RU224780U1 - Cable lug with the ability to irreversibly register heating above several threshold temperatures - Google Patents

Abstract

The utility model relates to cable lugs, namely to cable lugs designed with the ability to irreversibly register heating facts above two or more threshold temperatures. The cable lug is configured to register the fact of heating above two or more threshold temperatures (T1, T2, ... Tn) and includes a metal conductive part, designed to be attached to the wire core(s) by crimping; dielectric part connected to the conductive part. In this case, the dielectric part includes a base made with the possibility of fixing on the wire, the front surface of which includes at least two sections (1, 2,... n), on which heat-sensitive materials (TM1, TM2,... TMn) are applied, respectively, made with the possibility irreversibly change the transparency of at least part of the visible light when heated above the appropriate threshold temperature (T1, T2, ... Tn). The utility model provides increased fire safety and electrical safety during the operation of electrical equipment by providing a reliable contact connection with the ability to irreversibly register facts of exceeding two or more specified threshold temperatures for the timely detection of contact connection defects and determining the degree of their development. 18 salary f-ly, 10 ave., 8 ill.

Description

Field of technology to which the claimed utility model relates

The utility model relates to cable lugs, namely to cable lugs designed with the ability to irreversibly register heating facts above two or more threshold temperatures.

State of the art

Thermal monitoring of the state of contacts and contact connections of electrical installations is an important task in the operation of electrical equipment. Timely detection of contact defects allows you to prevent emergency situations that can lead to equipment damage, fires and fires. Excessive heating of contacts and contact connections is in most cases associated with an increase in transient contact resistance, which can occur during operation under the influence of various factors:

reducing the contact area of conductors;

oxidation of contact surfaces or formation of carbon deposits on them;

galvanic incompatibility of metals of connected conductors;

insufficient applied compressive force when installing the connection;

weakening of pressure during operation;

destruction of the surface of conductors due to aggressive chemicals or electrochemical effects;

mechanical impact followed by loosening of the contact connection and/or partial removal of the wire from the terminal under the influence of applied force.

Methods for monitoring and testing contacts and contact connections of electrical equipment and electrical devices are regulated by regulatory documents, in particular, GOST 17441-84 "Contact electrical connections. Acceptance rules and test methods" and GOST 10434-82 "Contact electrical connections. Classification, general technical requirements ", which disclose, among other things, methods for testing dismountable contact connections equipped with cable connectors for heating with a rated (long-term permissible) current, as well as accelerated testing in cyclic heating mode.

There are two approaches to ensuring the general safety of contact connections of electrical equipment:

regular thermal diagnostics of contacts and contact connections using a thermal imager or irreversible thermal indicators for timely detection and elimination of defects;

the use of special devices to increase the reliability of the contact connection, for example, terminal blocks, special connectors, conductive lubricants or cable lugs.

A cable lug (or “terminator”, “connector”) is a specially designed product for installation at the end of a wire, including a hollow conductive cylinder of fixed or variable diameter, on which an insulating element made in the form of a dielectric tube can be attached.

The use of cable connectors makes it possible to increase the reliability of the operated contact connection by preventing the growth of the transition contact connection by reducing external effects on the surface of metals (oxidation, chemical and electrochemical effects, etc.), tight crimping of the wire, increasing the area of the contacting surfaces of the conductors, as well as a number of other reasons .

However, the use of cable connectors does not completely eliminate the possibility of defects in contacts and contact connections during operation. The occurrence of defects and associated fire-hazardous heating can be caused by violations of the rules for selecting cable lugs (for example, the size of the lug does not match the cross-section of the wire or the conductor material) or violation of installation rules, for example, insufficient crimping of the wire.

To detect such defects in a timely manner, it is advisable to carry out regular thermal monitoring of contacts.

Existing diagnostic methods developed to identify defects in contact connections are based on identifying facts of exceeding the established maximum permissible temperatures of contact connections. However, in the case of using cable lugs, such methods are not sufficiently effective.

One of the methods of thermal control is thermal imaging control. However, using a thermal imager to assess the condition of contact connections made using cable lugs has a number of significant difficulties.

Firstly, when making contact connections using cable lugs, the contact point of the conductors is inaccessible for inspection, and the insulating element of the lug, as a rule, does not clamp the wire tightly enough and significantly distorts the actual heating temperature. Because of this, it is not possible to determine the exact heating temperature using a thermal imager.

Secondly, cable lugs are used only in electrical networks with voltages up to 1000 V, in which the use of a thermal imager as a thermal diagnostic tool is ineffective, since temperature measurement is carried out only at the time of inspection. At the same time, maximum heating temperatures of contact connections are achieved at maximum load currents.

In addition, the use of a thermal imager involves inspecting energized equipment and is associated with an increased danger to personnel.

A more effective method of thermal control of contact connections is thermal indicator control. The method is based on the use of irreversible thermal indicators, which are independent compositions (varnishes and paints) or devices that are fixed to the controlled elements and record the facts of exceeding a threshold temperature by changing color. However, when diagnosing contact connections made using cable lugs, this method also has a number of features, the main one of which is the need to place a heat-sensitive composition (that is, a color-changing material) as close as possible to the potential heating site (that is, the contact point).

For thermal monitoring of the condition of contact connections, thermal indicator stickers are most widely used.

However, in the case of cable lugs, the use of thermal indicator stickers is not effective. When a defect occurs in a contact connection, heating occurs at the point of contact. As you move away from the heating site, the temperature of the wire decreases significantly due to heat dissipation. Therefore, placing a thermal indicator on the wire outside the cable lug will be aimed at recording the heating of the wire, and not the point of contact, and will not allow obtaining reliable information about the heating temperature at the point of contact.

When installing thermal indicator stickers directly on the insulating part of the cable lug, a significant discrepancy between the temperature recorded by the thermal indicator and the actual heating temperature of the contact area is also possible. This is due not only to a significant temperature measurement as one moves away from the point of contact, but also to the presence of a large number of heat-insulating layers (wire insulation, material of the insulating part of the cable lug, adhesive layer, thermal indicator base, etc.). In addition, installing a thermal indicator on an already mounted cable lug may lead to deterioration of the contact connection due to the applied mechanical stress.

In some cases, placing thermal indicator stickers on contact connections is generally not possible due to insufficient area of the contact connection, small distance between elements of electrical equipment, etc.

The use of other types of temperature indicator devices also has a number of obvious limitations.

The temperature-sensitive composition used in temperature-indicating products can be of two types: reversible (changing appearance only when heated and returning it when cooled) and irreversible (changing appearance after exceeding a given temperature and maintaining it after cooling).

A feature of reversible temperature indicators is that they allow you to inform only about the current overheating, that is, whether the temperature exceeds the threshold values at the current time, and not about the maximum temperature to which the controlled element of electrical equipment was heated at the moment of maximum load during the entire period. service life.

Unlike reversible indicators, irreversible indicators make it possible not only to identify, but also to record the fact that a threshold temperature has been exceeded throughout the entire service life.

The importance of using irreversible thermal indicators, especially in the energy sector, is revealed, in particular, in the work of M.Yu. Lvov, A.V. Lesiv, “Thermal indicator monitoring of contacts and contact connections of electrical equipment and power lines,” Moscow NTF “Energoprogress”, Energetik, 2023. In the article M.Yu. Lvov, Doctor of Technical Sciences, S.D. Nikitina - JSC "UEC" ", Yu.N. Lvov, Doctor of Technical Sciences - "STC Rosseti FGC UES", A.V. Lesiv - LLC "ThermoElectrica", "On the standardization of requirements for thermal indicator monitoring of the condition of contacts and contact connections during the operation of electrical installations", "ENERGY OF A UNITED NETWORK" No. 1 (68) 2023, which provides standard requirements for thermal indicators, principles for their selection and a methodology for assessing the states of contacts and contact connections using thermal indicators, developed on the basis of research and accumulated operating experience. As the first and main requirement. for thermal indicators, the irreversibility of the thermal indicator is indicated: “For the purpose of assessing the condition of contacts and contact connections (monitoring the fact of reaching the set temperature during operation of electrical installations), only irreversible melting thermal indicators are used.”

Irreversible heat indicators can be classified according to the operating principle of the heat-sensitive material. Indicators are known that are based on the mechanical destruction of a temperature-sensitive element, on the chemical reaction of components of a thermal composition, or on the phase transition of a temperature-sensitive component. The use of thermal indicator compositions based on the mechanical destruction of a temperature-sensitive element is limited due to their features associated with a long response time, as well as the inability to create a flexible thermal indicator device that fits tightly to the controlled surface. Physico-chemical aspects during the reaction of the components of the thermal composition introduce a number of restrictions on the use of thermal indicators based on a chemical reaction, since such thermal indicators do not have sufficient accuracy, have a pronounced dependence of the response time on temperature and the possibility of returning the original color of the triggered indicator after a long exposure at low temperature due to reversibility of color transition reactions.

A separate disadvantage of indicators based on mechanical or chemical principles is that when the layer of the thermosensitive element is deformed, premature operation of the indicator may occur, and their initial design in the form of devices with a shape other than flat is not always possible.

The most accurate are irreversible temperature indicators based on a phase transition, namely the melting of a temperature-sensitive component. Since, unlike a chemical reaction, the phase transition temperature does not depend on the exposure time, such indicators have the greatest accuracy and are capable of maintaining the original state for a long time at a temperature slightly lower than the threshold.

One of the variants of thermal indicators known from the prior art, based on the phase transition of the thermal composition, are thermal indicator paints or varnishes, which can be applied to a surface of any shape and size without strong mechanical impact on the controlled element. However, they have a number of features that significantly limit their use, including making them ineffective when used for temperature control of contact connections equipped with cable lugs:

It is impossible to indicate the temperature on the paint. During a visual inspection of the equipment, the operator can only see the fact that the temperature has been exceeded, but cannot determine the numerical value of the exceeded threshold. To do this, you need to make special notes;

dripping of indicator paint when the threshold temperature is exceeded. When exposed to elevated temperatures and melting a heat-sensitive component, paint may drain from the surface and fall on open elements of the electrical installation or moving parts of mechanisms, which can lead to a short circuit or the creation of an insulating environment between the contacts;

the impossibility of applying a uniform and homogeneous layer on surfaces of complex shape. The consequence of this is the impossibility of determining the exact temperature of the controlled element, since the thicker the layer, the higher the difference between the temperature of the surface and the phase transition (operation);

low adhesion of varnishes and paints to the surface of controlled elements, difficulty in applying paint to non-adhesive materials (silicone, polyethylene, fluoroplastic). This leads to the fact that the composition is easily separated from the controlled surface under mechanical stress;

the dependence of the paint response temperature on the chemical composition of the surface on which it is applied. Since the paint comes into direct contact with the material on which it is applied, various substances, primarily flame retardants and plasticizers, can be extracted into the thermal indicator paint. Such substances may result in the formation of eutectic mixtures with the hot melt component or otherwise affect the response temperature.

In addition, the use of thermal indicator varnishes and paints does not allow organizing control of two or more different threshold temperatures.

Monitoring several threshold temperatures allows not only to determine the presence of a defect, but also to determine the degree of its development (initial stage of defect development, emergency defect, fire hazardous defect), as well as determine the dynamics of defect development, comparing the heating temperatures of identical elements (equipment units), in the case of the declared useful model - various contact connections, determine the excess temperature and defectiveness coefficient.

Multi-temperature thermal indicator stickers are known from the state of the art, among the manufacturers of which are: TermoElectrika LLC (https://www.lesiv.pro/%D0%BA%D0%BE%D0%BF%D0%B8%D1%8F- 1-mark-pro), LLC “Innovative company “YALOS” (https://www.yalosindicator.com/product/termoindikatory-kontrol-temperatury). However, the difficulties discussed above that prevent the use of thermal indicator stickers for monitoring the temperature of contact connections equipped with cable lugs make it necessary to develop a cable lug that has the properties of multi-temperature thermal indicators. The use of such a device will increase the operational safety of electrical equipment by ensuring reliability and the most prompt and reliable detection of defects accompanied by overheating, as well as determining the degree of their development. At the same time, in the existing state of the art, known to the authors, cable lugs with the properties of multi-temperature indicators are not described.

An example of a product that combines the function of a cable lug and the properties of a single-temperature temperature indicator is the device known from JP 2009198201 A, publication date 09/03/2009 and which consists of a temperature-sensitive part attached to a housing that provides close contact with an insulating cap attached to an electrical terminal fitting, revealing that the device discolors when heated. The body of the described device can be made in the form of a cylinder with a longitudinal slot or gap, a spring, and have fastening elements, a tightening part or other devices that ensure a tight fit to the electrical wires. The temperature-sensitive portion includes a temperature-sensitive color-changing body and a transparent color-detecting portion. In this case, the heat-sensitive part may have an adhesive layer attached to it, be supplied separately from the housing and mounted on it by gluing or other means. The use of a device consisting of two parts, each of which can be used independently, reduces the rate of registration of overheating due to the presence of an additional layer of the base of the temperature-sensitive part, separating the thermochromic material that responds to temperature changes from the controlled element. In addition, the thermochromic material according to the described invention is reversible, which makes it inapplicable in the energy sector, for the reasons described above.

