Fault arc energy measuring system and method

Abstract

The invention discloses a fault arc energy measuring system, a calorimetric sensor is used as a measuring element and is mainly composed of heat-conducting fins, a second shell, a thermocouple, a cavity and the like, and the heat-conducting fins are distributed in a cross arrangement mode. A thermoelectric force signal of a thermocouple is converted into a temperature signal through an AD conversion module, the temperature signal is transmitted to an upper computer through an RS485-to-USB interface, then temperature data are displayed on the upper computer in real time, then heat flux characteristic parameters of the heat conducting fins are used for calculating heat absorbed by the heat conducting fins, and the heat is electric arc energy. The invention further provides a fault arc energy measuring method, and the incident energy of the arc can be calculated through the method. According to the invention, the problems of low measurement success rate and inaccuracy caused by the randomness of the arc splashing direction can be well solved, the structural strength and the measurement precision are high, and the destructiveness generated by arc explosion can be resisted.

Description

Technical Field

[0001] The invention belongs to the technical field of arc energy measurement, and in particular relates to a fault arc energy measurement system and method. Background Art

[0002] Under normal environmental conditions, air has excellent electrical insulation properties, but when a sufficiently large electric field is applied at both ends of the gas gap, it will cause the current to break through the air medium. This phenomenon is called discharge. The arc phenomenon refers to a phenomenon in which the current breaks through the air medium to produce an arc in electrical equipment, accompanied by sudden energy accumulation and rapid release. It manifests itself in the form of strong light, strong heat, sound, and energy release when copper, steel, aluminum and other materials in electrical equipment parts vaporize and flash. The most direct and fatal hazard of arc accidents is that the thermal effect of the arc current causes burns to the human body.

[0003] Arc-proof textile materials have excellent heat resistance, flame retardancy, non-melting, H-class electrical insulation and permanent fireproof properties. When encountering an arc explosion, they can quickly carbonize to form a dense carbonized film to prevent heat from transferring to the inside of the arc-proof material. A simulation test was conducted on the arc explosion phenomenon. When equipped with arc-proof textile materials and different types of arc-proof textile materials, it is necessary to measure the energy during the arc explosion, so as to obtain the protective ability of arc-proof textile materials, and explore the carbonization mechanism of arc-proof textile materials to ensure the safety of maintenance personnel working with electricity and reduce the occurrence of accidents. The current copper calorimetric sensor measurement device uses a single copper sheet for measurement, but the splashing direction during the fault arc explosion is random. The existing device cannot guarantee that the copper calorimetric sensor will be hit every time during the measurement, resulting in low measurement success rate and inaccurate measurement. Summary of the invention

[0004] The purpose of the present invention is to accurately quantify the energy of an arc explosion, thereby proposing a fault arc energy measurement system and method.

[0005] To achieve the above-mentioned purpose, the present invention provides a fault arc energy measurement system, characterized in that it includes a calorimetric sensor, an AD conversion module and a host computer connected in sequence, wherein the calorimetric sensor includes a first shell and N calorimetric sensor monomers installed on the first shell, N≥4; the N calorimetric sensor monomers are arranged as follows: one calorimetric sensor monomer is located in the center, recorded as the central calorimetric sensor monomer, and the remaining sensors are located on the periphery of the central calorimetric sensor monomer.

[0006] Furthermore, N is 5, and the 5 calorimetric sensor units are arranged in a cross shape.

[0007] Furthermore, the calorimetric sensor unit includes a thermally conductive sheet, a second shell, a thermocouple and a cavity, the probe end of the thermocouple extends into the thermally conductive sheet, the upper part of the thermocouple is located in the cavity, and the remaining part is located in the second shell, the root of the thermocouple is fixed to the inner wall of the second shell, and the second shell is connected to the first shell.

[0008] Furthermore, the second shell and the first shell are made of calcium silicate board.

[0009] Furthermore, the outer surfaces of the second shell and the first shell are coated with heat-insulating paint.

[0010] Furthermore, the second shell and the first shell form an outer shell, and the outer shell is in a step shape.

[0011] Furthermore, the thermocouple is a K-type armored thermocouple.

[0012] Furthermore, the heat conducting sheet is a copper sheet.

