An isolated terminal temperature measuring device for an electric energy meter

Abstract

This utility model discloses an isolated terminal temperature measuring device for electricity meters, relating to the field of electricity meter temperature measurement technology, aiming to solve the problem of unsatisfactory temperature measurement effects in existing temperature measurement schemes. The isolated terminal temperature measuring device includes a neutral line temperature measuring circuit and a live line temperature measuring circuit with a built-in load switch. Both the live line and neutral line temperature measuring circuits include terminals and temperature-sensing resistors mounted on a PCB circuit board. The terminals are also connected to a metal strip, and an elastic insulating material is provided between the metal strip and the temperature-sensing resistor. This utility model optimizes the pairing structure of the temperature-sensing resistor, solving the problem of unsatisfactory temperature measurement effects in existing schemes, resulting in more accurate temperature measurement results. It also solves the problem of voltage isolation between the plug-in temperature measuring device and the 220Vac high-voltage power supply, making the product safer and more reliable. Furthermore, it solves the difficulties in manufacturing and installation of existing technologies, improving production efficiency.

Description

Technical Field

[0001] This utility model relates to the field of temperature measurement technology for electricity meters, and specifically to a temperature measurement device for isolated terminals of electricity meters. Background Technology

[0002] In recent years, to address core issues such as safety hazards, equipment damage, and metering inaccuracies caused by abnormal overheating of terminals in power systems, smart meters have added terminal temperature measurement functionality. Existing solutions, such as those published under CN220084207U and CN222850170U, involve creating a groove at the copper terminal to embed a temperature sensor. The design must ensure tight and reliable contact between the sensor and the copper terminal to guarantee accurate temperature measurement. However, due to dimensional tolerances between the sensor and the copper terminal groove, the temperature measurement results are not ideal. Furthermore, because existing solutions use plug-in temperature sensors, the exposed pins are almost in close contact with the high-voltage copper terminal (220Vac), requiring isolation of the device in the design; otherwise, certain safety hazards exist. Utility Model Content

[0003] This invention solves the problem of unsatisfactory temperature measurement results in existing temperature measurement schemes, and proposes an isolated terminal temperature measurement device for electricity meters, which can make the temperature measurement results more accurate and reduce safety hazards.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: an isolated terminal temperature measuring device for an energy meter, comprising a neutral line temperature measuring circuit and a live line temperature measuring circuit with a built-in load switch. Both the live line temperature measuring circuit and the neutral line temperature measuring circuit include terminals and temperature measuring resistors mounted on a PCB circuit board. The terminals are also connected to a metal strip, and an elastic insulating material is provided between the metal strip and the temperature measuring resistor.

[0005] In this technical solution, the main components include terminals, metal strips, elastic insulating material, PCB circuit boards, load switches located in the temperature measurement circuit of the live wire, and temperature measuring resistors. The external wiring of the energy meter is connected to the terminals. When the contact resistance of the external wiring increases due to improper installation, long-term loosening, or material aging, the temperature rises and is transmitted to the metal strip through the terminals. The metal strip is isolated from the PCB circuit board by elastic insulating material to solve the problem of withstand voltage safety distance. At the same time, the elastic insulating material transfers the heat from the external heat source to the temperature measuring resistor on the PCB circuit board. The resistance of the temperature measuring resistor changes with the temperature. The temperature of the external terminals is measured through a voltage signal.

[0006] The present invention is further configured such that: the zero-line temperature measuring circuit includes a first terminal block and a first metal strip fixedly connected to the first terminal block; the end of the first terminal block away from the first metal strip is also fixedly connected to a first terminal block seat; and the first metal strip is in contact with the temperature measuring resistor through an elastic insulating material.

[0007] In this technical solution, zero-line temperature measurement is achieved sequentially through a first terminal block, a first metal strip, an elastic insulating material, and a temperature measuring resistor.

