RU2816750C1 - Adaptive system for automatic detection of overheating of electrical equipment elements, method of use and testing thereof - Google Patents

Abstract

FIELD: fire-fighting equipment.

SUBSTANCE: group of inventions relates to systems for detection of emergency and pre-fire situations, namely to systems for automatic detection of overheating of electrical equipment elements, methods of their use and testing. Disclosed is a system for automatic detection of overheating of electrical equipment elements, which includes a gas sensor designed to detect gases, released during heating of the controlled element or thermally activated gas-releasing materials installed on it; controller connected or combined with gas sensor, made with the possibility of generating a notification on overheating of the monitored element and/or transmitting information on such overheating to another device when the sensor is exposed to gases taking into account the rate of change of their concentration.

EFFECT: improving reliability and safety of electrical equipment operation due to timely detection of defects accompanied by overheating of electrical equipment elements.

20 cl, 5 dwg, 4 tbl, 8 ex

Description

Field of technology to which the claimed group of inventions relates

The group of inventions relates to systems for detecting emergency and pre-fire situations, namely to systems for automatically detecting overheating of electrical equipment elements, methods of their use and testing.

State of the art

According to statistics, faulty electrical equipment is the cause of 30% of fires. Often such fires occur due to excessive heating of conductive elements, contact connections and insulation. Timely detection of electrical equipment defects accompanied by overheating makes it possible to eliminate faults before fires occur and thereby reduce the number of fires and technological violations. To detect overheating of electrical equipment elements, many methods have been developed that can be classified as direct (measuring the temperature of controlled equipment using temperature sensors), as well as indirect (measuring other parameters that change due to temperature increases). One example of an indirect method for determining overheating is the gas analytical method, the essence of which is the detection by gas sensors of substances released when the controlled elements are heated due to thermal destruction or combustion.

The gas analytical method uses semiconductor, thermocatalytic, conductometric, electrochemical or optical sensors with different principles of operation, but serving the same purpose of identifying products in the gas phase that indicate the presence of overheating.

The source [RU 2022250, publication date 10.30.1994] describes a device and method for informing about a pre-fire situation, based on the determination of thermal destruction products of various substances using infrared spectroscopy in three wavelength ranges, which are characterized by the absorption of hydrocarbon, chlorine-containing and oxygen-containing radicals and molecules , formed as a result of thermal decomposition or ignition of electrical insulating materials. Increased reliability of the device is achieved by subtracting signals corresponding to the permissible concentration of radicals from the simultaneously recorded values of the intensity of radiation passing through the analyzed gas-air mixture, and comparing this difference with a threshold value. A feature of the proposed device and method is that ensuring high accuracy and efficiency in determining the concentration of hydrocarbon, chlorine-containing and oxygen-containing radicals can only be achieved in closed premises of various classes and purposes: nuclear power plants, manned deep-sea vehicles, ship premises, coal mines, space and aircraft compartments devices, granaries, warehouses, etc., since when using the described invention in open rooms or in the open air, infrared sensors can also detect foreign gaseous substances that absorb in the same spectral ranges to which the sensors according to the described invention are tuned. In addition, the device detects gases released when a flame occurs, i.e. An alarm notification is generated after a fire.

The method for detecting a pre-fire situation and preventing a fire, described in the source [SU 1277159 A1, publication date 12/15/1986], is based on measuring the intensity of monochromatic radiation that changes upon absorption at a frequency corresponding to gaseous products of thermal destruction. When the threshold values are exceeded, the fire alarm control signal is triggered. This method is characterized by low reliability and a high probability of false positives. In addition, the method allows you to record only actively developing thermal destruction processes close to the moment of ignition, since the control signal is generated only on the basis of the signal exceeding a threshold value without taking into account the rate of increase in concentration, and also without taking into account the background concentration of the analyzed gases in the environment.

To reduce the number of false alarms that occur as a result of detection of third-party gases by sensors, as well as to identify facts of overheating of the controlled elements before thermal destruction begins, special thermally activated materials (stickers) are used, which are installed on the controlled elements. When heated above a predetermined threshold temperature, such stickers release signal gases that are detected by sensors. Thus, the source [JP 666648, publication date 03/11/1994] discloses a device for early detection of overheating in hard-to-reach places of electrical and mechanical equipment, consisting of an odorant encapsulated in a hot-melt composition and a sensor that detects the signal odorant. In this case, a hot-melt composition with an odorant is placed next to the controlled object. Alternative embodiments of the invention include hot-melt microcapsules filled with odorant, as well as odorants mixed with fatty acids such as waxes. The hot melt composition can be applied to sheet material with an adhesive layer to form a heat-sensitive stacker, or mixed with an adhesive agent to form an odor-releasing paint. A feature of this invention is the use of hot-melt polymers, which, when heated to a softening or melting temperature, can melt, drain from the controlled element or form a foam layer. Despite the fact that such systems are configured to register substances that are not contained in indoor air under normal operating conditions, they are nevertheless not immune from false alarms, since the sensors can detect foreign substances from the ambient air that are similar in their optical or other properties to the detected gases.

A system for detecting local overheating of electrical equipment is also known from the prior art, which discloses the use of a microporous polymer composite material capable of releasing pore contents in the mode of multiple heating and cooling cycles [RU 2596953, publication date 09/10/2016]. The described system consists of a gas sensor connected to a recorder, which is connected to a signal supply system, and a polymer composite material applied to areas of the electrical circuit that are prone to overheating and having an opening temperature in the range of 80-200°C. Despite the fact that special marker gases are used as the contents of the pores of the polymer composite material of the device according to this document, nevertheless, the sensor of the device can respond to the presence in the environment of third-party gases that are similar in spectral properties to the low-boiling substances used. In addition, systems based on the use of heat-sensitive gas-emitting stickers are able to control overheating only in the area of electrical equipment on which the stickers are installed.

It should be noted that the systems described above, based both on the use of gas-emitting stickers and on the detection of gases released during the thermolysis of insulating materials, include single sensors that analyze the gas environment only at the current time, which does not allow taking into account the presence of third-party substances in the environment gases Thus, the use of such systems is accompanied by a large number of false alarms due to the possible presence of third-party gases in the area of the controlled equipment.

Existing devices with multiple gas sensors, for example, [RU 111675 U1, publication date 12/20/2011; RU 159702 U1, date of publication 02/20/2016], as a rule, include gas sensors, an analog measuring part, a transceiver, a microprocessor module, a power supply circuit for the sensor device and the device as a whole and can be used, for example, as autonomous wireless pre-fire detectors or toxic gas sensors and, in particular, be configured to detect the concentration of methane or carbon monoxide in the air. Despite the fact that the proposed devices solve the problem of complete energy independence from mains power and increasing battery life, when used in large industrial enterprises or large installations, especially those located in the open air, the risk of false alarms increases due to the fixation of gases and aerosols having another source of occurrence and the sensors of the described systems entering the control zone as a result of diffusion.

The document [RU 2175779, publication date November 10, 2001] describes a method for diagnosing a pre-fire situation and preventing a fire by monitoring the values of informative parameters characterizing the state of air at a protected facility. The technical result is to simplify the method and provide early detection of fire by measuring the concentration of gaseous products of thermal destruction as informative parameters: CO, CO ₂ , NO _x HCl, H ₂ , CH ₄ , NH ₃ , O ₂ , Cl ₂ , H ₂ S, SO ₂ , НСО , C ₆ H ₅ OH and other reducing and oxidizing gases, as well as the concentration of suspended particles in the air and its temperature. Moreover, for each dependence of informative parameters on time, at least one value of the derivative is determined in the time interval of 0.1-60 s. Based on the results of processing these parameters, the occurrence of a pre-fire situation is judged.

The device described in the source [RU 95849, publication date 07/10/2010] is based on a similar mechanism of action, which determines the parameters of the gas environment, including the content of CO and H ₂ , which allows the device to be used as a fire detector. The invention consists of one or more gas sensors, the operating modes of which are controlled by a microprocessor module, an analog measuring part, a module for processing and storing measurements, as well as power supplies for the device. The hardware-software interface is integrated into the electronic circuit of the device for transmitting data and commands over wireless networks, and during the calibration interval the device can operate autonomously and uninterruptedly without replacing power supplies, thanks to the optimization of the measurement and data transmission algorithm.

Devices are also known from the prior art that include a single sensor, usually removed from the controlled area, as well as a system of suction pipes connecting the controlled areas with the sensor and supplying air samples from them to the sensitive element of the sensor [EP 2004/009450, publication date 04/24/2004; US 11189143, publication date 11/30/2021; EP 2881922, publication date 06/10/2015]. Such systems and devices may have algorithms for comparing signals received from a sensor over a certain period of time in order to confirm or refute a single signal indicating the occurrence of a pre-fire situation. For example, a method and device for detecting and determining the location of an ignition in one or more controlled zones, described in the source [RU 2342709 C2, publication date November 10, 2007] and consisting of a system of suction pipelines using an air intake device supplying air samples from each individual controlled zone into the sensor for detecting at least one combustion product in the selected air samples, after receiving a positive result from at least one air sample, analyzes a repeat sample taken from the same zone. By analyzing the concentrations in two consecutive air samples obtained from the same zone, a conclusion is made about the location of the ignition, as well as the degree of its development.

The difference in readings obtained sequentially from one sensor makes it possible to predict the development of a fire situation and trigger the appropriate fire protection mechanisms when using the utility model [RU 84717 U1, publication date 07.20.2009], selected as a prototype. At the same time, sequentially received data from one sensor is analyzed for the purpose of physical and mathematical modeling of accident development processes and prompt decision-making to eliminate an emergency situation and its consequences.

The above devices are distinguished by high sensitivity and selectivity to the detected gases and high reliability, since the fire hazard can be assessed by the concentrations of several controlled gas components, and the excess of normal operating values recorded by the sensor must be confirmed by a repeated signal from the same sensor. However, a common feature of these devices is the detection of the first signs of combustion, rather than excessive heating. The reason for this is the high threshold concentrations of thermolysis products, corresponding to the intensive development of the defect (combustion). A decrease in threshold concentrations in such systems will lead to multiple false alarms due to the presence in the ambient air of gases similar in their parameters to thermal destruction products. In other words, the sensors of the described devices can with a high probability capture foreign gases from the environment whose spectral or other properties are close to the marker substances used. False alarms of such systems are typical when operating in chemical plants, where emissions of various chemicals can occur, as well as near industrial enterprises and production and transport infrastructure.

Timely and accurate detection of emergency defects, accompanied by excessive heating up to the point of fire or smoldering, is an important task to ensure the safe operation of various equipment, including electrical equipment. Despite the existing variety of systems and methods for detecting pre-fire and emergency situations, their common drawback, which limits their widespread use, is the high probability of false alarms when foreign gases, similar in structure to thermal destruction products, enter the controlled objects. Existing gas analytical systems do not allow detecting defects at an early stage of their development due to the fact that, with a low concentration of thermal destruction products, they cannot be reliably detected against the background of high concentrations of other gases. Existing gas analytical systems, capable of numerically determining with high accuracy the absolute concentration of a given gas in the air, are used only in narrowly targeted areas due to the complexity of their maintenance, large dimensions and high cost and cannot be used in standard electrical installations.

Thus, there is a need to develop a simple, highly sensitive and reliable gas analytical system for automatically detecting overheating of electrical equipment elements that occurs long before the moment of fire, and taking into account the content of background gases in the air near the controlled area.

The group of inventions is aimed at increasing the reliability of identifying pre-fire situations occurring as a result of overheating of electrical equipment elements using the gas analytical method.

Terms and definitions used in this group of inventions

The terms presented below are explanatory in nature and do not limit the scope of legal protection of the claimed invention only to the stated wording.

"Running average" is a function whose value at each point of definition is equal to the average value of the original function for the previous period. In relation to the present group of inventions, the running average value of the gas concentration is the average value of the concentrations recorded by the sensor for a certain period up to the present moment.

“External zone” is an area of an electrical installation separated from the controlled area by walls or other partitions and communicating with the environment. In relation to the present invention, the external zone is the area of the electrical installation adjacent to the controlled zone, separated from it by a wall or partition.

