Deeply integrated zero sequence voltage sensor

Abstract

The utility model relates to power equipment technical field especially is depth fusion zero sequence voltage sensor, include: three sensing units, three sensing units set up in three solid -sealed pole respectively, correspond three -phase circuit respectively, every sensing unit all includes resistance row, overvoltage protection module and isolation transformer, the resistance row is constituted by multiple resistance series connection, overvoltage protection module is electrically connected in the output of resistance row, isolation transformer's input winding one end is electrically connected in overvoltage protection module, input winding other end connects sensor ground end, isolation transformer's output winding is used for output voltage signal after processing, the output winding of isolation transformer is exported through the aviation socket, and the aviation socket is exported through the aviation plug line, three signals are connected in series, and the signal after series connection is zero sequence voltage signal, realizes the effective, stable, high-precision output of zero sequence voltage.

Description

Technical Field

[0001] This utility model relates to the field of power equipment technology, and in particular to a deeply integrated zero-sequence voltage sensor. Background Technology

[0002] The distribution network is a crucial foundation of the energy internet and a key link affecting the level of power supply services. With the large-scale integration of electric vehicles, distributed energy sources, microgrids, energy storage devices, and other facilities, as well as the development of the electricity market and the emergence of various electricity demands, higher requirements are placed on the security, economy, and adaptability of the distribution network. It is imperative to build a first-class modern distribution network that is highly reliable, interactive, and cost-effective. The intelligentization of the distribution network relies on intelligent terminals. In the distribution network, voltage sensors, as key intelligent terminal devices, directly affect the accuracy and reliability of grid operation monitoring, fault diagnosis, and protection control.

[0003] However, in the existing technology, voltage sensors used inside the solid-sealed poles of medium-voltage power grid circuit breakers typically use thin-film capacitors as voltage dividing elements. In practical applications, these thin-film capacitors have revealed many technical defects, which seriously restrict the overall performance and reliability of the sensors.

[0004] First, the relatively low operating temperature range of film capacitors makes it difficult to match the high curing temperature of the epoxy resin used in solid-state terminals. This means that a one-time integral casting and solidification of the film capacitor and epoxy resin is not possible during manufacturing. To complete the encapsulation, secondary potting is typically required. This not only significantly increases the complexity of the manufacturing process and production costs, but more importantly, secondary potting introduces additional interfaces within the product. These interfaces can become potential weak points in the insulation, affecting the long-term reliability and insulation performance of the product, and reducing the overall protection level of the sensor.

[0005] Secondly, film capacitors exhibit significant temperature drift characteristics, meaning their capacitance values ​​easily change noticeably with variations in ambient temperature. This instability directly leads to a decrease in the accuracy of voltage measurements, making it difficult to meet the high-precision metering and monitoring requirements of modern power grids. This is especially true in application scenarios with large ambient temperature fluctuations, where measurement errors will further increase, impacting the precise control of power grid operation and fault diagnosis.

[0006] Furthermore, film capacitors have a relatively short lifespan, and their long-term stability and reliability are difficult to guarantee effectively. Over time, the performance of film capacitors gradually deteriorates, which not only shortens the lifespan of the entire solid-sealed terminal block and even the circuit breaker, but also increases the frequency and cost of equipment maintenance, posing potential risks and burdens to the stable operation of the power grid.

[0007] To address the aforementioned issues, existing technologies urgently need improvement. Utility Model Content

[0008] The purpose of this invention is to address the shortcomings of existing medium-voltage power grid circuit breaker solid-sealed pole internal voltage sensors, which use thin-film capacitor voltage dividers and have mismatches with epoxy resin curing temperatures, leading to secondary potting, significant temperature drift affecting measurement accuracy, and short service life. The proposed invention is a deeply integrated zero-sequence voltage sensor.