Another similar device, known from KR 102022029 B1, publication date 07/17/2019 and chosen by us as a prototype, is an insulating cap for a crimp terminal for wiring, part of which is made of polyvinyl chloride and is formed by the inclusion of a thermal ink pigment, which allows us to determine a sharp change in temperature between the wire and a crimp clamp, and the other part is made in the form of a solderless terminal, which improves the adhesion force of the tip body and the controlled electrical wiring elements, and parts of the device can overlap each other to improve the adhesion force between them. In this device, a thermal ink pigment is included in the material from which the first part of the device is made, as a result of which, when heated, this part of the device changes color and retains it upon subsequent cooling to normal operating temperature, and the operator monitoring the electrical wiring elements can determine the fact of heating of these elements above the maximum permissible temperature.

The document does not disclose the substances used as thermal coloring pigments, as well as the linear dimensions, thickness of the device and its individual parts. The document does not disclose the range of recorded temperatures, as well as the accuracy of their registration and the speed of operation of the device. However, due to the uniform distribution of thermal dye pigment in the material of a part of the device, if overheating of the controlled elements occurs, in order to change the color, it is necessary to warm up the entire volume of this part of the device, which will not allow recording short-term overheating of the controlled elements, will reduce the accuracy of recording overheating and can lead to false failures of the product.

The use of a thermo-coloring pigment, initially distributed throughout the volume of the polymer material, does not allow the device to be manufactured in a multi-temperature version, and also significantly reduces the possibilities for processing this material, in particular, it limits the use of methods such as casting, baking and other methods associated with increasing temperature, as this will cause the pigment to melt prematurely.

Based on the level of technology we have studied in detail, it follows that, despite the large selection of cable lugs and temperature indicators, different both in the mechanism of action and in design, there is a need for a cable lug made with the ability to irreversibly register facts of heating of a contact connection above two and more threshold temperatures, that is, with the function of irreversible multi-temperature thermal indicators, which will meet the requirements for thermal indicators used in the energy sector:

high accuracy, reliability and response speed;

irreversibility of operation;

low flammability and flammability;

high electrical strength and dielectric properties of the base part;

simplicity and safety of installation, replacement, dismantling of the temperature indicator and operation of the electrical equipment itself.

Moreover, a device with such characteristics can be used in any other field of technology.

Thus, the utility model is aimed at creating a cable lug made with the ability to irreversibly register the facts of heating a contact connection above two or more threshold temperatures with the accuracy, speed and reliability required in this field of technology, allowing timely detection of defects in contact connections and determining the degree of their development, excess temperature and defect rate.

Terms and definitions used in this utility model

“Wire” is a cable product containing one or more twisted wires or one or more insulated cores, on top of which, depending on installation and operating conditions, there may be a light non-metallic sheath, winding and (or) braid made of fibrous materials or wire, and not intended, as a rule, for installation in the ground [GOST 15845-80. Cable products. Terms and Definitions]. In relation to this utility model, the concept of “wire” also includes bare metal current-carrying wires (cores), one or more insulated wires twisted together, enclosed in a common sheath (cables).

In accordance with GOST 14312-79 "Electrical contacts. Terms and definitions" a "contact connection" is understood as a contact of an electrical circuit intended only for conducting electric current and not intended for switching an electrical circuit for a given operation of the device; “contact” means a part of an electrical circuit designed to switch and conduct electric current.

“Transition resistance of a contact (contact connection)” according to GOST 14312-79 means the electrical resistance of the contact zone, determined by the effective contact area and equal to the ratio of the voltage drop across the contact junction to the current through this junction.

"Crimping method (crimping, crimping, pressing, crimping)" is a method of connecting a wire or cable to a cable lug, usually carried out using a hydraulic or manual press (for example, crimping pliers), in which a bare conductor is inserted into a metal conductive part of a cable lug which is then compressed around it to form a strong connection.

The term "temperature-sensitive material" means a material that becomes more transparent to at least a portion of visible light relative to its original state when heated above a threshold temperature, and does not return to its original state upon subsequent cooling. The temperature-sensitive material may consist, for example, of an individual organic compound or a salt of an organic acid, which undergoes a phase transition when a threshold temperature is reached, or of a mixture of substances. In addition, the heat-sensitive material may additionally include a binder, such as organic resins, for better adhesion of the heat-sensitive material on a flexible base, and other additives.

The term "threshold temperature" or "threshold temperature" refers to the numerical value of temperature at which an irreversible change in the properties of the corresponding heat-sensitive material occurs. In the claimed utility model, the accuracy of recording exceeding the threshold temperature is 5°C.

The term “accuracy of recording of exceeding the threshold temperature” means the following:

1. Until the device reaches a temperature equal to the threshold temperature of the corresponding heat-sensitive material minus the value of the declared accuracy, there is no change in the transparency of the corresponding heat-sensitive material and the appearance of the device.

2. At a temperature equal to or greater than the threshold temperature of the corresponding temperature sensitive material plus the stated accuracy value, the corresponding temperature sensitive material is transparent and the device takes on a different appearance from the original one.

3. The exact value of the phase transition temperature of the thermosensitive component is within the declared range and is not further established. The accuracy of recording exceeding the threshold temperature determined by this utility model is 5°C.

“Phase transition” is the transition of a substance from one thermodynamic phase to another when external conditions change.

In this utility model, the term “actuation” is applied to a heat-sensitive material that has undergone a phase transition with an increase in transparency. A device in which the temperature-sensitive material has changed transparency is designated as “triggered.”

“Defect” is the non-compliance of an object with the requirements established by the documentation for at least one indicator.

A “cable lug” (or “terminator”) is understood as a product of a special design, including a hollow metal cylinder of fixed or variable diameter, on which an insulating element made in the form of a polymer tube is attached. The cable lug is designed to be installed on the end of a wire to provide a reliable and safe contact connection.

“Fire resistance” refers to the ability of a material to resist combustion under the influence of an ignition source.

The term "electric strength" or "dielectric strength" defines the ability of a given material or device to withstand an electrical voltage applied to it. In other words, electrical strength is the minimum electric field strength at which breakdown of the device occurs.

The term “dielectric” means the property of a given device to withstand an electrical voltage applied to it, while the minimum electric field strength at which breakdown of the device occurs exceeds the dielectric strength of air.

The term “elasticity” reveals the ability of a solid material to return to its original shape during elastic deformation, i.e. an elastic material is deformed after an external force is applied to it, but restores its original shape and size after the influence of this force ceases.

The term “elasticity” reveals the ability of a material, when bent around a cylindrical surface, to repeat its shape without loss of functional properties.

The terms "elastic base" and "elastic protective film" characterize the base or protective film material, which refers to materials that have the ability to change their shape without breaking under external influence.

"Microstructure" is the spatial arrangement of particles or individual phases of a material, reflecting the shapes and orientation of the particles that make up the material. Unlike chemical structure or nanoparticles, microstructure determines only the physical, optical and mechanical properties of the material, but does not affect the chemical properties of the substances that make up the microstructure. In relation to this utility model, “irreversible change in microstructure” means an irreversible change in the physical, optical or mechanical properties of a material relative to the initial state, accompanied by a change in its microstructure, that is, the spatial arrangement of particles or individual phases of the material, their size or shape, up to the complete merging of particles and formation of a single phase.

The term "solid phase" reveals the structure of a material containing particles of a solid substance of arbitrary shape, each of which has at least one point, face or edge in contact with an adjacent particle and interconnected in such a way that each element of the solid phase can be connected to another its element is a single broken line, each point of which is located inside this phase. Depending on the shape and particle size of the solid, the continuous solid phase may have a cellular, granular, fibrous, crystalline or scaly structure.

A “composite material” is a multicomponent material made from two or more components with substantially different physical and/or chemical properties, the combination of which results in new characteristics that are different from those of the individual components. In relation to the present utility model, the term “composite materials” includes polymer composite materials, at least one of the components of which is a polymer material, as well as ceramic-based composite materials. The composition and structure of the composite materials used in this utility model may be different, and their choice depends on the specific problem being solved.

“Specific thermal conductivity” (X) characterizes the ability of materials to conduct heat from more heated areas to less heated ones and is measured in W/(m*K).

The “heat transfer coefficient” (α) characterizes the intensity of heat exchange between the surface of the material and the environment. The heat transfer coefficient shows how much heat is transferred from a unit surface of a material to the environment per unit time when the temperature difference between the surface of the material and the environment is 1°C. The heat transfer coefficient depends on many factors: the composition of the material, the properties and shape of its surface, the presence or absence of airflow, etc.

Defectiveness coefficient is the ratio of the measured temperature rise of a contact connection to the temperature rise measured on the entire section of the bus (wire) located at a distance of at least 1 m from the contact connection.

Excess temperature is the excess of the measured temperature of the controlled unit over the temperature of similar units of other phases under the same conditions.

Fire hazardous heating - heating an element of an electrical installation to a temperature at which a fire hazard arises for the material.

Essence of a utility model

This utility model was created to improve the operational safety of electrical equipment, namely to prevent fires of contact connections by organizing a reliable contact connection and the ability to timely identify defects, as well as determine their extent and dynamics of development, and the causes of their occurrence.

The objective of this utility model is to create a cable lug that is capable of visually irreversibly recording heating facts above two or more threshold temperatures, with the accuracy, speed and reliability required in this field of technology.

The technical result of the claimed utility model is to increase fire safety and electrical safety during the operation of electrical equipment by providing a reliable contact connection with the possibility of irreversible visual registration of facts of exceeding two or more specified threshold temperatures for the timely detection of contact connection defects and determining the degree of their development.

The technical result is achieved through the use of a cable lug according to this utility model, made with the ability to register the fact of heating above two or more threshold temperatures (T1, T2, ... Tn), which includes:

a metal conductive part configured to be attached to the wire core(s) by crimping;

a dielectric part connected to a current-conducting part, wherein the dielectric part includes a base configured to be fixed on a wire, the front surface of which includes at least two sections (1, 2, ... n) on which heat-sensitive materials (TM1, TM2, ... TMn) respectively, configured to irreversibly change the transparency of at least part of the visible light when heated above a corresponding threshold temperature (T1, T2, ... Tn).

When installing a cable lug according to this utility model on a contact connection, the metal conductive part provides a larger contact area of the electrical equipment terminal with the non-insulated part of the wire (conductor or conductors) due to its compression, which allows increasing the contact area, preventing the increase in transient contact resistance over time and thereby reduce the risk of defect, failure or fire. Thanks to the presence of a metal conductive part, the device can also be simply and safely installed at the end of a wire and securely fixed, in particular, in the terminals of electrical devices, on dismountable contact connections of conductors with socket connections, on spring contact connections and other elements. In this case, when installing, replacing and dismantling the thermal indicator cable lug, there is no mechanical impact on the mounted contact connection and its loosening.

The structure of the dielectric part of the cable lug includes a base made of dielectric material and at least two sections (1, 2... n) with applied heat-sensitive materials (TM1, TM2,... TMn), and allows the use of various methods for manufacturing the dielectric part. Thus, in the manufacture of the base, you can use not only molding, but also casting, sintering and other methods that require heating to high temperatures, which cannot be used when heat-sensitive materials are initially mixed into the base. This significantly expands the choice of base materials used, including allowing the use of those that are not adapted for molding, in particular, thermoplastic polymers (for example, PVC), ceramics and composite materials.

The temperature-sensitive materials applied to the substrate of the dielectric part can be selected from a wide range of compounds without the limitations imposed by the incorporation of a thermal pigment into the substrate. In addition, the authors are not aware of the manufacture and use of a multi-temperature thermal indicator, the base of which is uniformly filled throughout its entire volume with two or more thermal pigments with different threshold temperatures.

Thus, in the proposed utility model, each of the layers of the dielectric part performs its own functions, the combination of which cannot be achieved using a thermal pigment evenly distributed in the base material.

The shape of the dielectric part of the tip makes it possible to reduce or completely eliminate the possibility of touching the uninsulated part of the wire, including fluffy strands of a stranded wire, when servicing an electrical installation, as well as slow down oxidative processes leading to the formation of oxide films on the contact surface. Also, the presence of a dielectric part reduces the likelihood of overlapping frayed wire strands and causing a short circuit.

The presence of at least two sections (1, 2,… n) with applied heat-sensitive materials (TM1, TM2,… TMn) on the dielectric part of the tip provides the ability to timely identify defects in contact connections accompanied by heating, as well as determine the degree of their development, the dynamics of development and the causes of occurrence. The use of irreversible heat-sensitive materials, the action of which is based on a change in transparency (namely, an increase in transparency) when a threshold temperature is exceeded, is associated with the need to determine the facts of excess heating of the contact connection at the time of maximum loads, including short-term ones. Reversible heat-sensitive materials or materials other than those specified by the type of response cannot be used within the framework of this solution, since they do not provide the necessary functional properties of the device, including the required accuracy, speed and reliability of overheat detection.

Thus, the entire set of features characterizing the cable lug, which has the properties of irreversible multi-temperature thermal indicators, ensures the solution of the problem and the achievement of the specified technical result.

It should be noted that the number of sections (1, 2,... n) can be equal to the number of threshold temperatures (T1, T2,... Tn) and temperature-sensitive materials (TM1, TM2,... TMn) (in this case, each section of the temperature-sensitive material corresponds to one threshold temperature). In other options, the number of sections (1, 2,... n) may be greater than the number of threshold temperatures (T1, T2,... Tn) and temperature-sensitive materials (TM1, TM2,... TMn) (in this case, several sections of temperature-sensitive materials may have the same threshold temperature, while heat-sensitive materials with different threshold temperatures can be alternated, as shown in Fig. 1c, or applied to the base in any other combination). In this case, such application of heat-sensitive materials will make it possible not only to determine the fact of surface heating above two or more threshold temperatures, but also to localize the exact location of heating.