[0013] A method for measuring arc fault energy comprises the following steps:

[0014] Step 1, place the calorimetric sensor at the location where the arc occurs, and the heat conducting sheet of the calorimetric sensor unit located at the center is facing the location where the arc occurs;

[0015] Step 2, recording the initial temperatures of all thermal conductive sheets, and calculating the average of the initial temperatures of all thermal conductive sheets, and the time when the calorimetric sensor begins to be exposed to the arc;

[0016] Step 3: The calorimetric sensor collects the thermoelectric potential signal in real time and transmits it to the AD conversion module, which converts the thermoelectric potential signal into a temperature signal and transmits the temperature signal to the host computer;

[0017] Step 4, the host computer records the temperatures of all the thermally conductive sheets when the thermally conductive sheet reaches the highest temperature and the time when the temperature is reached, and calculates the average temperature of all the thermally conductive sheets at that time;

[0018] Step 5, the host computer calculates the incident energy of the arc according to the average value of the initial temperatures of all the thermal conductive sheets before the arc occurs, the moment when the calorimetric sensor begins to be exposed to the arc, the average value of the temperatures of all the thermal conductive sheets when the maximum temperature is reached, the moment when the maximum temperature is reached, the stored average mass of the thermal conductive sheets, the specific heat capacity of the thermal conductive sheet material, the area of ​​a single thermal conductive sheet, and the paint value of the outer shell surface.

[0019] Furthermore, in step 5, the calculation formula for the incident energy of the arc is:

[0020]

[0021] Where, q - incident energy of the arc, - Average mass of all thermal pads, c p -Specific heat capacity of the thermal conductive sheet material, - the average temperature of all heatsinks when the maximum temperature is reached, - the average initial temperature of all heat conducting sheets, S- the area of ​​a single heat conducting sheet, k- the paint value of the shell surface, t 最终 - the moment when the calorimetric sensor reaches the maximum temperature when exposed to the arc, t 起始 - The moment when the calorimetric sensor starts to be exposed to the arc.

[0022] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0023] The invention provides a fault arc energy measurement system, in which a calorimetric sensor is used as a measuring element, so that the probability of capturing arc energy is increased, the arc energy measurement result is more reasonable, and the problem of low measurement success rate and inaccuracy caused by the randomness of the arc splashing direction is solved. In addition, its structural strength can meet the arc blasting requirements, and it has high measurement accuracy, long service life and low maintenance rate. The present invention can accurately measure arc energy with or without arc-proof textile materials and with different types of arc-proof textile materials, thereby facilitating SEM scanning electron microscopy analysis, TGA thermogravimetric analysis and FTIR infrared analysis of arc-proof textile materials, and exploring the carbonization mechanism of arc-proof textile materials.

[0024] Furthermore, the shell is made of calcium silicate board material, which has a strong heat insulation effect and can prevent the heat radiated by the arc from being transferred to the thermocouple through the calcium silicate board, thereby avoiding interference with the thermoelectric potential of the thermocouple.

[0025] Furthermore, the outer shell is coated with heat-insulating paint, which has a good heat-insulating effect and prevents the heat radiated by the arc from being transferred to the thermocouple through the shell and interfering with the test results.

[0026] Furthermore, the outer shell is stepped, which saves materials and is easy to demould.

[0027] Furthermore, the thermocouple adopts a high-response speed K-type armored thermocouple, which has a high response speed and can accurately record the temperature changes generated at the moment of arc explosion.

[0028] A fault arc energy measurement system provided by the present invention utilizes a central calorimetric sensor and calorimetric sensors located on the periphery of the central calorimetric sensor as measuring elements to increase the probability of capturing arc energy, and calculates the arc energy through reasonable records and calculation formulas, so that the arc energy measurement result is more reasonable. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the process structure of the system of the present invention;

[0030] Figure 2 This is a schematic diagram of the front structure of a cross-shaped five-copper sheet calorimetric sensor;

[0031] Figure 3 It is a schematic diagram of the back structure of the cross-shaped five-copper sheet calorimetric sensor;

[0032] Figure 4 It is a schematic diagram of the side structure of a cross-shaped five-copper sheet calorimetric sensor;

[0033] Figure 5 Schematic diagram of the cross-sectional structure of a cross-shaped five-copper sheet calorimetric sensor.