[0009] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a deeply integrated zero-sequence voltage sensor is applied inside the solid-sealed pole of a medium-voltage power grid circuit breaker, comprising: three sensing units, each corresponding to a three-phase circuit; each sensing unit includes a resistor array, an overvoltage protection module, and an isolation transformer. The resistor array is composed of multiple resistors connected in series and is used to divide the input voltage of the phase circuit. The overvoltage protection module is electrically connected to the output terminal of the resistor array. One end of the input winding of the isolation transformer is electrically connected to the overvoltage protection module, and the other end of the input winding is connected to the sensor grounding terminal. The output winding of the isolation transformer is used to output the processed voltage signal. The high-voltage terminals of the three resistor arrays corresponding to the three sensing units are respectively connected to the medium-voltage power grid incoming side at the upper end of the arc-extinguishing chamber of the corresponding phase of the circuit breaker through high-voltage leads; a signal series output unit includes an aviation socket. The output windings of the three isolation transformers are connected in series to form a series circuit. The beginning and end of the series circuit are connected to the aviation socket to form a zero-sequence voltage signal output terminal.

[0010] This technical solution enables deep integration of the sensor and the solid-sealed electrode, avoiding secondary potting, improving insulation reliability and production efficiency. At the same time, the use of resistor array voltage divider effectively solves the problems of temperature drift and short lifespan of thin-film capacitors, improving measurement accuracy and long-term stability, and achieving effective output of zero-sequence voltage.

[0011] Furthermore, in this deeply integrated zero-sequence voltage sensor, the overvoltage protection module is composed of a discharge tube and a ceramic capacitor connected in parallel.

[0012] This technical solution can effectively protect the internal circuitry of the sensor from overvoltage surges, thereby improving the sensor's voltage resistance and operational safety.

[0013] Preferably, the ceramic capacitor is a high-voltage ceramic capacitor.

[0014] This technical solution can further enhance the overvoltage protection module's withstand voltage performance, ensuring stable and reliable operation under high-pressure environments.

[0015] More specifically, in some implementations, the deep fusion zero-sequence voltage sensor also includes an epoxy resin encapsulation body, in which the three sensing units and the signal serial output unit are integrally cast and encapsulated within the encapsulated pole.

[0016] This technical solution enables seamless integration of the sensor's core components with the solid-sealed electrode, eliminating the secondary potting interface, significantly improving the product's insulation performance and mechanical strength, and reducing manufacturing costs.

[0017] Furthermore, the epoxy resin encapsulant is externally coated with a silicone rubber layer.

[0018] This technical solution provides additional external insulation and moisture protection for the sensor, enhancing its environmental adaptability and long-term operational reliability.

[0019] Preferably, the resistor array is composed of multiple low-temperature drift high-voltage resistors connected in series.

[0020] This technical solution can significantly reduce the temperature drift of the resistance array, ensure the accuracy and stability of voltage division under different ambient temperatures, and further improve measurement accuracy.

[0021] More specifically, in some implementations, the curing temperature of the epoxy resin encapsulant matches the withstand temperature of the resistive elements in the resistor array, forming an integral structure without a secondary potting interface after curing.

[0022] This technical solution enables the sensor and epoxy resin encapsulation to be cast as a single unit, completely eliminating the insulation weaknesses and process complexity caused by secondary potting, and significantly improving product reliability and production efficiency.

[0023] Preferably, the resistor array and the isolation transformer of each sensing unit are disposed on an isolation circuit board.

[0024] This technical solution optimizes the internal layout of the sensing unit, improves integration, and enhances electrical isolation between phases, ensuring the purity of the measurement signal.

[0025] Furthermore, a metal fastener is installed at the bottom of the epoxy resin sealant, which is used to fix the sensor and conduct grounding.

