a direct threat to personnel and equipment operation must be immediately stopped.

[0092] Thus, the combined use of the VTE and the LTE, in which the area of ​​the VTE differs significantly from the area of ​​the LTE (at least 3 times), is necessary to solve the following problems:

[0093] - increasing the visibility of a triggered temperature indicator when the monitored equipment reaches a critical temperature, including from a greater distance, in the dark or in poor lighting conditions;

[0094] - simplification of the interpretation of the results of the temperature indicator operation due to prioritization (focusing the attention of personnel) on a specific temperature.

[0095] Due to the size of the VTE, its operation is noticeable and clearly visible, which minimizes the possibility of error.

[0096] The use of a protective layer covering the VTE, NTE and at least part of the base free of TE allows:

[0097] - physically separate the VTE and NTE and ensure their mutual isolation in case of partial operation;

[0098] - protects the TE from the negative impact of the environment, ensures the safety of the TE before and after operation, preventing their contact with the controlled surface, reduces the impact of external factors, such as mechanical damage, moisture, UV radiation and others, on the TE.

[0099] Thus, the use of irreversible dual-temperature thermal indicators according to this utility model improves the reliability and safety of equipment operation through rapid and effective thermal state assessment during maintenance and repair, and the timely detection of critical defects during inspection of operating equipment, with unambiguous interpretation of thermal indicator monitoring results. Preferably, the minimum distance from the boundary of the high-temperature thermal element to the edge of the base ("2, Fig. 1") is at least 1 mm, most preferably 2 mm. This distance will, on the one hand, maximize the efficient use of the thermal indicator area by filling it with a high-temperature thermal element, and, on the other hand, ensure reliable adhesion of the protective layer and the base along the edges of the thermal indicator.Therefore, during operation of the temperature indicator, partial or complete peeling of the protective layer from the base will not occur, ensuring the integrity of the TE both before and after activation. The distance between the low-temperature element and the high-temperature element (al, Fig. 1) should also preferably be at least 1 mm, most preferably 2 mm. This is due to the need to ensure reliable adhesion of the protective layer and the base in the zone between the TE to avoid contact between the high-temperature element and the low-temperature element. As noted earlier, when TEs with different temperature-sensitive components come into contact, they may interpenetrate, forming eutectic mixtures whose activation temperature will differ from the initial threshold temperatures. Also, if the TE zones are insufficiently separated, a triggered low-temperature element may penetrate into the high-temperature element zone, leading to an erroneous interpretation of the temperature indicator's activation.

[0100] The VTE can be applied to the front surface of the temperature indicator base as a single zone or as several zones located adjacent to each other and separated by free areas of the base (Fig. 3). The location of the VTE and NTE on the base depends on the specific tasks performed during the operation of the temperature indicator.

[0101] The response speed of at least one of the high-temperature and low-temperature elements according to this utility model is no more than 10 seconds, preferably no more than 5 seconds. This speed is necessary to detect short-term heating events caused by peak (emergency) loads or, for example, short-circuit currents. In particular, this response speed requirement is essential for the use of temperature indicators in monitoring the condition of electrical equipment. This response speed is ensured, in particular, by the thickness of the temperature indicator base, which in preferred embodiments is no more than 0.5 mm.Using a base of this thickness also allows the temperature indicator to adhere tightly to surfaces with complex geometries, including conductive elements of electrical equipment. It allows for rapid warm-up of the heating elements during short-term overheating and their complete shutdown. It also ensures the necessary heat transfer during air cooling of operating devices. This allows for the detection of short-term emergency overheating caused by starting currents or short-circuit currents, excessive starting loads on motors, cold running, switching, or other processes.

[0102] The high-temperature elements and low-temperature elements used in the temperature indicator described in this utility model may differ in the operating principle of the temperature-sensitive component included within them. When selecting the type of temperature-sensitive component, the specific characteristics of each must be taken into account. Prior art includes temperature-sensitive elements based on a chemical reaction of their constituent substances, which begins upon reaching a certain temperature or upon melting. Prolonged exposure of temperature-sensitive elements based on a chemical reaction at a temperature slightly below the threshold value may lead to their premature activation, since the degree of chemical reaction is determined not only by temperature but also by time.

[0103] There are thermoelectric cells based on the mechanical destruction of one of the temperature-sensitive components when a threshold temperature is reached. Typically, such thermoelectric cells have a rigid structure, which precludes the creation of flexible temperature indicators.

[0104] The most common thermoelectric cells are those based on phase transition, primarily the melting of a heat-sensitive component, due to their high precision, response speed, and ability to maintain their original appearance indefinitely at temperatures slightly below the threshold. Prior art thermoelectric cells based on the phase transition of a heat-sensitive component can be classified by the operating principle that changes the device's appearance: a change in the transparency of the heat-sensitive component upon melting, dissolution of dyes in the melted heat-sensitive material, or absorption of the melted heat-sensitive component into a porous substrate.

[0105] FCs in which the change in appearance occurs due to the dissolution of a solid dye in a melt of a fusible substance usually have a short service life due to solid-phase diffusion of the dye.

[0106] The penetration of the molten component into the porous substrate, on the one hand, ensures a high contrast of the color transition, since the color of the substrate may differ from the original color of the solid hot-melt component, but on the other hand, the crystallization of the substance in the pores of the substrate upon cooling can lead to reversibility (returnability) of the color indication.The use of a thermo-sensitive element (TE) in a temperature indicator, the operating principle of which is based on an irreversible increase in the transparency of the heat-sensitive component due to its melting, has a number of advantages over the operating principles described above: high response accuracy due to the use of purified stable substances with a narrow range of melting points; ensuring the irreversibility of response (even with a long-term exposure of the triggered temperature indicator at a temperature below the threshold); high opacity of the heat-sensitive layer, allowing the production of flexible temperature indicators of small thickness; visibility of the triggered temperature indicator, ensured by the contrast of the color transition (e.g., white - black) due to the possibility of using a substrate of any color, in particular, black; the possibility of simplifying the assessment of the equipment condition during inspections due to the appearance of a special hazard sign or symbol (e.g., a flame sign, an exclamation mark, etc.) upon triggering of the TE.), located on the base under a layer of hot-melt material (Fig. 2-3); ensuring the possibility of registering local overheating due to the fact that only the area of ​​the TE that is heated above the threshold temperature is subject to melting, and the appearance of the remaining areas of the TE is preserved; high response speed due to the use of a thin layer of heat-sensitive component; long service life.

[0107] Based on this, in this utility model for VTEs, primarily VTEs and LTEs, the preferred method is to use TEs whose temperature-sensitive components operate based on a change in transparency upon melting. However, the utility model is not limited to the use of such components, and TEs can be constructed using components operating on different principles.

[0108] To enhance the technical benefit of enabling the detection of critical defects by visually inspecting small components of operating equipment from a safe distance, in preferred embodiments, the area occupied by the VTE is 45-70%, preferably 50-60%, of the total surface area of ​​the temperature indicator. This maximizes the visibility of the VTE, even from a distance. The area occupied by the NTE can be 1-10%, preferably 2-5%, of the total surface area of ​​the temperature indicator. Using a small NTE will save space for the VTE and prevent it from being confused with the VTE.

[0109] Since the thermal indicator according to the claimed utility model is intended to assess the condition and detect critical defects of small components of operating equipment (such as cable lugs, contact jaws, plug-in contacts, etc.), its linear dimensions generally do not exceed 70 x 50 mm. This thermal indicator size is the maximum possible for installation on electrical installations with a voltage of 110 kV and above, which are inspected from a distance of 10 meters or more, and is determined by the size of the busbars, equipment clamps, and cable lugs. With this thermal indicator size, it is preferable that the area of ​​the low-voltage element (NTE) does not exceed 100 mm. 2 Preferably, the linear dimensions of the temperature indicator do not exceed 35 x 35 mm, which allows it to be used to monitor the temperature of cable joints and plug-in contacts of electrical installations with a voltage of 6-35 kV. With this size of temperature indicator, it is preferable that the area of ​​the NTE does not exceed 50 mm. 2. It is preferable for the linear dimensions of the thermal indicator to not exceed 25 x 20 mm for its use on cable lugs and contact jaws of electrical installations with a voltage of 0.4 kV. With this size of thermal indicator, it is preferable for the area of ​​the NTE to not exceed 25 mm. 2 .