The term "ignition" refers to the process of a material starting to burn. In relation to the claimed group of inventions, fire includes the beginning of smoldering or burning of cables, contact connections, insulating materials or other elements of electrical equipment as a result of heating by electric current or arc.

“Gas analytical system” is a set of products and devices that make it possible to detect the fact of overheating of controlled elements using the gas analytical method. A gas analysis system may include one or more gas sensors interconnected by a controller, products or coatings that include thermally activated gas-emitting materials, control and receiving devices that process notifications received from the controller, an alarm system and other elements that provide visualization of the system’s operation , transmission of informing or control messages.

The “gas analytical method for determining overheating of electrical equipment elements” means a method for determining overheating of electrical equipment elements, which consists of registering in the gas phase one or more substances indicating heating of the controlled element above a certain temperature.

“Gas sensor” is a device designed to determine the content of one or more substances in a gas mixture, generating an electrical signal associated with the concentration of controlled substances in the gas phase and transmitting it to the controller. The following types of gas sensors are distinguished: semiconductor, thermocatalytic, conductometric, electrochemical, optical and other sensors. The sensor used in the present group of inventions is designed to simultaneously detect both background and signal gases.

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

“Overheat notification” is a set of commands, messages and alerts generated by the controller, intended to inform personnel or related systems about the occurrence of overheating. Notification may include light, graphic, sound, electronic or other types of personnel alerts, a packet of data transmitted to an adjacent system, a change in the position of a dry contact relay, and other actions.

The term "controller" as used herein means any logical devices with which one or more gas sensors may be combined or to which may be wired or wirelessly connected. The controller analyzes signals from gas sensors using a set of logical operations and generates a notification informing about the occurrence of overheating. Depending on the user characteristics, the notification can be generated in light, sound, graphic or other form, and can also be a data packet for transmission to adjacent systems or a change in the position of the dry contact relay. The notification may be transmitted by the controller to another device, in particular an external receiving device or a higher-level system. In this case, the notification may additionally include a control command, for example, to break the electrical network, start the fire extinguishing system, and others.

The “controlled area” refers to the area of the electrical installation, fully or partially limited by walls or other partitions, within which electrical equipment elements controlled by the system sensor are located. In a particular case, the controlled area can be the internal volume of an electrical panel, a section of distribution devices, a switch compartment, a box for a distribution unit of windings, etc., within which the elements to be controlled are located. The controlled area may be hermetically or non-hermetically separated from the external area and other controlled areas. The degree of leakage of the controlled area of electrical equipment can be determined by the IP class parameter.

The term “controlled element” describes an element of electrical equipment, the overheating of which is determined using a gas analytical system according to the claimed group of inventions.

“Part per million” or “ppm” is a unit of measurement of any relative value, equal to 1⋅10 ^-6 from the base indicator. In relation to the claimed group of inventions, the ppm value means the content of measured gases in the controlled area at a given time and determines the absolute concentration of these gases. Gas concentrations expressed in parts per million can be converted to percentage concentrations as follows: 1%=10,000 ppm.

The concept of “multiple system activations” characterizes the ability of a gas analytical system to register the fact of overheating in repeated heating-cooling cycles more than once without replacing system components.

The term “model gas” means a substance or group of substances that are used when testing a system and include compounds that are similar in some characteristics to signal, background gases or substances released when a thermally activated gas-emitting material overheats.

The term “overheating (heating, heating) of electrical equipment elements” refers to the achievement of electrical equipment elements at a temperature exceeding the temperature of normal operation due to the occurrence of a defect, arc discharges and other reasons.

The concept of “threshold concentration of a signal gas” or “threshold of a gas analytical system” is the minimum concentration of a signal gas or the minimum value of the signal from the gas sensor of a gas analytical system at which an alarm is generated.

The term “self-diagnosis” reveals a set of processes performed in automatic mode aimed at determining the operability of the system.

"Comparison sensor" is an additional gas sensor connected to the system of the present invention, intended for installation near the controlled area and recording the concentration of background gases.

“Gas sensor signal” and “gas sensor signal value” are an electrical signal generated by a gas sensor, one of the parameters of which depends on the concentration of specified substances (for example, signal or background gases) in the gas mixture. In accordance with the present invention, a signal is transmitted from the gas sensor to the controller via wired or wireless communication. The gas sensor may additionally include logic modules that convert or modulate the signal, various filters, signal amplifiers and other components.

The term “signal gas” means a substance or group of substances that are released into the gas phase when the controlled elements or thermally activated gas-emitting materials installed on them overheat and for which the gas sensor is configured to detect.

The “degree of leakage” of a closed volume characterizes the ratio of the total area of permanently open sections of a given volume to the area of the enclosing structures, expressed as a percentage. The IP rating can also be used to quantify the degree of leakage in electrical cabinets and distribution boards.

The IP code (according to GOST 14254-2015) denotes a codification system used to indicate the degrees of protection provided by enclosing structures from access to hazardous parts, ingress of external solid objects, water, as well as to provide additional information related to such protection.

Under the term "thermally activated gas-releasing material (TGM)"

refers to a material capable of releasing gas when heated above a given threshold temperature, mainly in the range of 60-150°C. In particular, such material can be part of thermally activated gas-emitting stickers, clips, cambrics, other products, as well as special coatings (varnishes, paints, etc.). The thermally activated gas-releasing material may include microcapsules or microporous components containing signal gases that the gas sensor is configured to detect. The mass fraction of substances that pass into the gas phase when the thermally activated gas-releasing material is heated to a threshold temperature must be at least 30%. The temperature at which a thermally activated outgassing material begins to emit gas is called the offgassing threshold temperature or simply threshold temperature. Depending on the structure of the thermally activated gas-releasing material, when heated to a threshold temperature, complete or partial release of the gas contained in it may occur. In the latter case, when reheated above the threshold temperature, the material will again release part of the gas it contains. This property of TGM provides the possibility of repeated operation of the gas analytical system.

The term “background gas” discloses a substance or group of substances that may be present in the air of the operating area of an electrical installation, can be detected by a gas sensor, and the occurrence of which is not associated with overheating of the controlled elements or thermally activated gas-emitting materials installed on them.

The term “electrical equipment” refers to a set of devices intended for the production, distribution, transmission and consumption of electricity, the basis of which is the principles of electrical engineering.

“Electrical cabinet” or “distribution board” is a frame in which various electrical equipment is installed, including those intended for receiving and distributing energy. An "enclosed electrical cabinet" is an enclosure, usually made of metal or plastic, that is completely or partially enclosed on all sides. The panel differs from the cabinet in that the equipment is mounted in a special niche in the wall and is closed only on the front side.

The essence of the group of inventions

The claimed group of inventions is aimed at increasing the reliability and reliability of identifying the initial stages of defects in electrical equipment elements using a gas analytical method that takes into account the concentration of background gases.

The problem to be solved by the stated group of inventions is to create a system, a method for testing it, as well as a method for automatically detecting overheating of electrical equipment elements with high reliability and sensitivity.

The technical result of the claimed group of inventions is to increase the reliability and safety of electrical equipment operation due to the timely detection of defects accompanied by overheating of electrical equipment elements. To achieve the specified technical result, the group of inventions uses the determination of overheating by the gas analytical method using algorithms that take into account the current concentration of background gases in the air of the controlled area, as well as their concentration in the previous period of time, which allows reducing the threshold concentration of the signal gas when generating an overheating notification, and also reduce the number of false positives.

As noted above, the main disadvantage of the gas analytical method for monitoring overheating of electrical equipment elements is the formation of false alarms when the sensor is exposed to background gases, that is, gases that can also be captured by the gas sensor, but the presence of which in the air of an electrical installation is not associated with overheating of the controlled elements. Such gases can be exhaust gases, vapors of fuels, lubricants or paints, solvents, chemical production emissions, flue gases, etc. To minimize such false alarms, as a rule, manufacturers of gas analytical systems increase the threshold concentration of the system. This approach has a number of disadvantages, including the general coarsening of the system, the inability to detect the initial stages of defects accompanied by the release of small amounts of signal gas in a concentration below the threshold value, the inability to control overheating of elements of leaking electrical equipment, the inability to control overheating at industrial facilities, transport, ships, as well as other electrical installations that may be exposed to background gases.

When studying the gas analytical monitoring method, it was unexpectedly shown that the number of false alarms can be significantly reduced and the threshold concentration lowered if we take into account the difference in the rate of change in the concentration of background and signal gases inside the electrical installation.

As a rule, background gases released from an external source and distributed in the ambient air enter the controlled zone of an electrical installation only due to the entropy factor (partial pressure gradient). This diffusion of gas into the electrical installation occurs much slower than the change in the concentration of the signal gas released when thermally activated gas-emitting materials are heated or the insulation decomposes inside the electrical panel. This is due to the fact that the processes of release of signal gases are of a chain nature. We have shown that changes in the concentration of the signal gas over time occur within a few seconds, while background gases inside electrical equipment change their concentration over several minutes or even tens of minutes.

The discovered pattern of changes in the concentration of signal and background gases over time was tested in various electrical installations of varying degrees of leakage (IP) and different voltage classes, from 220 V distribution panels to 500 kV switchgear cells.

The patterns found made it possible to formulate several simple and reliable algorithms that reduce the number of false alarms and lower the threshold value of the concentration of signal gases.

In the first option, the specified technical result is achieved through the use of a system for automatically detecting overheating of electrical equipment elements, including:

- a gas sensor designed to detect gases released when the controlled element or thermally activated gas-emitting materials installed on it are heated;

- a controller connected or combined with a gas sensor, configured to generate a notification about overheating of the controlled element and/or transmit information about such overheating to another device when the sensor is exposed to gases released when heating the controlled element or thermally activated gas-emitting materials installed on it, with taking into account the presence of background gases in the controlled area.

If the controller is combined with a sensor, the system can be a device made in one housing.

During the period of operation, the system sensor is affected by background gases present in the environment, while their quantitative and qualitative composition changes over time and is taken into account by the controller. When the controlled element or thermally activated gas-emitting materials installed on it are heated, the gas sensor, in addition to background gases, also detects signal gases. To recognize overheating of monitored elements and minimize false alarms associated with exposure of the sensor to background gases, the current value of the sensor signal is compared with the average concentration value recorded over a certain previous period of time. Moreover, the threshold value can be either fixed or adaptive (that is, changing over time by taking into account changes in the quantitative and qualitative composition of background gases over time).

Additionally, a group of inventions may include the use of thermally activated gas-emitting materials, predominantly reusable (TGM) and special signal processing algorithms that make it possible to detect a defect before the development of irreversible changes in the structure of the materials of the controlled elements, for example, thermal destruction of insulation. THMs used to detect overheating of electrical equipment elements have a fixed threshold temperature of gas evolution, which, as a rule, is lower than the temperature at which irreversible destruction of electrical equipment elements begins. Thus, the use of THM makes it possible to detect overheating at a stage that allows maintaining the operability of electrical installation elements. In addition, the ability of some THMs to emit a signal gas in repeated heating/cooling cycles makes it possible to repeatedly detect overheating of electrical equipment elements without replacing the system or its individual parts and to clarify the remaining operating life of the equipment.

Elements of electrical equipment are selected as the object of control for the present invention. This is due to several reasons. Firstly, the reliability and reliability of the functioning of electrical installations is an important and integral factor in ensuring the safety and reliability of the operation of almost all types of production, social facilities, transport, urban infrastructure, etc. Secondly, electrical installations are a source of increased fire danger. As already noted at the beginning of the application, fires due to violations of the rules for operating electrical equipment take first place after careless handling of fire. Thirdly, in most cases, electrical installations of a high voltage class do not allow for visual inspection under load, which does not allow timely detection of defects using thermal imaging inspection or visual inspection methods. Separately, it should be noted that the materials from which electrical equipment is made: wires, cables, insulators or electrical equipment housings are in most cases non-flammable. It is not possible to detect their overheating with standard fire (smoke, heat, infrared and other) sensors.

Taking into account the concentration of background gases in the air of the controlled area allows you to reduce the threshold value of the concentration of signal gases and generate an alarm about overheating when the sensor detects a signal gas in a minimum concentration. Taking into account the concentration of background gases also allows you to adjust the threshold value of the signal gas concentration for each specific electrical installation and further reduce the likelihood of false alarms caused by changes in the concentration of background gases in the ambient air, as well as reduce the response threshold of the gas analytical system.