[0026] This technical solution ensures the stable installation of the sensor within the solid-sealed electrode and provides a reliable grounding path, further enhancing the safety of equipment operation.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention effectively overcomes the drawbacks of film capacitors by using a resistor array as a voltage divider element. The resistor array has a wider operating temperature range and better temperature stability, matching the curing temperature of the epoxy resin used in the solid-encapsulated electrode. This allows for a one-time integral casting and solidification of the sensor and epoxy resin, forming a monolithic structure without secondary potting interfaces. This not only significantly simplifies the manufacturing process and reduces production costs, but more importantly, it eliminates insulation weaknesses that may be introduced by secondary potting, greatly improving the overall insulation performance and long-term reliability of the sensor, and enhancing the product's protection level. Furthermore, the temperature drift characteristics of the resistor array are far superior to those of film capacitors, ensuring that voltage measurement results remain highly accurate and stable even under large ambient temperature fluctuations, meeting the demands of modern power grids for precise metering and monitoring. Simultaneously, resistive elements typically have a longer service life and better long-term stability, thereby extending the service life of the entire solid-encapsulated electrode and even the circuit breaker, reducing maintenance frequency and costs.

[0029] This invention also integrates the output winding of the isolation transformer with an aviation socket. The aviation socket connects three signals in series via an aviation connector cable; the series signal is the zero-sequence voltage signal, achieving effective, stable, and high-precision zero-sequence voltage output. This deeply integrated design concept makes the sensor an integral part of the circuit breaker's solid-sealed pole, further improving the system's integration, reliability, and anti-interference capability. In summary, this deeply integrated zero-sequence voltage sensor solves existing technical problems while significantly improving the performance, reliability, and economy of voltage sensors in power distribution networks. Attached Figure Description

[0030] Figure 1 A cross-sectional view of a solid-sealed electrode for a deeply integrated zero-sequence voltage sensor;

[0031] Figure 2 This is a schematic diagram of the deeply integrated zero-sequence voltage sensor of this utility model.

[0032] In the diagram: 1. Sensing unit; 2. Arc-extinguishing chamber; 3. High-voltage lead; 4. Silicone rubber layer; 5. Metal fastener; 6. Isolation circuit board; 7. Epoxy resin encapsulation. Detailed Implementation

[0033] The following description is intended to disclose the present invention so that those skilled in the art can implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0034] Traditional medium-voltage circuit breakers typically use thin-film capacitors as voltage divider elements within their solid-sealed terminals for voltage measurement. However, these thin-film capacitors have several limitations in practical applications. For example, their relatively low operating temperature range makes it difficult to match the high curing temperature of the epoxy resin used in the solid-sealed terminals. This prevents one-time integral casting during manufacturing, requiring secondary potting. This secondary potting not only increases the complexity of the manufacturing process but may also introduce a secondary potting interface, affecting product reliability and insulation performance. Furthermore, the capacitance of thin-film capacitors is easily affected by changes in ambient temperature, resulting in significant temperature drift and impacting voltage measurement accuracy, failing to meet the requirements of high-precision metering. Even worse, thin-film capacitors have a relatively short lifespan, and their long-term stability and reliability are difficult to guarantee. This shortens the lifespan of the entire solid-sealed terminal and even the circuit breaker, increasing maintenance costs and operational risks.

[0035] If the above problems are not solved, with the intelligent development of the power distribution network and the higher requirements for power supply reliability and measurement accuracy, the existing voltage sensors will be unable to meet the needs of the future power grid, which may lead to an increase in equipment failure rate, increased maintenance costs, and affect the stable operation of the power grid and data accuracy.

[0036] To address this issue, this application proposes a deeply integrated zero-sequence voltage sensor, which is applied inside the solid-sealed pole of a medium-voltage power grid circuit breaker, aiming to overcome the shortcomings of existing technologies. This sensor achieves high-precision and high-reliability voltage measurement by employing a resistance array for voltage division and combining it with an overvoltage protection module and an isolation transformer T. Furthermore, the integrated casting and solidification significantly improves the overall performance and service life of the product.