[0110] Preferably, in their initial state, the main surface of the thermal indicator and the low-voltage element are identical, predominantly white. Upon activation, the base color reveals itself, providing a white-to-black color transition. This color scheme ensures maximum visibility of a partially or fully activated device by using the highest contrast, most noticeable under operating conditions, and an intuitively understandable color transition upon activation. This eliminates errors during equipment inspection in low light conditions, as well as by personnel with visual impairments, including the inability to distinguish primary colors of the spectrum (color blindness). It also eliminates false interpretation of activation if one of the thermal indicator colors is used for traditional marking (for example, blue, yellow, green, red, and brown are widely used in the power industry for phase marking).

[0111] In other versions, the color of the VTE when the threshold temperature is reached differs from the corresponding color change of the NTE after activation. This option can be used, for example, in cases where the NTE detects the achievement of the standard operating temperature, while the VTE detects the maximum permissible operating temperature. The shape of the VTE may differ from that of the NTE, which will also facilitate the interpretation of thermal monitoring results using the specified temperature indicator.

[0112] In order to increase the information content of thermal monitoring using a temperature indicator according to this utility model, in preferred embodiments, the threshold temperatures of the HTE and LTE are selected from the list of 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C. In this case, it is preferable that TwTE be higher than TnTE by 20-35 °C. This is due to the fact that most electrical equipment units have an operating temperature higher than the ambient temperature. An excess of this temperature by a certain value will indicate an incipient defect, reaching or exceeding the rated load, i.e. This indicates that this equipment component needs to be addressed during the next scheduled inspection. The TNTE can be selected to record precisely this temperature.A further temperature increase of 20-35°C would indicate, for example, an emergency, dangerous, fire-hazardous, or other special condition of the monitored equipment, requiring immediate personnel response. Therefore, the TWTE is preferably selected to detect critical overheating of the monitored components.

[0113] To make the VTE more visible and to facilitate the detection of local overheating, in some embodiments of the utility model its area is at least 25 mm 2 , preferably not less than 100 mm 2 .

[0114] In specific embodiments, the temperature indicator incorporates information elements that include color, alphabetic, numeric, or alphanumeric information, in particular, information for marking electrical equipment components or color-coded phase markings. Such information elements may be applied to the front surface of the base and / or the surface of the protective layer. In some embodiments, at least some of the information elements are located within the TE area, which allows for space savings on the base and increases the area of ​​the TE. Information elements on the base and / or protective layer may, in particular, contain information about the end-of-life date of the device. Additionally, when the TE is triggered, an additional information symbol may appear, such as an exclamation mark, a flame image, etc. (Figs. 2-3).

[0115] In particular cases, at least one TE, preferably a VTE, most preferably a VTE and a NTE may have one or more properties aimed at enhancing the technical result, in particular: includes a gas-filled hot-melt material (GFTM), preferably, the proportion of the gas phase in which is at least 10 vol.%; contains an absorbent material (AM); contains support elements (SE); contains at least one solid organic substance with a molecular weight of less than 2 kDa; changes appearance only in the region that was heated above the corresponding threshold temperature, while maintaining the original appearance of other regions of the TE, the temperature of which did not exceed the corresponding threshold temperature; includes at least one solid organic substance containing a structural fragment C nH(2n+i), where n> 5, and is preferably selected from the group consisting of fatty aliphatic acids containing structural fragments CnH(2n+i) with n> 12; salts of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 5; alkanes containing at least 20 carbon atoms; dialkylphosphinic acids containing structural fragments C n H(2n+i) with n > 5; amides of fatty aliphatic acids containing structural fragments CnH(2n+i) with n > 5; anhydrides of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 10; fatty aliphatic alcohols containing structural fragments C n H(2n+i) with n > 14; fatty aliphatic amines containing structural fragments C n H(2n+i) with n > 17; nitriles of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 19.

[0116] Preferred non-limiting examples of solid organic substances are palmitic acid, stearic acid, behenic acid, tetracosane, erucamide, stearic alcohol, cetyl alcohol, salts of saturated fatty carboxylic acids of rare earth metals, in particular lanthanum, yttrium, ytterbium, scandium.

[0117] The use of a thermal indicator (TI) ensures high accuracy and a long service life, and enables the use of minimal-thickness thermocouples while maintaining high opacity and a high luminance factor, irreversibly triggering at high speed and precision. These characteristics are achieved thanks to the TI's unique structure, which includes, in addition to a solid phase or phases, at least one of which contains a hot-melt substance or a mixture thereof, voids filled with a gas phase. Until the threshold temperature is exceeded, the gas phase within the TI is distributed predominantly uniformly. This creates multiple gas-solid interfaces at which light is refracted and reflected. This TI structure makes it opaque to at least some visible light, while maintaining a thinner layer thickness than a similar substance without a gas phase.

[0118] The structure of the GTPM also provides the ability to register the boundary of the thermal heating fields of the surface of the test object by changing the appearance of only that part of the GTPM that was heated above the corresponding threshold temperatures, and maintaining the original appearance of the rest of the GTPM.

[0119] When using heat-sensitive materials based on melting for the VTE, when a threshold temperature is exceeded, the VTE changes appearance only in the area heated above the corresponding threshold temperature, while maintaining the original appearance of other areas of the VTE whose temperature did not exceed the corresponding threshold temperature. This VTE design allows for the detection of localized overheating. The boundary of the heated area is determined with high accuracy, typically within 1-2 mm. This allows for highly reliable and accurate determination of the location of a localized overheating on the monitored surface. To enhance this characteristic, it is preferable to use gas-filled hot-melt materials, as discussed above.

[0120] When monitoring the thermal state of batteries, transformers, and cable joints, it is necessary to identify hotspots, as temperatures even at a short distance from the epicenter can vary significantly. This approach allows for the detection of an emergency situation even with short-term localized heating that is unable to uniformly heat the monitored surface under the entire temperature indicator scale. For example, consider a specific case (Fig. 6), where a short-term emergency heating above the VTE tripping temperature, occurring to the left of the temperature indicator (caused, for example, by a short-circuit current), triggers the low-temperature TE and partially the VTE. The readings of such an indicator with partial VTE tripping will be informative, since they are interpreted as an emergency defect. From this perspective, the larger the area occupied by the VTE and the more uniformly it is distributed over the temperature indicator, the more informative and reliable the information obtained upon its tripping.

[0121] Thus, the use of a heat-sensitive material based on melting for the VTE, as well as the VTE area, which occupies a large part of the front surface of the temperature indicator, allows: to increase the reliability of thermal control during local and short-term heating; to determine the location and direction of heating.

[0122] The temperature-sensitive materials used in this utility model may contain a single active substance or a mixture of active substances. The active substance or mixture of active substances is preferably a solid organic substance or a mixture of such substances. The specific substance is selected such that, upon reaching the appropriate threshold temperature in the range of no more than 5°C, preferably no more than 2°C, a change in its transparency occurs, ensuring a visually observable change in the appearance of the temperature indicator.

[0123] In preferred embodiments of the utility model, at least one active (main) substance of the hot-melt material has a molecular weight of less than 2 kDa (2000 amu). FCs with a low-molecular-weight active substance of the hot-melt material have a narrow melting point range, which leads to increased accuracy in detecting threshold temperature exceedances. The use of low-molecular-weight substances as active substances is only possible in HTPMs, since in the absence of a gas phase within the hot-melt material, multiple crystallization centers may form during cooling of the FC with a low-molecular-weight hot-melt substance, leading to the formation of an opaque solid and the return of the FC to its original form, i.e., to the reversibility of its operation.