The advisability of reducing the threshold concentration of the signal gas is associated with the following circumstance. As a rule, the rate of development of defects associated with overheating of electrical equipment depends exponentially on temperature. In other words, the lower the temperature, the slower the defect develops, and the greater the margin of time for repairs or preparation for shutdown. Therefore, it is most advisable to identify defects at the earliest stages of their development. However, with slight overheating of the controlled elements, the concentration of released gases is very small. This is due not only to the low rate of the depolymerization reaction, but also to the weathering of the released gases from the electrical installation over time. At the moment, a large number of sensors are known that make it possible to detect products released during the decomposition of insulation, or special signal gases in extremely low concentrations, equal to units or tens of ppm. However, such sensors work well only in an ideal environment, that is, at constant temperature, humidity, CO ₂ content, oxygen and other atmospheric gases. It is impossible to ensure such “ideal” conditions in electrical installations. Changing the impact of the above-mentioned factors during operation leads either to the need to significantly roughen the system and raise the response threshold of the gas analytical system, or to put up with a large number of false alarms. The above circumstance is one of the significant factors limiting the scope of application of the gas analytical system. An equally significant factor is the change in sensor sensitivity over time, as well as the dependence of the sensor signal on temperature, magnetic fields and other factors.

The gas analysis system must have the necessary versatility, and also operate efficiently and reliably, regardless of external conditions and the type of insulating materials used. As a rule, it is impossible to predict the environmental conditions under which the system will be operated, as well as the composition and amount of background gases to which the system will be exposed during operation.

The signal gases that the gas sensor used in the gas analytical system is configured to detect are not an individual substance, but a collection of substances, the qualitative and quantitative composition of which can vary significantly. For this reason, the sensor used in the gas analytical method is, as a rule, tuned not to an individual substance, but to a group of substances united by the presence of one or another structural fragment.

Taking into account that any parameter measured by such a sensor directly characterizes the concentration (content) of a gas or group of gases in a gas-air environment, in this application the concept of “concentration” will be used when referring to the content of signal or background gases. In this case, the sensor generates a signal, the value of which is determined by the measured parameter of the gas mixture, so we can say that the value of the signal received from the sensor by the controller also characterizes the content of a certain set of substances in the controlled area and is somehow related to their concentration.

The main difficulty in increasing the sensitivity of the system when detecting signal gases is that when the sensor is configured to determine the maximum value of the parameter X - I _max (X), which best characterizes the signal gas (Fig. 5a, solid lines b), it, therefore however, it can respond to the presence of other background substances, the maximum value of the X parameter for which is close to the detected value. This is due to the fact that, as a rule, graphs of the dependence of the parameter values I(X) on concentration have a shape close to the Gaussian distribution. Therefore, even if the maximum values of the X parameters do not coincide, the standard deviation from I _max (X) of background gases (Fig. 5a, dotted lines a) can overlap with I _max (X) of signal gases, which, with a high content of foreign substances, can lead to triggering systems.

The use of products in the system that include thermally activated gas-emitting materials (TGM) and are installed on controlled elements, or thermally activated gas-emitting coatings applied to these elements, allows you to configure sensors to register specific signal gases that are released when the TMG is heated above a threshold temperature. Such signal gases, as a rule, are selected in such a way that the maximum value of the parameter X - I _max (X) - differs as much as possible from the maximum values of this parameter for other background gases (for example, CO ₂ , oxygen, water and other atmospheric gases) , as indicated in Fig. 5a, thick line p. However, in practice, the I(X) dependence recorded by the sensor will look similar to the graph shown in Fig. 5b, and since the content of background gases under certain conditions can be thousands of times higher than the concentration of the signal gas, the region with the maximum value of parameter X, characteristic of signal gases released from the THM, partially overlaps, and false alarms of the system occur.

In this regard, an important task of modern systems for detecting overheating using gas analytical methods is the combination of the ability to register the low content of gases released during overheating of controlled elements of electrical equipment or thermally activated gas-emitting materials installed on them, and minimizing false alarms. We found that taking into account the current content of background gases allows us to greatly increase the sensitivity of the system, as well as significantly reduce the number of false alarms that occur due to the detection of third-party gases by sensors.

The essence of the present invention is that the sensor detects gases released when the controlled elements or thermally activated gas-emitting materials installed on them are heated, taking into account the concentration of background gases determined by this sensor in the air of the controlled area. Typically the sensor is located inside electrical equipment next to or above the element(s) being monitored. In the claimed group of inventions, the zero value (baseline), relative to which the controller analyzes the gas content in the controlled area and makes a decision on generating an alarm, is defined as the average value of the signal generated by the sensor over a certain past period of time (running average). This approach allows you to reduce the threshold value of the content of controlled gases when generating an alarm and reduce the likelihood of false alarms. Taking into account the exponential dependence of the rate of defect development on temperature, the use of this approach can significantly increase the detection of defects in the early stages and reduce the number of false positives.

In the simplest case, the system takes the value of the signal I ₁ generated by the sensor during the time period t ₁ as the baseline. The controller generates an overheating notification when the value of the signal I _n , recorded by the sensor and characterizing the content of signal gases at time t _n , deviates from this baseline towards an increase in accordance with the formula: I _n -I ₁ >С _pore , where С _pore - threshold concentration value. In addition, more complex algorithms may be used, as disclosed in the description below.

The present invention can use various methods for comparing the values of signals recorded by the sensor, characterizing the gas content: the absolute values of the signals at each point in time, the average values of the signals over different time periods, the integral or differential values of the signals can be compared (in the latter case, not the relative values themselves will be taken into account signals, and the rate of their growth). All these approaches make it possible to optimize the operation of the system for a specific application task, since each type of defect has its own development characteristics. What is common in all cases is that the current concentration, or the concentration averaged over a short time period, is determined relative to the background gas content, which is taken to be the average value of the gas sensor signal recorded over a long time period.

Taking into account the current content of background gases by determining their concentration in the air of the controlled area makes it possible to reduce the threshold concentration of the signal gas required for generating a notification, as well as to recognize and minimize false alarms associated with changes in the composition of atmospheric (background) gases over time. Early detection of defects associated with overheating of electrical equipment elements ensures increased reliability and safety of electrical equipment operation.

In some cases, adaptive logic of system operation can be implemented. In this case, the initial threshold concentration value is adjusted by the controller during operation, based on the maximum change (oscillation amplitude) of the sensor signals over a long period. This approach is preferable, since depending on the external conditions and characteristics of the controlled electrical equipment, it is not always possible to reliably determine the threshold values of the signal gas, and the use of a single fixed (universal) threshold value for all types of electrical installations can lead to either false alarms or, conversely, reducing the sensitivity of the system. In the case of adaptive logic, the controller generates an overheating notification when the baseline sensor signal exceeds not a fixed threshold value, but a constantly changing threshold value. In the simplest case, the value of the adaptive threshold can be equal to the maximum difference between the values recorded by the sensor at the current and previous times, multiplied by a constant (the value of which is mainly in the range from 2 to 5). In another calculation option, an array of signal values received from the sensor over a certain period of time forms the dispersion (i.e., a measure of spread) of the values of background gas signals relative to the average value of these signals. From this data, the controller can also calculate the standard deviation, which is usually the square root of the variance, or calculated by other calculation methods. An overheat notification is generated only if the signal recorded by the sensor at the current time is out of the set formed by the dispersion or standard deviation from the average value of the signals recorded by this sensor at previous times. If the values of the signals recorded by the sensor at the current time are within the specified set, then an overheating notification is not generated. The claimed system may contain additional sensors installed in the external zone, outside the controlled area (comparison sensors, S _cp ), or installed in other controlled areas (control sensors, S _k ). In the case of an additional connection with the controller of one or more comparison sensors S _cf , the formation of notifications about overheating of electrical equipment elements and/or transfer of information about such overheating to another device can occur by comparing the current signal value recorded by the main sensor of the system with pre-averaged signal values, characterizing the content of background gases detected by all or some _Sr with the same or different contribution from each individual sensor. Similarly, when using several monitoring sensors, different algorithms for calculating the value of the signal gas can be used: based on the average concentration or based on the smaller recorded signal value.

If the controller is additionally connected to one or more monitoring sensors _Sk installed in other controlled areas, the formation of a notification about overheating of electrical equipment elements and/or transmission of information about such overheating to another device can occur when the average value of signals characterizing the gas content is exceeded , recorded by all or some of the sensors present in the system, with the same or different contribution of exceeded signal values recorded by each individual sensor. The adaptive threshold value and the use of the principle of operation of the system described above in the case of the additional presence of one or more comparison sensors S _cf and/or monitoring sensors S _k additionally increases the reliability of detecting overheating of electrical equipment, since it allows reducing the absolute value of the threshold concentration, upon determination of which the system is triggered, and makes the system independent of the established threshold values.

An increase in the number of monitoring sensors additionally helps to increase the reliability of detecting overheating of electrical equipment elements, especially in large-sized electrical equipment, for example, such as large-volume distribution cabinets, since each _S will analyze a certain volume of air surrounding it. Gases released during overheating of equipment elements or thermally activated gas-emitting materials installed on them are initially localized in the immediate vicinity of the overheating site and spread throughout the volume of electrical equipment over time due to diffusion processes, the speed of which depends on many factors, for example, forced ventilation. In this case, it is important that _Sk is located as close as possible to the place of overheating to reduce the delay in the system generating notifications about local overheating. Therefore, the placement of several S _to in different places of controlled areas will allow timely detection of pre-fire situations associated with the release of polymer insulation products and other materials.

As a rule, the average volume of one cell of electrical equipment (for example, electrical panels, complete switchgears, low-voltage complete devices, winding distribution box boxes, etc.) ranges from 100 liters to 1000 liters (1 m ³ ). It was experimentally established that the mass of products released from insulating materials during overheating of electrical equipment elements or thermally activated gas-emitting materials installed on them, the content of which is determined by gas sensors, does not exceed 1 g. Under normal conditions, the molar volume of any gas is taken to be 22.4 l/mol , the molar mass of air is 29 g/mol, and the average molar mass of the signal gases is 200 g/mol. Then the concentration of measured products in the controlled area will average 30-300 ppm. Therefore, for reliable and reliable operation, the system must detect the excess of signal gases in the range of 30-300 ppm. At the same time, the concentration of other gases, which can also be captured by sensors, is much higher; for example, the concentration of CO ₂ in the atmosphere in some cases can reach 1000 ppm or higher. This fact further indicates the need to use a comparison sensor.

As noted above, in order to continuously monitor the release of gases formed during overheating of electrical equipment elements or thermally activated gas-emitting materials installed on them, it is not advisable to quantify only one specific substance, but it is necessary to record a group of substances similar in structure. For this purpose, it is necessary to select a sensor that changes some parameter upon adsorption or reaction with a certain class of substances. For example, a sensor can measure the conductivity of a medium between two sensitive elements, depending on the composition of this medium, and generate a signal, the value of which will be higher, the higher the content of the gases that caused this change. In this case, the absolute concentration of the signal gases will be unknown, but its change will lead to a change in one of the sensor parameters, which will lead to the formation of a signal by the gas sensor and will indicate a change in the composition of the air environment. Sensors that detect a change in the composition of a gas-air environment by an indirect change in their parameters and generate a signal proportional to this change are widely used in various gas analytical systems due to their convenience, reliability, ease of use, compactness and low cost, and therefore their use is preferable within the stated group inventions.

Semiconductor, thermocatalytic, conductometric, electrochemical, optical and other types of sensors, each of which has a number of features, can be used as gas sensors in the claimed group of inventions.

Thermocatalytic sensors monitor the heat release resulting from the oxidation of the analyzed gas on the surface of a thermocatalytic element, which is a platinum filament heated to a high temperature, coated with a layer of catalyst, and the value of the heat release directly depends on the molar concentration of this gas. Their advantages are high performance and the presence of an explosion-proof shell, however, the thermocatalytic element quickly degrades, and the sensor itself has high power consumption and requires a constant connection to the electrical network, which limits the scope of their use.