[0037] The deeply integrated zero-sequence voltage sensor disclosed in this application, as the name suggests, is a sensor that can be deeply integrated into the interior of power equipment for accurate measurement of zero-sequence voltage. "Deep integration" means that the sensor is designed to be integrated seamlessly with the solid-sealed pole of a medium-voltage power grid circuit breaker, rather than being a simple external addition, thereby improving the overall structural compactness, reliability, and insulation performance. "Zero-sequence voltage" refers to the vector sum of three-phase voltages. When the three-phase voltages are unbalanced, a zero-sequence voltage is generated, and its measurement is crucial for fault detection, protection, and operational status monitoring of the power grid. This sensor is mainly used inside the solid-sealed pole of a medium-voltage power grid circuit breaker. The solid-sealed pole is a core component of the circuit breaker, typically cast from insulating materials such as epoxy resin, used to encapsulate the arc-extinguishing chamber 2 and the conductive circuit, providing insulation and mechanical support. Medium-voltage power grids generally refer to power networks with voltage levels between 1kV and 35kV.

[0038] See also, as in this application Figures 1 to 2The deeply integrated zero-sequence voltage sensor shown is applied inside the solid-sealed pole of a medium-voltage power grid circuit breaker, and includes:

[0039] Three sensing units 1 are disposed in the solid-sealed poles, each corresponding to a three-phase circuit;

[0040] Each sensing unit 1 includes a resistor array, an overvoltage protection module, and an isolation transformer T. The resistor array is composed of multiple resistors connected in series and is used to divide the input voltage of the phase circuit. The overvoltage protection module is electrically connected to the output terminal of the resistor array. One end of the input winding of the isolation transformer T is electrically connected to the overvoltage protection module, and the other end of the input winding is connected to the sensor ground terminal. The output winding of the isolation transformer T is used to output the processed voltage signal. The high-voltage terminals of the three resistor arrays corresponding to the three sensing units 1 are respectively connected to the medium-voltage power grid incoming side at the upper end of the arc-extinguishing chamber 2 of the corresponding phase of the circuit breaker through high-voltage leads 3.

[0041] The signal series output unit includes an aviation socket, and the output windings of three isolation transformers T are connected in series to form a series circuit. The beginning and end of the series circuit are connected to the aviation socket to form a zero-sequence voltage signal output terminal.

[0042] Specifically, three sensing units 1 are housed within solid-sealed poles, corresponding to the three-phase circuit of the medium-voltage power grid, namely phase A, phase B, and phase C. Each sensing unit 1 is designed to independently process the voltage signal of its corresponding phase. Each sensing unit 1 includes a resistor array, an overvoltage protection module, and an isolation transformer T. The resistor array, composed of multiple resistors connected in series, primarily functions to perform high-precision voltage division on the input voltage of the corresponding phase circuit. For example, when the voltage from the high-voltage power grid is introduced through the high-voltage lead 3, the resistor array can proportionally reduce it to a safe voltage range suitable for subsequent circuit processing. The overvoltage protection module is electrically connected to the output terminal of the resistor array. Its function is to quickly activate when the input voltage is momentarily too high, such as in the event of a lightning strike or operational overvoltage, limiting the excessive voltage to a safe level, thereby effectively protecting subsequent sensitive electronic components, especially the isolation transformer T, from damage. The main function of the isolation transformer T is to provide electrical isolation, completely isolating the high-voltage side from the low-voltage side to ensure the safety of the measured signal, while also further transforming and filtering the voltage signal after voltage division. The output winding of the isolation transformer T is used to output a processed voltage signal, which has good linearity and stability and can be used by subsequent measurement and control systems.

[0043] Compared to existing voltage sensors that use thin-film capacitors as voltage divider elements, the deeply fused zero-sequence voltage sensor disclosed in this embodiment has significant advantages. First, by employing a resistor array for voltage division, its operating temperature range is wider, better matching the higher curing temperature of the epoxy resin used in the solidified electrode, thus achieving a one-time integral casting and solidification of the sensor element and epoxy resin. This not only simplifies the manufacturing process and eliminates the secondary potting interface, but also significantly improves product reliability and insulation performance, reducing the risk of failure due to interface issues. Second, the temperature drift characteristics of resistor arrays are generally better than those of thin-film capacitors, meaning that their voltage division ratio is less affected by changes in ambient temperature, thereby greatly improving the accuracy of voltage measurement and meeting the requirements of high-precision metrology. Furthermore, the lifespan of resistive elements is generally longer than that of thin-film capacitors, effectively ensuring the long-term stability and reliability of this sensor, extending the lifespan of the entire solidified electrode and even the circuit breaker, and reducing equipment maintenance costs and operational risks. Therefore, this deeply fused zero-sequence voltage sensor also demonstrates superiority in reducing load power, heat generation, size, and cost, while simultaneously improving the protection level and insulation performance of the equipment.