[0124] The use of active substances containing one or more aliphatic hydrocarbon chains is preferable due to the fact that such organic substances have a crystalline packing in which the elongated structural fragments of linear hydrocarbons are oriented parallel to each other, which ensures the formation of predominantly flat particles such as scales, plates or fibers (Kitaigorodskii A.I. Molecular Crystals: Monograph. Moscow: Nauka. 1971. 424 p. pp. 228-232). Such crystalline packing causes the anisotropy of the solid organic substance, as a result of which the properties of the material in the direction parallel to the surface of the base and the protective coating differ from the properties of the material in the direction perpendicular to the surface of the base and the protective coating.The anisotropy of the properties of a hot-melt material affects the strength of the material during bending and mechanical impacts: applying impact in directions close to perpendicular to the surface of the base will not lead to damage to the material (Kitaigorodskii A.I. Organic crystal chemistry: monograph. Moscow: Publishing house of the Academy of Sciences of the USSR, 1955. 558 p. pp. 134-136).

[0125] Use of aliphatic compounds with C n H(2n+i), where n > 5, is also preferable due to the fact that, due to its crystalline packaging, the heat-sensitive material exhibits the ability to bend and stretch / compress without deformation and loss of functional properties due to layer-by-layer shear of particles.

[0126] The described shape and characteristics of the active substance particles are preferred, but do not limit the claimed utility model. They can also be achieved using substituted aromatic and heteroaromatic compounds. In this case, the substituents can be either long hydrocarbon fragments, which further facilitate the formation of planar oriented particles, or heteroatomic substituents, which promote layered packing of molecules, in which bulky heteroatoms are located in the interlayer space (Bokiy, G.B. Crystal Chemistry: Monograph. 3rd revised and enlarged ed. Moscow: Nauka, 1971. 401 p. pp. 362-365).

[0127] However, it should be noted that the claimed utility model is not limited exclusively to the use of substances with a molecular weight of less than 2 kDa, which include one or more aliphatic hydrocarbon chains with a structural fragment C nH(2n+i), where n > 5. In particular, the hot-melt material may include at least one solid polymeric organic substance, selected without limitation from polyethylene, phenolic and phenol-acetylene resins, waxes, paraffins and other substances that provide an increase in the transparency of the material upon reaching the threshold temperature and possessing the necessary properties.

[0128] In preferred embodiments, the volumetric gas content of the thermal fusible composite is at least 10%, most preferably at least 50%. Using a thermal fusible composite with this volumetric gas content allows for a significant reduction in the thickness of the hot-melt material layer to ensure adequate hiding power, compared to the thickness of a non-gas-filled material required to achieve the same hiding power. To prevent delamination of the thermal fusible composite during heating due to thermal expansion of the gas phase, it is preferable for the pressure within the thermal fusible composite to be below atmospheric pressure, and for most of the pores filled with the gas phase to be non-isolated, i.e., to communicate with one another.

[0129] Using at least one gas-phase thermal indicator with the specified volumetric gas content increases the service life of the thermal indicator and improves the reliability of overheating detection by preventing the aggregation of solid organic particles separated by the gas phase. This also virtually eliminates the possibility of the thermal indicator's appearance returning to its original state when the triggered device is exposed to low temperatures and temperature fluctuations.

[0130] Increasing the volumetric gas content in the gas-fuel mixtures used also reduces their apparent density. This reduces the amount of heat required to melt the gas-fuel mixture and increases the response speed of the fuel element. In preferred embodiments of the invention, to ensure irreversibility of the fuel element's response, the volumetric gas content in the gas-fuel mixture during melting is reduced by at least half.

[0131] An absorbent (ABM) or microporous material can be placed between the base and the temperature-sensitive material. In this case, when the thermoelectric element is triggered, the temperature-sensitive material is absorbed or penetrated by the ABM. The use of ABM prevents partial opacity of the melted temperature-sensitive layer when the triggered thermoelectric element is subjected to mechanical stress, such as bending or vibration.

[0132] One embodiment of the utility model may utilize a base comprising multiple support elements (SEs), between which the heat-sensitive component of the TE is positioned. The TE may also contain multiple SEs located within the heat-sensitive phase. This protects the TE from mechanical impacts (pressure, friction, increased pressure, etc.) by redistributing the load from the heat-sensitive phase to the support elements.

[0133] When using a fuel cell incorporating a gas-phase thermal generator (GPM), when the threshold temperature is exceeded, the gas phase emerges to the surface, causing an air bubble to form under the protective layer. Since this process occurs during heating, the volume of the resulting bubble increases due to thermal expansion. As the device cools further, the volume of the gaseous medium decreases, and the size of the bubble under the surface of the protective layer decreases. To remove the bubble that forms when the threshold temperature is exceeded, according to some embodiments of the proposed utility model, micro-holes can be made in the protective layer, allowing the gas released during operation to escape while also providing the necessary protection for the fuel cell from external influences.

[0134] The temperature indicator may also, in particular cases, have one or more properties aimed at enhancing the technical result, in particular: be made in the form of a sticker; be elastic; be designed with the possibility of marking elements of electrical equipment or color marking of phases; the back side of the base may contain an adhesive layer of constant tack with an adhesion of at least 10 N / 25 mm to stainless steel, measured by the FINAT TM1 method after 24 hours; the base may be made of halogen-containing polymers, preferably PVC, more preferably cast PVC; the protective layer may be made of halogen-containing polymers, preferably PVC, and be transparent to at least part of the visible light, at least in the area of ​​the TE; the protective layer may be attached to the base in the area free of the TE, including the area between the HTE and the LTE;the base can be partially colored using a heat-sensitive material that reversibly changes its appearance when heated above the corresponding threshold temperature.

[0135] The thermal indicator according to the claimed utility model can be implemented, in particular, in the form of a sticker, tape, clip, tip, etc. Thermal indicator stickers have found the widest application in technology due to their ease of installation, availability, and ease of use.

[0136] When the claimed utility model is implemented as a sticker, the back of the base is provided with a permanent adhesive layer with an adhesion of at least 10 N / 25 mm to stainless steel, measured using the FINAT TM1 method after 24 hours, to ensure reliable contact between the temperature indicator and the monitored surface throughout the entire service life of the temperature indicator. In preferred embodiments, the adhesive layer is made using acrylic, polyurethane, rubber, silicone, PVC polymers, or adhesives based on these materials.

[0137] In preferred embodiments of the utility model, the base of the temperature indicator is flexible and made of a thermoplastic polymeric material. Preferably, the base material contains halogen atoms, primarily chlorine atoms in polyvinyl chloride, most preferably cast polyvinyl chloride. The use of a halogen-containing polymer base enables the temperature indicator to visually record when at least one temperature threshold is exceeded on the surfaces of conductive components of electrical installations, since halogen-containing polymers have a dielectric strength of at least 5 kV / mm and are fire-resistant.

[0138] Polymeric materials containing halogen atoms in their structure exhibit some of the highest flexibility and elasticity among known polymers. The introduction of halogen atoms into the monomers used as feedstock for polymerization disrupts their symmetry and creates multiple chiral centers in the polymer. Polymerization or polycondensation of such monomers, either with each other or with other halogen-containing or halogen-free monomers, results in the formation of polymer chains with a large number of stereocenters. Regular polymers obtained from non-halogenated monomers lacking chiral centers tend to form crystalline structures, which reduces their elasticity, while the large number of diastereomers formed during halogenation of the monomers imparts stereochemical disorder to halogenated polymers, which prevents crystallization.Thus, halogen-containing polymeric materials possess high elasticity and flexibility due to their chemical structure, which is determined by the presence of halogen atoms in the polymer structure. Furthermore, halogen-containing materials exhibit good adhesion and low flammability, which further ensures the safety of the device.