To further increase fire safety and electrical safety when using a cable lug, as well as rapid heating of the substrate to ensure the possibility of recording short-term overheating, such properties of the substrate as dielectric strength and thermal conductivity are important. The authors of this utility model, based on the research conducted, have established that the following values of these parameters are optimal: dielectric strength of at least 3 kV/mm, thermal conductivity coefficient of at least 0.1 W/(m*K).

In particular cases, the minimum distance from the metal conductive part to the closest area/s of the heat-sensitive material does not exceed 10 mm. And the minimum distance between sections of heat-sensitive materials (if they are applied with sequential removal from the metal conductive part) preferably does not exceed 5 mm. This is due to the fact that when a defect occurs in a contact connection, only the contact patch on the uninsulated end of the wire is subject to heating, and as it moves away from the heating site, the heat quickly dissipates. At the same time, the accuracy of overheat registration, in accordance with current regulatory documents, should not exceed 10°C.

The distance at which the temperature of the tip material decreases by 10°C can be roughly estimated based on the Fourier law of thermal conductivity and the Newton-Richmann law.

In accordance with Fourier's law of thermal conductivity, the heat flow removed through a unit area per unit time will be proportional to the thermal conductivity coefficient of the material and the temperature gradient:

where X is the specific thermal conductivity, and ΔT is the temperature change along the length .

We will assume that the same heat flow is dissipated into the environment in accordance with the Newton-Richmann law in direct proportion to the difference between the temperature of the cable lug material and the ambient air temperature:

where α is the heat transfer coefficient between the tip and the environment (air), T is the temperature of the cable lug, T _ambient is the ambient temperature.

From these relations, equating the two heat flows, for the length we obtain the following relation:

As a typical value of the heat transfer coefficient, let’s take α equal to 3 W/(m ² *K). Let us take the thermal conductivity coefficient for the base material to be 0.2 W/(m*K) (the average value of the thermal conductivity coefficient for polymer materials, composite materials and ceramics). Let's assume the ambient temperature is 20°C and the tip temperature is 70°C. With these parameters, a temperature gradient equal to ΔT=10°С will correspond to the length ≈13 mm.

Based on averaging the parameters of cable lugs, their installation locations, the environments in which they are used, the range of recorded temperatures, etc., known to the authors based on research and experience in this field of technology, the authors of this utility model have experimentally established that the maximum permissible the value of the minimum distance from the metal conductive part to the closest section/s of the heat-sensitive material does not exceed 10 mm, and the value of the minimum distance between sections of the heat-sensitive materials (in the case of their application with a sequential distance from the metal conductive part) does not exceed 5 mm.

The cable lug preferably has a variable diameter, tapering in the area of the metallic conductive portion, to provide close contact between the walls of the cable lug and the wire, both in the insulated portion (in the area of the dielectric portion) and in the non-insulated portion of the wire (in the area of the metallic conductive portion). The metal part may have a through hole or be sealed on one side (away from the dielectric part). The ratio of the inner diameter of the base of the dielectric part (D) to the inner diameter of the metal conductive part (d) is preferably 1.1 to 2, which is related to the thickness of the wire insulation. If the ratio of these diameters is more than two, a sufficiently tight fit of the base of the dielectric part of the cable lug to the wire will not be ensured, which can negatively affect the accuracy of determining the heating temperature of the contact connection and affect the safety of operation of electrical equipment. The ratio of the length of the metal conductive part (L1) to the length of the base of the dielectric part (L2) is preferably 0.5 to 1.5, preferably 1.0 to 1.5. This is due to the need to isolate the unraveled cores of multi-core wires that did not fall into the metal conductive part when installing the cable lug, to increase electrical safety and reduce the risk of a short circuit when cores of opposite phases touch. It is taken into account that the length of the uninsulated part of the wire and its cores is approximately equal to the length of the metal conductive part. Depending on the cross-section of the controlled elements, the internal diameter of the base of the dielectric part of the cable lug (internal diameter of the through section D) can in particular cases be 1-25 mm. In these cases, the inner diameter d of the metal conductive part may preferably be 0.5 to 22.7 mm. The length of the base of the dielectric part (L2) of the cable lug, and, as a consequence, the length of the through hole in it, is preferably 3-25 mm and is selected based on the size of the elements being controlled, as well as the area and location of the heat-sensitive material on the outer surface of the base of the dielectric part. In these cases, the length of the metal conductive part L1 may preferably be 3-30 mm. Preferably, the device is designed to be mounted on electrical wires with a diameter of 1 to 10 mm, without additional elements, due to its design features, which ensures ease and safety of installation, replacement and dismantling, and also further increases the accuracy of heat detection with a heat-sensitive material.

In preferred embodiments, to ensure a tight and secure fit of the cable lug to the wire and easy and safe attachment to it, the base of the dielectric part is elastic and/or elastic. Also, the dielectric part can have a longitudinal cut, which makes it possible to conveniently, quickly and safely fix the cable lug on the controlled elements due to the elastic properties of the material.

In preferred embodiments, the area of the front surface of the base of the dielectric part is at least 3 mm ² , preferably at least 10 mm ² , most preferably at least 100 mm ² and is selected based on the cross-section of the controlled elements, the location of the cable lug, designed to register the fact of heating above the threshold temperature, and distance from the inspection point. In particular cases, the area of the outer surface of the base of the dielectric part must ensure the placement of at least two sections (1, 2,...n) of temperature-sensitive materials (TM1, TM2,...TMn) with a total area of at least 10 mm ² to simplify visual registration of facts exceeding two and more threshold temperatures. Ensuring visibility, as well as reliability of detection of local heating of elements of electrical equipment can also be achieved using a variant of the device with the surface area of the base of the dielectric part, covered with at least two sections (1, 2, ... n) of temperature-sensitive materials (TM1, TM2, ... TMn ), from 3 to 97% of the front surface area of the dielectric part base, preferably at least 30% of the front surface area of the dielectric part base.

To increase the speed of visual transition of heat-sensitive materials when the corresponding threshold temperature is exceeded, as well as the accuracy of determining the heating temperature, the thickness of the base of the dielectric part in the areas of heat-sensitive materials is no more than 3 mm, preferably no more than 2 mm. The use of a base with greater thickness does not ensure the necessary heat transfer of the conductor during operation of electrical installations (air cooling). In this case, the base of the dielectric part can have either the same thickness or a smaller thickness in areas of heat-sensitive materials; in particular, recesses can be made in the base of the dielectric part for filling them with appropriate heat-sensitive materials. The arrangement of heat-sensitive materials in the appropriate recesses makes it possible to reduce the thickness of the base of the dielectric part in areas of heat-sensitive materials in some cases to 1 mm or less, without losing the strength characteristics of the device itself, which increases the rate of heating and, as a consequence, the response of heat-sensitive materials when overheated above the corresponding threshold temperature . Also, the arrangement of heat-sensitive materials in the recesses protects them from abrasion during installation and prevents the flow of molten heat-sensitive materials during a phase transition into the contact zone with subsequent combustion.

In preferred embodiments, at least one of the heat-sensitive materials used is configured to change transparency when heated to above a threshold temperature in no more than 5 seconds, preferably no more than 2 seconds. This is due to the fact that the thickness of the layer of heat-sensitive material and its structure, together with the thickness of the base of the dielectric part, is selected in such a way as to allow heating of the heat-sensitive material when short-term overheating occurs during peak load periods and completely transforming it into a melt with an “opaque-transparent” color transition. for no more than 5 seconds, preferably no more than 2 seconds.

In preferred embodiments, at least one of the heat-sensitive materials used irreversibly changes transparency when heated within a range not exceeding 5°C, preferably not exceeding 2°C, relative to the threshold temperature indicated on the device. In this case, the minimum distance from the metal conductive part to the closest section/s of the heat-sensitive material and the minimum distance between sections of the heat-sensitive materials are also calculated using the above formula (3) taking into account the required operating accuracy.

In preferred embodiments, the dielectric part includes polymer materials, preferably halogen-containing polymers, preferably containing a structural unit -CH ₂ CHCl-, preferably polyvinyl chloride, most preferably cast polyvinyl chloride, or ceramic materials, preferably porcelain, or composite materials, preferably textolite.

If the base of the dielectric part is made of polymers, the base material is preferably selected in such a way as to ensure simultaneous fulfillment of the following criteria:

elasticity, flexibility and elasticity necessary for a tight fit of the device to the surfaces of the controlled elements of electrical equipment, which often have complex geometry, while maintaining the ability to register overheating with the stated accuracy;

ensuring the necessary pressing and fixation of the device for its reliable fixation while maintaining a tight fit, including during vibration, under the influence of various environmental factors, mechanical stress, thermal expansion of the material of the controlled element of electrical equipment;

ensuring the necessary adhesion between the protective film and the heat-sensitive material;

resistance to ignition and ability to self-extinguish when exposed to an open flame. Ignition of the device, in turn, can lead to a fire in the electrical installation or an electric arc;

thermal conductivity sufficient to ensure rapid heating of the device and the heat-sensitive layer to a threshold temperature for reliable and reliable recording of short-term overheating, as well as heat removal from heating wires and contact connections;

low electrical conductivity, allowing the device to be installed not only on electrical equipment elements coated with insulating materials, but also on contact connections without insulation. High electrical strength and dielectric properties of the device as a whole are necessary to ensure safe use in electrical installations, motors or various electrical mechanisms. The lack of conductivity and the high value of the breakdown voltage makes it possible to prevent the failure of electrical circuits, the occurrence of a short circuit or the ignition of an electric arc when the thermal indicator comes into contact with open conductive elements;

preservation of the original shape when heated, i.e. the materials of the polymer dielectric part of the base and the protective film should not melt to their current state when heated to high temperatures, in order to avoid the separation of the thermal indicator from the wire, the flow of softened material and its contact with elements of electrical equipment;

ensuring stable attachment to the controlled element over a wide temperature range (decomposition temperature, preferably above 150°C).

The most suitable polymer materials for this purpose are halogen-containing polymers, mainly polyvinyl chloride. Polymer materials containing halogen atoms in their structure have some of the highest flexibility and elasticity among known polymers. The introduction of halogen atoms into monomers used as feedstock for polymerization breaks their symmetry and creates many chiral centers in the polymer. Polymerization or polycondensation of such monomers, both with each other and with other halogen-containing or non-halogen-containing monomers, leads to the formation of polymer chains with a large number of stereocenters. Regular polymers derived from non-halogenated monomers without chiral centers tend to form crystalline structures, which reduces their elasticity, while the large number of diastereomers resulting from halogenation of monomers imparts stereochemical disorder to halogenated polymers, which prevents crystallization. Thus, halogen-containing polymer materials have high elasticity and flexibility due to the peculiarities of their chemical structure due to the presence of halogen atoms in the structure of polymers. In addition, halogen-containing materials have good adhesion and low flammability, which further ensures the operational safety of the claimed device and the electrical equipment on which it is placed.

Based on this, in preferred embodiments, the dielectric portion of the cable lug is resilient and elastic and includes halogen-containing polymers, preferably containing a -CH ₂ CHCl- structural unit, preferably polyvinyl chloride, most preferably cast polyvinyl chloride.

Making the base of the dielectric part from ceramic materials provides the cable lug with increased strength and durability, and also increases the service life of the device, due to the high degree of resistance of ceramics to mechanical stress, chemicals and moisture. In addition, ceramic products are not subject to corrosion, do not burn and do not emit substances of a high hazard class, which also has a positive effect on the safety of operation of cable lugs with a ceramic base of the dielectric part.

The use of composite materials as the base material of the dielectric part makes it possible to give the cable lug high rigidity, which may be necessary in cases requiring reliable and precise fixation of the direction of the wire. Composite materials are also highly stable when used in extreme conditions and have high strength characteristics, which allows you to increase the service life of the device. In addition, composite materials have a low specific gravity.

At least one of the heat-sensitive materials used can be coated with an elastic protective film that is transparent to at least part of visible light, which additionally protects the heat-sensitive material and the cable lug itself from external environmental influences, humidity, UV irradiation and mechanical damage, and increases service life device and prevents heat-sensitive material from draining during phase transition.

The elastic protective film may be attached to the device by fusion (welding), adhesive, or other methods known in the art. The protective film is preferably made of polyvinyl chloride, most preferably cast polyvinyl chloride, taking into account the properties of these materials described above.

The metal conductive part can be made of aluminum, copper or their alloys and, in some cases, have a tinned coating to protect against the formation of an oxide film. The choice of materials for the conductive part is due to their high electrical and thermal conductivity, high relative corrosion resistance, as well as resistance to external influences, such as temperature, ultraviolet radiation, and chemical exposure. In addition, the metal of the conductive part must be soft to allow fastening to the wires using the crimp method, but at the same time ductile to avoid cracking and breaking during installation.

In private versions, the dielectric part of the cable lug can be used to mark elements of electrical equipment or have a numerical designation. For example, the dielectric part may have a color that corresponds to the established rules for marking elements of electrical equipment. Also, the front surface of the dielectric part may contain digital, color or other markings, in particular, an inscription containing color, letter, numeric or alphanumeric marking information. In one case, the inscription may reflect the values of the recorded threshold temperatures, and also contain information about the expiration date of the device.