The operating principle of electrochemical sensors is based on the interaction of the analyzed gas with a sensitive layer located directly on the working electrode or in a layer of electrolyte solution near it. Such sensors provide high selectivity and measurement accuracy, however, the presence of a liquid electrolyte reduces their service life and makes them less preferable for use in electrical installations.

Optical gas sensors are based on the absorption of gases at specific wavelengths, typically in the infrared range. In this case, the absorption coefficient is directly proportional to the concentration of gases. The advantage of optical sensors is their long service life and the absence of aging effects, since the sensitive element of the sensor is protected from exposure to the analyzed gases. Sensors of this type can also operate over a wide range of concentrations. However, despite the fact that optical sensors can be tuned to absorb certain wavelengths, such sensors are highly sensitive to the concentration of water, carbon dioxide and other compounds that the atmosphere may contain (for example, flammable liquid vapor). This leads to significant fluctuations in the measured parameters of both the monitoring sensor and the comparison sensor over time. The latter circumstance prevents a decrease in the sensitivity threshold of this type of sensor. Tuning optical sensors to determine the absorption of wavelengths allows increasing selectivity and sensitivity, but significantly complicates the system.

Semiconductor sensors are one of the main types of sensors used in gas analytical systems. Their principle of operation is based on a change in the resistance of the sensitive layer when exposed to the measured gas. As such a sensitive layer, as a rule, wide-gap semiconductors are used (oxides and chalcogenides of metals: SnO ₂ , ZnO, TiO ₂ , WO ₃ , SnO ₂ , etc.), reversible chemisorption of the measured gases on which leads to reversible changes in conductivity. Their advantage is not only high sensitivity, a wide dynamic range of measured concentrations, but also low power consumption.

The preference for using sensors of this type for the claimed system for automatically detecting overheating of elements of electrical equipment is determined by the fact that when the insulating materials of the controlled elements of electrical equipment overheat, usually including cross-linked polyethylene (PE), polyvinyl chloride (PVC), rubber, silicone, epoxy resin, etc. ., reducing gases are released (for example, ethylene, vinyl chloride, isoprene, butylene, HCl, H ₂ , CO, etc.), which can be determined by oxidizing semiconductor materials in low concentrations. At the same time, semiconductor sensors react poorly to the products of complete oxidation of organic substances, for example, CO ₂ , oxygen, and other substances with low reactivity, which are present in the air in relatively high concentrations. This makes it possible to further increase the sensitivity of the system and ensure its reliable operation at low concentrations of substances formed as a result of overheating of electrical equipment elements (for example, the occurrence of partial arc discharges), indicating the initial stage of development of a defect.

At the same time, it should be noted that the claimed group of inventions is not limited to the use of a certain type of gas sensor. For reliable and reliable operation of the claimed group of inventions, an important criterion when choosing the type of sensor used is the selective registration of products released during overheating of the insulating materials of electrical equipment elements or thermally activated gas-emitting materials installed on them, relative to gases that may be present in the atmosphere during normal operation of the system. These gases include: flammable liquids used in the maintenance of electrical installations, as well as during repair and paint work; flue gases released during the operation of internal combustion engines, boilers, gas turbines, etc.; methane, gasoline or diesel fuel vapors, emissions from chemical plants; odorants; detergents and disinfectants, etc.

All the sensors described above, which can be used in the stated group of inventions, provide continuous and repeated registration of products released during overheating of controlled elements of electrical equipment or thermally activated gas-emitting materials installed on them, as well as background gases in the controlled area throughout the entire service life, which also ensures reliable detection of overheating of electrical equipment elements.

In the preferred embodiment, the sensor used in the inventive system is a semiconductor type sensor, the sensitive element of which is configured to continuously or repeatedly detect gases released when heating insulating materials, including, in particular, cross-linked polyethylene (PE), polyvinyl chloride (PVC), rubber, silicone, epoxy resin. In particular, the sensor is designed to register these gases in concentrations from 30-100 ppm.

To increase the sensitivity of the system and detect defects with a heating temperature below the thermal destruction temperature of insulating materials, it is preferable to use thermally activated gas-emitting materials (TGM). In particular cases, the sensitive element of the sensor is configured to register products released during heating of thermally activated materials, preferably of multiple action, that are part of products or coatings installed or applied to controlled elements of electrical equipment.

THMs contain an encapsulated or otherwise hermetically sealed signal gas from the environment, the release of which occurs at a relatively low temperature. Encapsulated materials existing on the market have a high content of signal gases (more than 30%) and an initial gas release temperature that is set with sufficiently high accuracy. THMs are usually used in special stickers, clips, varnishes or coatings.

Thermally activated gas-emitting materials are suitable for use in the following cases:

- control of overheating of metal elements that are not coated with polymer materials and are not capable of releasing a signal gas when overheated;

- control of other elements of the electrical installation at a temperature below the beginning of decomposition (thermal destruction) of polymer materials;

- selective control of individual elements (those on which TGMs are applied or installed);

- increasing the sensitivity of the system and reducing the number of false alarms due to the fact that the amount of signal gases released from the THM is significantly higher than during the decomposition of polymer insulation. The signal gases contained in the THM can be selected in such a way that the sensitivity and selectivity of the sensor with respect to these gases is maximized.

Another advantage of using thermally activated gas-emitting materials is the possibility of recording the overheating temperature of the controlled element through the use of THM with a given threshold temperature.

The release of gas from thermally activated materials when heated to a threshold temperature, as a rule, occurs abruptly, which leads to a sharp increase in the concentration of signal gases. This makes it possible to increase the reliability of detecting overheating of electrical equipment elements, especially in relation to the system operation algorithms described in this application. In addition, as mentioned above, the signal gases used in TGM are usually selected in such a way that their measured parameters are outside the areas overlapped by the parameters of the background gases, which allows for more selective tuning of the sensitive elements of the sensors, thereby increasing their sensitivity . High sensitivity allows the use of products containing THMs of relatively small sizes, for example, stickers 1-20 cm long and 0.5-5 mm thick, or coatings containing THMs. On the one hand, the content of signal gases in such products (coatings) is low, due to the small volume of the heat-sensitive layer. On the other hand, this amount is sufficient for reliable detection of overheating. The small size of products containing THMs allows them to be installed on small elements of electrical installations: wires with a cross-section of 0.75 mm ² , terminal blocks, blocks, circuit breakers and other small equipment, the control of overheating of which is impossible by other methods. Another important advantage of increasing sensitivity by the described method is the possibility of using the invention, including THM, even in ventilated electrical installations.

Thus, the use of the system according to this group of inventions in conjunction with TGM allows one to significantly increase sensitivity, reduce the likelihood of false alarms and register the achievement of overheating of local elements to specified temperatures before the development of emergency defects or fire.

In electrical equipment, as a rule, heating is associated with load current. The dependence is quadratic and obeys the Joule-Lenz law. Since the load on electrical equipment often changes significantly during operation, heating may occur cyclically after a defect occurs. In this case, the insulation materials of the heated element will gradually, from cycle to cycle, release a small portion of the signal gas, until the complete destruction of the material. In this case, the system according to the claimed group of inventions will generate a notification whenever it overheats. In the case of thermally activated gas-emitting materials, as mentioned above, multiple registrations can be ensured by the structural features of the THM, for example, the content of a large number of microencapsulated particles of different sizes and different opening temperatures.

In the claimed group of inventions, as products containing THMs, it is preferable to use thermally activated reusable gas-emitting stickers made of a polymer composite material containing a continuous phase formed by a thermosetting polymer, the pores of which are filled with a sulfur-containing odorant or freon [EA 201890482, publication date 06/29/2018] . Thanks to the special structure of the material and the use of thermosetting polymers, when a given temperature is reached, only part of the pores are opened, releasing the gas contained in them and maintaining the integrity of the remaining pores, which ensures repeated gas release in repeated heating/cooling cycles. Therefore, the use of such thermally activated stickers makes it possible to repeatedly detect overheating of electrical equipment elements without replacing the system or its individual parts. In addition, in these stickers, the combination of a polymer composite material with odorants filling its pores ensures not only the integrity of the material at temperatures close to, but not yet reached the opening temperature, but also the explosive destruction of part of the pores when heated to threshold values, leading to the immediate release of sufficient for detecting the amount of signal gas by the sensor. Thus, the use of predominantly thermally activated gas-emitting stickers, described in the source [EA 201890482], ensures multiple operation of the system according to the stated group of inventions, as well as its speed.

In a preferred embodiment, the sensor has a sensitive element configured to register gases belonging to classes of compounds selected from the list: halocarbons, hydrogen halides, halohydrocarbons, alkenes, alkanes, mercaptans, acids or mixtures thereof, preferably gases selected from the list: tetrafluoride carbon, tetrafluoroethylene, tetrachlorethylene, trifluorochloromethane, chloroform, dichloromethane, methyl chloride, methyl bromide, trifluoromethane, ethyl chloride, vinyl chloride, hydrogen fluoride, hydrogen chloride, ethylene, propylene, butadiene, isoprene, methane, ethane, butane, hexane, methyl mercaptan, dimethyl sulfide, ethyl mercaptan, diethyl sulfide, nitric acid, nitrous acid or mixtures thereof.

As noted above, the sensor of the gas analytical system according to the stated group of inventions generates a response (signal) not to any specific gas, but, most often, to several gases (gas mixture). At the same time, some gases can make a greater contribution to this response, while others less. Thus, the sensor must be installed in such a way as to detect, to the maximum extent, precisely the products released when the monitored elements or thermally activated gas-emitting materials installed on them overheat. It is preferable to install the sensor above the controlled element. The values of the signals characterizing the content of gases for which the sensitive element of the sensor is configured to detect are transmitted to the controller, which processes the data received from the sensor.

The controller according to the claimed group of inventions is configured to generate an overheating notification after receiving and processing, using a set of logical operations, data received from a sensor associated or combined with it. The controller can provide notification of overheating of the controlled elements in the form of a sound, light, graphic or other notification, or in the form of a control command, for example, to turn off or reduce the load. The controller can also transmit the generated notification to another device, for example, to an external receiving device. The type of notification used about the occurrence of a pre-fire or emergency situation is determined on the basis of the technical documentation of the controlled electrical equipment, as well as the ease of use of the system.

In particular cases, the controller is configured to generate notifications about overheating of elements of electrical equipment, and/or control them, when the sensor is exposed to products released during overheating of controlled elements of electrical equipment or thermally activated gas-emitting materials installed on them, in a concentration above a specified limit value, regardless of concentrations of background gases determined by this sensor over previous periods of time. This feature allows you to identify rapidly developing defects that lead to instant overheating, fire and excess concentration of signal gases. In this case, timely shutdown of the electrical installation helps prevent the development of a fire and minimize damage to adjacent equipment.

To further ensure the reliability and reliability of detecting overheating of electrical equipment elements, the claimed system can use various algorithms when generating a notification about overheating of electrical equipment elements and/or transmitting information about such overheating to another device.

The controller can use one or more of the following algorithms to process signals received from the gas sensor: - zero value adjustment;

- calculation of the running average value of the sensor for a given period of time;

- definition of the reduced running average value as the difference between two running average values obtained over two different periods of time, a short period of less than one minute, and a long period of more than 5 minutes;

- comparison of the given running average value with a threshold value and generation of an alarm if it is exceeded;

- determination of the average value of the signal received from the sensor by averaging the given running average values; - comparison of the difference between the given running average values of signals from the sensor, including those calculated for different time periods, with a given threshold value; - determination of the growth rate of the reduced running average value and its comparison with the established threshold value;

- comparison of the signal with a set threshold value; - determining the growth rate of the difference in the reduced running average value of the sensor signal and comparing it with a set threshold value or the value of an identical indicator of other sensors;

- determination or change of threshold values based on the analysis of signal values received from the sensor during operation.

The implementation of the claimed group of inventions using the specified algorithms will be described in more detail in the section “Implementation of the invention”.

In particular cases, the system according to the claimed group of inventions can additionally be equipped with temperature sensors to further increase the accuracy and determine the numerical value of the temperature to which overheating occurred.

In preferred embodiments, the claimed system additionally has a self-diagnosis function, informing about the need to replace the sensitive element of the sensor, which increases the overall safety of using both the system and electrical equipment as a whole. Sensor diagnostics, as a rule, consists of regularly automatically measuring the resistance of the sensing element and/or heater or other sensor parameters and generating an appropriate notification when the resistance value goes beyond the established limits.