[0139] As mentioned above, the use of a protective layer protects the FC from adverse environmental impacts both before and after activation. A hermetically sealed protective layer also allows for the creation of reduced or excess gas pressure within the FC. Preferably, the protective layer is made of flexible polymeric materials, particularly halogen-containing polymers, most preferably PVC or cast PVC, and is transparent to at least some visible light, at least in the area of ​​the FC.

[0140] The use of thermoplastic polymers as the base and / or protective layer material allows for an effective and hermetically sealed connection between the protective layer and the base, for example, by welding. The protective layer is preferably attached to the base over the entire area of ​​the temperature indicator free of the TE. Attaching the protective layer to the base around the perimeter of the temperature indicator ensures a hermetic seal, preventing vapors and liquids that come into contact with the indicator during operation from penetrating. Attaching the protective layer to the base in the area between the TE and LT elements isolates them from each other both before and after activation, preventing contact between temperature-sensitive substances and maintaining the initial threshold temperatures.

[0141] The use of elastic materials for the base and protective layer ensures the overall elasticity of the device, which ensures a tight fit of the temperature indicator to surfaces with complex geometries, including those with small radii of curvature, such as conductive elements of electrical equipment.

[0142] The base and / or protective layer may also be colored to comply with established electrical equipment marking regulations. The above features serve to give the temperature indicator the properties of electrical equipment marking elements.

[0143] To increase the visibility of both the temperature indicator itself and the fact of its operation, and, as a consequence, to further increase the safety of equipment operation, the base and / or protective layer may have reflective or luminescent properties.

[0144] Also, the base or some portion of it can be painted using a substance capable of reversibly changing its appearance upon heating. For example, a layer of heat-sensitive paint with the above-mentioned properties can be applied to the front surface.

[0145] The presence of a substance capable of reversibly changing its appearance when heated allows personnel to be informed not only of past temperature threshold exceedances but also of overheating events during the inspection. The activation of such a substance during an inspection indicates that the equipment is currently in emergency mode and may pose a potential hazard. Thus, the presence of a substance capable of reversibly changing its appearance when heated further enhances the safety of equipment operation.

[0146] The presented examples describe only specific use cases for the device according to this utility model and do not limit its functionality and scope of application.

[0147] Brief description of the drawings

[0148] Fig. 1 - general view of the temperature indicator in the initial state, including two TE (LTTE and VTE) of different sizes - VTE is at least 3 times larger than the LTTE.

[0149] Fig. 2 - external appearance of the temperature indicator according to the present utility model, including two TE (LTTE and VTE), in which the VTE has a threshold temperature of 90 °C, and the LTE - 60 °C. 2a - temperature indicator in the initial state, 2b - temperature indicator after exceeding Tnte and changing the color of the LTE, 2c - temperature indicator after exceeding Tvte and changing the color of the VTE.

[0150] Fig. 3 - external view of the temperature indicator according to the present utility model, including two TE (LTTE and VTE), in which the VTE is divided into three isolated zones and has a threshold temperature of 85 °C, and the LTE has a threshold temperature of 50 °C. 3a - temperature indicator in the initial state, 3b - temperature indicator after exceeding Tnte and changing the color of the LTE, 3v - temperature indicator after exceeding Tvte and changing the color of the VTE and the reversible temperature indicator, 3g - temperature indicator after cooling to room temperature.

[0151] Fig. 4 is an external view of the temperature indicator according to the present utility model, including two TEs (LTTE and VTE), in which the VTE has a threshold temperature of 95 °C, and the LTE - 70 °C, wherein the VTE has the shape of a circle, and the LTE is located around the VTE, at a distance of "1" from the VTE. 4a is the temperature indicator in the initial state, 4b is the temperature indicator after exceeding Tntte and changing the color of the LTE, 4c is the temperature indicator after exceeding Tvte and changing the color of the VTE.

[0152] Fig. 5 - layered structure of a thermal indicator made in the form of a sticker, in an embodiment in which the low-temperature element and the high-temperature element have different color transitions (white-red, white-black).

[0153] Fig. 6 - activation of the thermal indicator during a short-term emergency heating that occurred to the left of the thermal indicator.

[0154] Detailed description of the drawings

[0155] Fig. 1 shows the general appearance of the thermal indicator 1 in its initial state, including two TE 2 (LTTE 2' and VTE 2") of different sizes - the VTE is at least 3 times larger than the LTTE, the VTE 2" has a threshold temperature of 90 °C, and the LTTE 2' - 60 °C, while the LTTE and VTE have different shapes. The thermal indicator 1 in the area free from TE 2 is colored yellow to mark the phases of the electrical equipment. Information elements 3, showing the numerical values ​​of the threshold temperatures 3' TntE and Tvte, are located in the region of the LTE 2' and VTE 2", respectively. In Fig. 1, the minimum distance "1 from the boundary of the LTE 2' to the boundary of the VTE 2", the minimum distance "2 from the boundary of the VTE 2" to the edge of the base, and the minimum distance "3 from the boundary of the LTE 2' to the edge of the base are also indicated.

[0156] Fig. 2 shows a temperature indicator 1 according to the present utility model, including two TE 2 (LTTE 2' and VTE 2"), in which VTE 2" has a threshold temperature of 90 °C, and LTE 2' - 60 °C. 2a - temperature indicator in the initial state, 2b - temperature indicator after exceeding Tnte and changing the color of LTE, 2c - temperature indicator after exceeding Tvte and changing the color of VTE. In the initial state, the NTE 2' and VTE 2" are white (Fig. 2a), and when the corresponding threshold temperature is exceeded, a white-black color transition is ensured for the NTE (Fig. 2b) and white-red for the VTE (Fig. 2c). The temperature indicator 1 in the area free from the TE 2 has light-reflecting properties. Information elements 3, showing the numerical values ​​of the threshold temperatures 3' Tnte and Tvte, are located in the area of ​​the NTE 2' and VTE 2", respectively. In the area of ​​VTE 2", in addition to the numerical value of the threshold temperature 3', information signs warning of danger 3" are additionally located.

[0157] Fig. 3 shows the external appearance of the temperature indicator 1 according to the present utility model, including two TE 2 (LTTE 2' and VTE 2"), in which VTE 2" is divided into three isolated zones and has a threshold temperature of 85 °C, and LTE 2' has a threshold temperature of 50 °C. The base is painted using a reversible heat-sensitive material 4, the temperature of which is equal to Tvte. 3a is the temperature indicator in the initial state, 3b is the temperature indicator after exceeding Tnte and changing the color of LTE 2', 3b is the temperature indicator after exceeding Tvte and changing the color of VTE 2" and the reversible temperature indicator, 3g is the temperature indicator after cooling to room temperature. LTE 2' and VTE 2" in the initial state are white (Fig. 3a), and when the corresponding threshold temperature is exceeded, an irreversible white-black color transition is ensured (Figs. 3b-g). The reversible temperature-sensitive material 4 in its initial state has a green color (Fig. 3a-b), and when the threshold temperature is exceeded, it reversibly changes color to red (Fig. 3b).Information elements 3, showing the numerical values ​​of threshold temperatures 3' TntE and Tvte, are located in the NTE 2' and VTE 2" areas, respectively. In the VTE 2" area, in addition to the numerical value of the threshold temperature 3', information signs warning of the danger 3" are also located.