The features listed above serve to give the cable lug, which is capable of recording heating facts above two or more threshold temperatures, the properties of electrical equipment marking elements, which also additionally ensures the safe operation of the equipment on which such devices are placed, due to the following. In the case of contact connections, wires or electrical components, we are talking about small surfaces that, on the one hand, require marking, and on the other hand, temperature control. However, using two types of devices at once: devices for marking and devices for recording temperature rises separately is often not possible due to insufficient space on the controlled surface, as well as the need to take into account the decrease in heating temperature with distance from the control point. Using only a cable lug, designed to record heating facts above two or more threshold temperatures, without markings can lead to incorrect identification of a defective unit. Thus, the use of a cable lug that combines the properties of a marking device, as well as the properties of irreversible multi-temperature indicators, will have a positive effect on the safety of operation of electrical equipment.

To increase the visibility of both the cable lug itself and the fact of its activation, on equipment elements, including those that are difficult to inspect due to the large size of the installations, the location of the installations in the open air or due to inspection in bad weather conditions and in conditions of insufficient visibility, in at night using a flashlight, as well as for inspecting equipment without artificial lighting and windows, and, as a result, further increasing the safety of operation of the equipment, the dielectric part may have reflective properties or be painted using a substance with luminescent properties.

In particular cases, the dielectric part can be painted using a substance (dye) designed to irreversibly change color when heated.

When painting the dielectric part, the use of substances capable of irreversibly changing color when heated to a temperature below the threshold temperature of the main heat-sensitive material, for example, by 10-30 ° C, allows you to inform personnel about the risk of an emergency defect in the future, and thereby ensures the possibility of its prevention, with proper response from the personnel responsible for this equipment. Thus, the activation of such a substance, in the absence of activation of the main heat-sensitive materials, indicates the presence of overheating of the equipment that has not reached the maximum permissible values (T1, T2, ... Tn), corresponding to the threshold temperatures of the main heat-sensitive materials (TM1, TM2, ... TMn), and the need its inspection in order to identify and eliminate problems that in the future could lead to the development of an emergency defect. Thus, the presence of a substance capable of irreversibly changing color when heated to a temperature below the threshold temperature of the main heat-sensitive materials, in particular, 10-30 ° C below the minimum value of the recorded threshold temperatures T1, further increases the safety of operation of the claimed device, and equipment in general.

The dielectric part of the cable lug can be fully or partially painted using dyes designed to reversibly change color when heated. For example, a layer of heat-sensitive paint having the above properties can be applied to the front surface of the base.

The use of dyes designed to reversibly change color when heated makes it possible to inform personnel about overheating at the time of inspection. Heating of the tip at the time of inspection indicates that the equipment is in emergency mode at the CURRENT moment and may be a source of increased danger. At the same time, the activation of the main heat-sensitive materials (TM1, TM2,... TMn), irreversibly changing transparency when two or more corresponding threshold temperatures (T1, T2,... Tn) are exceeded, informs personnel about the facts of overheating and their maximum temperature that occurred BEFORE the inspection . Thus, the presence of a substance capable of reversibly changing color when heated further increases the operational safety of both the claimed cable lug and the equipment as a whole.

In preferred embodiments, the operating principle of at least one of the heat-sensitive materials used, which irreversibly changes transparency when heated above an appropriate threshold temperature, is to melt the heat-sensitive component. Preferably, at least one of the heat-sensitive materials used is initially opaque to at least part of visible light, for example, white, and when heated above an appropriate threshold temperature, an irreversible increase in transparency occurs with the appearance of the color of the dielectric part of the base. In particular cases, the dielectric part under at least one of the used heat-sensitive materials can be painted black, which, when using a heat-sensitive material that is initially white, provides a color transition with maximum white-black contrast, which further increases visibility of the triggered cable lug and, as a result, will increase the safety of operation of the controlled elements of electrical equipment.

The use of heat-sensitive materials based on melting, accompanied by an irreversible increase in transparency relative to the initial state when heated to the appropriate threshold temperature, additionally provides and enhances such properties as:

irreversibility of the visual trigger effect;

high speed of operation of the device;

preservation of the original state at a temperature slightly lower than the threshold;

the required accuracy in determining the response temperature, regardless of the time of exposure to temperature.

The threshold temperature can be selected from the range of 50-210°C, preferably 50°C, 55°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C. The applied heat-sensitive materials are selected based on two or more threshold temperature values selected for registration, which, in turn, are regulated by standard instructions, and are also determined by the type of materials of the contacting surfaces in the contact connection, the voltage class of the electrical equipment, as well as the insulation class and other parameters.

In particular cases, at least one of the heat-sensitive materials used in the initial state has a microstructure that includes a solid phase and voids forming a continuous gas phase, the volume fraction of which is at least 10%, and is designed to irreversibly change its appearance upon reaching the specified threshold temperature due to the destruction of the microstructure of a thermosensitive material, accompanied by the fusion of particles of solid organic matter, a decrease in the volume fraction of voids and an increase in its transparency with the appearance of the color of the base.

The use of heat-sensitive materials with voids makes it possible to increase the service life, further increase the reliability of determining overheating due to the impossibility of aggregation of solid particles through the gas phase and eliminate the possibility of the material returning to its original state after actuation due to an irreversible change in the microstructure, which also has a positive effect on the safety of operation as a cable the tip and the equipment itself. When a thermosensitive material containing voids is melted, an irreversible change in the initial microstructure of the material occurs with a decrease in the proportion of voids in it, associated with the fusion of particles of solid organic matter and with a decrease in the area of the solid-gas interface due to the irreversible release of the gas contained in the voids to the surface and separation of gas and non-gas media. As a result, upon further cooling, the solid organic substance crystallizes without voids, thereby irreversibly changing the transparency (increases relative to the initial state) of the material for at least part of the visible light, creating a visual effect of changing the appearance of the device with high contrast, which ensures high reliability of exceedance registration temperature is higher than the set value. Preferably, the proportion of voids of the heat-sensitive material after heating above the threshold temperature value decreases by at least 2 times relative to the initial state, which further increases the contrast of the color transition of the cable lug when the threshold temperature value is exceeded.

The solid phase of at least one of the used thermosensitive materials may include an organic substance containing a structural fragment C _n H _(2n+1) , where n≥5, and preferably selected from the group: aliphatic fatty acids containing structural fragments C _n H _{(2n +1)} with n≥12; salts of fatty aliphatic acids containing structural fragments C _n H _(2n+1) with n≥5; alkanes containing at least 20 carbon atoms; dialkylphosphinic acids containing structural fragments C _n H _(2n+1) with n≥5; amides of aliphatic fatty acids containing structural fragments C _n H _(2n+1) with n≥5; aliphatic fatty acid anhydrides containing structural fragments C _n H _(2n+1) with n≥10; fatty aliphatic alcohols containing structural fragments C _n H _(2n+1) with n≥14; fatty aliphatic amines containing structural fragments C _n H _(2n+1) with n≥17; nitriles of fatty aliphatic acids containing structural fragments C _n H _(2n+1) with n≥19.

The use of at least one of the used thermosensitive materials as an organic substance in the solid phase of such organic compounds, which include one or more aliphatic hydrocarbon chain C _n H _(2n+1) with n≥5, promotes the formation of a crystalline package in which elongated structural fragments of linear hydrocarbons are oriented parallel to each other (A.I. Kitaigorodsky, Molecular Crystals, M.: Nauka, 1971). Due to the fact that particles of solid organic matter are formed in the form of fibers, scales or flat or elongated crystals, that is, they have a two-dimensional structure, the thermosensitive material forms a special microstructure capable of bending and stretching without deformation and loss of functional properties.

Also, the use of solid organic compounds, which include non-polar aliphatic fragments, additionally helps to increase the electrical strength of the cable lug as a whole, since such fatty aliphatic derivatives have good dielectric properties.

In particular cases, the organic matter of the solid phase of at least one of the used heat-sensitive materials can be selected from the group: palmitic acid, stearic acid, behenic acid, tetracosane, erucamide, stearic alcohol, cetyl alcohol, polyethylene, wax, paraffin, saturated fatty acid salts carboxylic acids of rare earth metals, in particular lanthanum, yttrium, ytterbium, scandium.

In particular cases, the microstructure of at least one of the used thermosensitive materials additionally contains a polymer binder that is transparent to at least part of visible light, the phase transition temperature of which is higher than the phase transition temperature of the solid organic substance of the corresponding thermosensitive material. In this case, the heat-sensitive material contains phase boundaries “solid-transparent solid-gas”; during melting, an irreversible change in the microstructure of the material also occurs, as a result of which the number of voids decreases relative to the initial state due to the release of the gas contained in them to the surface of the material and gas delamination occurs and non-gas environments, as a result of which there is a decrease in the contact area of the solid phase and voids, i.e. reducing the area of phase boundaries.

Preferably, the volumetric solids content of the at least one temperature-sensitive material is no more than 90 vol.%. In other words, the heat-sensitive material contains at least 10 vol.% voids filled with the gas phase (air).

The polymeric binder is preferably present in at least one of the heat-sensitive materials used in an amount of 1-30 vol.%. In particular cases, a polymer binder coats each individual structural particle of solid organic matter, providing it with “glazing.” The binder is selected to ensure wettability, but not dissolution, of the solid organic matter particles in the polymer binder. Due to this, when “glazing” grains, crystals, fibers, flakes or conglomerates of these particles, additional capture of gas occurs, in the environment of which a thermosensitive material is formed, and its distribution between the “glazed” binder particles of solid organic matter.

In preferred embodiments, at least one heat-sensitive material used, including due to its microstructure, is configured to register local overheating of the surface by changing the transparency of only that part of the heat-sensitive material that was heated above the threshold temperature and maintaining the original color of the heat-sensitive material, which was not heated above the threshold temperature, with uneven heating.

Brief description of drawings

The utility model will be more understandable from the description, which is not restrictive and is given with reference to the accompanying drawings, which show:

Fig. 1 - Three-dimensional model (1a,c) and frontal view (1b) of a cable lug, designed to record heating facts above two or more threshold temperatures, which includes a metal conductive part (1a,c with an open hole, 1b with a sealed hole) and dielectric part of variable diameter (1a,b without a cut, 1c with a longitudinal cut), on sections of the front surface of the base of which thermosensitive materials are applied (1a: two thermosensitive materials TM1 and TM2, located around the circumference, 1b: two thermosensitive materials TM1 and TM2 in the form rectangular sections applied sequentially from the metal conductive part with the shown linear dimensions (length) of the metal conductive and dielectric parts, as well as the minimum distance from the metal conductive part to the section of the thermosensitive material closest to it ( ) and the distance between participants of heat-sensitive materials ( '), 1c: three heat-sensitive materials TM1, TM2, TM3, sequentially alternating around the circumference of the dielectric part containing a longitudinal section).

Fig. 2 - Sectional view of a cable lug, designed to record heating facts above two or more threshold temperatures, which includes a metal conductive part (2a with an open hole, 2b, 2c with a sealed hole) and a dielectric part (2a,b without a cut, 2c with a longitudinal section), on sections of the front surface of the base of which heat-sensitive materials are applied (2a: two heat-sensitive materials TM1 and TM2, sequentially alternating around the circumference of the dielectric part, 2b: two heat-sensitive materials TM1 and TM2, located at the same distance from the metal conductive part and located in recesses made in the base material of the dielectric part, 2c: option in which heat-sensitive materials (TM1, TM2, ... TMn) are located on the dielectric part in the form of rectangular sections applied sequentially from the metal conductive part), with the base of the dielectric part painted black paint in areas of heat-sensitive materials and a protective layer (2a, 2b, 2c), with the internal diameters of the metal conductive and dielectric parts shown (2c).

Fig. 3 - View of a cable lug, configured to record heating facts above three threshold temperatures, with a wire placed with a bare end.

Fig. 4 - Demountable contact connection of a conductor terminated with a cable lug, configured to record heating facts above two threshold temperatures, in the socket terminal.

Fig. 5 - A cable lug with an open hole, made with the ability to record heating facts above two threshold temperatures, the base of the dielectric part of which has reflective and/or luminescent properties, with the base painted with black paint in the area of heat-sensitive materials, and indicating the value of the threshold temperatures in these areas: (a) initial view of the cable lug, (b) - cable lug with triggered temperature-sensitive material TM1 after heating the controlled surface above the first threshold temperature T1, (c) - cable lug with triggered temperature-sensitive materials TM1 and TM2 after heating the controlled surface above the second threshold temperature values T2, provided that T2 is higher than T1, (d) - view of the cable lug after cooling to room temperature.

Fig. 6 - Cable lug with a sealed hole, configured to record the facts of heating above two threshold temperatures, with the base painted with black paint in the area of temperature-sensitive materials, and indicating the values of threshold temperatures in areas free of heat-sensitive materials, as well as with reversible heat-sensitive material applied on the surface of the base of the dielectric part, free from irreversible heat-sensitive materials: (a) the initial appearance of the cable lug, (b) - cable lug with triggered heat-sensitive materials TM1 and TM2 after heating the controlled surface above the second threshold temperature T2, provided that T2 is higher than T1 and the temperature of the reversible temperature-sensitive material is below T2, (c) - view of the cable lug after cooling to a temperature below the threshold temperature of the reversible temperature-sensitive material.

Fig. 7 - Cable lug, made with the ability to register heating facts above two threshold temperatures, the base of the dielectric part of which in areas of heat-sensitive materials is painted black: (a) - the original appearance of the cable lug, (b) cable lug with partially activated heat-sensitive materials TM1 and TM2, after spot heating of the controlled surface above the threshold temperature T2, provided that T2 is higher than T1, with a change in the transparency of only those areas of heat-sensitive materials that were subject to heating above the threshold temperature, while maintaining the opaque area of these materials in their remaining areas that were not heated.

