Fourth order voltage sensor

Abstract

This utility model relates to the field of power equipment technology, and in particular to a fourth-order voltage sensor, comprising: a high-voltage lead connected to the upper or lower end of the arc-extinguishing chamber of a circuit breaker at a medium-voltage power grid access point; a resistor array composed of multiple low-temperature drift high-voltage resistors connected in series, with its high-voltage end connected to the high-voltage lead; an isolation circuit board integrating an isolation signal processing unit, which includes an isolation transformer and an overvoltage protection module composed of parallel discharge tubes and ceramic capacitors, one end of the input winding of the isolation transformer being connected to the overvoltage protection module, and the other end being connected to the sensor grounding terminal; and an aviation socket connected to the output winding of the isolation transformer. By employing a resistor array and achieving one-time integral casting and solidification, the sensor achieves one-time integral casting and solidification, improving voltage measurement accuracy, enhancing product reliability, and extending service life.

Description

Technical Field

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

[0002] The power distribution network is a crucial foundation of the energy internet, and its operational status directly impacts the security and reliability of power supply. With the integration of numerous new power facilities such as distributed energy sources, electric vehicles, and energy storage devices, and the advancement of power market reforms, higher demands are being placed on the intelligence, reliability, and economy of the power distribution network. Circuit breakers, as key control devices in the distribution network, are vital for ensuring the stable operation of the grid. In medium-voltage distribution networks, solid-sealed pole technology is widely used in circuit breakers to improve their insulation performance and environmental adaptability. To achieve intelligent monitoring and control of the distribution network, voltage sensors need to be integrated inside the circuit breakers to acquire grid voltage signals in real time and accurately.

[0003] However, current voltage sensors used inside solid-encapsulated terminals typically employ thin-film capacitors as voltage dividing elements. These thin-film capacitors suffer from several technical drawbacks. First, their relatively low operating temperature range makes it difficult to match the high curing temperature of the epoxy resin used in the solid-encapsulated terminals. This prevents a single, integral encapsulation of the capacitor and epoxy resin during manufacturing, requiring secondary potting. This increases manufacturing complexity and may introduce a secondary potting interface, affecting product reliability and insulation performance. Second, thin-film capacitors exhibit significant temperature drift, meaning their capacitance value changes considerably with ambient temperature, impacting voltage measurement accuracy and failing to meet high-precision metering requirements. Furthermore, their relatively short lifespan and unreliable long-term stability shorten the lifespan of the entire solid-encapsulated terminal and even the circuit breaker, increasing maintenance costs and operational risks.

[0004] To address the aforementioned issues, existing technologies urgently need improvement. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a fourth-order voltage sensor.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a fourth-order voltage sensor, comprising a solid-sealed pole applied inside a medium-voltage power grid circuit breaker, including:

[0007] The high-voltage lead is connected to the medium-voltage power grid access point at the upper or lower end of the arc-extinguishing chamber of the circuit breaker.

[0008] The resistor array consists of multiple cryogenic high-voltage resistors connected in series, with its high-voltage end connected to the high-voltage lead.

[0009] An isolation circuit board is provided, which integrates an isolation signal processing unit. The isolation signal processing unit includes an isolation transformer T and an overvoltage protection module consisting of a discharge tube and a ceramic capacitor C connected in parallel. One end of the input winding of the isolation transformer T is connected to the overvoltage protection module, and the other end is connected to the sensor grounding terminal.

[0010] An aviation socket is used to connect the output winding of the isolation transformer T.

[0011] Fixed connector, electrically connecting the low-voltage end of the resistor array to the input end of the isolation circuit board;

[0012] The epoxy resin encapsulation body encapsulates the high-voltage leads, resistor arrays, fixing connectors, isolation circuit boards, and aviation sockets into a single integrated structure.

[0013] Silicone rubber, coated on the outer surface of an epoxy resin sealant, is used for UV protection and environmental sealing.