[0044] When using this deeply fused zero-sequence voltage sensor, the voltage signal from the medium-voltage power grid is first introduced into three sensing units 1 inside the circuit breaker's sealed pole via high-voltage lead 3. In each sensing unit 1, the high-voltage signal is precisely divided by a resistor array, reducing its voltage to a safe and manageable level. Subsequently, the divided voltage signal enters the overvoltage protection module, which effectively suppresses transient overvoltages, protecting the subsequent isolation transformer T. The protected signal then undergoes electrical isolation and signal transformation through the isolation transformer T, ensuring the purity and safety of the measurement signal. The voltage signal output by the output winding of the isolation transformer T in each sensing unit 1 represents the processed voltage of the corresponding phase. To obtain the zero-sequence voltage signal, the output windings of these three isolation transformers T are cleverly connected in series to form a series circuit. Since the zero-sequence voltage is the vector sum of the three-phase voltages, this series connection naturally achieves the superposition of the three-phase voltage signals, thus directly generating the zero-sequence voltage signal. Finally, the beginning and end of this series circuit are connected to the aviation socket in the signal series output unit. Through this aviation socket, the processed zero-sequence voltage signal can be reliably output to an external measurement, monitoring, or control system. The entire sensor, including three sensing units 1 and the signal series output unit, is integrally cast and sealed within a solid-state post, forming a compact, robust, and highly insulating overall structure. This effectively solves the problems of temperature mismatch between film capacitors and epoxy resin curing, secondary potting, large temperature drift, and short lifespan in existing technologies, significantly improving the accuracy, reliability, and service life of zero-sequence voltage measurement.

[0045] In one embodiment of this utility model, the overvoltage protection module is composed of a discharge tube Rn and a ceramic capacitor C connected in parallel.

[0046] The discharge tube Rn is an overvoltage protection device that rapidly conducts when the voltage exceeds a preset threshold, effectively dissipating the overvoltage energy. The ceramic capacitor C has high voltage withstand characteristics and is mainly used to absorb transient high-voltage pulses. It works in conjunction with the discharge tube Rn to provide a smoother voltage clamping effect. The discharge tube Rn and the ceramic capacitor C are connected in parallel between the output terminal of the resistor array and the input winding of the isolation transformer T.

[0047] Under normal operating conditions, when the input voltage is within a safe range, the discharge transistor Rn remains in the off state, while the ceramic capacitor C filters high-frequency noise in the circuit. When a transient overvoltage occurs in the circuit, once the input voltage rises and exceeds the breakdown voltage of the discharge transistor Rn, Rn will quickly turn on, thereby dissipating the overvoltage energy to ground through its own path, effectively limiting the voltage applied to subsequent circuits, especially the isolation transformer T. At the same time, the ceramic capacitor C can absorb some transient energy, helping to smooth voltage spikes and thus preventing the discharge transistor Rn from being damaged by frequent operation or excessive impact.

[0048] The above technical solution, employing a parallel combination of the discharge tube Rn and the ceramic capacitor C, provides efficient and reliable overvoltage protection for the deeply integrated zero-sequence voltage sensor. The fast response capability of the discharge tube Rn ensures rapid clamping of high voltage, while the ceramic capacitor C absorbs transient energy, effectively reducing the impact on the discharge tube Rn, thereby extending its service life and providing additional filtering protection for the stability of the output signal. Consequently, the isolation transformer T and subsequent circuitry are effectively protected from overvoltage damage, significantly improving the overall reliability and service life of the sensor.

[0049] In one embodiment of this utility model, the ceramic capacitor C is a high-voltage ceramic capacitor.