[0034] Among them: 1 is a cross-shaped five-copper sheet calorimetric sensor, 2 is an AD conversion module, 3 is an RS485 to USB interface, 101 is a copper sheet, 102 is a shell, 1021 is a first shell, 1022 is a second shell, 103 is a thermocouple, and 104 is a cavity. DETAILED DESCRIPTION

[0035] In order to make the purpose and technical solution of the present invention clearer and easier to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] Example 1

[0038] Reference Figure 1 , a fault arc energy measurement system comprises a calorimetric sensor 1, an AD conversion module 2, an RS485 to USB interface 3 and a host computer 4. In this embodiment, the calorimetric sensor 1 is a cross-shaped five-copper sheet calorimetric sensor.

[0039] Reference Figures 2 to 5 The cross-shaped five-copper sheet calorimetric sensor includes a first shell 1021 and five calorimetric sensor monomers arranged in a cross shape. The five heat-conducting sheets are embedded in the top of the convex groove of the first shell 1021 in a cross-shaped arrangement and are flush with the bottom of the convex groove. The calorimetric sensor monomer includes a heat-conducting sheet 101, a second shell 1022, a thermocouple 103 and a cavity 104. The heat-conducting sheet 101 and the cavity 104 are located in the first shell 1021. The probe end of the thermocouple 103 extends into the 2mm thick heat-conducting sheet 101, and is 1.7mm away from the upper surface of the heat-conducting sheet 101. The upper part of the thermocouple 103 is located in the cavity 104, and the rest is located in the second shell 1022. The root of the thermocouple 103 is fixed to the inner wall of the second shell 1022 through a dispensing tube cover. The five cross-shaped calorimetric sensor monomers are combined into a complete cross-shaped five-copper sheet calorimetric sensor, which has high structural strength and measurement accuracy. This system can effectively solve the problem of low measurement success rate and inaccuracy caused by the randomness of the arc splashing direction. At the same time, because the overall shape is close to the structure of a cube, it is not easily damaged when impacted from the front. It has high structural strength and measurement accuracy and can resist the destructiveness caused by arc explosions.

[0040] Preferably, the heat conducting sheet 101 is made of a material having a density of 8.96 g / cm 3 The copper sheets made of red copper material have excellent thermal conductivity and are arranged in a cross shape on the surface.

[0041] Preferably, the first shell 1021 and the second shell 1022 are fixedly connected and internally communicated to form a shell 102. The shell 102 is made of calcium silicate board material, which has a strong heat insulation effect and can prevent the heat radiated by the arc from being transferred to the thermocouple through the calcium silicate board, thereby avoiding interference with the thermoelectric potential of the thermocouple.

[0042] Preferably, the housing 102 is stepped to save material and facilitate demoulding.

[0043] Preferably, the outer surface of the housing is coated with black heat-insulating paint.

[0044] Preferably, the thermocouple 103 adopts a high-response speed K-type armored thermocouple, which has a high response speed and can accurately record the temperature changes generated at the moment of arc explosion.

[0045] Preferably, the AD conversion module 2 is an integral packaging structure, and its built-in program can convert the thermoelectric potential signal of the thermocouple into a temperature signal in real time and accurately.

[0046] Preferably, the RS485 to USB interface 3 can transmit the temperature signal to the host computer to control the channel enable / disable of the AD conversion module. The temperature value can be obtained in the corresponding channel by configuring the baud rate parameters and data address of the port and selecting the signal channel through the host computer 4.