[0014] Metal fasteners are installed at the bottom of the epoxy resin seal and are used to fix the sensor to the circuit breaker housing and make the sensor grounding terminal connected to the ground.

[0015] Preferably, when the high-voltage lead is positioned at the upper end of the arc-extinguishing chamber, it is connected to the incoming side of the medium-voltage power grid, or when positioned at the lower end of the arc-extinguishing chamber, it is connected to the outgoing side of the medium-voltage power grid, in order to obtain the incoming side voltage or outgoing side voltage signal.

[0016] Preferably, the resistor array is a metal film resistor.

[0017] Preferably, the curing temperature of the epoxy resin encapsulation body matches the resistance busbar's withstand temperature.

[0018] Preferably, the epoxy resin sealant is a one-time integral casting and sealing structure without a secondary potting interface.

[0019] Preferably, the silicone rubber has a thickness of 3-5 mm and is resistant to ultraviolet aging and has water-repellent properties.

[0020] Preferably, the ceramic capacitor C is a high-voltage ceramic capacitor used to absorb transient overvoltages.

[0021] Preferably, the fixing connector is a metal conductive screw that passes through the resistor array and the isolation circuit board to achieve mechanical fixing and electrical connection.

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

[0023] By employing a resistance array and achieving one-time integral casting and sealing, the product achieves one-time integral casting and sealing, improves voltage measurement accuracy, enhances product reliability, and extends service life. Attached Figure Description

[0024] Figure 1 Cross-section of the fourth-order voltage sensor on the outgoing line side Figure 1 .

[0025] Figure 2 Cross-section of the fourth-order voltage sensor on the incoming line side Figure 2 .

[0026] Figure 3 This is a schematic diagram of the fourth-order voltage sensor on the incoming line side of this utility model.

[0027] Figure 4 This is a schematic diagram of the fourth-order voltage sensor on the output side of this utility model.

[0028] In the diagram: 1. High-voltage lead; 2. Resistor busbar; 3. Fixing connector; 4. Isolation circuit board; 5. Aviation socket; 6. Epoxy resin encapsulation; 7. Silicone rubber; 8. Fixing component. Detailed Implementation

[0029] 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.

[0030] like Figures 1 to 4 The fourth-order voltage sensor shown is used inside the solid-sealed pole of a medium-voltage power grid circuit breaker, and includes:

[0031] High-voltage lead 1 is connected to the medium-voltage power grid access point at the upper or lower end of the arc-extinguishing chamber of the circuit breaker.

[0032] The resistor array consists of multiple cryogenic high-voltage resistors connected in series, forming resistor array 2, with its high-voltage end connected to high-voltage lead 1.

[0033] The isolation circuit board 4 integrates an isolation signal processing unit, which includes an isolation transformer T and an overvoltage protection module consisting of a discharge tube and a ceramic capacitor C connected in parallel. One end of the input winding of the isolation transformer T is connected to the overvoltage protection module, and the other end is connected to the sensor grounding terminal.

[0034] Aviation socket 5 connects to the output winding of isolation transformer T;

[0035] Fixed connector 3 connects the low-voltage end of electrical connection resistor array 2 to the input end of isolation circuit board 4;

[0036] The epoxy resin encapsulation body 6 encapsulates the high-voltage lead 1, resistor array 2, fixing connector 3, isolation circuit board 4, and aviation socket 5 into a single integral structure.

[0037] Silicone rubber 7 is coated on the outer surface of epoxy resin sealant 6 for UV protection and environmental sealing.

[0038] Metal fastener 8 is installed at the bottom of epoxy resin seal 6 to fix the sensor to the circuit breaker housing and make the sensor grounding terminal connected to the ground.