[0008] The present invention is further configured such that: the temperature measuring circuit of the fire line includes a second terminal block and a second metal strip fixedly connected to the second terminal block; a second terminal block seat is fixedly connected to the end of the second terminal block away from the second metal strip; and the second metal strip is in contact with the temperature measuring resistor through an elastic insulating material.

[0009] In this technical solution, the temperature measurement of the live circuit is achieved sequentially through the second terminal block, the second metal strip, the elastic insulating material, and the temperature measuring resistor.

[0010] The present invention is further configured such that: the temperature measuring resistor is encapsulated on a PCB circuit board, and the distance between the PCB circuit board containing the temperature measuring resistor and the metal strip is less than the thickness of the elastic insulating material.

[0011] In this technical solution, the distance between the metal strip and the PCB circuit board is slightly less than the thickness of the elastic insulating material. The elasticity of the elastic insulating material is used to ensure reliable contact between the temperature measuring resistor and the circuit board.

[0012] The present invention is further configured such that: one end of the temperature measuring resistor is connected to a fixed resistor R1 and a voltage output terminal, the voltage output terminal is connected to the MCU on the PCB circuit board; the other end of the temperature measuring resistor is grounded, and the end of the fixed resistor R1 away from the temperature measuring resistor is connected to a power supply terminal.

[0013] In this technical solution, the temperature sensing resistor is a temperature-sensitive resistor. After sensing the corresponding temperature change, its resistance value will change. The voltage is output to the MCU on the PCB circuit board through the voltage output terminal. The MCU's ADC function and processing function are used to realize the temperature measurement of the external terminal. The ADC function can convert the acquired continuous voltage signal into a discrete voltage signal, and the processing function can convert the discrete voltage signal into an NTC resistance value. Based on the relationship between the NTC resistance value and the temperature, the current temperature is determined.

[0014] The present invention is further configured such that: the first metal strip includes a first contact portion that contacts the first terminal, a second contact portion that contacts the elastic insulating material, and a first intermediate extension portion that connects the first contact portion and the second contact portion.

[0015] The present invention is further configured such that: the second metal strip includes a third contact portion that contacts the second terminal, a fourth contact portion that contacts the elastic insulating material, and a second intermediate extension portion that connects the third contact portion and the fourth contact portion.

[0016] The present invention is further configured such that the load switch is connected to the second metal strip.

[0017] The present invention is further configured such that: the elastic insulating material is specifically thermally conductive silicone, and the thermally conductive silicone is elastically connected to the temperature measuring resistor.

[0018] In this technical solution, the elasticity of thermally conductive silicone is used to ensure a reliable connection with the temperature sensing resistor.

[0019] The present invention is further configured such that the metal strip is a copper strip.

[0020] In this technical solution, both the first metal strip and the second metal strip are copper strips.

[0021] This utility model can bring the following beneficial effects: This utility model relates to an isolated terminal temperature measuring device for an electricity meter. It optimizes the pairing structure of the temperature measuring resistor, which solves the problem of unsatisfactory temperature measurement effect in existing temperature measurement schemes, and enables more accurate temperature measurement results. At the same time, it solves the problem of voltage isolation between plug-in temperature measuring devices and 220Vac high voltage, making the product safer and more reliable. In addition, it also solves the problem of difficult production, manufacturing and installation in existing technologies, and improves production efficiency. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an isolated terminal temperature measuring device for an electricity meter according to this application.

[0023] Figure 2 This is a schematic diagram of an isolated terminal temperature measuring device for an electricity meter that does not include a PCB circuit board, as described in this application.

[0024] Figure 3 This is a partial schematic diagram from one perspective of an isolated terminal temperature measuring device for an electricity meter according to this application.

[0025] Figure 4 This is a partial schematic diagram from another perspective of the isolated terminal temperature measuring device for an electricity meter according to this application.

[0026] Figure 5 This is a partial schematic diagram from another perspective of the isolated terminal temperature measuring device for an electricity meter according to this application.

[0027] Figure 6 This is a schematic diagram showing the connection relationship of the temperature measuring resistor in the isolated terminal temperature measuring device of an electricity meter according to this application.