[0158] Fig. 4 shows the external appearance of the temperature indicator 1 according to the present utility model, including two TE 2 (LTTE 2' and VTE 2"), in which VTE 2" has a threshold temperature of 95 °C, and LTE 2' - 70 °C, wherein VTE 2" has the shape of a circle, and LTE 2' is located around the VTE, at a distance of "1" from the VTE. 4a - temperature indicator in the initial state, 4b - temperature indicator after exceeding Tnte and changing the color of LTE 2', 4c - temperature indicator after exceeding Twte and changing the color of VTE 2". In the initial state, the NTE 2' and the VTE 2" are white (Fig. 4a), and when the corresponding threshold temperature is exceeded, a white-to-black color transition is provided for the NTE (Fig. 4b) and a white-to-red transition is provided for the VTE (Fig. 4c). The thermal indicator 1 in the area free from the TE 2 is colored green to mark the phases of the electrical equipment. Information elements 3, showing the numerical values ​​of the threshold temperatures 3' Tnte and Twte, are located in the area of ​​the NTE 2' and the VTE 2", respectively.

[0159] Fig. 5 is a layered structure of a thermal indicator 1 made in the form of a sticker, in an embodiment in which the NTE 2' and the VTE 2" have different color transitions (white-red, white-black) and are located from each other at a distance of al. The sticker includes a base 5 having a yellow color, the back side of which is covered with an adhesive layer of permanent stickiness 6 and protected by a release 7, a protective layer 8 covering the TE and attached to the base in areas free of TE.

[0160] Fig. 6 shows the operation of the thermal indicator 1, which includes two TE 2 (NTE 2' and VTE 2") with threshold temperatures of 60 °C and 100 °C, respectively, during a short-term emergency heating above 100 °C that occurred to the left of the thermal indicator, with full operation of NTE 2' and operation of a part of the surface of VTE 2".

[0161] Implementation of a utility model

[0162] Selecting the base of the device

[0163] The base 5 of the claimed irreversible temperature indicator is preferably made of polymeric materials, but the use of materials such as paper, cellulose, and woven materials is not excluded. The base material 5 should preferably be elastic and flexible to allow the temperature indicator to be mounted on a surface with complex geometry, including surfaces with a small radius of curvature. Halogen-containing polymeric materials are preferably used in the claimed utility model without limitation, in particular chlorine-containing polymers, such as vinyl chloride copolymers, namely: copolymer C-15 (a copolymer of vinyl chloride and vinyl acetate), copolymer VHVD-40 (a copolymer of vinyl chloride and vinylidene chloride), polyvinyl chloride (PVC), cast PVC, polyvinylidene fluoride PVDF, fluoroplastic M-40, as well as polyesters with the addition of 6.5% hexabromocyclododecane or polyesters modified with 15% trichloroisopropyl phosphate.

[0164] When using a halogen-containing polymer base, the dielectric strength of the temperature indicator is preferably at least 5 kV / mm, which is preferred for use in the power industry. Halogen-containing materials also have low flammability. When selecting the base material, consider its melting or decomposition temperature, which should be higher than the response temperature of the VTE temperature indicator.

[0165] In one embodiment, the temperature indicator may be implemented as a sticker (Fig. 5). In this case, the base 5 is coated on the back with a permanent adhesive 6 and protected by a release 7. Acrylic, polyurethane, rubber, silicone, or PVC-based adhesives can be used as the permanent adhesive layer. Preferably, the adhesion of the adhesive layer to stainless steel, measured using the FINAT TM1 method after 24 hours, is at least 10 N / 25 mm.

[0166] In other embodiments, the base 5 of the temperature indicator may be a hollow cylinder, with or without a slit, to produce devices in the form of temperature indicator clips, cambric sleeves, or tips. In this case, the base 5 is preferably made of polymeric materials with elasticity and flexibility to ensure secure attachment to wires and other round electrical components without the use of adhesives or other fastening methods.

[0167] Regardless of the design options, the thickness of the base, at least in the TE area, is generally no more than 0.5 mm.

[0168] At the final stage of manufacturing, the temperature indicator is coated with a protective layer 8, which protects the FC and the device itself from external environmental influences, humidity, UV radiation, and mechanical damage, increasing the device's service life. The material of protective layer 8 is preferably selected from transparent elastic polymers, preferably halogen-containing polymers, in particular polyvinyl chloride, most preferably cast polyvinyl chloride. Flexible elastic polymer films made of polyvinyl chloride, polyurethane, polyurea, and other polymers can be used as materials for protective layer 10.

[0169] The protective layer 8 is preferably attached to the base in areas free of TE, including areas between the HTE and LTE (Fig. 5). Welding or gluing methods can be used to connect the protective layer and the base.

[0170] The base 5 and / or protective layer 8 (in areas free from TE) may have reflective or luminescent properties to increase the visibility of both the temperature indicator itself and the fact of its operation to improve the safety of the operation of the equipment on which the temperature indicator is installed.

[0171] In specific cases, base 5 and / or protective layer 8, or a portion thereof, may be colored in accordance with the requirements for marking cable phases, installation wires, harnesses, and other electrical equipment components. The color of base 5 may be initially selected in accordance with GOST 28763-90, which establishes, among other things, color coding in electrical engineering.

[0172] To enhance the contrast of the color transition, the base in the TE zone can be painted. Information, including threshold temperature values ​​3', hazard signs 3', the device's expiration date, and other data, can also be applied to the surface of the base 5 and / or protective layer 8. Preferably, at least some of the information elements, in particular the threshold temperature values ​​3', are located in the TE zone.

[0173] In one embodiment, a base 5 and / or a protective layer 8 may be used that include multiple support elements (SE) between which at least part of the heat-sensitive material is located.

[0174] In other embodiments, the base 5 may be partially colored using a heat-sensitive material that reversibly changes its appearance when heated above the corresponding threshold temperature.

[0175] Manufacturing of heat-sensitive material for fuel cells

[0176] The claimed utility model may utilize various thermoelectric cells whose operating principle is based on a change in appearance upon reaching a threshold temperature. It is preferable to use a single thermoelectric cell type in a single temperature indicator; however, if necessary, thermoelectric cells with different operating principles may be used. The preferred method is to use thermoelectric cells whose temperature-sensitive components operate by changing their transparency upon melting.

[0177] In specific cases, the change in transparency of at least one TE, preferably a HTE, and most preferably a HTE and a LTE, upon reaching the appropriate threshold temperature is achieved by melting the substance or group of substances comprising the TE. When thermal indicator 1 is activated with such TE, the color of the underlying substrate becomes apparent. Depending on the color of the substrate beneath the TE, the activation of each TE may result in the same or different color transitions. Preferably, the substrate beneath all TEs is colored black. In this case, all TEs are preferably white in their initial state, thereby ensuring a visually observable "white-to-black" transition upon activation.

[0178] At least one TE, preferably VTE 2”, most preferably NTE 2' and VTE 2”, may include: a gas-filled hot-melt material (GFTM), preferably, the proportion of the gas phase in which is at least 10 vol.%; an absorbent material; support elements; at least one solid organic substance with a molecular weight of less than 2 kDa; at least one solid organic substance containing a structural fragment C n H(2n+i), where n > 5, and is preferably selected from the group consisting of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 12; salts of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 5; alkanes containing at least 20 carbon atoms; dialkylphosphinic acids containing structural fragments C n H(2n+i) with n > 5; amides of fatty aliphatic acids containing structural fragments C nH(2n+i) with n > 5; anhydrides of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 10; fatty aliphatic alcohols containing structural fragments C n H(2n+i) with n > 14; fatty aliphatic amines containing structural fragments C n H(2n+i) with n > 17; nitriles of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 19.