[0050] This embodiment upgrades the ceramic capacitor C in the overvoltage protection module to a high-voltage ceramic capacitor C, significantly improving the overall withstand voltage and reliability of the overvoltage protection module. When a transient overvoltage occurs in the power grid, the high-voltage ceramic capacitor C can more effectively absorb and disperse the overvoltage energy, preventing the overvoltage from directly acting on the isolation transformer T or other sensitive components, thereby avoiding component damage or performance degradation. It is precisely because the high-voltage ceramic capacitor C has a higher withstand voltage rating and stronger energy absorption capacity that the deeply integrated zero-sequence voltage sensor can provide more stable and reliable overvoltage protection in medium-voltage power grid environments, ensuring the long-term safe operation of the sensor.

[0051] As one embodiment of this utility model, it also includes an epoxy resin encapsulation body 7, which integrally casts and encapsulates the three sensing units 1 and the signal series output unit within the encapsulation pole.

[0052] This embodiment utilizes an epoxy resin encapsulation body 7 to integrally cast and encapsulate the three sensing units 1 and the signal serial output unit, effectively improving the reliability and environmental adaptability of the deeply fused zero-sequence voltage sensor. The epoxy resin encapsulation body 7 provides excellent insulation, environmental protection, and mechanical protection, ensuring stable and reliable operation of the sensor in various harsh environments. Simultaneously, the epoxy resin encapsulation body 7 also fixes the internal components together, forming a unified structure, thus improving the sensor's accuracy and stability.

[0053] In a preferred embodiment, during the production of the deeply fused zero-sequence voltage sensor, the three sensing units 1, including a resistor array, an overvoltage protection module, an isolation transformer T, and a signal series output unit, are first assembled and then placed into a mold. Next, epoxy resin material is mixed evenly in a certain proportion and injected into the mold, completely covering the sensing units 1 and the signal series output unit. Then, the mold is placed in an oven and cured according to the set temperature and time. After curing, the sensor is removed, and necessary adjustments and tests are performed to obtain the deeply fused zero-sequence voltage sensor with an epoxy resin encapsulation body 7.

[0054] As one embodiment of this utility model, the epoxy resin encapsulant 7 is externally covered with a silicone rubber layer 4.

[0055] The silicone rubber layer 4 is an elastic material with good weather resistance, corrosion resistance, and insulation properties. By adding a silicone rubber layer 4 to the outside of the epoxy resin encapsulation 7, the erosion of the epoxy resin encapsulation 7 by factors such as moisture, chemicals, and ultraviolet rays in the external environment can be effectively isolated, thereby extending the service life of the sensor.

[0056] Specifically, the main function of the epoxy resin encapsulation 7 is to fix and protect the internal sensing unit 1 and signal serial output unit, while the silicone rubber layer 4 provides additional environmental protection on this basis. The silicone rubber layer 4 is tightly bonded to the epoxy resin encapsulation 7, forming a whole, which can effectively prevent moisture and corrosive substances from penetrating into the sensor. In addition, the silicone rubber layer 4 also has a certain buffering effect, which can reduce the impact of external shocks and vibrations on the sensor.

[0057] In the embodiments described above in this application, a resistor array is used to divide the input voltage of the phase circuit. However, the resistance of ordinary resistors changes at different temperatures, causing deviations in the voltage signal after voltage division and affecting the measurement accuracy of the zero-sequence voltage sensor. Therefore, as an embodiment of this invention, the resistor array is composed of multiple low-temperature drift high-voltage resistors connected in series.

[0058] In a preferred embodiment, the resistor array is composed of multiple low-temperature-drift, high-voltage resistors connected in series, which effectively reduces the impact of temperature changes on the overall resistance of the array. Specifically, when the temperature rises, the resistance of each low-temperature-drift, high-voltage resistor increases slightly, but due to their low temperature coefficient, the increase is very small. Moreover, since the multiple low-temperature-drift, high-voltage resistors are connected in series, the change in the overall resistance of the array is the sum of the changes in the resistance of each individual resistor. Because the change in the resistance of each individual resistor is very small, the change in the overall resistance of the array is also very small, thus ensuring the stability of the voltage signal after voltage division.