Fig. 8 - Microstructure of at least one of the used heat-sensitive materials with particles of organic matter in the form of flakes and their conglomerates, binder and voids forming a continuous gas phase, before actuation (a) and after actuation (b).

Detailed description of drawings

In fig. Figure 1 shows a three-dimensional model (1a, c) and a frontal view (1b) of a cable lug, designed to record heating facts above two or more threshold temperatures, which includes a metal conductive part 6 with a circular cross-section (Fig. 1a, c with an open hole, Fig. 1b with a sealed hole) and a dielectric part 1', the base 1 of which has a circular cross-section of variable diameter (Fig. 1a, 1b without a cut, Fig. 1c with a longitudinal section 15), and heat-sensitive parts are applied to the front surface of the base 1. materials 2a, 2b, 2c (Fig. 1a: two heat-sensitive materials TM1 2a and TM2 2b, located around the circle, Fig. 1b: two heat-sensitive materials TM1 2a and TM2 2b in the form of rectangular sections, applied sequentially from the metal conductive part 6 with the shown linear dimensions (length) of the metal conductive part 6 and dielectric part 1', as well as the minimum distance from the metal conductive part 6 to the closest section of the heat-sensitive material 2a ( ) and the distance between participants of thermosensitive materials 2a, 2b ( '), fig. 1c: three heat-sensitive materials TM1, TM2, TM3 2a, 2b, 2c, sequentially alternating around the circumference of the dielectric part 1' containing a longitudinal section 15).

In fig. 2 shows a cross-sectional view of a cable lug, configured to record heating facts above two or more threshold temperatures, which includes a metal conductive part 6 (Fig. 2a with an open hole, Fig. 2b, 2c with a sealed hole) and a dielectric part (Fig. 2a, 2b without a cut, Fig. 2c with a longitudinal section 15), on sections of the front surface of the base of which heat-sensitive materials 2a, 2b, 2c are applied (Fig. 2a: two heat-sensitive materials TM1 and TM2 2a, 2b, sequentially alternating around the circumference of the dielectric part 1', Fig. 2b: two heat-sensitive materials TM1 and TM2 2a, 2b, located at the same distance from the metal conductive part 6, and located in the recesses made in the base material of the dielectric part 1', Fig. 2c: an option in which the heat-sensitive materials (TM1, TM2,… TMn) 2 are located on the dielectric part 1' in the form of rectangular sections applied sequentially from the metal conductive part 6), with the base of the dielectric part being painted with black paint 3 in areas of heat-sensitive materials 2 and a protective layer 5 (2a, 2b ), with the shown internal diameters of the metal conductive 6 and dielectric parts 1' (2c).

In fig. Figure 3 shows a view of a cable lug, made with the ability to record heating facts above three threshold temperatures, which includes a metal conductive part 6 and a dielectric part, on sections of the front surface of which heat-sensitive materials 2a, 2b, 2c are applied, with a wire placed, while at the base 1 The dielectric part contains the insulated part of the wire 12, and the non-insulated end of the wire (core) 11 is placed in the metal conductive part.

In fig. Figure 4 shows a collapsible contact connection of a conductor 12, terminated with a cable lug, configured to record heating facts above two threshold temperatures, which includes a metal conductive part 6 and a dielectric part, on sections of the front surface of which heat-sensitive materials 2a, 2b are applied, in the socket terminal 13, equipped with screw 14.

In fig. 5 shows a cable lug, configured to record heating facts above two threshold temperatures, with an open end of a metal conductive part 6, the base 1 of the dielectric part of which has reflective and/or luminescent properties, with the base 1 painted with black paint 3 in areas of heat-sensitive materials 2a, 2b, and indicating the value of threshold temperatures 4 in these areas, demonstrating the irreversibility of heat-sensitive materials: FIG. 5a: initial view of the cable lug, Fig. 5b: cable lug with activated temperature-sensitive material TM1 2a after heating the controlled surface above the first threshold temperature T1, FIG. 5c: cable lug with activated temperature-sensitive materials TM1 2a and TM2 2b after heating the controlled surface above the second threshold temperature T2, provided that T2 is higher than T1, Fig. 5d: view of the cable lug after cooling to room temperature (25°C).

In fig. 6 shows a cable lug, made with the ability to register heating facts above two threshold temperatures, with an open end of a metal conductive part 6, the base 1 of the dielectric part of which is coated with a reversible heat-sensitive composition in an area free of irreversible heat-sensitive materials 2a, 2b with the base 1 painted with black paint 3 in the areas of heat-sensitive materials 2a, 2b, and indicating the value of the threshold temperature 4 in areas free of heat-sensitive materials 2a, 2b, demonstrating the irreversibility of the heat-sensitive materials and the reversibility of the color change of the reversible heat-sensitive composition (green-red-green): FIG. 6a: initial view of the cable lug, Fig. 6b: cable lug with activated heat-sensitive materials TM1 2a and TM2 2b after heating the controlled surface above the second threshold temperature T2, provided that T2 is above T1 and the temperature of the reversible heat-sensitive material is below T2, FIG. 6c: - view of the cable lug after cooling to a temperature below the threshold temperature of reversible heat-sensitive materials in this case up to 25°C.

In fig. 7 shows a cable lug configured to register heating facts above two threshold temperatures, the base 1 of the dielectric part of which in the zones of heat-sensitive materials 2a, 2b is painted black 3: FIG. 7a: initial view of the cable lug, Fig. 7b: cable lug with partially activated heat-sensitive materials TM1 2a and TM2 2b, after spot heating of the controlled surface above the threshold temperature T2, provided that T2 is higher than T1, with a change in the transparency of only those areas of the heat-sensitive materials that were subject to heating above the threshold temperature , while maintaining the opaque region of these materials in their remaining zones that were not subject to heating.

In fig. Figure 8 shows at least one of the used heat-sensitive materials 2 with particles of organic matter 7 made in the form of flakes and their conglomerates, a binder 10 and voids 8 forming a continuous gas phase before heating (Fig. 8a) and the microstructure of the heat-sensitive material 2 with reduced fractions of voids 8 and with increased apparent density, after the release of the gas phase to the surface, and with particles 7 that have undergone fusion and lost their original shape after heating above a threshold temperature (Fig. 8b).

Implementation of a utility model

General technology for manufacturing the device.

The cable lug includes a conductive metal fragment 6, made, in particular, of copper, aluminum or their alloys, for reliable and tight fastening of the cable lug to the uninsulated end of the wire 11 by crimping, as well as for ensuring high thermal and electrical conductivity. In some cases, a conductive metal fragment may have a tin-plated coating to protect it from the formation of an oxide film. The conductive metal fragment 6 may have a through hole or be sealed on one side (remote from the dielectric polymer part). Preferably, but is not limited to, the conductive metal piece has a circular cross-section.

As the basis 1 of the dielectric part 1' of the claimed device, polymeric materials can be used, predominantly halogen-containing polymeric materials, in particular chlorine-containing polymers, for example, vinyl chloride copolymers, namely: copolymer C-15 (copolymer of vinyl chloride and vinyl acetate), copolymer VHVD-40 (copolymer of vinyl chloride and vinylidene chloride), polyvinyl chloride (PVC), cast PVC, as well as polyvinylidene fluoride PVDF, fluoroplastic M-40, as well as polyesters with additives of 6.5% hexabromocyclododecane or polyesters modified with 15% trichloroisopropyl phosphate. In the case of using polymer materials, the device also acquires its characteristic elasticity, resilience and flexibility.

In addition, ceramic materials, mainly porcelain, can be used. Also, in a number of options, porcelain stoneware, terracotta, faience and other types of ceramics can be used. Composite materials, mainly textolite, can be used. In particular cases, fiberglass, carbon fiber, cermet and other composite materials can be used. These materials have the necessary strength, give the device fire resistance and have a dielectric strength of at least 3 kV/mm and a thermal conductivity coefficient of at least 0.1 W/(m*K).

To make it easier to attach the cable lug to the wire, the dielectric part may have a longitudinal section.

Table 1 shows some characteristics of the base of the dielectric part 1'. The choice of a specific value is based, in particular, on the type, size and location of the equipment being monitored, as well as its distance from the inspection point.

The base of the dielectric part preferably has a circular cross-section, but is not limited to it. To reduce the thickness of the base of the dielectric part in areas of heat-sensitive materials, as well as to ensure the safety of these materials, the base of the dielectric part may contain recesses (Fig. 2b, c), in which irreversible heat-sensitive materials 2 are respectively placed.

In some embodiments, the base 1 of the dielectric part 1' may have reflective properties or may be colored using a substance having luminescent properties to increase the visibility of both the device itself and the fact of its operation, which further increases the safety of operation of the equipment. Also, in special cases, the dielectric part can be painted to allow the use of the claimed multi-temperature thermal indicator for color marking of phases of electrical equipment (cables, installation wires, harnesses and other elements of electrical equipment), and the color of the dielectric part 1' is selected in accordance with GOST 28763-90, establishing, in particular, color marking in the field of electrical engineering. The color does not affect the visual registration of exceeding threshold temperatures of the equipment surface, but provides the marking of the device necessary to increase the overall safety of the equipment operation.

In particular cases, the base 1 of the dielectric part 1' can be colored using a substance capable of irreversibly changing color when heated. The presence of an additional substance capable of irreversibly changing color when heated to a temperature below the threshold temperatures (T1, T2, ... Tn) of the main heat-sensitive materials (TM1, TM2, ... TMn), in particular, 10-30 ° C below the minimum value recorded threshold temperatures T1, allows you to detect overheating of equipment that has not reached the maximum permissible values, and, as a result, ensure the prevention of an emergency defect.

Also, the base 1 of the dielectric part 1' can be colored using a substance capable of reversibly changing color when heated (Fig. 6). For example, a layer of heat-sensitive paint having the above properties can be applied to the front surface. The presence of a substance capable of reversibly changing color when heated makes it possible to inform personnel not only about exceeding a threshold temperature in the past, but also about overheating at the time of inspection.

In particular cases, the area of the base 1 of the dielectric part 1' under the areas of at least one of the used heat-sensitive materials can be painted black 3, which, when using heat-sensitive materials that are initially white, provides a color transition with a maximum contrast of "white" -black".

The conductive metal part 6 and the dielectric part 1' are connected to form a single structure at the manufacturing plant.

The dielectric part 1' and, first of all, at least one of the used heat-sensitive materials 2 can be covered with a protective polymer film 5. Polymer materials, preferably halogen-containing polymers, in particular PVC films, or polyurethane, can also be used as a protective film films modified with 15% trichloroisopropyl phosphate. However, it must be taken into account that if they are used for protective films, they must be transparent to at least part of visible light.

Preparation of heat-sensitive material.

Preferably, the solid phase of at least one of the used thermosensitive materials 2 includes an organic substance containing a C _n H _(2n+1) structural moiety, where n≥5: aliphatic fatty acids containing a C _n H _(2n+1) structural moieties n≥12; salts of fatty aliphatic acids containing structural fragments C _n H _(2n+1) with n≥5; alkanes containing at least 20 carbon atoms; dialkylphosphinic acids containing structural fragments C _n H _(2n+1) with n≥5; amides of aliphatic fatty acids containing structural fragments C _n H _(2n+1) with n≥5; aliphatic fatty acid anhydrides containing structural fragments C _n H _(2n+1) with n≥10; fatty aliphatic alcohols containing structural fragments C _n H _(2n+1) with n≥14; fatty aliphatic amines containing structural fragments C _n H _(2n+1) with n≥17; nitriles of fatty aliphatic acids containing structural fragments C _n H _(2n+1) with n≥19, for example, palmitic acid, stearic acid, behenic acid, tetracosane, erucamide, stearic alcohol, cetyl alcohol, polyethylene, wax, paraffin, saturated salts fatty carboxylic acids of rare earth metals, in particular lanthanum, yttrium, ytterbium, scandium, or a mixture thereof with a melting point that differs from the threshold temperature by no more than 5°C.

In preferred embodiments, the volumetric solids content of at least one of the used heat-sensitive materials, including organic matter, is no more than 90 vol.%, most preferably no more than 50 vol.%.

The organic substance is selected in such a way that when a threshold temperature is reached in the range of no more than 5°C, preferably no more than 2°C, it melts with a visual opaque-transparent transition for no more than 5 seconds, preferably no more than 2 seconds.

In various embodiments, the organic matter of the solid phase of at least one thermosensitive material is selected in such a way that the threshold temperature can be selected from the range from 50°C to 210°C, in particular cases, the temperature threshold is selected from the group: 50°C, 55 °С, 60°С, 70°С, 80°С, 90°С, 100°С, 110°С, 120°С, 130°С, 140°С, 150°С.

For example, for a device containing three different temperature-sensitive materials, the threshold temperatures could be 50°C, 55°C, 60°C, that is, the first temperature-sensitive material changes transparency when it reaches 50°C, the second temperature-sensitive material changes transparency when it reaches 55 °C, and the third - when the temperature reaches 60°C, in the range of no more than 5°C. In other embodiments, the threshold temperatures may be 50°C, 60°C, 70°C, or 50°C, 70°C, 80°C, or 60°C, 70°C, 80°C, or 60°C , 80°С, 100°С, or 60°С, 90°С, 110°С, or 70°С, 80°С, 90°С, or 70°С, 90°С, 110°С, or 70 °С, 100°С, 120°С, or 70°С, 110°С, 130°С, or 80°С, 90°С, 100°С, or 80°С, 120°С, 140°С, or 80°С, 120°С, 150°С, or 90°С, 100°С, 110°С, or 90°С, 110°С, 130°С, or 100°С, 120°С, 140° WITH.