In the second option, the specified technical result is achieved through a method of testing the specified system, including the following actions:

- installing the sensor in the gas chamber, connecting the controller to the sensor, if it is not combined,

- determination or confirmation of threshold concentrations by dosing model gas into the gas chamber at different rates.

In this case, heating the model element may include heating a thermally activated gas-emitting material, preferably included in a thermally activated gas-emitting sticker, preferably of multiple action, installed on the controlled element in the gas chamber.

This method provides a clear, regulated check of the system’s compliance with the conditions and algorithms described in the first object of the claimed group of inventions for its further use in identifying overheating of electrical equipment elements. Using this method, if for a system according to the claimed group of inventions, a threshold concentration value is set, upon reaching which the system is triggered, this value is confirmed taking into account the concentration of background gases. If this value is not specified, then this method is used to determine this threshold value taking into account the concentration of background gases. The inventive method also makes it possible to determine and/or confirm threshold concentrations for each class of compounds for which the gas sensor is configured to detect, separately.

In the third embodiment, the specified technical result is achieved through a method for automatically detecting overheating of electrical equipment elements, including placing the system according to claim 1 in an electrical installation and processing a notification about overheating generated by the controller, followed by issuing an information message and/or transferring data to another device.

The sensor can be installed inside an electrical installation near the controlled elements of electrical equipment, that is, inside the controlled zone, in such a way as to register products released when the controlled elements of electrical equipment or thermally activated gas-emitting materials installed on them overheat

The location of the controller does not affect the operation of the system according to the invention. It is noted that it is recommended to install the controller in a place convenient for installation and maintenance during system operation.

The group of inventions, in particular cases, is intended to detect overheating of contacts and contact connections of closed electrical equipment, including contact connections of electrical panels, complete switchgears, low-voltage complete devices, distribution unit boxes and windings. Also, a group of inventions may be intended to detect overheating of insulating materials of electrical equipment elements, including cable couplings, as well as to prevent fires and identify defects in the insulating materials of electrical equipment elements resulting from the passage of arc discharges.

Brief description of drawings

The group of inventions will be more clear from the description, which is not restrictive and is given with reference to the attached drawings, which show:

Fig. 1 - A system for automatically detecting overheating of electrical equipment elements, including a gas sensor installed inside the controlled area near the controlled element of electrical equipment, and a controller connected to the sensor by wired (a) and wireless (b) communication and combined with the sensor (c).

Fig. 2 A system for automatically detecting overheating of elements of electrical equipment, including a gas sensor installed inside the controlled area near the controlled element of electrical equipment and combined (a) with the controller or connected (b) to it by wire, and the controlled element additionally contains a thermally activated gas-emitting material (TGM). In fig. Figure 2 shows a special case using a thermally activated gas-emitting sticker as a THM.

Fig. 3 System for automatic detection of overheating of electrical equipment elements, including a device that is a gas sensor combined with a controller and placed in a gas chamber (a), in a gas chamber containing a control element (b) or in a gas chamber containing a heating element with THM ( V). In fig. Figure 3c shows a special case using a thermally activated gas-emitting sticker as a THM.

Fig. 4 - A system for automatically detecting overheating of electrical equipment elements, including several monitoring gas sensors S _to m, each of which is installed inside a separate controlled zone near the controlled elements of electrical equipment, several comparison gas sensors S _cp n installed in the external zone, outside these controlled zones, and a controller connected to all sensors by wire. In fig. Figure 4 shows a special case with three control sensors (m=3) and three comparison sensors (n=3).

Fig. 5 Schematic diagram of the dependence of the intensity I of the signal recorded by the gas sensor on the parameter X of the gas mixture separately for background gases, products released during overheating of the controlled elements of electrical equipment, and gases released during overheating of thermally activated gas-emitting materials installed on the controlled elements of electrical equipment (a) and in generalized form (b).

In fig. 1 shows a system for automatically detecting overheating of elements of electrical equipment, placed on electrical equipment in such a way that the gas sensor 5 is located in the controlled zone 1, in close proximity to the controlled element of electrical equipment 2, to enable registration of products 4 released when overheating 3 of this element, while the sensor is connected to the controller 7 by wired (Fig. 1a) or wireless (Fig. 1b) communication 10 or 11, respectively, or combined with it 12 in one device housing (Fig. 1c) (system options).

In fig. Figure 2 shows a system for automatically detecting overheating of electrical equipment elements, placed on the electrical equipment in such a way that device 12 (Fig. 2a), which is a gas sensor combined with a controller, or gas sensor 5 (Fig. 2b), connected to controller 7 by wire connection 10 (system options) are located in the controlled zone 1, in close proximity to the controlled element of electrical equipment 2, on which the TGM 8 is located, to enable registration of products (gases) 4 released when this material 8 is activated as a result of overheating 3 of this element. In fig. Figure 2 shows a special case in which a thermally activated gas-emitting sticker with an activation temperature range of 50-90°C is used as a THM.

In fig. Figure 3 shows a system for automatically detecting overheating of electrical equipment elements installed in gas chambers to illustrate the method of use and method of testing this system, so that device 12, which is a gas sensor combined with a controller, is placed in gas chamber 9 (Fig. 3a), or in a gas chamber 9 containing a controlled heating element 2 (Fig. 3b), or in a gas chamber 9 containing a controlled heating element 2 on which a TGM 8 is located (in Fig. 3c, as an example of using a TGM, a thermally activated gas-emitting sticker with a temperature activation range 50-90°C), releasing gases 4 as a result of overheating 3, for which the sensor is configured to register (system options).

In fig. Figure 4 shows a system for automatically detecting overheating of electrical equipment elements, located on electrical equipment consisting of three closed controlled zones EO1-EO3, in such a way that the monitoring gas sensors S _to 1-S _to 3 5 are located in controlled zones 1, in close proximity to the controlled elements 2 inside the corresponding closed controlled zones 1 EO1-EO3 to ensure the possibility of recording products 4 released during overheating 3 of these elements, three comparison gas sensors S _cp 1-S _cp 3 6 are located in the external zone outside the controlled zones 1, outside the closed volumes of electrical equipment so as to record background gases without taking into account the content of products 4 released during overheating of 3 controlled elements 2, while all sensors are connected to the controller 7 by wire connection 10 (versions of the system with three comparison sensors and three monitoring sensors).

In fig. 5a schematically shows an approximate graph of the dependence of the intensity (I) of the signal recorded by the gas sensor on the parameter of the gas mixture (X) separately for background gases (dashed line, a), products released during overheating of the controlled elements of electrical equipment (solid line, b ), and signal gases (thick line, c). The graph shows the possible overlap of the signal characterizing the content of products released during overheating of the controlled elements with signals characterizing the content of background gases, even in the region of maximum intensity _Imax , as well as the preferred location of the signal characterizing the content of gases released from thermally activated gas-emitting materials relative to the signals characterizing the content of background gases. In fig. Figure 5b schematically shows an approximate graph of the dependence of the intensity (I) of the signal recorded by the gas sensor on the parameter of the gas mixture (X) in a generalized form.

Implementation of the claimed group of inventions

The group of inventions may be intended to detect overheating of conductive elements, cables and cable couplings, contacts and contact connections, as well as other elements of closed electrical equipment, including contact connections of electrical panels, complete switchgears, low-voltage complete devices, distribution box boxes of the beginning of the windings. Also, a group of inventions may be intended to detect overheating of insulating materials of electrical equipment elements, including cable couplings, to prevent electrical equipment fires, and to identify defects in the insulating materials of electrical equipment elements resulting from the passage of arc discharges.

In accordance with the first variant of the claimed group of inventions, the system for automatically detecting overheating of electrical equipment elements (Fig. 1-2) includes: a gas sensor 5 designed to detect gases 4 released when heating 3 of the controlled element 2 or thermally activated gas-emitting materials 8 installed on it; controller 7, configured to connect to gas sensor 5, connected to it by wireless or wired communication 11 or 10, respectively, or combined with it 12 in one device housing, and generate notification of overheating and/or transmit information about such overheating to another device.

As a gas sensor in the claimed group of inventions, sensors with various types of sensitive elements and based on the detection of various air parameters can be used. In particular, such sensors can be semiconductor, thermocatalytic, conductometric, electrochemical, optical and others.

If the system contains several sensors designed to detect background gases outside the controlled area (comparison sensors) and/or several sensors designed to detect gases released when the controlled element is heated or thermally activated gas-emitting materials installed on it in other controlled areas (controlling sensors ), their operating principle may vary. However, in preferred embodiments, the condition for the controller to generate an overheat notification is to register the impact on the control sensor of products released when the controlled element or thermally activated gas-emitting materials installed on it overheat, taking into account the concentration of background gases detected over the previous period of time.

The type of sensors, their sensitivity and quantity are determined based on the specific task to be solved by the use of the claimed group of inventions, the type of electrical equipment being controlled and other factors. It is most preferable to use in the system according to the claimed group of inventions semiconductor-type sensors, a sensitive element which is designed to detect gases released when heating the following types of insulating materials, including, in particular, cross-linked polyethylene (PE), polyvinyl chloride (PVC), rubber, silicone, epoxy resin, as well as in case of overheating of thermally activated gas-emitting stickers installed on the controlled elements, due to the higher sensitivity of such sensors to the products of thermal destruction of the insulating materials of the controlled elements of electrical equipment, lower energy consumption and longer service life compared to other sensors

The system may additionally include thermally activated gas-emitting materials, mainly reusable, included in the composition of products or coatings installed or applied to the controlled elements.

Gas sensor 5 according to the stated group of inventions should preferably have the following technical characteristics: the minimum threshold concentration of controlled gases is 100 ppm for freons and CO, 50 ppm for alkanes ( _{CnH2n +2} ) and _alkenes ( _CnH2n ) with n<4; It is structurally designed as a single module, which is connected to the controller via a wired or wireless communication line, or combined with the controller. If executed as a separate module; The sensor supply voltage is 5 V DC. The service life of the sensor is at least 10 years from the date of manufacture.

To detect overheating of electrical equipment elements that are not covered with insulating or other materials that are subject to thermal destruction or other types of decomposition when the temperature rises, the system may contain special thermally activated gas-emitting materials (TGM), preferably reusable, which emit signal gases when heated above a threshold temperature (Fig. 2). Such materials can be part of thermally activated gas-emitting stickers 8, clips or cambrics, as well as thermally activated paints, varnishes or coatings, and can be installed or applied to controlled non-insulated elements of electrical equipment 2, when overheated 3 the integrity of the THM layer 8 is violated and the contents contained in the material are released. gas 4, which sensor 5 is configured to detect. The advantage of using such materials is that, as a rule, they contain gases that are rarely found in the air under normal conditions, even near such sources of third-party gases as large chemical plants, busy highways, etc. In addition, THMs have the ability to repeatedly release gas in repeated heating/cooling cycles, which makes it possible to repeatedly detect overheating of electrical equipment elements without replacing the system or its individual parts.

The claimed group of inventions primarily uses thermally activated reusable gas-emitting stickers produced by ThermoElectrika LLC and made of a polymer composite material containing a continuous phase formed by a thermosetting polymer, the pores of which are filled with a sulfur-containing odorant or freon. In this case, the system's sensors are tuned to selective gases released from these thermally activated gas-emitting stickers. The advantage of these stickers is that with a single heating to a temperature exceeding the threshold, only part of the pores filled with odorant are opened and gas is partially released. The ability of these stickers to repeatedly release signal gases in repeated cycles of heating to a threshold temperature and cooling ensures repeated activation of the system according to the claimed group of inventions.

Mainly, TGM 8 must have the following set of technical characteristics: signal gas content - at least 50%; response temperature 80-150°C; the signal gas released from the THM has a hazard class of at least 4 and an electrical strength of at least 15 kV/cm; the threshold sensitivity of sensors to the signal gas released from THM is at least 100 ppm; THMs do not emit harmful substances and are classified as low-hazard in terms of the degree of impact on the human body; retain their characteristics after five times cooling to the minimum operating temperature followed by heating to a temperature 10°C below the operating temperature. In particular, thermally activated gas-emitting stickers, in addition to the above characteristics, can also have adhesion of the adhesive layer to stainless steel of at least 15 N/25 mm and stability of the adhesive layer under conditions of exposure to various oils, fats, water, acids, salts, alkalis, and solvents; have an electrical strength of at least 18 kV/mm; minimum bending radius at 24°C - 2 mm, at 0°C - 12 mm; service life is at least 10 years from the date of manufacture.