[0028] Reference numerals: 1. First terminal block; 2. First terminal; 3. First metal strip; 4. Insulating thermally conductive silicone; 5. PCB circuit board; 6. Load switch; 7. Temperature resistor; 8. Second terminal block; 9. Second terminal; 10. Second metal strip; 31. First contact portion; 32. First intermediate extension portion; 33. Second contact portion; 101. Third contact portion; 102. Second intermediate extension portion; 103. Fourth contact portion. Detailed Implementation

[0029] Example 1 To address the shortcomings of existing technologies, this embodiment proposes an isolated terminal temperature measuring device for electricity meters, referencing... Figures 1 to 5 It mainly includes a neutral line temperature measurement circuit and a live line temperature measurement circuit. The live line temperature measurement circuit has a built-in load switch 6. Both the neutral line temperature measurement circuit and the live line temperature measurement circuit include terminals and temperature measuring resistors 7. The temperature measuring resistors 7 are mounted on the PCB circuit board 5. The terminals are connected to a metal strip, and an elastic insulating material is placed between the metal strip and the temperature measuring resistors 7. Currently, a groove is usually made at the copper terminal to embed the temperature sensor. The design needs to consider that the temperature sensor and the copper terminal have a tight and reliable contact to ensure accurate temperature measurement. However, due to the dimensional tolerances of the temperature sensor and the copper terminal groove, some temperature measurement results are not ideal. Therefore, another design scheme exists in the industry. Generally, liquid thermally conductive silicone is poured into the groove, and then the temperature sensor is embedded in the copper terminal groove. Because the liquid thermally conductive silicone has fluidity, it can ensure reliable contact between the temperature sensor and the copper terminal, so that the temperature measurement of the copper terminal is accurate. Because the current solution uses plug-in temperature sensing devices, the exposed pins are almost in close contact with the high-voltage copper terminals (220Vac). Therefore, the design generally requires isolation of the device; otherwise, there is a certain safety hazard. From a manufacturing perspective, a major issue is the installation of the temperature sensor. Whether the temperature sensor is installed on the PCB circuit board first and then embedded in the copper terminal hole, or embedded in the copper terminal hole first and then installed, plug-in devices are prone to misalignment, and the temperature sensor or the recessed area on the copper terminal is in a blind spot during installation. Therefore, the design presents significant installation problems, impacting production efficiency.

[0030] This embodiment of an isolated terminal temperature measuring device for an energy meter is designed to solve the above-mentioned problems. The technical solution of this embodiment includes a neutral line temperature measuring circuit and a live line temperature measuring circuit. The live line temperature measuring circuit has a corresponding load switch 6 built in. Both the neutral line temperature measuring circuit and the live line temperature measuring circuit include terminals and a temperature measuring resistor 7. The temperature measuring resistor 7 is mounted on a PCB circuit board 5. The terminals are connected to a metal strip. An elastic insulating material is provided between the metal strip and the temperature measuring resistor 7.

[0031] refer to Figure 1 , Figure 2 and Figure 3 The zero-line temperature measurement circuit mainly includes a first terminal block 2 and a first metal strip 3. The first metal strip 3 and the first terminal block 2 are fixedly connected. The end of the first terminal block 2 away from the first metal strip 3 is fixedly connected to the first terminal block seat 1. The first metal strip 3 is connected to the temperature measuring resistor 7 through an elastic insulating material.

[0032] In this technical solution, zero-line temperature measurement is achieved sequentially through the first terminal 2, the first metal strip 3, the elastic insulating material, and the temperature measuring resistor 7.

[0033] Continue to refer to Figure 1 , Figure 2 and Figure 3 The live wire temperature measurement circuit mainly includes a second terminal block 9 and a second metal strip 10. The second metal strip 10 and the second terminal block 9 are fixedly connected. The end of the second terminal block 9 away from the second metal strip 10 is fixedly connected to the second terminal block seat 8. The second metal strip 10 is connected to the temperature measuring resistor 7 through elastic insulating material.