For a device containing four different temperature sensitive materials, the threshold temperatures may be 50°C, 55°C, 60°C, 70°C, or 50°C, 60°C, 70°C, 80°C, or 50°C , 70°С, 90°С, 110°С, or 60°С, 70°С, 80°С, 90°С, or 60°С, 70°С, 80°С, 100°С, or 60° С, 80°С, 90°С, 110°С, or 70°С, 80°С, 90°С, 100°С, or 70°С, 90°С, 100°С, 120°С, or 70 °С, 90°С, 110°С, 130°С, or 80°С, 90°С, 100°С, 110°С, or 80°С, 100°С, 120°С, 140°С, or 80°C, 100°C, 120°C, 150°C.

To manufacture at least one of the heat-sensitive materials used, the solid phase of the corresponding heat-sensitive material, including an organic substance, is ground in a ball mill to a size of 2-3 μm, a liquid phase represented by water or an organic solvent with a boiling point of less than 180 ° C is sequentially added, and The resulting suspension is stirred, and preferably, during this period, periodic dispersion of the mixture with access of air is ensured until a constant density of the mixture is obtained. The liquid phase is preferably water or an organic solvent in which the solubility of the solid phase of the thermosensitive material does not exceed 10 g/kg.

In preferred embodiments of the invention, the liquid phase is added in an amount of from 50 vol.% to 90 vol.%.

The difference in density between the liquid phase and the solid phase is preferably less than 0.2 g/cm ³ . For this purpose, the liquid phase can be selected from the group: isopropanol, water, methanol, 1-propanol, isobutanol, ethylene glycol monomethyl ether, 1-butanol, acetonitrile, acetic acid, hexane, heptane, 1,1,1-trifluoroethanol, 1, 1,1,3,3,3-hexafluoroisopropanol, dimethylformamide, ethanol, butyl acetate, water, acetone, toluene, or mixtures thereof, but are not limited to.

With this production method, at least one of the resulting heat-sensitive materials 2 is preferably represented by two continuous phases: solid 7 and gas 8. In this case, the solid phase 7 is represented by particles predominantly oriented parallel to the surface of the base 1.

In this case, at least one of the resulting heat-sensitive materials 2 in the initial state is opaque to at least part of visible light and in the initial state includes a solid phase 7 and voids 8 filled with a gas phase, the volume fraction of which in the initial state is at least 10 vol.%, and when heated above the corresponding threshold temperature, an irreversible change in the microstructure of the corresponding heat-sensitive materials 2 occurs, accompanied by the fusion of particles of solid organic matter, a decrease in the proportion of voids, preferably 2 or more times (Fig. 8), and an increase in its transparency with the appearance color of the base, and upon subsequent cooling to 20°C and holding at this temperature for at least one month, preferably one year or more, the transparency of the corresponding heat-sensitive material does not return to its original values.

Depending on the nature of the solid phase 7 and the organic matter included in its composition, the type of the resulting particles of the solid phase 7 may be grains, crystals, fibers, flakes or conglomerates of these particles.

In particular cases, at least one of the used heat-sensitive materials 2 additionally contains a polymer binder 10 that is transparent to at least part of visible light, the phase transition temperature of which is higher than the phase transition temperature of the organic substance of the solid phase 7. In this case, the crushed solid phase is suspended in a solution of transparent at least for the visible light portion of the binder in the liquid phase. In preferred embodiments of the utility model, the binder is present in the resulting heat-sensitive material in an amount of 1-30 wt.%, to ensure the effect of glazing particles of solid organic matter.

In particular cases, the transparent polymer binder is selected from phenol-formaldehyde resin, butyl methacrylic resin, melamine formaldehyde resin, polyvinyl butyral, polybutyl methacrylate, polyisobutyl methacrylate, polybutyl acrylate, phenoxy resin, polystyrene-acrylic emulsion, polyolefin, polystyrene, polyacrylate, polyethersulfone, polyethyl ene, polypropylene, polystyrene, polyvinylidene fluoride, polytetrafluoroethylene , polyethersulfone, polyisoprene, polypropylene, polybutadiene, polyisobutylene, polyvinyl acetate, polymethacrylate, ethylcellulose, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polycaprolactone, polyethylene terephthalate resin, polybutylene terephthalate resin, polyamide resin, polyvinylidene fluoride, polyester, polyester hydroxyethylcellulose, methylcellulose, ethylcellulose, nitrocellulose, carboxymethylcellulose, gelatin, agar-agar, casein, gum arabic, polyvinyl alcohol, polyethylene oxide or mixtures thereof.

On the front surface of the dielectric part 1' of the cable lug, in some cases, an inscription 4 was applied with information about the recorded threshold temperatures. In special cases, in addition to threshold temperatures, information about the expiration date was also included. In one embodiment, a drawing intended for marking phases or components of electrical equipment, containing graphic, numerical or text information, can be applied to the surface of the cable lug, including the dielectric part.

In general, the process of applying heat-sensitive materials 2 may include the steps of applying one or more layers of a suspension of solid phase particles in the liquid phase of each of the heat-sensitive materials to individual areas of the opaque base 1 of the dielectric part 1', removing the liquid phase from the applied layers of the suspension, and also covering the front surface of the workpiece with a transparent protective layer 5.

To obtain the microstructure of at least one of the applied heat-sensitive materials 2, including a solid phase 7 and voids 8 filled with a gas phase, the volume fraction of which in the initial state is at least 10%, and providing an irreversible change in appearance when a threshold temperature is reached, which is accompanied by by melting the particles of the solid phase, reducing the proportion of voids and increasing its transparency with the appearance of the color of the base 1 of the dielectric part 1', you can use, in particular, the following techniques at the previously disclosed stages of the method:

at least one of the above stages of the method (applying a suspension of particles of solid organic matter in the liquid phase, removing the liquid phase from the applied layers of the suspension, covering the front surface of the workpiece with a transparent protective layer) is carried out at a pressure below atmospheric.

at least 3 cycles of applying layers of a suspension of solid phase particles in the liquid phase and removing the liquid phase from the applied layers of this suspension are carried out, while applying a suspension of solid phase particles in the liquid phase is carried out by a method selected from the group: screen printing, flexographic printing, tampon printing, silk-screen printing, producing a microstructure of a heat-sensitive material in which the particles of the solid phase are oriented predominantly parallel to the plane of the base surface.

Removal of the liquid phase from deposited layers of a suspension of solid phase particles in the liquid phase or from each layer separately can be carried out both at subatmospheric pressure and at atmospheric pressure, depending on the chosen method of manufacturing the device.

Pressure below atmospheric, in particular cases of obtaining a device, can be used both immediately after applying each individual layer of a suspension of solid organic matter in the liquid phase, and at the drying stage (i.e., removing the liquid phase) of the required number of applied layers of a suspension of solid organic matter in the liquid phase. In this case, spontaneous release of the liquid phase occurs from the volume of the material (sequentially from each layer or from the entire volume of the material) with the formation of a larger number of unstructured voids.

Layer-by-layer deposition of a suspension of a solid phase in a liquid phase can also provide the preferred structure of temperature-sensitive materials. In this case, after applying one or more heat-sensitive materials, the device is dried by selecting the mode of removing the liquid phase from the applied suspension layers, preferably at a temperature of (20±2)°C for 10 minutes in an air atmosphere, then the layer-by-layer application procedure is repeated until required coating thickness. The formation of a microstructure, including particles of the solid phase and a large proportion of voids filled with the gas phase, occurs layer by layer. The desired microstructure can also be achieved through the use of a dilute suspension of particles of the solid phase in the liquid phase (dilution of more than 50%), since in a large volume the orientation of the flakes will take place in the desired manner and their settling in an orderly manner (the “closed blinds” principle, if observed, a thin layer of flakes is sufficient to cover the color of the base), as opposed to using more concentrated suspensions. Another factor influencing the rate and nature of sedimentation of solid phase particles is the relative difference in the densities of the solvent and solid phase particles. If there is a large difference in densities (more than 0.2 g/cm ³ ), solid phase particles will settle from the suspension too quickly according to the principle of open blinds, not providing sufficient coverage. At comparable densities or with a difference in densities of less than 0.2 g/cm ^3, a slow settling of solid phase particles will be observed with the formation of the necessary ordered microstructure of the material and compliance with the principle of closed shutters.

Thus, adherence to the principle of closed shutters when forming the microstructure of at least one heat-sensitive material makes it possible to obtain a material whose microstructure in the initial state has a predominant orientation of solid phase particles parallel to the surface of the polymer dielectric part of the base and protective coating.

In the case of sequential application of heat-sensitive materials, when applying a suspension of solid phase particles in the liquid phase, the area of the front surface of the base 1 of the dielectric part 1' of the device, which should not be exposed to the first heat-sensitive material, is sealed with polyethylene film. A layer of the first suspension of solid phase particles in the liquid phase is uniformly applied to the uncovered area of the base using one of the techniques described above or other methods that ensure the formation of the described microstructure. After the layer has completely dried using one of the methods described above, the protective film is removed and the procedure for applying the second and subsequent suspensions of solid phase particles in the liquid phase is sequentially repeated to obtain several sections of heat-sensitive materials.

In advantageous embodiments, the layer thickness of at least one of the heat-sensitive materials used is no more than 800 microns, preferably no more than 450 microns, most preferably no more than 150 microns. The use of a specified thickness of a layer of heat-sensitive material promotes its operation at a speed of less than 5 seconds, preferably less than 2 seconds, when heated above the appropriate threshold temperature. This is due to the fact that this thickness of the material layer, in combination with the thickness of the base of the dielectric part, allows the heat-sensitive material to be heated when short-term overheating occurs during peak load periods and completely transforms it into a melt with an “opaque-transparent” color transition in less than 5 seconds, as well as provides the necessary heat transfer during air cooling of operating devices.

The surface area of the base 1 of the dielectric part 1' of the cable lug, coated with sections of heat-sensitive materials 2, is preferably from 3 to 97% of the front surface area of the base 1 of the dielectric part 1', preferably not less than 30% of the front surface area of the base 1 of the dielectric part 1', which makes it possible to identify triggered devices from a long distance, and also allows you to identify spot heating 9 of a large surface of installations.

The number of heat-sensitive materials is not limited by an upper limit, and depends on the practical task implemented when using the declared device (type of equipment, required step of the determined overheating temperature, area of the surface being tested for heating, etc.).

At the final stage of preparation, at least one of the heat-sensitive materials can be covered with an elastic protective film 5, transparent to at least part of visible light, which protects the material and the device itself from external environmental influences, humidity, UV irradiation and mechanical damage, increases the lifespan device service and prevents heat-sensitive material from draining during phase transition. Thus, the device is configured to register the excess of a threshold temperature of conductive elements in the open air.

In some variants of the utility model, a gap can be made between the protective film 5 and the dielectric part 1', or micro-holes can be made in the transparent protective film 5, allowing the gas phase to leave the device after exceeding the recorded temperature. Preferably, the transparent protective film 5 is selected from transparent elastic polymers.

In preferred embodiments, heat-sensitive materials 2 are configured to register local overheating of the surface by changing the color of only that part of the heat-sensitive materials 9 that were heated above the corresponding threshold temperatures and maintaining the original color of the heat-sensitive materials that were not heated above the corresponding threshold temperature during uneven heating .

The principle of operation of the device.

A cable lug configured to register the fact of heating above two or more threshold temperatures (T1, T2, ... Tn), which includes a metal conductive part 6, configured to be mounted on the non-insulated end of the wire 11 by crimping; dielectric part 1' with a through hole, on the front surface of the base 1 of which two or more heat-sensitive materials (TM1, TM2, ... TMn) 2 are applied, irreversibly changing the transparency when heated above the threshold temperature corresponding to each material (T1, T2, ... Tn). The specified tip is installed on the surface of the electrical wire 12, ensuring a tight fit of the device due to compression of the conductive metal part 6 and the properties of the base material 1 of the dielectric part 1', preferably without additional fasteners, and is fixed into the terminals of electrical devices, onto the collapsible contact connections of conductors with socket connections, spring contact connections and other elements of electrical equipment. Such fastening of the cable lug ensures increased operational safety of electrical equipment by ensuring reliable contact connection of elements, with the possibility of irreversible registration of the fact of exceeding two or more threshold temperatures (T1, T2, ... Tn) and, as a consequence, timely detection of contact connection defects, as well as the degree and the dynamics of their development.

Regardless of the design of the cable lug, which is designed to register the fact of heating above two or more threshold temperatures (T1, T2, ... Tn), as well as the type of element being monitored and fastening to it, the principle of operation of the device does not change significantly.

The cable lug, configured to register the excess of two or more threshold temperatures (T1, T2, ... Tn), with areas on which heat-sensitive materials 2 are applied, operates as follows. The applied heat-sensitive materials 2 in the initial state and until they are heated to the threshold temperature corresponding to each of them are opaque to at least part of visible light and, in advantageous embodiments of the utility model, are white.