In a preferred embodiment, sensor 5 is configured to detect gases belonging to classes of compounds selected from the list: halocarbons, hydrogen halides, halohydrocarbons, alkenes, alkanes, mercaptans, acids or mixtures thereof, preferably gases selected from the list: carbon tetrafluoride, tetrafluoroethylene, tetrachloroethylene, trifluorochloromethane, chloroform, dichloromethane, methyl chloride, methyl bromide, trifluoromethane, ethyl chloride, vinyl chloride, hydrogen fluoride, hydrogen chloride, ethylene, propylene, butadiene, isoprene, methane, ethane, butane, hexane, methyl mercaptan, dimethyl sulfide, ethyl mercaptan, diethyl sulfide, nitric acid, nitric acid oh acid or mixtures thereof.

For reliable and reliable operation of the system, it is necessary and sufficient to have one sensor 5 (Fig. 1), which is installed inside the controlled zone 1 near the controlled elements of electrical equipment 2 in such a way as to determine the concentration of products 4 released when the 3 controlled elements of electrical equipment 2 overheat. sensor 5 can be either connected to controller 7 by wired or wireless communication 10 or 11, respectively, or combined with it 12. In the simplest case, the analysis of signals received by the controller from the sensor is carried out by comparing the difference, calculated as the difference in the average values of the signals over a small and long periods of time, or using more complex algorithms, including adaptive or predetermined threshold values.

The system according to the present group of inventions can take into account the values of gas concentrations received from the sensor over a long time and adjust the threshold concentration.

In another embodiment of the claimed system, the baseline characterizing the background gas content is determined by the value of the long running average values of the signals received from the sensor, and the current content of signal gases in the controlled area is determined as the short running average value of the sensor signals. Advantageously, the time period for calculating the long running average is more than 5 minutes, and the time period for calculating the short running average is less than 1 minute. At the same time, the system can adjust the optimal time period of running average values and adjust adaptive thresholds, which allows you to cut off false alarms caused by changes in the concentration of background gases.

Other possible algorithms for the operation of the system according to the claimed group of inventions are discussed in more detail below.

Regardless of the implemented algorithm for generating an overheat notification, the controller 7 is preferably designed to take into account the concentration of background or signal gases that affected the sensor 5 during the previous period of time.

The claimed system may contain additional sensors installed in the external zone, outside the controlled area (comparison sensors, S _cp 6), or installed in other controlled areas (control sensors, S _to 5) (Fig. 5). If the system contains more than one S _cp 6, the formation of a notification about overheating of the controlled element and/or transmission of information about such overheating to another device can occur taking into account the average value of gas concentrations determined by all or some S _cp 6, with the same or different contribution of the content of background gases, the concentration of which is determined by each individual S _cp 6. If the system contains more than one S _to 5, the formation of a notification about overheating 3 of the controlled element 2 and/or transmission of information about such overheating to another device can occur when the average value is exceeded concentration of gases detected by all or some S _to 5, with the same or different contribution of the exceeded concentration of products 4 released during overheating of 3 controlled elements 2 of electrical equipment or thermally activated gas-emitting materials 8 installed on them, detected by each individual S _to 5, specified threshold values.

In particular cases, the system according to the claimed group of inventions can be additionally equipped with one or more temperature sensors, based on which the controller can also generate an alarm about overheating and adjust the threshold value of the concentration of signal gases. The presence of temperature sensors can further increase the reliability of detecting overheating of electrical equipment elements or determining the fact of a fire.

The sensor 5 is connected to the controller 7 using a wired 10 or wireless 11 connection or can be combined with it 12. Thus, the controller 7 is configured to generate an overheating notification when receiving data from the sensor and processing it using a set of algorithms.

Depending on the task, the controller 7 can issue both a notification informing about overheating of the controlled elements 2 of electrical equipment, in the form of a sound, light, graphic or other notification, and a control notification, for example, to disconnect emergency equipment from the network. Also, the controller 7 can transmit a notification about overheating of the controlled elements of electrical equipment to an external receiving device and/or provide a combined notification, for example, transmitting a notification about overheating of the controlled elements of electrical equipment to an external receiving device and a control notification to the control elements of the controlled electrical equipment. The type of notification used regarding overheating of controlled elements is determined on the basis of the technical documentation of the controlled electrical equipment, as well as the ease of use of the system.

The controller 7 used for the claimed system may preferably have the following technical characteristics: the presence of an RS-485 digital communication line interface; Availability of Modbus RTU digital communication line protocol; has the following control and indication elements: buttons for setting parameters, digital indicator for displaying the device address and setting parameters, LEDs for the status of connected sensors; supply voltage ranges from 12 to 28 V DC (nominal value - 24 V); has EMC compatibility in accordance with GOST for residential, commercial and industrial areas with low energy consumption or for substations and power plants; the degree of protection of the housing is at least IP 20; presence of a discrete output "Alarm"; service life is at least 10 years from the date of manufacture.

The controller 7 can be additionally configured to generate a notification about overheating 3 of the controlled element 2 and/or transmit information about such overheating to another device when the sensor 5 detects products 4 released when the 3 controlled elements 2 of electrical equipment or thermally activated gas-emitting materials 8 installed on them are overheated , in a concentration above a specified limit value, regardless of the concentration of background gases recorded by this sensor over previous periods of time.

In preferred embodiments, the claimed system additionally has a self-diagnosis function, informing about the need to replace the sensitive element of the sensor. The need to replace the sensing element may be due, in particular, to its degradation over time or the end of its specified service life.

The system can use the following algorithms when generating a notification about overheating 3 of the controlled element 2 and/or transmitting information about such overheating to another device:

- zero value adjustment;

- calculation of the running average value of the sensor for a given period of time;

- definition of the reduced running average value as the difference between two running average values obtained over two different periods of time, a short period of less than one minute, and a long period of more than 5 minutes;

- comparison of the given running average value with a threshold value and generation of an alarm if it is exceeded;

- determination of the average value of the signal received from the sensor by averaging the given running average values;

- comparison of the difference between the given running average values of signals from the sensor, including those calculated for different time periods, with a specified threshold value;

- determination of the growth rate of the reduced running average value and its comparison with the established threshold value;

- comparison of the signal with a set threshold value;

- determining the growth rate of the difference in the reduced running average value of the sensor signal and comparing it with a set threshold value or the value of an identical indicator of other sensors;

- determination or change of threshold values based on the analysis of signal values received from the sensor during operation. Let's look at them in more detail:

1. Calculation of the running average value from each sensor for a given period of time. In this case, the system generates a baseline against which the current concentration determined by sensor 5 is compared based on the running average concentration values determined by this sensor for previous specified periods of time. The baseline can be obtained by averaging the running average data using a set of mathematical operations. The running average is calculated at each point in time using the formula:

Where - running average, x(t) - instantaneous signal value, T _ƒ - time for which averaging occurs, N - number of points over which averaging occurs.

2. Correction of the reference (zero) value and calibration of the sensor sensitivity. Due to the fact that sensor 5, depending on external conditions and manufacturing features, has a certain aging rate, in order to maintain the original high sensitivity and accuracy of the system, the sensor used in it must be made with the ability to constantly smoothly take into account these features. Correction of the reference (zero) value, the drift of which occurs due to degradation of the sensing element, changes in temperature and humidity of the environment, as well as due to the possible presence of foreign gases in the atmosphere, is carried out in order to take into account slow processes that lead to changes in the characteristics of the sensor and are not obviously associated with the release of signal gas or products of thermal destruction of insulating materials. The reference value is adjusted by calculating the running average over a relatively long period of time, which is more than 5 minutes.

3. Definition of the reduced running average value as the difference between two running average values received from the sensor over two different periods of time. At each moment of time, the system compares two main parameters with each other: a long running average (reference value), obtained from the gas sensor over a time period, mainly more than 5 minutes, and characterizing the background concentration of gases, and a short running average, obtained from the same gas sensor for a period of time, preferably not exceeding 1 minute, and characterizing the current concentration of signal gases in the controlled area. A short running average allows you to smooth out signal fluctuations that occur over short time intervals and are associated with possible electromagnetic interference. The reduced running average is defined as the difference between two obtained values: short and long running averages.

4. Comparison of the given running average value with the threshold value and generation of an overheating notification if it is exceeded. Short and long running averages are calculated according to the algorithm given in paragraph 1. The given running average concentration is obtained using two values: short and long running averages - as a result of their difference or calculated using a more complex mathematical algorithm. An overheat notification is generated when the running average value exceeds a certain specified threshold value.

5. Determination of the average signal value received from the sensor over a long period of time by averaging the given running average values. The system determines short and long running averages according to the algorithm given in paragraph 1, but the obtained data is averaged using a set of mathematical operations. To generate a notification about overheating, the average values are compared by calculating their difference or using more complex algorithms.

6. Comparison of the difference between the reduced running average values of signals from the sensor, calculated over different time periods, with a given threshold value. Short and long running average values are calculated for the sensor according to the algorithm given in paragraph 1. The comparison can be made over a certain period of time, the duration of which is determined experimentally and takes into account the delay in the entry and release of gas from the controlled area, which characterizes the degree of leakage of electrical equipment.

7. Determination of the growth rate of the reduced running average value and its comparison with the established threshold value. The reduced running average value is calculated similarly to the algorithm given in paragraph 3. The rate of increase of the reduced running average value of the signal gas concentration recorded by gas sensor 5, in the absence of overheating of the controlled elements, should be equal to zero. In the event of overheating 3, leading to the release of products 4, for registration of which the gas sensor 5 is configured, the value of the rate of increase of the reduced running average will increase abruptly, which will lead to the generation of an overheating notification by the controller 7, even if the threshold concentration has not been reached.

8. Comparison of the signal received from the sensor with the set threshold value. The system can generate a notification about overheating 3 if the monitoring sensor 5 registers a sharp significant increase in the concentration of products 4 (exceeding the threshold value several times) released when 3 controlled elements 2 of electrical equipment or thermally activated gas-emitting materials 8 installed on them are overheated, and the established threshold values are exceeded without taking into account the concentration of background gases determined by sensor 5 for previous periods of time. For example, such a situation may arise when an electric arc burns or insulating materials catch fire.

9. Determination of the growth rate of the difference in the reduced running average value of the sensor signal and its comparison with the set threshold value or the value of an identical indicator of other sensors. The reduced running average value is calculated for sensor 5 similarly to the algorithm given in paragraph 4. One of the criteria for generating an overheat notification 3 is to compare the rate of increase of the reduced running average value of the signal gas content recorded by the sensor at the current time with the same indicator obtained for previous periods of time. When an external background source of signal gases appears, the rate of increase of the reduced running average values G ₁ and G ₂ recorded by the sensor at times t ₁ and t ₂ , respectively, will be either equal (in the case of a low degree of tightness of the electrical installation or high diffusion of signal gases), or G ₂ <G ₁ (if the electrical installation is sufficiently sealed and the diffusion of foreign gases into the electrical installation occurs slowly) and the system will not operate. If G ₂ >G ₁ , then the controller 7 will generate a notification about overheating 3, which will indicate a sharp increase in the concentration of signal gases 4 inside the electrical installation as a result of overheating of the 3 controlled elements 2.

10. Determination or change of threshold values based on the values of signals received from the sensor during operation. The system for automatically detecting overheating 3 elements of electrical equipment 2 is made with the ability to determine and calibrate the maximum concentration of gases 4, which the sensor 5 is configured to detect, at which the system is triggered, using the method of testing the system according to the claimed group of inventions. Threshold values can be set by the controller 7 either manually when installing the system, or fixed in advance during the manufacture of the system, or be adaptive and dynamically changing depending on the operating conditions of the system.