[0179] In particular embodiments, the solid organic substance / a TE is, without limitation, selected from the group consisting of: yttrium caproate, yttrium behenate, yttrium undecanoate, yttrium laurate, yttrium tridecanelaurate, yttrium tridecanepentadecanate, yttrium tridecanoate, yttrium pentadecanoate, yttrium palmitate, ytterbium caprylate, lanthanum palmitate, lanthanum nonadecynate, lanthanum caproate, erbium undecanate, zinc nonadecanoate, zinc palmitate, zinc caproate, zinc myristicate, zinc stearate, cadmium laurate, cadmium laurinmyristate, lead caproate, lead stearate, lead laurate, lead laurinmyristate, stearate copper, calcium stearate, lithium stearate, stearic acid, lauric acid, docosanoic acid, eicosanoic acid, crotonic acid, arachidic acid, myristic acid, palmitic acid, adipic acid, octanoic acid, capric acid, tricosanic acid, tetratriacontanoic acid, 2,3-dimethylnonanoic acid, brassidic acid,2-methyl-2-dodecenoic acid, eleostearic acid, behenolic acid, behenic acid, oleamide, stearamide, lauramide, erucylamide, capric amide, myristic amide, caprylic amide, palmitic anilide, salicylic anilide, beta-naphthylamide caproic acid, enanthic phenylhydrazide, hexylamide, octacosylamide, N-methylheptacosylamide, salicylamide, hexadecanol, ecucamide, 1-docosonol, trilaurin, tricose amine, dioctadecylamine, T4, T4-dimethyloctylamine, dioctylphosphinic acid, tritriacontane, tetracosane, stearyl alcohol, cetyl alcohol, stearic acid chloride, palmitic acid anhydride, stearic and acetic acid anhydride, lauric acid anhydride or mixtures thereof with a melting point that differs from the threshold temperature by no more than 5 °C.,

[0180] When using a gas-fuel mixture (GPM) in at least one fuel cell, it is preferable that upon reaching the appropriate threshold temperature, the volume fraction of gas within the GPM decreases by at least a factor of two. This ensures that the change in transparency of the GPM is irreversible when the appropriate threshold temperature is exceeded.

[0181] The use of at least one TE, including a gas-filled thermocouple (GFT) with a gas content of at least 10% by volume, also extends the service life of the temperature indicator and improves the reliability of overheating detection by preventing the aggregation of solid organic matter through the gas phase. Furthermore, the higher the gas content in the GFT, the higher the initial refractive index, the more pronounced the change in appearance due to a significant reduction in refractive index when the corresponding threshold temperature is exceeded, and the greater the separation of the gas and other phases after the GFT is triggered. This eliminates the possibility of the GFT returning to its original gas-filled state when the triggered temperature indicator is maintained at low temperatures and during temperature fluctuations.

[0182] The process of manufacturing a fuel cell including a gas-temperature thermal module is described in detail in a number of the authors' patents, in particular, in patent RU 2800396 C1, published on July 21, 2023, and can be used to create a temperature indicator based on this utility model.

[0183] To produce at least one HTPM, the solid organic substance is ground in a ball mill to a particle size of 2-3 µm. A liquid phase consisting of water or an organic solvent with a boiling point below 180°C is added, and the resulting suspension is mixed, preferably with periodic dispersion of the mixture under air access until the mixture's density remains constant. The liquid phase is preferably water or an organic solvent in which the solubility of the solid organic substance of the HTPM does not exceed 100 g / kg.

[0184] In preferred embodiments of the utility model, the liquid phase is added in an amount of at least 50 wt.%, most preferably from 50 wt.% to 90 wt.%.

[0185] The difference in density between the liquid phase and the solid organic matter is preferably less than 0.2 g / cm 3 . For this purpose, the liquid phase can be selected without limitation from the group consisting of isopropanol, water, methanol, G-propanol, isobutanol, ethylene glycol monomethyl ether, 1-butanol, acetonitrile, acetic acid, hexane, heptane, octane, nonane, 1,1,1-trifluoroethanol, 1, 1,1, 3,3,3-hexafluoroisopropanol, NM-dimethylformamide, toluene, xylene, ethanol, butyl acetate, acetone and mixtures thereof. The resulting suspension or paste is applied to the base and / or protective layer and / or absorbent material and dried under the action of dry air, temperature or vacuum.

[0186] This method produces a gas-fueled composite material (GPM) containing a solid organic substance, preferably in the form of particles with uniformly distributed gas-filled voids. Depending on the nature of the solid organic substance, the resulting particles can predominantly be grains, crystals, fibers, flakes, or agglomerates thereof.

[0187] In particular cases, at least one HTPM further comprises a polymer binder that is transparent to at least some visible light. In some embodiments, the binder ensures adhesion of the HTPM to the base or absorbent material. In this case, the crushed solid organic substance is suspended in a solution of a binder that is transparent to at least some visible light in a solvent with a boiling point below 150°C. In preferred embodiments of the invention, to ensure a glazing effect on the solid organic substance, the binder is present in the resulting HTPM in an amount of 1-30% by weight.

[0188] The transparent polymer binder may be selected without limitation from the group consisting of phenol-formaldehyde resin, butyl methacrylate resin, melamine-formaldehyde resin, polyvinyl butyral, polybutyl methacrylate, polyisobutyl methacrylate, polybutyl acrylate, phenoxy resin, polystyrene-acrylic emulsion, polyolefin, polystyrene, polyacrylate, polyethersulfone, polyethylene, polypropylene, polystyrene, polyvinylidene fluoride, polytetrafluoroethylene, polyethersulfone, polyisoprene, polypropylene, polybutadiene, polyisobutylene, polyvinyl acetate, polymethacrylate, ethyl cellulose, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polycaprolactone, polyethylene terephthalate resin, polybutylene terephthalate resin, polyamide resins, polyvinylidene fluoride, polyester, polyester resins, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, nitrocellulose, carboxymethyl cellulose, gelatin, agar-agar, casein, gum arabic, polyvinyl alcohol, polyethylene oxide or mixtures thereof,but not limited to them.,

[0189] The WTE and LTE are selected such that, upon reaching the corresponding threshold temperature, the response time is no more than 5 seconds, preferably no more than 2 seconds. The change in transparency of the TE occurs within a range of no more than 5°C, preferably no more than 2°C. In various embodiments, the solid organic substance of the TE is selected such that TwTE is higher than TnTE by 20-35°C and can be selected from a range of 50 to 210°C. In this case, the numerical values ​​of the threshold temperatures of the TE can be selected, in particular, from the group of 50 °C, 55 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C.

[0190] For example, the threshold temperatures of the LTE and VTE may be, respectively, 50 °C and 70 °C, or 50 °C and 80 °C, or 50 °C and 85 °C, or 60 °C and 80 °C, or 60 °C and 90 °C, or 60 °C and 100 °C, or 70 °C and 90 °C, or 70 °C and 100 °C, or 70 °C and 105 °C, or 70 °C and 130 °C, or 80 °C and 100 °C, or 80 °C and 110 °C, or 80 °C and 115 °C, or 90 °C and 110 °C, or 90 °C and 120 °C, or 100 °C and 135 °C.

[0191] In specific implementation cases of the utility model, one or both TEs may contain supporting elements uniformly distributed within the heat-sensitive material, which are added to it during its manufacture. Supporting elements may be made of a material with a melting point higher than the TE's response temperature. Polymeric materials, particularly halogen-containing polymers such as polyvinyl chloride and cast polyvinyl chloride, as well as glass, ceramics, metals, non-metals, and products based on them, such as mesh, fibers, microspheres, woven or non-woven materials with the above characteristics, can be used as supporting elements.

[0192] In specific implementation cases of the utility model, one or both TEs may include a VM, which absorbs the molten hot-melt material during its activation. The use of a VM improves the accuracy of interpreting temperature indicator test results by maintaining the contrast of the color transition, even under mechanical impacts (including vibration loads) on the activated TE, due to the absence of rebound response. Furthermore, the VM can perform the functions of the TE described above.

[0193] In certain cases, the EM is made of porous or absorbent materials, preferably microporous materials. EM can be selected without limitation from paper, microcellulose, wool, silk, felt, cotton, linen, molecular sieves, zeolites, silica gel, aerosil, microspheres, and ceramics. Microporous materials with a pore diameter of no more than 2 µm are most preferred. The EM can be colored. In this case, the color of the EM will appear upon activation. Alternatively, the EM can become transparent upon absorption of a melt (silica gel, aerosil). In this case, the color of the base will appear upon activation of the TE.