[0059] In the embodiments described above in this application, the zero-sequence voltage sensor integrally encapsulates the sensing unit 1 and the signal series output unit within the encapsulated electrode using an epoxy resin encapsulation body 7. However, improper control of the curing temperature during the epoxy resin curing process may damage the resistive elements in the resistance array, affecting the sensor's accuracy and reliability. Therefore, as an embodiment of this invention, the curing temperature of the epoxy resin encapsulation body 7 is matched with the withstand temperature of the resistive elements in the resistance array, forming an integral structure without a secondary potting interface after curing, thereby ensuring the sensor's performance and reliability.

[0060] Specifically, the curing temperature can be matched by selecting appropriate epoxy resin materials and curing processes. For example, a low-temperature curing epoxy resin material can be selected, or a staged curing process can be used to gradually increase the curing temperature, thereby preventing the resistive element from being damaged due to excessive temperature. In addition, the thermal conductivity of the epoxy resin encapsulation 7 can be improved by adding thermally conductive fillers to the epoxy resin, thereby reducing the temperature of the resistive element.

[0061] Furthermore, the solidified structure forms an integral structure without a secondary potting interface, avoiding stress concentration and cracking problems caused by the presence of a secondary potting interface, thus improving the reliability of the sensor. As a preferred embodiment, the amount of epoxy resin and the potting process can be precisely controlled during the primary potting process to ensure that the epoxy resin completely fills the space within the solidified electrode post, thereby forming an integral structure without a secondary potting interface.

[0062] In some embodiments of this application, the layout of the resistor array and isolation transformer T of the sensing unit 1 may not be compact enough, resulting in a large overall sensor size, which is not conducive to integration inside the solid-state electrode. To address this, this application proposes to place the resistor array and isolation transformer T of each sensing unit 1 on an isolation circuit board 6. By optimizing the layout, the size of the sensing unit 1 can be effectively reduced, and the space utilization rate can be improved.

[0063] The isolation circuit board 6 refers to a circuit board with insulating properties used to carry and connect electronic components. The resistor array, composed of multiple resistors connected in series, is used to divide the input voltage of this phase circuit. One end of the input winding of the isolation transformer T is electrically connected to the overvoltage protection module, and the other end is connected to the sensor grounding terminal. The output winding of the isolation transformer T is used to output the processed voltage signal. Integrating the resistor array and the isolation transformer T onto the same isolation circuit board 6 reduces the number of connecting lines between components, lowers electromagnetic interference, and improves the reliability of signal transmission.

[0064] As one embodiment of this utility model, a metal fastener 5 is installed at the bottom of the epoxy resin sealant 7. The metal fastener 5 is used to fix the sensor and conduct to ground.

[0065] Specifically, the metal fastener 5 can be made of metal materials, such as aluminum, copper, or steel, possessing sufficient strength and rigidity to support and secure the entire sensor. The shape and size of the metal fastener 5 can be designed according to actual needs, for example, it can be plate-shaped, block-shaped, or frame-shaped. The metal fastener 5 can be fixed to the bottom of the epoxy resin seal 7 by means of bolts, welding, or bonding, ensuring the reliability and stability of the connection. A reliable electrical connection is formed between the metal fastener 5 and the grounding device, ensuring that the sensor can be effectively grounded and avoiding potential drift and interference.