[0034] In this technical solution, the temperature measurement of the live circuit is achieved sequentially through the second terminal 9, the second metal strip 10, the elastic insulating material, and the temperature measuring resistor 7.

[0035] The load switch 6 is specifically connected to the second metal strip 10.

[0036] In this embodiment, the aforementioned elastic insulating material is specifically an insulating thermally conductive silicone 4, which can make reliable elastic contact with the temperature measuring resistor 7.

[0037] In this embodiment, the metal strip mentioned above is specifically a copper strip; both the first metal strip 3 and the second metal strip 10 are copper strips, and the corresponding terminals are also copper terminals, that is, both the first terminal 2 and the second terminal 9 are copper terminals.

[0038] refer to Figure 3 , Figure 4 as well as Figure 5The temperature measuring resistor 7 is specifically encapsulated on the PCB circuit board 5. Above the temperature measuring resistor 7 is the elastic insulating material, which is the thermally conductive silicone 4 in this embodiment. The distance between the PCB circuit board 5 with the temperature measuring resistor 7 soldered on and the lower end of the metal strip is less than the thickness of the elastic insulating material.

[0039] In this embodiment, the distance between the metal strip and the PCB circuit board 5 is set to be slightly less than the thickness of the elastic insulating material, and the elasticity of the elastic insulating material is used to ensure that the temperature measuring resistor 7 can be reliably connected.

[0040] Furthermore, refer to Figure 6 The sampling circuit of the temperature measuring resistor 7 is set up. The temperature measuring resistor 7 is the NTC resistor in the figure. One end of the temperature measuring resistor 7 is connected to the fixed resistor R1, and it is also connected to the corresponding voltage output terminal. The voltage output terminal can be connected to the MCU on the PCB circuit board. The other end of the temperature measuring resistor 7 is grounded. The fixed resistor R1 is connected to the power supply terminal at the end away from the temperature measuring resistor 7.

[0041] Specifically, the MCU acquires the voltage value of the aforementioned temperature-sensing resistor 7, i.e., the NTC resistor. The voltage value is V = 3.3 * NTC / (NTC + R1). The NTC resistance changes rapidly with temperature. The fixed resistor R1 is designed to be far from heat sources on the PCB board 5, and the effect of temperature on the resistance value of the fixed resistor R1 is negligible. Therefore, the MCU determines the resistance value of the NTC resistor using the aforementioned voltage value, and then determines the current temperature by referring to the relationship between resistance and temperature in the NTC datasheet.

[0042] In this embodiment, the power supply terminal is connected to a 3.3V power supply; the temperature sensing resistor 7 mentioned above is a surface mount NTC resistor. This type of resistor can be mass-produced using an automatic surface mount machine, which has high production efficiency. At the same time, the cost of a single surface mount NTC resistor is only about 0.02 to 0.03 yuan, which is far lower than the cost of 0.7 yuan per unit of the existing customized plug-in NTC resistor.

[0043] Based on the voltage-to-NTC resistor conversion formula, the factors affecting temperature measurement accuracy mainly consist of three parts: the 3.3V power supply, the NTC resistor, and the fixed resistor R1, including their accuracy and temperature drift. In parameter simulation tests, temperature deviation simulations show that the temperature deviation can be controlled within ±4℃ within the range of 0–150℃. Actual testing included a comparison with thermocouple temperature measurement, specifically comparing NTC and thermocouple temperature measurements. Test data shows that at different temperatures, the difference between the two is minimal, with a live wire deviation of approximately 1℃ and a neutral wire deviation of approximately 3℃, consistent with the simulation results. Furthermore, the temperature deviation meets the State Grid's temperature measurement technical requirements.

[0044] For more details, see the reference. Figure 4 and Figure 5The first metal strip 3 mainly includes a first contact portion 31, a second contact portion 33 and a first intermediate extension portion 32. The first contact portion 31 is in contact with the first terminal 2. The specific connection method is not limited here. The second contact portion 33 can be in contact with the elastic insulating material. The first intermediate extension portion 32 is also provided between the first contact portion 32 and the second contact portion 33.