[0039] The high-voltage lead 1 serves as the input terminal for the voltage signal, connecting to the power grid connection point of the circuit breaker's arc-extinguishing chamber. The resistor array 2, composed of multiple resistors connected in series, has its high-voltage end electrically connected to the high-voltage lead 1, achieving initial voltage division. The low-voltage end of the resistor array 2 is electrically connected to the input terminal of the isolation circuit board 4 via a fixed connector 3, transmitting the divided voltage signal. The isolation circuit board 4 is equipped with an isolation signal processing unit, which includes an isolation transformer T and an overvoltage protection module. One end of the input winding of the isolation transformer T is connected to the overvoltage protection module, and the other end is connected to the grounding terminal of the sensor, achieving signal isolation. The overvoltage protection module, consisting of parallel discharge tubes and ceramic capacitors C, is connected to the input terminal of the isolation transformer T, providing overvoltage protection. The output winding of the isolation transformer T is connected to an aviation socket 5 for outputting the processed voltage signal. An epoxy resin encapsulation body 6 encapsulates the main internal components, including the high-voltage lead 1, resistor array 2, fixed connector 3, isolation circuit board 4, and aviation socket 5, in a single, integrated manner, providing insulation and mechanical support. Silicone rubber 7 covers the exterior of the epoxy resin enclosure 6, providing additional environmental protection. A metal fastener 8 is located at the bottom of the epoxy resin enclosure 6 and is used to mount the sensor to the circuit breaker housing and ensure that the sensor grounding terminal is connected to earth.

[0040] Specifically, the sensor connects to the medium-voltage power grid via the high-voltage lead 1 from the circuit breaker's arc-extinguishing chamber. The introduced voltage is divided by the resistor array 2, reducing the high voltage to a lower level. The resistor array 2 uses low-temperature drift resistors, thereby reducing the impact of temperature changes on voltage accuracy. The signal is then transmitted to the isolation circuit board 4 via the fixed connector 3. The isolation signal processing unit on the isolation circuit board 4 further processes the signal. The isolation transformer T provides electrical isolation between the high-voltage and low-voltage sides, improving system safety. The discharge tube and ceramic capacitor C in the overvoltage protection module provide protection in the event of transient overvoltage, absorbing overvoltage energy and protecting subsequent circuits. The processed signal is output to the aviation socket 5 via the output winding of the isolation transformer T for external equipment to collect and use. The high-voltage lead 1, resistor array 2, fixed connector 3, isolation circuit board 4, and aviation socket 5 are integrally encapsulated by an epoxy resin encapsulation body 6 in a single process, avoiding interface problems caused by secondary encapsulation and improving structural reliability and lifespan. The curing temperature of the epoxy resin encapsulation body 6 matches the tolerance temperature of the internal components, ensuring compatibility during manufacturing. The silicone rubber outer layer 7 provides UV resistance and environmental sealing, enhancing the sensor's environmental adaptability. The metal fastener 8 provides mechanical mounting and grounding connection. Thus, this sensor solves the problems of low accuracy due to temperature fluctuations, incompatible manufacturing processes, and short lifespan in existing voltage sensors.

[0041] In some specific embodiments, the high-voltage lead 1 uses copper wire with a cross-sectional area of ​​approximately 1 mm², connected to the upper end of the arc-extinguishing chamber. The resistor array 2 consists of 160 series-connected metal film resistors, each with a resistance of 249 kΩ, for a total resistance of approximately 40 MΩ. The fixing connector 3 uses M4 brass screws. The isolation transformer T is integrated on the isolation circuit board 4. The discharge tube in the overvoltage protection module uses a gas discharge tube with a nominal breakdown voltage of 1 kV, and the ceramic capacitor C uses a high-voltage ceramic capacitor with a withstand voltage of 1 kV and a capacitance of 10 nF. The aviation socket 5 uses a 9-pin circular connector. The epoxy resin encapsulation 6 uses a two-component epoxy resin system with a curing temperature of 150°C. The silicone rubber 7 has a coating thickness of 3 mm. The metal fastener 8 uses stainless steel external hexagonal studs. These components are cast into the epoxy resin encapsulation 6 in one piece, forming a compact integral structure.