Until the entire surface of the cable lug or its individual sections located under the heat-sensitive materials 2 are heated to the minimum recorded threshold temperature T1, all heat-sensitive materials 2 remain opaque to at least part of visible light, thereby maintaining the original appearance of the cable lug. When the surface is heated above the threshold temperature T1 with the stated accuracy on the entire surface of the first heat-sensitive material 2a, or predominantly on the surface of the heated section 9 of the corresponding heat-sensitive material 2a, respectively, having a threshold temperature T1, irreversible destruction of the microstructure of the corresponding heat-sensitive material 2a occurs, accompanied by the fusion of solid particles phase 7, a decrease in the proportion of voids 8 and, as a consequence, an increase in transparency. This results in an increase in the apparent density of the corresponding heat-sensitive material 2a. The heat-sensitive material 2a having a threshold temperature T1 is transparent with a modified microstructure and exhibits the color of the base 1 of the dielectric part 1' underneath the material or the color of the paint 3 applied to the base in the area of the heat-sensitive material.

At the same time, other heat-sensitive materials (TM2...TMn), having threshold temperatures (T2...Tn)>T ₁ , do not undergo a change in transparency and retain their original appearance. A further increase in the temperature of the surface on which the cable lug is placed to a temperature T2...Tn will lead to sequential activation of all areas with temperature-sensitive materials with threshold temperatures T2...Tn. In this case, if the maximum heating temperature of the cable lug is lower than at least one of the threshold temperatures of the temperature-sensitive materials Tn, then the corresponding sections of the temperature-sensitive materials TMn will remain opaque. Upon subsequent cooling of the controlled surface, the triggered heat-sensitive materials 2 or their parts 9 remain transparent and the appearance of the cable lug does not return to its original state. This ensures the possibility of irreversible visual registration of temperature rises above the corresponding two or more threshold temperature values, both at the moment of overheating and after a long time, and makes it possible to determine the degree of development of the defect.

When repeated overheating of the controlled surface occurs to the threshold temperatures of previously unworked areas with heat-sensitive materials TMn with a given accuracy, irreversible destruction of the microstructure of the corresponding heat-sensitive materials 2 occurs, accompanied by the fusion of particles of the solid phase 7, a decrease in the proportion of voids 8, an increase in the apparent density of the material and, as a consequence, increasing transparency.

When spot heating a controlled surface, a transparent zone 9 is formed only in that area of the corresponding heat-sensitive material or heat-sensitive materials 2, which was exposed to heating above the corresponding threshold temperature(s), while maintaining the opaque area of this material or these materials in the areas of which were not subjected to heating (Fig. 7).

Numerical values of threshold temperatures 4 can be applied to the front side of the dielectric part 1'; in particular cases, threshold temperature values can be applied in areas free from the corresponding heat-sensitive material 2, but next to it (Fig. 6), or on the base 1 of the dielectric part 1' under the corresponding heat-sensitive material 2 (Fig. 5), in the latter case, when the corresponding temperature exceeds the threshold value, after an irreversible change in the microstructure of the corresponding heat-sensitive material 2, the color of the base 1 of the dielectric part 1' and the corresponding numerical value of the threshold temperature 4 appear In particular embodiments, the dielectric part may be black, and at least one heat-sensitive material in the initial opaque state may be white. In this case, after the temperature exceeds the corresponding threshold value, a change is observed in at least part of the thermal indicator with a maximum white-black contrast, which additionally ensures the visibility of the triggered thermal indicator and facilitates its visual identification. A similar purpose is served by the implementation of a cable lug, in which the base of the dielectric part has a color other than black, and in the area under at least one heat-sensitive material 2, which is white in the initial state, black paint 3 is applied. In this case, also when triggered at least one heat-sensitive material exhibits a white-to-black color transition in at least a portion of the device.

In the case of a cable lug hermetically coated with an elastic transparent protective layer 5 at atmospheric pressure, at the moment of operation, as a result of the destruction of the microstructure of at least one heat-sensitive material 2 and the delamination of gas and non-gas media, a bubble will form on the surface of the protective layer 5, which decreases as the device cools . When using a thermal indicator with a sealed protective layer 5 and a pressure inside the voids 8 of the thermosensitive material 2 below atmospheric pressure, the formation of a bubble on the surface of the protective layer 5 will not be observed when at least one threshold temperature is exceeded, due to the fact that the pressure of the gas phase inside the voids 8 created at stage of obtaining a thermal indicator blank when applying a protective layer 5, in the initial state below atmospheric and compensates for the thermal expansion of the gas released when the microstructure of the thermally sensitive material 2 is destroyed. In other embodiments, the implementation of a cable lug to prevent the occurrence of a bubble when at least one threshold temperature is exceeded between the transparent protective a gap can be made between the layer and the base, or micro-holes can be made in the protective layer, allowing the gas released during activation to escape.

Versions of the cable lug, in which the composition of at least one heat-sensitive material 2 includes particles of the solid phase 7, voids 8 and a binder 10, have a similar operating principle. When the temperature exceeds the corresponding threshold value of at least one heat-sensitive material 2, the fusion of particles 7, “glazed” with the binder 10, occurs with the release of the gas phase and the separation of gas and non-gas environments, as a result of which irreversible destruction of the microstructure of the corresponding heat-sensitive material 2 also occurs, accompanied by a decrease in the proportion of voids 8 and, as a consequence, an increase in the transparency of this material.

Thus, versions of the cable lug have an operating principle based on the irreversible destruction of the microstructure of at least one heat-sensitive material 2, accompanied by the fusion of particles of the solid phase 7, a decrease in the proportion of voids 8 and, as a consequence, an increase in the transparency of this material and an irreversible change in the appearance of the material. at least part of the temperature indicator. Moreover, when the cable lug and the corresponding heat-sensitive material are cooled, the appearance of the device does not return to its original state; preferably, the reduction in the transparency of the corresponding triggered heat-sensitive material or its section 9 to the original values does not occur when cooled to 20°C and held at this temperature for at least one month, preferably one year or more.

Thus, upon visual inspection of the cable lug, it can reliably and with high accuracy (in the range of +/-10°C, preferably +/-5°C, most preferably +/-2°C, relative to the corresponding indicated on the cable lug at least one threshold temperature) and speed (no more than 5 seconds, preferably no more than 2 seconds) to record the fact that at least one temperature of the entire surface or its local area exceeds the corresponding threshold value, which helps to identify defects in the contact connection and determine the degree of development of the defect.

Below are preferred embodiments of the claimed utility model, which are illustrative and do not in any way limit the scope of the requested legal protection.

Examples

Example 1. General technology for manufacturing the device

Preparation of thermosensitive material: 100 g of a substance with a melting point corresponding to the threshold registration temperature in the range of 5°C, crushed to a size of 2-3 microns, 300 g of water, methanol, ethanol, isopropanol, ethylene glycol, ethylene glycol monomethyl ether, acetonitrile or their mixtures or 3-33% solution of the binder in water, methanol, ethanol, isopropanol, ethylene glycol, ethylene glycol monomethyl ether, acetonitrile or mixtures thereof and stirred until smooth. The suspension was immediately used to apply the composition.

The metal conductive element of the cable lug was preferably made of copper, aluminum or combinations thereof in the form of a tube, inside of which there is a through hole or a hole sealed at one end. The base of the dielectric part was preferably made of polymer materials, predominantly halogen-containing polymers, as well as ceramic or composite materials with fire resistance, electrical strength of at least 3 kV/mm and a thermal conductivity coefficient of at least 0.1 W/(m*K). The base of the dielectric part was made in the form of a hollow tube, preferably no more than 2 mm thick, with a through hole, preferably 3-25 mm long and preferably 1-25 mm in diameter, for fastening to wires, preferably with a diameter of 1 to 10 mm, without additional fastening elements. In this case, the diameter of the through hole can be either constant or variable. In some cases, the ratio of the diameter of the through hole of the base of the dielectric part to the diameter of the through hole of the metal conductive part is from 1.1 to 2. Moreover, the ratio of the length of the metal conductive part to the length of the dielectric part, in particular cases, is from 0.5 to 1, 5.

The conductive part is attached to the dielectric part to form a single structure at the manufacturing plant. If the base is made of polymer materials, the dielectric part is also elastic and/or has a longitudinal section.

If this is necessary, then information elements are applied to the base of the dielectric part using solvent dyes, for example, containing the value of the threshold operating temperatures in degrees Celsius.

The area of the dielectric part, which should not be exposed to the first heat-sensitive material, was sealed with plastic film. The first heat-sensitive material in 5-7 layers was applied to the film-free area using silk-screen printing. Between applications, the composition was dried in a vacuum chamber or in a thermostat at a temperature not higher than the temperature at which the composition operates. After the thermosensitive material had completely dried, the film was removed. The procedure was repeated for the second and subsequent temperature-sensitive materials. In the initial state, all heat-sensitive materials are white. In this case, in advantageous cases, the distance from the metal conductive part to the nearest heat-sensitive material does not exceed the parameter , calculated by formula (3) taking into account the thermal conductivity coefficient of the base materials used for the dielectric part and the threshold temperature of the selected thermosensitive material closest to the metal part. The minimum distance between sections of heat-sensitive materials preferably does not exceed the parameter '.

Example 2.

Yttrium behenate with a phase transition temperature of 90°C, lanthanum palmitate with a phase transition temperature of 100°C and lanthanum nonadecynate with a phase transition temperature of 110°C were used as substances for the preparation of thermosensitive materials according to example 1; methanol was used as a solvent. The suspensions were applied by silk-screen printing onto a base with a constant internal diameter of a through hole of 15 mm and a length of 25 mm made of black Oramask 831 PVC, with a thickness of 2 mm, according to the method described in example 1. The distance from the metal conductive part to the temperature-sensitive material closest to it was 5 mm. The distance between sections of heat-sensitive materials was 1 mm. The conductive part is made of copper, has a diameter of 10 mm, a length of 15 mm and an open hole. The number of layers of each heat-sensitive material was 7; between applications, the compositions were dried in a vacuum chamber at 100 mmHg. and 20°C for one hour. The thickness of each layer of heat-sensitive material was 0.6 mm, and their total area was 30% of the area of the front surface of the dielectric part of the device base.

Example 3.

Tetracosane with a phase transition temperature of 50°C, ytterbium caprylate with a phase transition temperature of 60°C, eicosanoic acid with a phase transition temperature of 70°C and dioctylphosphinic acid with a phase transition temperature of 80°C were used as substances for the preparation of thermosensitive materials according to Example 1. Polyvinyl butyral was used as a binder, and a mixture of methanol and ethylene glycol methyl ether (50/50 vol.%) was used as a solvent. The suspensions were applied by silk-screen printing onto a base with a constant internal diameter of a through hole of 1 mm and a length of 3 mm, made of red M-40 fluoroplastic and having a thickness of 0.2 mm, according to the method described in example 1. Distance from the metal conductive part to the nearest the temperature-sensitive material to it was 1 mm. The distance between sections of heat-sensitive materials was 1 mm. The conductive part is made of copper, has a diameter of 1 mm, a length of 3 mm and an open hole. The number of layers of each heat-sensitive material was 7; between applications, the compositions were dried in a thermostat at a temperature of 40°C for three hours. The thickness of the layer of each heat-sensitive material was 0.8 mm, and their total area was 97% of the area of the front surface of the dielectric part of the device base. The device was covered with a transparent protective film made of PVC, 0.15 mm thick.

Example 4.

Lanthanum capronate with a phase transition temperature of 120°C, zinc nonadecanoate with a phase transition temperature of 130°C and zinc palmitate with a phase transition temperature of 140°C were used as substances for the preparation of thermosensitive materials according to example 1, melamine-formaldehyde resin was used as a binder, and as a solvent - a mixture of methanol and isobutanol (90/10 vol.%). The suspensions were applied by silk-screen printing onto a base with a variable internal diameter of the through hole from 5 to 10 mm and a length of 25 mm, made of a copolymer of vinyl chloride and vinyl acetate of red color, with a thickness of 0.2 mm, according to the method described in example 1, and in heat-sensitive areas Before applying the materials, numerical values of the corresponding threshold temperatures were applied, as well as black paint. The distance of the metal conductive part to the temperature-sensitive material closest to it was 7 mm. The distance between sections of heat-sensitive materials was 2 mm. The conductive part is made of aluminum, has a diameter of 5 mm, a length of 25 mm and a closed hole. The number of layers of each heat-sensitive material was 5; between applications, the compositions were dried for 24 hours at room temperature. The thickness of the layer of each heat-sensitive material was 0.2 mm, and their total area was 70% of the area of the front surface of the dielectric part of the device base. The device was covered with a transparent protective film made of polyurethane modified with 15% trichloroisopropyl phosphate, 0.15 mm thick.

Example 5.

Yttrium capronate with a phase transition temperature of 55°C, zinc capronate with a phase transition temperature of 150°C and lithium stearate with a phase transition temperature of 210°C were used as substances for the preparation of thermosensitive materials according to example 1; polyvinyl butyral was used as a binder, and polyvinyl butyral was used as a binder, and solvent - ethanol. The suspensions were applied by silk-screen printing onto a base with a constant internal diameter of a through hole of 10 mm and a length of 25 mm, made of a copolymer of vinyl chloride and vinylidene chloride of green color with reflective properties, having a thickness of 0.35 mm, according to the method described in example 1, and in heat-sensitive areas Before applying materials, numerical values of the corresponding threshold temperatures were applied, as well as black paint, and in an area free of heat-sensitive materials, information about the service life was applied. The distance from the metal conductive part to the temperature-sensitive material closest to it was 10 mm. The distance between sections of heat-sensitive materials was 3 mm. The conductive part is made of copper, has a diameter of 5 mm, a length of 30 mm and a closed hole. The number of layers of each heat-sensitive material was 5; between applications, the compositions were dried in a vacuum chamber at 100 mmHg. and 20°C for one hour. The thickness of the layer of each heat-sensitive material was 0.4 mm, and their total area was 3% of the area of the front surface of the dielectric part of the device base.