[0045] In this embodiment, the first contact portion 31 is specifically horizontal and is located below the first terminal 2.

[0046] In this embodiment, the second contact portion 33 is specifically horizontal and is disposed above the elastic insulating material, i.e., the thermally conductive silicone 4.

[0047] The area of ​​the second contact portion 33 is the same as the cross-sectional area of ​​the elastic insulating material to facilitate positioning and installation.

[0048] In this embodiment, the first intermediate extension 32 can connect the two horizontally oriented first contact portions 31 and second contact portions 33. Its specific shape is sufficient to ensure that it does not interfere with external components.

[0049] The second metal strip 10 mainly includes a third contact portion 101, a fourth contact portion 103, and a second intermediate extension portion 102. The third contact portion 101 is in contact with the second terminal 9. The specific connection method is not limited here. The fourth contact portion 103 can be in contact with an elastic insulating material. The second intermediate extension portion 102 is also provided between the third contact portion 101 and the fourth contact portion 103.

[0050] In this embodiment, the third contact portion 101 is specifically horizontal and is disposed below the second terminal 9.

[0051] In this embodiment, the fourth contact portion 103 is specifically horizontal and is disposed above the elastic insulating material, i.e., the thermally conductive silicone 4.

[0052] refer to Figure 5 The fourth contact portion 103 includes a cross-sectional portion located on the left side and a receiving section between the cross-sectional portion and the second intermediate extension portion 102, the width of which is smaller than the width of the cross-sectional portion.

[0053] The cross-sectional area on its left side is the same as the cross-sectional area of ​​the elastic insulating material to facilitate positioning and installation.

[0054] In this embodiment, the second intermediate extension 102 can connect the two horizontally oriented third contact portions 101 and fourth contact portions 103. Its specific shape can ensure that it does not interfere with external components.

[0055] The technical solution of this embodiment addresses the following specific technical problems: With the increasing prevalence of distributed photovoltaic and electric vehicle charging scenarios, current fluctuations are intensifying, significantly increasing the risk of terminal temperature rise. Simultaneously, improper installation, long-term loosening, or material aging at the wiring terminals of electricity meters leads to increased contact resistance and temperature rise, easily causing meter burnout or even electrical fires. To solve the core problems of safety hazards, equipment damage, and metering inaccuracies caused by abnormal heating of wiring terminals in power systems, smart electricity meters have added a wiring terminal temperature measurement function. Chinese patent CN220084207U includes a terminal block connector, a terminal block connecting copper strip on the terminal block connector that connects to the terminal block, and a PCB circuit board. The terminal block connecting copper strip has a temperature-conducting connection hole or groove. A temperature-sensing resistor is soldered on the PCB circuit board. The temperature-sensing resistor has a temperature-sensing resistor ceramic shell. A thermally conductive silicone sleeve is fitted onto the end of the temperature-sensing resistor ceramic shell. The end of the temperature-sensing resistor ceramic shell, fitted with the thermally conductive silicone sleeve, is pressed into the temperature-conducting connection hole or groove and connected to the terminal block connecting copper strip. After being compressed and deformed, the thermally conductive silicone sleeve fills the entire mating gap. Chinese patent CN222850170U includes a terminal, a temperature sensor, and a temperature sensing bracket. The outer wall of the terminal has a circumferential annular groove, and the bottom wall of the annular groove has a radially formed temperature measuring hole. The temperature sensor is disposed in the temperature measuring hole to monitor the temperature of the terminal. The temperature sensing bracket includes an elastic snap ring with an opening. The elastic snap ring is shaped to fit and clamps onto the annular groove, and at least partially covers the temperature measuring hole, thereby preventing the temperature sensor from detaching from the temperature measuring hole.