[0042] In one embodiment of this utility model, the high-voltage lead 1 is connected to the incoming side of the medium-voltage power grid when it is positioned at the upper end of the arc-extinguishing chamber, or connected to the outgoing side of the medium-voltage power grid when it is positioned at the lower end of the arc-extinguishing chamber, so as to obtain the incoming side voltage or the outgoing side voltage signal.

[0043] The connection position of high-voltage lead 1 determines the type of voltage signal acquired by the sensor. When high-voltage lead 1 is connected to the upper end of the circuit breaker's arc-extinguishing chamber, this connection point corresponds to the incoming side of the medium-voltage power grid. When high-voltage lead 1 is connected to the lower end of the circuit breaker's arc-extinguishing chamber, this connection point corresponds to the outgoing side of the medium-voltage power grid. By selecting the connection position of high-voltage lead 1, the sensor can be controlled to measure either the incoming or outgoing voltage.

[0044] Specifically, regarding the issue of how to obtain a specific voltage signal through connection methods, this problem was solved by clarifying the correspondence between the connection position of high-voltage lead 1 and the type of voltage signal obtained. When high-voltage lead 1 is installed at the upper end of the arc-extinguishing chamber, it is connected to the incoming side of the medium-voltage power grid, and the sensor obtains the voltage signal from the incoming side. When high-voltage lead 1 is installed at the lower end of the arc-extinguishing chamber, it is connected to the outgoing side of the medium-voltage power grid, and the sensor obtains the voltage signal from the outgoing side. This connection rule allows the sensor to measure the voltage on either side of the circuit breaker according to actual needs, improving the sensor's application flexibility and functionality.

[0045] In one embodiment of this utility model, the resistor of resistor array 2 is a metal film resistor.

[0046] Specifically, in existing technologies, the voltage divider elements of voltage sensors suffer from significant temperature drift, affecting measurement accuracy. This solution employs a resistor array 2 for voltage division, consisting of multiple resistors connected in series. By using metal film resistors as components of resistor array 2, the temperature drift problem is solved. The resistance of the metal film resistor changes little with temperature. When the sensor's operating environment temperature changes, the low temperature drift characteristic of the metal film resistor ensures that the resistance values ​​of each resistor in resistor array 2 remain relatively stable. This maintains the stability of the total resistance of resistor array 2. The stability of the total resistance ensures that high-voltage signals can be accurately converted into low-voltage signals, improving the measurement accuracy of the voltage sensor under different temperature conditions.

[0047] As one embodiment of this utility model, the curing temperature of the epoxy resin encapsulant 6 is matched with the resistance bar 2's tolerance temperature.

[0048] The curing temperature of the epoxy resin encapsulation 6 is matched to the temperature that the resistance array 2 can withstand. This matching is achieved by selecting an epoxy resin material with a specific curing temperature range and choosing a resistance array 2 with a corresponding or higher temperature tolerance rating. Therefore, during the curing process of the epoxy resin to form the integral structure, the resistance array 2 will not experience performance degradation or structural changes due to temperatures exceeding its tolerance range.

[0049] Specifically, the power distribution network is the foundation of the energy internet and affects the level of power supply services. With the access of various facilities and the emergence of electricity demand, requirements are placed on the safety, economy, and adaptability of the power distribution network. Modern power distribution network construction requires intelligence and relies on intelligent terminals. Currently, the high-voltage capacitors used in the voltage sensors of solid-encapsulated terminals are thin-film capacitors. Thin-film capacitors have low operating temperatures, which are incompatible with the curing temperature of the epoxy resin in the solid-encapsulated terminals. This leads to secondary solidification of the thin-film capacitors, resulting in large temperature drift, difficulty in accurate measurement, and short service life, thus affecting the lifespan of the solid-encapsulated terminals. The fourth-order voltage sensor proposed in this solution uses a high-voltage, low-temperature drift resistor internally, which is unaffected by ambient temperature changes in accuracy. The epoxy resin encapsulation body 6 integrates the high-voltage lead 1, resistor array 2, fixing connector 3, isolation circuit board 4, and aviation socket 5 into a single structure. A certain temperature is required during the epoxy resin curing process. If the epoxy resin curing temperature is incompatible with the resistance array 2's tolerance temperature, it may affect the performance of the resistance array 2 or cause structural changes. By ensuring that the curing temperature of the epoxy resin encapsulation body 6 matches the resistance array 2's tolerance temperature, performance degradation or structural changes of the resistance array due to high temperatures during the solidification process are avoided. The technical feature of matching the curing temperature of the epoxy resin encapsulation 6 with the temperature tolerance of the resistance array 2 ensures that the resistance array 2 will not be subjected to thermal stress beyond its tolerance range during the manufacturing process of integrally casting and curing the sensor assembly, thereby maintaining the electrical performance and structural stability of the resistance array 2. This matching is key to achieving sensor reliability and long-term stable operation.