[0047] The AD conversion module has a built-in program that can process the thermoelectric potential signal of the thermocouple and directly output the temperature value T of each thermal conductive sheet. Based on this, the average temperature of the five thermal conductive sheets when the five thermal conductive sheets reach the highest temperature can be calculated. And the average of the initial temperatures of the five thermal pads Using the calculation formula of the energy absorbed by the thermal conductive sheet material, the incident energy q of the arc can be calculated:

[0048]

[0049] q- incident energy of the arc, in kilowatts per square meter (kW / m 2 );

[0050] -The average mass of the five thermally conductive sheets, in grams (g);

[0051] c p -Specific heat capacity of the thermal conductive sheet material, in joules per gram Celsius [J / (g.℃)];

[0052] -The average temperature of the five thermal conductive sheets when the maximum temperature is reached, in degrees Celsius (℃). The moment when the highest temperature is reached among all the collected temperatures is the moment when the maximum temperature is reached;

[0053] - The average value of the initial temperature of the five heat conducting plates, in degrees Celsius (°C), i.e. the average value of the temperature of each heat conducting plate before the arc appears;

[0054] S-area of ​​a single thermal conductive sheet, in square centimeters (cm 2 );

[0055] k- the paint value of the shell surface, usually 0.9 for general materials;

[0056] t 最终 -The time when the calorimetric sensor reaches the highest temperature when exposed to the arc, in seconds (s), and the time when the temperature of all thermal conductive sheets is the highest is the time when the highest temperature is reached;

[0057] t 起始- The time in seconds (s) when the calorimeter sensor begins to be exposed to the arc.

[0058] The above-mentioned fault arc energy measurement system utilizes the good thermal conductivity of copper material, and the arc explosion radiation heat is transferred to the cross-shaped five-copper calorimetric sensor, wherein the cross-shaped five-copper calorimetric sensor is used as a measuring element, so that the probability of capturing arc energy is increased, the arc energy measurement result is more reasonable, and the problem of low measurement success rate and inaccuracy caused by the randomness of arc splashing direction is solved. It has the characteristics of structural strength that can meet the requirements of arc explosion, high measurement accuracy, long life, and low maintenance rate. The AD conversion module is powered by a 12-24V DC power supply. The AD conversion module has a built-in program that converts the thermoelectric potential signal of the thermocouple into a temperature signal, and transmits the temperature signal to the host computer through the RS485 to USB interface. The host computer can configure the interface baud rate parameters and control the channel enable / disable of the AD conversion module. The temperature data can be displayed in real time on the host computer, and then the heat flux characteristic parameters of the thermal conductive sheet are used to calculate its absorbed heat, which is the arc energy.

[0059] Example 2

[0060] The difference between this embodiment and embodiment 1 is that the number of calorimetric sensor monomers is different, which can be 4, 6 or 8, etc. The specific arrangement is: there is a calorimetric sensor monomer A in the middle, and the remaining calorimetric sensor monomers B are arranged on the periphery of the calorimetric sensor monomer A, evenly arranged along the circumferential direction, and there are gaps between adjacent calorimetric sensor monomers B.

[0061] Example 3

[0062] A method for measuring arc fault energy comprises the following steps:

[0063] Step 1, placing the calorimetric sensor 1 near the arc occurrence location, and making the heat conductive sheet of the middle calorimetric sensor unit face the arc occurrence location;

[0064] Step 2, recording the initial temperatures of the five thermally conductive sheets, and calculating the average of the initial temperatures of the five thermally conductive sheets, that is, the average of the temperatures of the thermally conductive sheets before the arc appears, and the time when the calorimetric sensor 1 begins to be exposed to the arc;

[0065] Step 3: The thermocouple 103 in the calorimetric sensor 1 detects the temperature change and collects the thermoelectric potential signal in real time, and transmits it to the AD conversion module 2. The AD conversion module 2 converts the thermoelectric potential signal into a temperature signal, and transmits the temperature signal to the host computer 4 through the RS485 to USB interface;

[0066] Step 4, the host computer 4 identifies and records the temperatures of the five heat conducting sheets when the heat conducting sheets reach the highest temperature and the time when the temperature is reached, and calculates the average temperature of all the heat conducting sheets at that time, in degrees Celsius (°C), and the time when the highest temperature among all the collected temperatures is the time when the highest temperature is reached;

[0067] Step 5, the host computer 4 calculates the incident energy of the arc using formula (1) according to the average value of the initial temperatures of the five thermal conductive sheets before the arc occurs, the moment when the calorimetric sensor 1 begins to be exposed to the arc, the average value of the temperatures of the five thermal conductive sheets when the maximum temperature is reached, the moment when the maximum temperature is reached, and the average mass of the thermal conductive sheets stored in the host computer 4, the specific heat capacity of the thermal conductive sheet material, the area of ​​a single thermal conductive sheet, and the paint value of the shell surface.