[0056] Combination Figures 1 to 5 As can be seen, this embodiment provides a low-cost, high-efficiency, and efficient technical solution that meets the temperature measurement requirements of the State Grid. Its main components include terminals, a metal strip, elastic insulating material, a PCB circuit board 5, a load switch 6 located in the temperature measurement circuit of the live line, and a temperature-sensing resistor 7. The external wiring of the energy meter is connected to the terminals. When the external wiring experiences increased contact resistance and temperature rise due to improper installation, long-term loosening, or material aging, the temperature is transmitted to the metal strip through the terminals. The metal strip and the PCB circuit board 5 are isolated by elastic insulating material to address the pressure resistance safety distance issue. Simultaneously, the elastic insulating material transfers heat from the external heat source to the temperature-sensing resistor 7 on the PCB circuit board 5. The resistance of the temperature-sensing resistor 7 changes with temperature, and the temperature of the external terminals is measured via a voltage signal.

Claims

1. An electric energy meter isolated terminal temperature measuring device, characterized in that, It includes a zero-line temperature measurement circuit and a live-line temperature measurement circuit with a built-in load switch (6). Both the live-line temperature measurement circuit and the zero-line temperature measurement circuit include terminals and a temperature measuring resistor (7) set on a PCB circuit board (5). The terminals are also connected to a metal strip, and an elastic insulating material is provided between the metal strip and the temperature measuring resistor (7).

2. The electric energy meter isolated terminal temperature measuring device according to claim 1, characterized in that, The zero-line temperature measurement circuit includes a first terminal block (2) and a first metal strip (3) fixedly connected to the first terminal block (2). The end of the first terminal block (2) away from the first metal strip (3) is also fixedly connected to a first terminal block seat (1). The first metal strip (3) is in contact with the temperature measuring resistor (7) through an elastic insulating material.

3. The electric energy meter isolated terminal temperature measuring device according to claim 1 or 2, characterized in that, The fire line temperature measuring circuit includes a second terminal (9) and a second metal strip (10) fixedly connected to the second terminal (9). The end of the second terminal (9) away from the second metal strip (10) is also fixedly connected to a second terminal block (8). The second metal strip (10) is in contact with the temperature measuring resistor (7) through an elastic insulating material.

4. The electric energy meter isolated terminal temperature measuring device according to claim 1, characterized in that, The temperature measuring resistor (7) is encapsulated on the PCB circuit board (5), and the distance between the PCB circuit board (5) containing the temperature measuring resistor (7) and the metal strip is less than the thickness of the elastic insulating material.

5. The electric energy meter isolated terminal temperature measuring device according to claim 1 or 4, characterized in that, One end of the temperature measuring resistor (7) is connected to a fixed resistor R1 and a voltage output terminal. The voltage output terminal is connected to the MCU on the PCB circuit board. The other end of the temperature measuring resistor (7) is grounded. The end of the fixed resistor R1 away from the temperature measuring resistor (7) is connected to a power supply terminal.

6. The temperature measuring device for isolated terminals of an electricity meter according to claim 2, characterized in that, The first metal strip (3) includes a first contact portion (31) that contacts the first terminal (2), a second contact portion (33) that contacts the elastic insulating material, and a first intermediate extension portion (32) that connects the first contact portion (31) and the second contact portion (33).

7. The temperature measuring device for isolated terminals of an electricity meter according to claim 3, characterized in that, The second metal strip (10) includes a third contact portion (101) that contacts the second terminal (9), a fourth contact portion (103) that contacts the elastic insulating material, and a second intermediate extension portion (102) that connects the third contact portion (101) and the fourth contact portion (103).

8. The temperature measuring device for isolated terminals of an electricity meter according to claim 1, characterized in that, The load switch (6) is connected to the second metal strip (10).

9. A temperature measuring device for isolated terminals of an electricity meter according to claim 1 or 2, characterized in that, The elastic insulating material is specifically thermally conductive silicone (4), which is elastically connected to the temperature measuring resistor (7).

10. The temperature measuring device for isolated terminals of an electricity meter according to claim 1, characterized in that, The metal strip is a copper strip.

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