[0050] In some specific embodiments, an epoxy resin material is selected, with a recommended curing temperature range of 140°C to 180°C. Simultaneously, a metal film resistor is selected as the resistance array, with a maximum operating temperature or withstand temperature of 300°C. When the resistance array and epoxy resin are integrally cast and cured in a single process, the maximum temperature during curing is controlled within the epoxy resin's curing temperature range, for example, set to 150°C. Since 150°C is lower than the resistance array's withstand temperature of 300°C, the resistance array will not be damaged or its performance degraded due to excessively high temperatures during curing. This ensures the performance stability and long-term reliability of the resistance array after curing.

[0051] As one embodiment of this utility model, the epoxy resin sealant 6 is a one-time integral casting and sealing structure without a secondary potting interface.

[0052] During implementation, the epoxy resin encapsulation adopts a one-time monolithic casting structure, encapsulating the internal components in a single process. This structure eliminates the interfaces that may arise from secondary potting. Secondary potting interfaces are the bonding surfaces between different batches or types of casting materials, which may exhibit stress concentration, air gaps, or poor bonding, becoming weak points in electrical insulation, prone to partial discharge, and reducing insulation performance. Simultaneously, interfaces can also affect the mechanical strength and sealing of the encapsulation, leading to moisture intrusion. The one-time monolithic casting, forming a continuous encapsulation, avoids the existence of interfaces.

[0053] As one embodiment of this utility model, the silicone rubber 7 has a thickness of 3-5mm and has resistance to ultraviolet aging and water repellency.

[0054] In implementation, the silicone rubber 7 protective layer, serving as the outermost protective structure of the sensor, has a thickness set within the range of 3-5 mm. This provides sufficient material thickness to form an effective physical barrier, enhancing the protection of the internal epoxy resin encapsulation 6. The silicone rubber 7 protective layer is resistant to ultraviolet aging, meaning that its material structure is not easily degraded when exposed to sunlight for extended periods, maintaining its protective function and preventing problems such as material embrittlement and cracking caused by ultraviolet radiation. Simultaneously, the silicone rubber 7 protective layer is water-repellent, meaning it is hydrophobic. This prevents water droplets from easily remaining on the surface and penetrating, effectively preventing moisture from entering the sensor and avoiding adverse effects of a humid environment on internal electrical components and insulation performance. By combining appropriate thickness with resistance to ultraviolet aging and water repellency, the silicone rubber layer reliably protects the internal structure from the erosion of harsh environmental factors, thereby ensuring the stability and reliability of the sensor during long-term outdoor operation and extending the overall lifespan of the sensor.

[0055] In one embodiment of this utility model, the ceramic capacitor C is a high-voltage ceramic capacitor used to absorb transient overvoltage.

[0056] In implementation, the high-voltage ceramic capacitor and the discharge tube are connected in parallel to form an overvoltage protection module. The high-voltage ceramic capacitor is connected to one end of the input winding of the isolation transformer. When a transient overvoltage occurs, the high-voltage ceramic capacitor provides a low-impedance path. The high-voltage ceramic capacitor absorbs the energy of the transient overvoltage. The high-voltage ceramic capacitor limits the voltage amplitude. The high-voltage ceramic capacitor protects the input winding of the isolation transformer. The high-voltage ceramic capacitor withstands high voltages under medium-voltage power grid conditions. The high-voltage ceramic capacitor operates reliably when overvoltage occurs.