[0068] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A fault arc energy measurement system, characterized in that: The invention comprises a calorimetric sensor (1), an AD conversion module (2) and a host computer (4) connected in sequence, wherein the calorimetric sensor (1) comprises a first shell (1021) and N calorimetric sensor monomers installed on the first shell (1021), where N is greater than or equal to 4; the N calorimetric sensor monomers are arranged in such a manner that one calorimetric sensor monomer is located at the center, which is recorded as the center calorimetric sensor monomer, and the remaining sensors are located at the periphery of the center calorimetric sensor monomer.

2. A fault arc energy measurement system according to claim 1, characterized in that: The N is 5, and the 5 calorimetric sensor units are arranged in a cross shape.

3. A fault arc energy measurement system according to claim 1 or 2, characterized in that: The calorimetric sensor unit comprises a thermally conductive sheet (101), a second shell (1022), a thermocouple (103) and a cavity (104); a probe end of the thermocouple (103) extends into the thermally conductive sheet (101); an upper portion of the thermocouple (103) is located in the cavity (104); the remaining portion is located in the second shell (1022); a root portion of the thermocouple (103) is fixed to an inner wall of the second shell (1022); and the second shell (1022) is connected to the first shell (1021).

4. A fault arc energy measurement system according to claim 3, characterized in that: The second shell (1022) and the first shell (1021) are made of calcium silicate board.

5. A fault arc energy measurement system according to claim 3, characterized in that: The outer surfaces of the second shell (1022) and the first shell (1021) are coated with heat-insulating paint.

6. A fault arc energy measurement system according to claim 3, characterized in that: The second shell (1022) and the first shell (1021) form an outer shell (102), and the outer shell (102) is in a step shape.

7. A fault arc energy measurement system according to claim 3, characterized in that: The thermocouple (103) is a K-type armored thermocouple.

8. A fault arc energy measurement system according to claim 1, characterized in that: The heat conducting sheet (101) is a copper sheet.

9. A method for measuring arc fault energy, characterized in that: The following steps are involved: Step 1, placing the calorimetric sensor (1) at the location where the arc occurs, with the heat conducting sheet of the calorimetric sensor unit located at the center facing the location where the arc occurs; Step 2, recording the initial temperatures of all the heat conducting sheets, and calculating the average of the initial temperatures of all the heat conducting sheets, and the time when the calorimetric sensor (1) begins to be exposed to the arc; Step 3, the calorimetric sensor (1) collects the thermoelectric potential signal in real time and transmits it to the AD conversion module (2), the AD conversion module (2) converts the thermoelectric potential signal into a temperature signal, and transmits the temperature signal to the host computer (4); Step 4, the host computer (4) records the temperatures of all the heat conducting sheets when the heat conducting sheet reaches the highest temperature and the time when the temperature is reached, and calculates the average temperature of all the heat conducting sheets at that time; Step 5, the host computer (4) calculates the incident energy of the arc according to the average value of the initial temperatures of all the thermal conductive sheets before the arc occurs, the moment when the calorimetric sensor (1) begins to be exposed to the arc, the average value of the temperatures of all the thermal conductive sheets when the maximum temperature is reached, the moment when the maximum temperature is reached, the stored average mass of the thermal conductive sheets, the specific heat capacity of the thermal conductive sheet material, the area of ​​a single thermal conductive sheet, and the paint value of the outer shell surface.

10. A method for measuring arc fault energy according to claim 9, characterized in that: In step 5, the arc incident energy calculation formula is: Where, q - incident energy of the arc, - Average mass of all thermal pads, c p -Specific heat capacity of the thermal conductive sheet material, - the average temperature of all heatsinks when the maximum temperature is reached, - the average initial temperature of all heat conducting sheets, S- the area of ​​a single heat conducting sheet, k- the paint value of the shell surface, t 最终 - the moment when the calorimetric sensor reaches the maximum temperature when exposed to the arc, t 起始 - The moment when the calorimetric sensor starts to be exposed to the arc.

Images