In a preferred embodiment, during operation, the threshold value can be automatically adjusted in a specified range of values depending on the magnitude of fluctuations of foreign gases over a long period of time (more than 1 day). In such an algorithm, when the sensor is initially turned on, the threshold value is taken equal to some initial value. Then, during a given time interval, the maximum concentration value is recorded, which is recorded by the sensor, but which does not trigger the system. Based on the results of comparing the value of this maximum concentration with the threshold value, a decision is made to increase or decrease the threshold value.

In this case, the controller 7 can be configured in such a way as to compare the data received from the sensor 5 both in real time and with a certain time delay, determined experimentally and taking into account the delay in the entry and release of gas from the controlled area, which characterizes the degree of leakage of the electrical equipment.

The system may contain additional comparison sensors S _cp 6, or monitoring sensors S _to 5 (Fig. 4). Let's consider a system with m control sensors and n comparison sensors (Fig. 4, m=3, n=3). Such a system can, for example, be installed in several adjacent electrical panels 1, with at least one S _to 5 installed inside each panel, and at least one S _cp 6 mounted, for example, on the outer surface of the panel 1. In this case the minimum concentration of products 4, determined by one of the monitoring sensors 5, released during overheating of 3 controlled elements 2, (C _to m), sufficient for the controller 7 to generate a notification about overheating, may depend on the current concentration of background gases, determined by all S _cp 6, or in to an equal degree, or according to formula (1), taking into account the contribution of each comparison sensor separately:

where k _{n are} coefficients of uneven distribution of gas, determined experimentally for each of the n sensors, taking into account the characteristics of their locations, for example, depending on the degree of leakage of the controlled electrical equipment 1 or on the distance of the comparison sensor 6 from the monitoring sensor 5. In the vast majority of cases, k lies in within [0;1], preferably selected from the group: 0; 0.5; 1. Thus, depending on the system settings, the signals received by the controller 7 from individual comparison sensors 6 can be either fully taken into account (k=1), or partially taken into account, or completely ignored (k=0). With the value of all coefficients k _n =1, the contribution of each comparison sensor separately to the limiting value C _to m will be equal. In particular, the system can be configured in such a way that the controller does not take into account the extreme values of the background gas concentrations determined by the comparison sensors, i.e. in this case, the coefficient k will not be fixed and can take a zero value depending on the data received from _Sr.

To test the specified system, a method can be implemented that includes the following steps:

- installing the sensor in the gas chamber, connecting the controller to the sensor, if it is not combined,

- determination or confirmation of threshold concentrations by dosing model gas into the gas chamber at different rates.

Heating the model element may include heating the thermally activated material in a gas chamber containing the sensor.

Testing the system in this manner provides a clear, regulated check of the system’s compliance with the conditions and algorithms described in the first object of the claimed group of inventions, as well as for its further use in identifying overheating of electrical equipment elements. This method also allows you to determine the threshold concentration, taking into account the concentration of background gases, upon reaching which the system is triggered, or confirm this threshold value, taking into account the concentration of background gases, if it is not specified.

The implementation of the method in particular cases can be presented as follows: device 12, which is a gas sensor combined with a controller (Fig. 3a), is placed in a gas chamber 9 filled with a neutral gas, which can be used, for example, nitrogen. The absence of system operation in this state is recorded. Then, a model gas simulating a signal gas is dosed into the gas chamber 9 at a high speed of at least 5 ppm/min, and the minimum concentration _C of this model gas is recorded, at which the system is triggered and an overheating notification is generated by the controller, thereby determining threshold value in the absence of background gases.

In other cases of implementation of the method, device 12, which is a gas sensor (Fig. 3b), is placed in a gas chamber 9 filled with a neutral gas, which can be used, for example, nitrogen, while a model controlled element 2 is located in the gas chamber. Fixed the system does not operate in this state. Then a model gas simulating a signal gas is dosed into the gas chamber 9 in a known concentration C ₁ exceeding the threshold concentration established earlier or initially set for this system (C ₁ > C _pore ) at a low speed not exceeding 1 ppm/min, at which the system does not operate even when the current concentration of the model gas (C ₁ ) reaches and further exceeds the threshold values ( _Cpore ), and the absence of this operation is recorded. After this, the model controlled element is heated until thermal destruction of the insulating materials of this element begins and the system is activated and the controller generates a notification about overheating in the presence of background gases.

In another embodiment of the method of testing a system according to the stated group of inventions, device 12, which is a gas sensor combined with a controller, is placed in a gas chamber 9 filled with neutral gas, a heating element 2 is installed, on which a thermally activated gas-emitting sticker 8 is placed (used in this case as a product containing THMs) (Fig. 3c). The absence of system operation in this state is recorded. Then a model gas simulating a signal gas is dosed into the gas chamber 9 in a known concentration C ₁ exceeding the threshold concentration established earlier or initially set for this system (C ₁ > C _pore ) at a low speed not exceeding 1 ppm/min, at which the system does not operate even when the current concentration of the model gas (C ₁ ) reaches and further exceeds the threshold values ( _Cpore ), and the absence of this operation is recorded. After this, the heating element 2 is heated to the activation temperature of the gas-emitting sticker 8 and the operation of the system is recorded by registering an overheating notice issued by the controller 7, informing about the overheating of electrical equipment elements.

Another option for implementing a method for testing a system according to the stated group of inventions is to install a device 12, which is a gas sensor combined with a controller, in a gas chamber 9 filled with a neutral gas, which can be used, for example, nitrogen (Fig. 3a). The absence of system operation in this state is recorded. Then a model gas simulating a signal gas is dosed into the gas chamber 9 in a known concentration C ₁ exceeding the threshold concentration established earlier or initially set for this system (C ₁ > C _pore ) at a low speed not exceeding 1 ppm/min, at which the system does not operate even when the current concentration of the model gas (C ₁ ) reaches and further exceeds the threshold values ( _Cpore ), and the absence of this operation is recorded. After this, a model gas simulating a signal gas is dosed into the gas chamber 9 at a high speed of at least 5 ppm/min, and the minimum concentration _C of this model gas is recorded, at which the system is triggered and the controller generates an overheating notification, thereby thereby determining the threshold value in the presence of background gases.

According to the claimed group of inventions, a system for automatically detecting overheating of electrical equipment elements is used in accordance with the following method:

- placement of the system according to the first option in the electrical installation;

- processing of an overheating notification generated by the controller with subsequent issuance of an information message and/or transfer of data to another device.

The method may also implement algorithms, in particular those disclosed in this application when describing the system. In particular, the controller 7 can additionally generate a notification about overheating 3 when the sensor 5 detects at the current moment in time gases 4 released when 3 controlled elements 2 are heated or thermally activated gas-emitting materials 8 installed on it, in a concentration above a specified limit value, regardless of the background content gases detected by this sensor in previous time periods.

In the preferred embodiment, the detection of overheating 3 of the controlled elements 2 of electrical equipment occurs through the registration of signal gases released from thermally activated gas-emitting materials 8 of predominantly reusable action, included in the composition of products or coatings installed or applied to the controlled elements 2.

Let us consider special cases of implementation of the specified claimed group of inventions.

Examples.

Example 1.

The system according to the claimed group of inventions is installed as follows: the semiconductor sensor is placed in a sealed gas chamber with a volume of 100 liters, filled with nitrogen, and containing a heating element coated with an insulating material. The sensor is connected to the controller via a wired connection and the system is not activated in this state. Then the heating element is heated to a temperature of 100°C, at which thermal destruction of the insulating materials begins, but no fire occurs. The operation of the system is recorded by registering a notification issued by the controller informing about overheating of electrical equipment elements. In this example, the system is triggered due to the sensor detecting gases released as a result of heating the model element, in the absence of background gases in previous time periods.

Example 2.

The system according to the claimed group of inventions is installed as follows: the semiconductor sensor is placed in a sealed gas chamber with a volume of 100 liters, filled with nitrogen. The sensor is connected to the controller via a wired connection and the system is not activated in this state. Then, a model gas simulating signal gases is dosed into the gas chamber in a continuous mode at a rate of 10 ppm/min. The system does not operate within the first five minutes (with signal gas content up to 50 ppm). The operation of the system is recorded at the fifth minute by registering a notification issued by the controller informing about overheating of electrical equipment elements, and the content of model gas in the gas chamber at this moment is determined. The test is repeated three times, determining the average threshold concentration, which in this example was 57 ppm. In this example, the system is triggered by the sensor detecting model gases that simulate gases released as a result of heating the model element, taking into account the gas content recorded by the sensor over previous periods of time.

Example 3.

The system according to the claimed group of inventions is installed as follows: the semiconductor sensor is placed in a sealed gas chamber with a volume of 100 liters, filled with nitrogen. The sensor is connected to the controller via a wired connection and the system is not activated in this state. Then a model gas simulating a signal gas is dosed into the gas chamber simultaneously in an amount of C ₁ =100 ppm. In this case, the system is triggered due to the detection at the current moment of time by the sensor of model gases simulating signal gases in a concentration exceeding a threshold value, regardless of the concentration of gases recorded in previous time periods.

Next, in order for the system to exit the operation mode, the gas chamber is ventilated and refilled with nitrogen. After this, a model gas simulating a signal gas (C ₂ ) is dosed into the gas chamber in continuous mode at a speed of 10 ppm/min. The absence of operation of the system is recorded in the first five minutes, when the content of model gases in the chamber did not exceed 50 ppm. After the content of model gases in the gas chamber reaches 50 ppm, the operation of the system is recorded by registering a notification issued by the controller. This confirms the threshold concentration of the system, which in this case is equal to 50 ppm. In this case, the system is triggered due to the detection by the sensor of model gases simulating signal gases, taking into account the content of the same model gases recorded by the sensor earlier.

Next, in order for the system to exit the operation mode, the gas chamber is ventilated and refilled with nitrogen, after which it begins to continuously dose the model gas, simulating the signal gas, at a rate of 50 ppm/hour until its actual content is reached, equal to 100 ppm. The change in the reference (zero) value of the sensor signal is recorded due to the system implementing zero value drift algorithms and a low rate of increase in the signal gas concentration. Then, 50 ppm of a model gas simulating a signal gas is simultaneously dosed into the gas chamber, while the actual content of this gas in the chamber was 150 ppm. The operation of the system is recorded by registering a notification issued by the controller. In this case, the possibility of multiple actions of the system is realized, as well as the system is triggered due to the detection of gases by the sensor at the current moment in time, under conditions of the background concentration of gases recorded by the sensor for previous time periods, taking into account the drift of the zero value.

Example 4.

The system according to the claimed group of inventions is installed as follows: the optical sensor is placed in a sealed gas chamber with a volume of 100 liters, filled with nitrogen, and containing a heating element on which a thermally activated gas-emitting sticker with an activation temperature of 100°C is placed. The sensor is connected to the controller via wireless communication and the system is not activated in this state. Then the heating element in the chamber is heated to a temperature of 100°C, at which thermal activation of the sticker begins and signal gases are released from it. The operation of the system is recorded by registering a notification issued by the controller informing about overheating of electrical equipment elements. In this case, the system is triggered due to the sensor detecting gases released during activation of a thermally activated gas-emitting material, in the absence of background gases recorded by the sensor in previous periods.

Next, the gas chamber is ventilated so that the system exits the operation mode, it is refilled with nitrogen, and the heating element is cooled to room temperature. After this, the heating element is again heated to a temperature of 100°C and the operation of the system is recorded. In this case, the possibility of repeated operation of the system when using thermally activated gas-emitting materials is realized.

Example 5.

The system according to the claimed group of inventions is installed as follows: the semiconductor sensor is placed in a sealed gas chamber with a volume of 100 liters, filled with nitrogen, and containing a heating element coated with an insulating material. The sensor is connected to the controller via a wired connection and the system is not activated in this state. Then, 500 ppm of model gas, simulating the background gas, is dosed into the gas chamber for 10 hours at a rate of 50 ppm per hour. The absence of system activation is recorded due to the system implementing an algorithm that takes into account the drift of the zero value. After this, the heating element installed in the chamber is heated to a temperature of 200°C, at which thermal destruction of the insulating materials occurs, but no fire occurs. The operation of the system is recorded by registering a notification issued by the controller informing about overheating of electrical equipment elements. In this example, the system is triggered due to the detection at the current moment of time by the sensor of gases released as a result of heating of the model element, in conditions of background gases recorded by the sensor for previous time periods, taking into account the drift of the zero value.