[0194] General technology for manufacturing a temperature indicator. A partially or completely painted or unpainted base is covered with a protective polymer film, with the exception of the area where the VTE is to be located. The VTE 2" is applied using a selected method depending on the type of heat-sensitive material used. In some embodiments, the VTE 2" can be applied as separate isolated or contacting elements (Fig. 3). The film is then removed and the sequence of actions for applying the remaining NTE 2' is repeated. In this case, the area of ​​the VTE 2" must be at least 3 times larger than the area of ​​the NTE 2', and the area occupied by the VTE 2" must be at least 40% of the total area of ​​the front surface of the base 5. The shape of the VTE 2" and NTE 2' can be the same or different depending on the requirements for the temperature indicator 1.The area of ​​the base 5 free from TE can be covered with a heat-sensitive material 4 that reversibly changes its appearance when heated above the corresponding threshold temperature (Fig. 3).

[0195] In the mutual arrangement of the VTE 2" and the NTE 2' on the surface of the base 5, the following requirements are preferably met: the area occupied by the VTE is 45-70%, preferably 50-60%, and the area occupied by the NTE is 1-10%, preferably 2-5% relative to the total area of ​​the front surface of the temperature indicator; the minimum distance from the boundary of the VTE to the edge of the base 5 and / or the distance between the TE is at least 1 mm, most preferably 2 mm; in which the area of ​​the VTE is at least 25 mm 2 , preferably not less than 100 2 mm; the shape of the VTE differs from the shape of the NTE.

[0196] The linear dimensions of the surface of the base 5 and, accordingly, the temperature indicator 1 itself, preferably do not exceed 70x50 mm, while the area of ​​the NTE does not exceed 100 mm 2; preferably do not exceed 35x35 mm, while the area of ​​the NTE does not exceed 50 mm 2 ; more preferably, they do not exceed 25x20 mm, while the area of ​​the NTE does not exceed 25 2 MM.

[0197] After applying all the TEs, in some embodiments of the utility model, the thermal indicator 1 is covered with a protective layer 8 that is transparent, at least for part of the visible light, at least in the area of ​​the TE 2. To release the gas phase and avoid the formation of an air bubble between the heat-sensitive material and the protective layer, micro-holes are made in the protective layer.

[0198] How a temperature indicator works

[0199] The temperature indicator according to the claimed utility model operates as follows. In their initial state, the low-temperature element (LTE) and the low-temperature element (LTE) are preferably the same color, primarily white. Until the entire surface of the temperature indicator, or individual sections located beneath the LTE, heats up to the low-temperature LTE threshold (LTE), the temperature indicator retains its original appearance. When the surface heats up above the low-temperature element (LTE) threshold temperature (LTE), the LTE's external color irreversibly changes. A LTE with a threshold temperature TLTE > TLTE by at least 10°C retains its original appearance. A further increase in the surface temperature on which the temperature indicator fragment is located to TLTE leads to irreversible activation of the LTE and a change in its appearance (color). Upon subsequent cooling, the LTE retains its original appearance, resulting in the entire temperature indicator not returning to its original state.This ensures the possibility of visually recording the temperature exceeding the threshold temperature values ​​both at the moment of overheating and after a long period of time.

[0200] In the case of using heat-sensitive materials for the VTE, the operation of which is based on the floating of a hot-melt component, when the controlled surface is heated locally to the VTE operation temperature, a partial change in its appearance occurs only in the area that was heated above the threshold temperature, while maintaining the original appearance of the remaining areas that were not subject to heating.

[0201] It is preferable to use fuel cells that ensure the temperature indicator's original appearance remains intact when the device is cooled to 20°C and maintained at this temperature for at least one month, preferably one year or more. In preferred embodiments, the temperature indicator has a service life of at least five years, preferably at least ten years.

[0202] The thermal indicator according to the claimed utility model is primarily intended for thermal monitoring of contact connections of high-voltage equipment, bearing assemblies and gearboxes of rotating machines, fuses of high-temperature furnaces, autoclave valves and other small-sized equipment.

[0203] However, the temperature indicator can be used in a wide variety of industrial or domestic facilities that require temperature control.

[0204] By visually inspecting a temperature indicator mounted on equipment, one can quickly and effectively assess the condition and identify critical defects by visually inspecting small components of operating equipment from a safe distance.

[0205] Examples

[0206] Below are presented preferred embodiments of the claimed utility model, which are illustrative and in no way limit the scope of the requested legal protection.

[0207] Example 1.

[0208] We made two temperature indicators measuring 70*50 mm (3500 mm) 2 ) with the VTE and NTE applied to a base with reflective properties, as shown in Fig. 2. A heat-sensitive composition with a threshold temperature of 60 °C was used as the NTE, and a heat-sensitive composition with a threshold temperature of 90 °C was used as the VTE. In the initial state, the VTE and NTE are white. The VTE has a rectangular shape and a size of 65 * 30 mm (1950 mm 2), which is 56% of the total surface area of ​​the temperature indicator. The NTE has a rectangular shape and a size of 10 * 10 mm (100 mm 2 ). Thus, the area of ​​the VTE is 9 times larger than the area of ​​the LTE. The device was covered with a transparent protective layer made of 0.05 mm PVC, and the base and protective layer were bonded in areas free of the TE, including between the TE, isolating the VTE from the LTE. The distance al between the boundaries of the LTE and VTE and the boundary of the VTE and the edge of the base is the same and is 2 mm.

[0209] To test its operation, the first thermal indicator was installed on a heating element at room temperature. The heating element was then heated in a controlled, uniform manner at a rate of 5°C / min to a temperature of 60°C with a specified accuracy. Heating was stopped, and the activation of the low-temperature element was recorded by visually observing a white-to-black color transition. The surface was then uniformly heated to a temperature of 90°C, and the activation of the high-temperature element was recorded by visually observing a white-to-red color transition. The activation time and change in appearance of the low-temperature element was 2 seconds, and the high-temperature element was 1 second. After the device had cooled to room temperature, the altered appearance of the low-temperature element and high-temperature element was visually observed.

[0210] To test operation under localized heating, a second temperature indicator was mounted at room temperature on the surface of a thin metal plate. A spot heating source was applied to the back of the plate, close to the top edge, and heated in a controlled manner at a rate of 5°C / min to a temperature of 90°C. A change in the appearance of the portion of the VTE closest to the heat source was recorded by visually observing a white-to-red color transition, while the portion of the VTE located farthest from the heat source retained its original appearance. A change in the appearance of the LTE was also recorded. After the device cooled to room temperature, the altered appearance of both the VTE portion and the entire LTE was visually observed to persist.Thus, when using a TE whose operation is based on the melting of a heat-sensitive component, as a result of partial activation of the device due to point heating of the surface and the location of the heat source above the device, the location of the activated part of the HTE, as well as the activation of the LTE, allows not only to determine the maximum temperature to which heating occurred, but also to assume the location of the heat source.

[0211] Example 2.

[0212] We made a temperature indicator measuring 25*20 mm (500 cm) 2) with the VTE and NTE applied to the base as shown in Fig. 3. Before applying the TE, the base was coated with Tempilaq pigmented green reversible thermal paint with an appearance change temperature of 82 °C. A heat-sensitive compound with a threshold temperature of 50 °C was used as the NTE, and a heat-sensitive compound with a threshold temperature of 85 °C was used as the VTE. The VTE has a rectangular shape measuring 20 x 13 mm and is divided into three zones, the thickness of the dividers is 0.5 mm. Thus, the total area of ​​the VTE is 240 mm 2 (48% of the total surface area of ​​the temperature indicator). The NTE has an oval shape with an area of ​​20 mm 2Thus, the area of ​​the VTE is 4 times larger than the area of ​​the LTE. The device was covered with a transparent protective layer made of 0.02 mm thick polytetrafluoroethylene, and the base and protective layer were bonded in areas free of the TE, including between the TE, isolating the VTE from the LTE. The distance al between the boundaries of the LTE and VTE is 1 mm, and the distance between the boundary of the VTE and the edges of the base is 2.5 mm.