Example 6.

n-hexadecyl-n-pentylhydrogen phosphate with a phase transition temperature of 40°C, palmitic acid anhydride with a phase transition temperature of 60°C and erucamide with a phase transition temperature of 80°C were used as substances for the preparation of thermosensitive materials according to example 1; polybutyl methacrylate, and ethanol as a solvent. The suspensions were applied by silk-screen printing onto a base with a constant internal diameter of a through hole of 2 mm and a length of 10 mm, made of polyvinylidene fluoride, painted with orange paint with luminescent properties, having a thickness of 0.15 mm, according to the method described in example 1, and in heat-sensitive areas materials, prior to their application, black paint was applied, and in an area free of heat-sensitive materials, numerical values of the corresponding threshold temperatures were applied. The distance from the metal conductive part to the temperature-sensitive material closest to it was 5 mm. The distance between sections of heat-sensitive materials was 1 mm. The conductive part is made of copper, has a diameter of 1 mm, a length of 5 mm and an open hole. The number of layers of each heat-sensitive material was 5; between applications, the composition was dried in a thermostat at a temperature of 70°C for three hours. The thickness of the layer of each heat-sensitive material was 0.2 mm, and their total area was 30% of the area of the front surface of the dielectric part of the device base. The device was covered with a transparent protective film made of PVC, 0.05 mm thick.

Example 7.

1-tetradecanol with a phase transition temperature of 40°C, docosanitrile with a phase transition temperature of 55°C and n-docosylamine with a phase transition temperature of 65°C were used as substances for the preparation of thermosensitive materials according to example 1; gelatin was used as a binder, and as a solvent - isopropanol. The suspensions were applied by silk-screen printing onto a base with a constant internal diameter of a through hole of 5 mm and a length of 20 mm, made of polyester modified with 6.5% hexabromocyclododecane, yellow in color, with a thickness of 0.3 mm, according to the method described in example 1, and in In areas of heat-sensitive materials, prior to their application, numerical values of the corresponding threshold temperatures, as well as black paint, were applied. The distance from the metal conductive part to the temperature-sensitive material closest to it was 10 mm. The distance between sections of heat-sensitive materials was 1 mm. The conductive part is made of steel, has a diameter of 5 mm, a length of 20 mm and an open hole. The number of layers of each heat-sensitive material was 6; between applications, the compositions were dried for 24 hours at room temperature. The thickness of the layer of each heat-sensitive material was 0.5 mm, and their total area was 30% of the area of the front surface of the dielectric part of the device base. The device was covered with a transparent protective film made of PVC, 0.05 mm thick.

Example 8.

Yttrium capronate with a phase transition temperature of 55°C and n-docosylamine with a phase transition temperature of 65°C were used as substances for the preparation of thermosensitive materials according to Example 1; phenoxy resin was used as a binder, and ethylene glycol was used as a solvent. The suspensions were applied by silk-screen printing onto a base with a constant internal diameter of a through hole of 15 mm and a length of 30 mm, made of brown textolite, with a thickness of 5 mm, according to the method described in example 1, and in areas free of heat-sensitive materials, numerical values were applied corresponding threshold temperatures. The distance from the metal conductive part to the temperature-sensitive material closest to it was 9 mm. The distance between sections of heat-sensitive materials was 5 mm. The conductive part is made of duralumin, has a diameter of 10 mm, a length of 10 mm and an open hole. The number of layers of each heat-sensitive material was 6; between applications, the compositions were dried in a vacuum chamber at 100 mmHg. and 20°C for one hour. The thickness of the layer of each heat-sensitive material was 0.5 mm, and their total area was 70% of the area of the front surface of the dielectric part of the device base.

Example 9.

The base area with a constant internal diameter of the through hole of 10 mm and a length of 20 mm, made of white porcelain, on which heat-sensitive materials will be applied, was sealed with a protective polyethylene film, the free area was covered with pigmented yellow Tempilaq thermal paint with a reversible color change temperature of 113 ° C. After the paint had dried, the protective polyethylene film was removed and numerical values of threshold temperatures were applied to the surface of the base containing thermal paint using solvent dyes. The thickness of the base containing thermal paint was 0.45 mm. Then a protective polyethylene film was glued to the area where the first heat-sensitive material should not fall, and the first thermal composition was applied using silk-screen printing in 7 layers. After the layer had completely dried, the protective film was removed and the procedure for applying the second heat-sensitive material was repeated. Zinc capronate with a phase transition temperature of 150°C and lithium stearate with a phase transition temperature of 210°C were used as substances for the preparation of thermosensitive materials according to example 1; butyl methacrylic resin was used as a binder, and ethanol was used as a solvent. The distance from the metal conductive part to the temperature-sensitive material closest to it was 3 mm. The distance between sections of heat-sensitive materials was 5 mm. The conductive part is made of copper, has a diameter of 5 mm, a length of 20 mm and an open hole. The number of layers of each heat-sensitive material was 6; between applications, the compositions were dried in a thermostat at a temperature of 40°C for three hours. The thickness of the layer of each heat-sensitive material was 0.6 mm, and their total area was 70% of the area of the front surface of the dielectric part of the device base. The device was covered with a transparent elastic protective film made of PVC, 0.05 mm thick.

Example 10.

The base area with a constant internal diameter of the through hole of 10 mm and a length of 25 mm, made of black OraJet 3951 PVC, on which heat-sensitive materials will be applied, was sealed with a protective polyethylene film, the free area was covered with pigmented yellow Hallcrest SC thermal paint with a temperature of irreversible color change of 80° WITH. After the paint had dried, the protective polyethylene film was removed and numerical values of threshold temperatures were applied to the surface of the base containing thermal paint using solvent dyes. The thickness of the base containing thermal paint was 0.55 mm. Then the protective polyethylene film was glued to the area where the first heat-sensitive material should not be exposed, the area was covered with solvent black dye, and the first heat-sensitive compound was applied using silk-screen printing in 6 layers. After the layer had completely dried, the protective film was removed and the procedure for applying the second heat-sensitive material was repeated. Lanthanum capronate with a phase transition temperature of 120°C and zinc capronate with a phase transition temperature of 150°C were used as substances for the preparation of thermosensitive materials according to example 1; phenol-formaldehyde resin was used as a binder, and ethanol was used as a solvent. The distance from the metal conductive part to the temperature-sensitive material closest to it was 10 mm. The distance between sections of heat-sensitive materials was 3 mm. The conductive part is made of copper, has a diameter of 8 mm, a length of 30 mm and an open hole. The number of layers of each heat-sensitive material was 6; between applications, the composition was dried in a vacuum chamber at 100 mmHg. and 20°C for one hour. The thickness of the layer of each heat-sensitive material was 0.45 mm, and their total area was 30% of the area of the front surface of the dielectric part of the device base. The device was covered with a transparent elastic protective film made of PVC, 0.15 mm thick.

These examples do not limit the claimed utility model, however, they clearly reveal special cases of implementation of the claimed utility model, and also confirm the achievement of a technical result associated with ensuring increased fire safety and electrical safety during the operation of electrical equipment by ensuring a reliable contact connection with the possibility of irreversible registration of facts exceeding two and more specified threshold temperatures for the timely detection of contact connection defects and determination of the degree of their development, by irreversibly recording the facts of an element of electrical equipment exceeding two or more specified threshold temperatures by a device that is conveniently and reliably mounted on wires and other elements of electrical equipment.

The utility model has been disclosed above with reference to a specific embodiment thereof. For specialists, other embodiments of the utility model may be obvious, without changing its essence, as it is disclosed in the present description. Accordingly, the utility model should be considered not limited in scope by the given description and examples.

Claims (22)

1. Cable lug, designed to register the fact of heating above two or more threshold temperatures (T1, T2, ... Tn), which includes: a metal conductive part configured to be attached to the wire core(s) by crimping; dielectric part connected to the conductive part, wherein the dielectric part includes a base made with the possibility of fixing on the wire, the front surface of which includes at least two sections (1, 2 ... m), on which heat-sensitive materials (TM1, TM2, ... TMn) are applied, respectively, made with the possibility of irreversibly change the transparency of at least part of the visible light when heated above the appropriate threshold temperature (T1, T2, ... Tn). 2. Cable lug according to claim 1, in which the minimum distance from the metal conductive part to the section of the heat-sensitive material closest to it does not exceed 10 mm, and the base has a dielectric strength of at least 3 kV/mm and a thermal conductivity coefficient of at least 0.1 W/ (m*K). 3. Cable lug according to claim 1, in which the minimum distance between sections of heat-sensitive materials does not exceed 5 mm. 4. The cable lug according to claim 1, in which the dielectric part includes polymeric materials, preferably halogen-containing polymers, preferably containing a structural unit -CH ₂ CHCl-, preferably polyvinyl chloride, most preferably cast polyvinyl chloride, or ceramic materials, preferably porcelain, or composite materials, mainly textolite. 5. Cable lug according to claim 1, in which the dielectric part is elastic and/or has a longitudinal section. 6. Cable lug according to claim 1, in which the dielectric part has at least one of the properties: the area of the front surface of the base of the dielectric part is at least 3 mm ² , preferably at least 10 mm ² ; the ratio of the inner diameter of the base of the dielectric part to the inner diameter of the metal conductive part is from 1.1 to 2, and the ratio of the length of the metal conductive part to the length of the base of the dielectric part is from 0.5 to 1.5; the base of the dielectric part has a through hole with an internal diameter of 1-25 mm and a length of 3-25 mm; The thickness of the base of the dielectric part is no more than 2 mm. 7. Cable lug according to claim 1, characterized in that the heat-sensitive materials are located in recesses made in the material from which the base of the dielectric part is made, and the thickness of the base of the dielectric part in the recess areas does not exceed 1 mm. 8. Cable lug according to claim 1, in which the metal conductive part is made of aluminum, copper or their alloys. 9. Cable lug according to claim 1, characterized in that the dielectric part can be used to mark elements of electrical equipment and (or) contains digital, color or other markings, including indicating the value of the recorded threshold temperature. 10. The cable lug according to claim 1, wherein the dielectric part has reflective properties or is colored using a substance having luminescent properties. 11. The cable lug according to claim 1, wherein the dielectric portion is at least partially colored using a substance capable of reversibly changing color when heated. 12. The cable lug according to claim 1, wherein the at least one heat-sensitive material is covered with a flexible protective film transparent to at least part of visible light, preferably made of polyvinyl chloride, most preferably cast polyvinyl chloride. 13. Cable lug according to claim 1, in which at least one heat-sensitive material is colored white in the initial state, and as the transparency of the heat-sensitive material increases, a visual color transition from white to black occurs. 14. The cable lug according to claim 1, in which at least one heat-sensitive material in the initial state has a microstructure including a solid phase and voids forming a continuous gas phase, the volume fraction of which in the heat-sensitive material is at least 10 vol.%, and is made with the ability to irreversibly change its appearance when a threshold temperature is reached due to the destruction of the microstructure of the thermosensitive material, accompanied by the fusion of solid phase particles, a decrease in the volume fraction of voids and an increase in its transparency with the appearance of the color of the polymer dielectric part. 15. Cable lug according to claim 14, in which the solid phase of at least one temperature-sensitive material includes an organic substance containing a structural fragment C _n H _(2n+1) , where n ≥ 5, and preferably selected from the group: aliphatic fatty acids, containing structural fragments C _n H _(2n+1) with n ≥ 12; salts of fatty aliphatic acids containing structural fragments C _n H _(2n+1) with n ≥ 5; alkanes containing at least 20 carbon atoms; dialkylphosphinic acids containing structural fragments C _n H _(2n+1) with n ≥ 5; amides of fatty aliphatic acids containing structural fragments C _n H _(2n+1) with n ≥ 5; aliphatic fatty acid anhydrides containing structural fragments C _n H _(2n+1) with n ≥ 10; fatty aliphatic alcohols containing structural fragments C _n H _(2n+1) with n ≥ 14; fatty aliphatic amines containing structural fragments C _n H _(2n+1) with n ≥ 17; nitriles of fatty aliphatic acids containing structural fragments C _n H _(2n+1) with n ≥ 19, preferably selected from the group: palmitic acid, stearic acid, behenic acid, tetracosane, erucamide, stearic alcohol, cetyl alcohol, polyethylene, wax, paraffin, salts of saturated fatty carboxylic acids of rare earth metals, in particular lanthanum, yttrium, ytterbium, scandium. 16. The cable lug according to claim 14, wherein the volumetric solids content of the at least one temperature-sensitive material is no more than 90 vol.%. 17. The cable lug according to claim 1, wherein the at least one temperature-sensitive material contains a polymer binder that is transparent to at least part of visible light in an amount of 1-30 vol.%. 18. The cable lug according to claim 1, wherein the at least one heat-sensitive material is configured to change transparency when heated to a temperature exceeding a threshold temperature, preferably in a range not exceeding 5°C, preferably not exceeding 2°C relative to the threshold temperature, and for no more than 5 seconds, preferably no more than 2 seconds. 19. Cable lug according to claim 1, characterized in that with uneven heating, a change in transparency occurs only in that area of the heat-sensitive material that was heated above the corresponding threshold temperature.