[0066] Working principle of this utility model:

[0067] When using this deeply fused zero-sequence voltage sensor, the voltage signal from the medium-voltage power grid is first introduced into three sensing units 1 inside the circuit breaker's sealed pole via high-voltage lead 3. In each sensing unit 1, the high-voltage signal is precisely divided by a resistor array, reducing its voltage to a safe and manageable level. Subsequently, the divided voltage signal enters the overvoltage protection module, which effectively suppresses transient overvoltages, protecting the subsequent isolation transformer T. The protected signal then undergoes electrical isolation and signal transformation through the isolation transformer T, ensuring the purity and safety of the measurement signal. The voltage signal output by the output winding of the isolation transformer T in each sensing unit 1 represents the processed voltage of the corresponding phase. To obtain the zero-sequence voltage signal, the output windings of these three isolation transformers T are cleverly connected in series to form a series circuit. Since the zero-sequence voltage is the vector sum of the three-phase voltages, this series connection naturally achieves the superposition of the three-phase voltage signals, thus directly generating the zero-sequence voltage signal. Finally, the beginning and end of this series circuit are connected to the aviation socket in the signal series output unit. Through this aviation socket, the processed zero-sequence voltage signal can be reliably output to an external measurement, monitoring, or control system. The entire sensor, including three sensing units 1 and the signal series output unit, is integrally cast and sealed within a solid-state post, forming a compact, robust, and highly insulating overall structure. This effectively solves the problems of temperature mismatch between film capacitors and epoxy resin curing, secondary potting, large temperature drift, and short lifespan in existing technologies, significantly improving the accuracy, reliability, and service life of zero-sequence voltage measurement.

[0068] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope. All such changes and modifications fall within the scope of protection claimed by this utility model, which is defined by the appended claims and their equivalents.

Claims

1. A deeply integrated zero-sequence voltage sensor, applied inside the solid-sealed pole of a medium-voltage power grid circuit breaker, characterized in that, include: Three sensing units (1) are set inside the solid-sealed pole, each corresponding to a three-phase circuit; Each of the sensing units (1) includes a resistor array, an overvoltage protection module and an isolation transformer. The resistor array is composed of multiple resistors connected in series and is used to divide the input voltage of the phase circuit. The overvoltage protection module is electrically connected to the output terminal of the resistor array. One end of the input winding of the isolation transformer is electrically connected to the overvoltage protection module, and the other end of the input winding is connected to the sensor ground terminal. The output winding of the isolation transformer is used to output the processed voltage signal. The high-voltage terminals of the three resistor arrays corresponding to the three sensing units (1) are respectively connected to the medium-voltage grid incoming side at the upper end of the arc-extinguishing chamber (2) of the corresponding phase of the circuit breaker through high-voltage leads (3). The signal series output unit includes an aviation socket, and the output windings of the three isolation transformers are connected in series to form a series circuit. The beginning and end of the series circuit are connected to the aviation socket to form a zero-sequence voltage signal output terminal.

2. The deeply fused zero-sequence voltage sensor according to claim 1, characterized in that, The overvoltage protection module consists of a discharge tube and a ceramic capacitor connected in parallel.

3. The deeply fused zero-sequence voltage sensor according to claim 2, characterized in that, The ceramic capacitor is a high-voltage ceramic capacitor.

4. The deeply fused zero-sequence voltage sensor according to claim 1, characterized in that, It also includes an epoxy resin encapsulation body (7), which integrally casts and encapsulates the three sensing units (1) and the signal series output unit within the encapsulation pole.

5. The deeply fused zero-sequence voltage sensor according to claim 4, characterized in that, The epoxy resin sealant (7) is covered with a silicone rubber layer (4).

6. The deep fusion zero-sequence voltage sensor according to claim 1, characterized in that, The resistor array is composed of multiple low-temperature drifting high-voltage resistors connected in series.

7. The deeply fused zero-sequence voltage sensor according to claim 4, characterized in that, The curing temperature of the epoxy resin encapsulant (7) matches the withstand temperature of the resistor element in the resistor array, and after curing, an overall structure without a secondary potting interface is formed.

8. The deeply fused zero-sequence voltage sensor according to claim 1, characterized in that, The resistor array and the isolation transformer of each of the sensing units (1) are disposed on an isolation circuit board (6).

9. The deeply fused zero-sequence voltage sensor according to claim 4, characterized in that, The bottom of the epoxy resin sealant (7) is fitted with a metal fastener (5), which is used to fix the sensor and conduct grounding.

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