Example 6.

The system according to the claimed group of inventions is installed as follows: the semiconductor sensor is placed in a sealed gas chamber with a volume of 100 liters, filled with nitrogen. The sensor is connected to the controller via a wired connection and the system is not activated in this state. Then, 500 ppm model gas, simulating a signal gas, is dosed into the gas chamber for 10 hours at a rate of 50 ppm per hour. The absence of system activation is recorded due to the system implementing an algorithm that takes into account the rate of increase in the concentration of the signal gas. After this, a model gas simulating a signal gas in an amount of 50 ppm is simultaneously introduced into the gas chamber. The operation of the system is recorded by registering a notification issued by the controller informing about overheating of electrical equipment elements. In this example, the system is triggered due to the detection by the sensor at the current moment of time of a model gas simulating a signal gas, under conditions of a rapid increase in its concentration and taking into account its influence on this sensor over previous periods of time.

Example 7.

The system according to the claimed group of inventions, including three comparison sensors and three control sensors, is installed as follows: each of the semiconductor sensors S _k is placed in a separate sealed gas chamber with a volume of 100 l, filled with nitrogen. Each of the semiconductor sensors S _cp is placed in a separate sealed gas chamber with a volume of 100 l, filled with nitrogen. All sensors are connected to the controller via wired communication and record the absence of system operation in this state. The controller is configured to take into account the content of background gases recorded by each of the comparison sensors, according to formula (1), which takes into account the contribution of each comparison sensor separately.

Let's consider one of the controlling sensors (S _to 1), for which the following formula (2) will be valid:

where C _to 1 is the maximum detectable S _to 1 value of the content of products released during overheating of the controlled elements, sufficient for the system to operate, C _av 1-C _ap 3 - values of the content of background gases detected by comparison sensors S _cp 1-S _cp 3, respectively, k ₁ -k ₃ coefficients of gas distribution unevenness, determined experimentally for each comparison sensor. In this case: k ₁ =1, k ₂ =0.5, k ₃ =0.

A model gas simulating the background gas is continuously dosed into all gas chambers containing reference sensors at a rate of 50 ppm/min until its content in each chamber is reached, presented in Table 1. Then, according to formula (2) C _to 1=(1*250 +0.5*1000+0*1500)/3=250 ppm.

At the same time, a model gas simulating a signal gas is continuously dosed into the first gas chamber containing S _to 1 at a rate of 50 ppm/min. In the first 5 minutes of dosing, until the model gas content in this gas chamber reaches 250 ppm, the absence of system activation is recorded by taking into account the concentrations of foreign gases measured by comparison sensors. With further dosing and the content of the model gas, simulating the signal gas, reaches more than 300 ppm in the first gas chamber, the operation of the system is recorded by recording the signal issued by the controller, informing about overheating of the electrical equipment elements.

In this example, the system is triggered due to the detection by the monitoring sensor of a model gas simulating a signal gas, under the influence of background gases on the comparison sensors, taking into account the different contribution of each comparison sensor.

Example 8.

An example of the implementation of algorithms for processing the concentrations measured by the sensor by the controller and generating a notification about overheating in the system according to the claimed group of inventions, which includes a sensor connected to the controller.

Initial signal averaging: To filter out possible instantaneous signal jumps that may be associated with induced electromagnetic interference, the signal is quickly averaged.

Signal used for further analysis calculated as a result of averaging over T _ƒ seconds (running average), over N values of the instantaneous signal

Adjustment of the reference (zero) signal level:

The reference (zero) value of the signal is constantly subject to smooth adjustment, as it changes over time (drifts) due to degradation of the sensitive element, changes in temperature and humidity of the environment, and also due to the possible presence of foreign gases in the atmosphere.

The average value of the absolute value of the characteristic measured by the sensor is taken as the zero value of Z(t) for the last T _d minutes. If the signal value falls below the zero value, then the zero value becomes equal to

In this case, the relative value of concentration in arbitrary units will be equal at each moment of time:

Constant threshold:

A notification about overheating of monitored elements (transition to alarm mode) is generated by default when the concentration threshold value is exceeded.

X(t)>P _i

Depending on the controller sensitivity level setting, the threshold gas concentration changes:

At low (LF mode) sensitivity P ₁

At medium (mid mode) sensitivity P ₂

At high (HF mode) sensitivity P ₃

The alarm mode is exited when the sensor concentration drops below half the corresponding threshold value.

Floating threshold:

In this mode, the threshold value P is adjusted depending on the magnitude of fluctuations of external gases. When the sensor is turned on, the threshold value is assumed constant and equal to P=P ₂ (average sensitivity). Within T _ƒ days (1 day or more), the maximum value of the signal S _{max is recorded.} , which does not lead to the formation of an alarm signal (that is, does not exceed the current threshold value) If this value is less than the current threshold by K times (for example, K=3), then the threshold is reduced by 1.1 times. If this condition is not met, then the threshold is increased by 1.1 times.

The threshold change can only occur in the range between P ₁ and P ₃ . When the floating threshold value P ₃ is exceeded, it is assumed to be equal to P ₃ . When the floating threshold is lowered below the value P _{1 ,} it is assumed to be equal to P ₁ .

Algorithm for taking into account the signal measured by the comparison sensor, if present:

The comparison sensor is installed in a place where the probability of an increase in the concentration of the signal gas or thermal degradation products of insulation will be minimal and serves to detect false alarms.

To take into account possible delays in gas propagation, the concentrations of the reference sensor are taken into account as follows. During the time T _ext , the maximum concentration value measured by the comparison sensor is determined:

at T _ext <T≤t

The operation of the monitoring sensor will be interpreted as false if, during the transition of generating a notification about the heating of the controlled elements, the following condition is met:

Generating a fire or fire notification:

The gas sensor is triggered, regardless of the concentrations of background gases recorded by this sensor over previous periods of time, when the following condition is met:

X(t)>P _fire

where P _fire is the threshold value of gas concentration, which indicates the possible occurrence of a fire.

Tables 2-4 present possible settings for the controller that implements the considered example of mathematical algorithms.

The results of the tests prove the implementation of the stated purpose of the system and methods for the declared group of inventions and the achievement of a technical result.

The group of inventions was disclosed above with reference to a specific embodiment. For specialists, other embodiments of the claimed group of inventions may be obvious, without changing its essence, as it is disclosed in this description. Accordingly, the group of inventions should be considered not limited in scope by the given description and examples.

Claims (37)

1. System for automatic detection of overheating of electrical equipment elements, including: - a gas sensor sensitive to at least one of the signal gases, including: products released during thermal destruction of polymer insulating materials of wires; gases included in the composition of thermally activated gas-emitting materials, released from them when a fixed threshold gas-emitting temperature is reached; as well as at least one of the background gases, including exhaust gases, vapors of fuels, lubricants or paints, solvents, emissions from chemical industries, flue gases; - a controller connected or combined with a gas sensor, configured to generate a notification about overheating of the controlled element and/or transmit information about such overheating to another device when the sensor is exposed to gases, taking into account the rate of change in their concentration. 2. The system according to claim 1, in which the sensor is a semiconductor type sensor, the sensitive element of which is designed to detect gases released during thermal destruction of insulating polymer materials, including, in particular, cross-linked polyethylene (PE), polyvinyl chloride (PVC), rubber, silicone, epoxy resin, and/or designed to detect gases released by heating thermally activated gas-emitting stickers installed on controlled elements. 3. The system according to claim 1, characterized in that it additionally includes thermally activated gas-emitting materials, mainly reusable, included in the composition of products or coatings installed or applied to the controlled elements. 4. The system according to claim 1, characterized in that the sensor has a sensitive element configured to detect gases belonging to classes of compounds selected from the list: halocarbons, hydrogen halides, halohydrocarbons, alkenes, alkanes, mercaptans, acids or mixtures thereof, preferably gases selected from the list: carbon tetrafluoride, tetrafluoroethylene, tetrachlorethylene, trifluorochloromethane, chloroform, dichloromethane, methyl chloride, methyl bromide, trifluoromethane, ethyl chloride, vinyl chloride, hydrogen fluoride, hydrogen chloride, ethylene, propylene, butadiene, isoprene, methane, ethane, butane, hexane, methyl mercap tan , dimethyl sulfide, ethyl mercaptan, diethyl sulfide, nitric acid, nitrous acid or mixtures thereof. 5. The system according to claim 1, characterized in that the controller is connected to additional sensors designed to detect background gases outside the controlled area, or gases released when the controlled element is heated or thermally activated gas-emitting materials installed on it in other controlled areas. 6. The system according to claim 1, characterized in that it is designed to detect overheating of contacts and contact connections of closed electrical equipment, including contact connections of electrical panels, complete switchgears, low-voltage complete devices, distribution block boxes and windings. 7. The system according to claim 1, characterized in that it is designed to detect overheating of insulating materials of electrical equipment elements, including cable couplings. 8. The system according to claim 1, characterized in that it is designed to prevent fires in electrical equipment. 9. The system according to claim 1, characterized in that it additionally has a self-diagnosis function that informs about the need to replace the sensitive element of the sensor. 10. The system according to claim 1, characterized in that it is additionally equipped with one or more temperature sensors. 11. The system according to claim 1, characterized in that the controller uses one or more of the following algorithms to process signals received from gas sensors: - zero value adjustment; - calculation of the running average value of the sensor for a given period of time; - determination of the reduced running average value as the difference between two running average values obtained over two different periods of time: a short period of less than one minute and a long period of more than 5 minutes; - comparison of the given running average value with a threshold value and generation of an alarm if it is exceeded; - determination of the average value of the signal received from the sensor by averaging the given running average values; - comparison of the difference between the given running average values of signals from the sensor, including those calculated for different time periods, with a specified threshold value; - determination of the growth rate of the reduced running average value and its comparison with the established threshold value; - comparison of the signal with a set threshold value; - determining the growth rate of the difference in the reduced running average value of the sensor signal and comparing it with a set threshold value or the value of an identical indicator of other sensors; - determination or change of threshold values based on the analysis of signal values received from the sensor during operation. 12. Method of testing the system according to claim 1, including: - installing the sensor in the gas chamber, connecting the controller to the sensor, if it is not combined, - determination or confirmation of the threshold concentration at which an overheating notification is generated by simultaneously dosing model gas into the gas chamber. 13. The test method according to claim 12, characterized in that it additionally includes at least one of the test stages from the following list: - confirmation of the fact that no overheating notification is generated when dosing model gas at a given speed, at which overheating notification should not be generated; - confirmation of the fact of generation of an overheating notification when dosing model gas at a given rate equal to or exceeding the rate of change in gas concentration at which the overheating notification should be generated; - confirmation of the fact of formation of a notification about overheating when dosing model gas at a rate not exceeding the rate of change in gas concentration at which the formation of a notification about overheating should occur, followed by simultaneous dosing of the model gas until the threshold concentration is reached or with a subsequent increase in the rate of dosing of the model gas to the value , equal to or exceeding the rate of change in gas concentration at which an overheating notification should be generated, regardless of the absolute concentration of the model gas. 14. The test method according to claim 12, including the stage of ventilating the gas chamber and filling it with neutral gas between test stages. 15. A method for automatically detecting overheating of electrical equipment elements, including placing the system according to claim 1 in an electrical installation and processing a notification about overheating generated by the controller, followed by issuing an information message and/or transferring data to another device. 16. The method according to claim 15, characterized in that it is intended to detect overheating of contacts and contact connections of closed electrical equipment, including contact connections of electrical panels, complete switchgears, low-voltage complete devices, distribution unit boxes and windings. 17. The method according to claim 15, characterized in that it is intended to detect overheating of insulating materials of electrical equipment elements, including cable couplings. 18. The method according to claim 15, characterized in that it is intended to prevent fires in electrical equipment. 19. The method according to claim 15, characterized in that it is intended to detect defects in the insulating materials of electrical equipment elements resulting from the passage of arc discharges. 20. The method according to claim 15, characterized in that it is intended to detect overheating using thermally activated gas-emitting materials, mainly of repeated action, included in the composition of products or coatings installed or applied to the controlled elements.