[0057] In one embodiment of this utility model, the fixing connector 3 is a metal conductive screw that passes through the resistor array 2 and the isolation circuit board 4 to achieve mechanical fixing and electrical connection.

[0058] In implementation, the fixing connector 3 uses a metal conductive screw. Its metal material provides an electrical conduction path between the low-voltage end of the resistor array 2 and the input end of the isolation circuit board 4, completing signal transmission. The metal conductive screw passes through both the resistor array 2 and the isolation circuit board 4, and the two components are firmly connected together by a threaded connection or a nut, providing mechanical support. Thus, a single component simultaneously achieves the functions of mechanical fixing and electrical conduction, solving the potential mechanical instability problem in the connection between the resistor array 2 and the isolation circuit board 4, ensuring the structural integrity of the sensor during manufacturing and the connection reliability during operation. The mechanical fixing function guarantees the stability of the electrical connection, preventing poor contact or disconnection due to mechanical stress.

[0059] 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 fourth-order voltage sensor for use inside a sealed pole of a medium voltage network circuit breaker, characterized in that, include: High voltage lead (1) is connected to the medium voltage power grid access point at the upper or lower end of the arc-extinguishing chamber of the circuit breaker; The resistor array consists of multiple low-temperature drift high-voltage resistors connected in series (2), and its high-voltage end is connected to the high-voltage lead (1). An isolation circuit board (4) is integrated with an isolation signal processing unit. The isolation signal processing unit includes an isolation transformer and an overvoltage protection module consisting of a discharge tube and a ceramic capacitor connected in parallel. One end of the input winding of the isolation transformer is connected to the overvoltage protection module, and the other end is connected to the sensor grounding terminal. Aviation socket (5) is connected to the output winding of the isolation transformer; Fixed connector (3), electrical connection resistor bar (2) low voltage end and isolation circuit board (4) input end; The epoxy resin encapsulation body (6) encapsulates the high voltage lead (1), resistor array (2), fixing connector (3), isolation circuit board (4) and aviation socket (5) into a single integral structure. Silicone rubber (7) is coated on the outer surface of epoxy resin sealant (6) for UV protection and environmental sealing. Metal fastener (8) is installed at the bottom of epoxy resin seal (6) to fix the sensor to the circuit breaker housing and make the sensor grounding terminal connected to the ground.

2. The fourth-order voltage sensor of claim 1, wherein, When the high-voltage lead (1) is placed at the upper end of the arc-extinguishing chamber, it is connected to the incoming side of the medium-voltage power grid, or when it is placed at the lower end of the arc-extinguishing chamber, it is connected to the outgoing side of the medium-voltage power grid to obtain the incoming side voltage or outgoing side voltage signal.

3. The fourth-order voltage sensor of claim 1, wherein, The resistance of the resistor array (2) is a metal film resistor.

4. The fourth-order voltage sensor according to claim 1, characterized in that, The curing temperature of the epoxy resin sealant (6) matches the resistance temperature of the resistor array (2).

5. The fourth-order voltage sensor according to claim 1, characterized in that, The epoxy resin sealant (6) is a one-time integral casting and sealing structure without a secondary potting interface.

6. The fourth-order voltage sensor according to claim 1, characterized in that, The silicone rubber (7) has a thickness of 3-5 mm and is resistant to ultraviolet aging and has hydrophobic properties.

7. The fourth-order voltage sensor according to claim 1, characterized in that, The ceramic capacitor is a high-voltage ceramic capacitor used to absorb transient overvoltages.

8. The fourth-order voltage sensor according to claim 1, characterized in that, The fixed connector (3) is a metal conductive screw that passes through the resistor bar (2) and the isolation circuit board (4) to achieve mechanical fixation and electrical conductive connection.

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