[0213] To test the thermal indicator's operation, it was mounted on a heating element at room temperature. The heating element was then heated in a controlled, uniform manner at a rate of 5°C / min to a temperature of 50°C with a specified accuracy. Heating was stopped, and the activation of the low-temperature element was recorded by visually observing a white-to-black color transition. The surface was then uniformly heated to a temperature exceeding 85°C, and the activation of the high-temperature element was recorded by visually observing a white-to-black color transition, as well as the activation of the thermal paint with a green-to-red color transition. The activation time and change in appearance of the low-temperature element was 2 seconds, while the high-temperature element was 1 second. After the device had cooled to room temperature, the changed appearance of all areas containing heat-sensitive materials was visually observed, and the thermal paint returned to its original green color.

[0214] Example 3.

[0215] We made a temperature indicator measuring 35*35 mm (1225 cm) 2 ) with the LTE and VTE applied to the base as shown in Fig. 4. A heat-sensitive composition with a threshold temperature of 70 °C was used as the LTE, and a heat-sensitive composition with a threshold temperature of 95 °C was used as the VTE. The VTE has the shape of a ring with a thickness of 5 mm (area of ​​864 mm 2 ), which is 70% of the total surface area of ​​the temperature indicator. The NTE has a round shape with a diameter of 5 mm (50 mm 2 ). Thus, the area of ​​the VTE is 4.3 times larger than the area of ​​the LTE. The device was coated with a transparent protective layer made of a 0.04 mm thick vinyl chloride-vinyl acetate copolymer, and the base and protective layer were bonded in areas free of the TE, including between the TE, isolating the VTE from the LTE. The distance al between the LTE and VTE boundaries is 2 mm, and the distance between the VTE boundary and the edges of the base is 2.5 mm.

[0216] To test the temperature indicator, it was installed on a heating element at room temperature. The heating element was then heated in a controlled, uniform manner at a rate of 5°C / min to a temperature of 70°C with the specified accuracy. Heating was stopped, and the activation of the low-temperature element was recorded by visually observing a white-to-black color transition. The surface was then sequentially uniformly heated to a temperature of 95°C, and the activation of the high-temperature element was recorded by visually observing a white-to-red color transition. The activation time and change in appearance of the low-temperature element was 3 seconds, while the high-temperature element lasted 1 second. After the device had cooled to room temperature, the changed appearance of all areas containing heat-sensitive materials was visually observed.

[0217] All manufactured temperature indicators have confirmed the ability to quickly and effectively assess the condition and identify critical defects, as well as the unambiguous interpretation of temperature indicator monitoring results.

[0218] In addition, the developed temperature indicators have high speed, accuracy, and irreversibility of response, which makes them preferable for use in the energy sector.

Claims

Formula 1. An irreversible two-temperature temperature indicator (TI) comprising: a flexible base; a high-temperature heat-sensitive element (HTE) located on the front surface of the base, configured to irreversibly change transparency upon reaching a threshold temperature (TtSE), wherein the area occupied by the HTE is at least 40% of the total area of ​​the front surface of the base; a low-temperature heat-sensitive element (LTE) located on the front surface of the base, isolated from the LTE, and configured to irreversibly change transparency upon reaching a threshold temperature (TntSE); a protective layer covering the LTE, the LTE, and at least a portion of the base free of heat-sensitive elements (TE); characterized in that the area of ​​the HTE is at least 3 times greater than the area of ​​the LTE, and TtSE is greater than TntSE by at least 10 °C.

2. A temperature indicator according to claim 1, in which the minimum distance between the VTE and the NTE and / or the minimum distance from the edge of the base to the NTE and VTE is at least 1 mm, most preferably 2 mm, and the service life is at least 2 years.

3. A thermal indicator according to item 1, in which the thickness of the base is no more than 0.5 mm, and the response speed of the VTE and NTE is no more than 10 seconds, preferably no more than 5 seconds.

4. A temperature indicator according to claim 1, in which the change in the appearance of the VTE, preferably the VNE and NTE, is associated with the melting of a substance or group of substances included in their composition.

5. The temperature indicator according to claim 1, in which the area occupied by the VTE is 45-70%, preferably 50-60% relative to the total area of ​​the front surface of the base, and the area occupied by the NTE is 1-10%, preferably 2-5%, relative to the total area of ​​the front surface of the base.

6. A temperature indicator according to paragraph 1, characterized in that the linear dimensions of the base do not exceed 70x50 mm, and the area of ​​the NTE is 100 mm 2 , preferably do not exceed 35x35 mm, and the area of ​​the NTE is 50 mm 2 , it is more preferable not to exceed 25x20 mm, and the area of ​​the NTE is 20 mm 2 .

7. A thermal indicator according to item 1, in which, in the initial state, the main area of ​​the VTE and NTE has the same, predominantly white, color, and when triggered, a white-to-black color transition is ensured.

8. A thermal indicator according to item 1, in which the color of the VTE and NTE after operation differs.

9. The temperature indicator according to I.1, in which Twte is higher than Tnte, preferably by 20-35 °C, and Twte and Tnte can be selected from the list of 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C.

10. A temperature indicator according to item 1, in which the area of ​​the WTE is at least 25 mm 2 , preferably not less than 100 mm2 .

11. A temperature indicator according to I.1, in which the form of the VTE differs from the form of the NTE.

12. A thermal indicator according to item 1, on which information elements are located, including color, letter, digital or alphanumeric information.

13. A temperature indicator according to item 12, in which at least part of the information elements are located in the TE region.

14. A thermal indicator according to item 12, in which at least part of the information elements are located on the protective layer.

15. A thermal indicator according to claim 1, in which micro-holes are made in the protective layer.

16. A temperature indicator according to claim 1, characterized in that at least one TE, preferably a VTE, most preferably a VTE and a LTE, has at least one property selected from the group of properties (1) - (6): (1) includes a gas-filled hot-melt material (GFTM), preferably, the proportion of the gas phase in which is at least 10 vol.%.; (2) contains absorbent material (AM); (3) contains supporting elements (SE); (4) includes at least one solid organic substance with a molecular weight of less than 2 kDa; (5) changes the appearance only in the region that was heated above the corresponding threshold temperature, while maintaining the original appearance of other regions of the FC whose temperature did not exceed the corresponding threshold temperature; (6) includes at least one solid organic substance containing a structural fragment C n H(2n+i), where n > 5, and is preferably chosen from a group consisting of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 12; salts of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 5; alkanes containing at least 20 carbon atoms; dialkylphosphinic acids containing structural fragments C nH(2n+i) with n > 5; amides of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 5; anhydrides of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 10; fatty aliphatic alcohols containing structural fragments C n H(2n+i) with n > 14; fatty aliphatic amines containing structural fragments C n H(2n+i) with n > 17; nitriles of fatty aliphatic acids containing structural fragments C n H(2n+i) with n > 19.

17. A temperature indicator according to item 1, characterized in that it has at least one property selected from the group of properties (1) - (8): (1) made in the form of a self-adhesive sticker; (2) is elastic; (3) designed with the possibility of marking the elements of electrical equipment or color marking the phases; (4) the back side of the base contains an adhesive layer of permanent tack with adhesion of at least 10 N / 25 mm to stainless steel, measured by the FIN AT TM1 method after 24 hours; (5) the base is made of halogen-containing polymers, preferably PVC, more preferably cast PVC; (6) the protective layer is made of halogen-containing polymers, preferably PVC, and is transparent to at least part of the visible light, at least in the TE region; (7) the protective layer is attached to the base in the region free from the TE, including the region between the VTE and the NTE; (8) the base is partially colored using a heat-sensitive material that reversibly changes its appearance when heated above the appropriate threshold temperature.

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