Shielded voltage transformer with temperature measurement function

Abstract

This invention relates to the field of metering and protection technology for high-voltage power systems, specifically a shielded voltage transformer with temperature measurement function. The invention includes a metal support frame, a sealed housing, a high-voltage insulating tube sealed and installed through the outer wall of the sealed housing, a meter box, and a secondary junction box. A primary conductive rod is installed inside the high-voltage insulating tube, with one end extending into the sealed housing to receive high-voltage current and transmit it to the voltage transformer body. This invention employs a parallel and linked design of a temperature-sensitive mechanism and a pneumatic drive unit. Utilizing the thermal expansion and contraction characteristics of the solid-state temperature-sensitive expansion core, it accurately responds to abnormal winding temperatures and triggers shielding protection. The pneumatic drive unit relies on the pressure difference between SF₆ gas pressure and the metal bellows. When SF₆ leakage leads to a decrease in insulation capacity, it triggers shielding extension without manual intervention, replacing part of the SF₆ insulation effect with a strong shielding effect, thus preventing electric field concentration and partial discharge.

Description

Technical Field

[0001] This invention relates to the field of metering and protection technology for high-voltage power systems, specifically a shielded voltage transformer with temperature measurement function. Background Technology

[0002] The rapid development of the smart grid industry and the widespread adoption of intelligent power distribution systems have placed higher demands on the metering accuracy, operational safety, and adaptive protection capabilities of high-voltage power equipment. In the field of metering and protection of high-voltage power systems, shielded voltage transformers are one of the core devices. Their main function is to convert high-voltage electrical energy into measurable and protectable low-voltage induced signals, while simultaneously suppressing electric field interference through a shielding structure to ensure metering accuracy and equipment operational safety.

[0003] Currently, most high-voltage shielded voltage transformers use SF6 gas as the core insulating medium, utilizing its excellent insulation and arc-extinguishing properties to block the strong electric field at the end of the primary winding and avoid partial discharge, so as to meet the operating requirements of high-voltage conditions.

[0004] In order to maintain a good shielding effect under abnormal conditions, traditional shielding structures are mostly set with the longest fixed dimension of the shield. Although this setting can achieve basic electric field isolation, the eddy current loss generated by the alternating magnetic field cutting the conductive shield is large, which affects the operating efficiency of the equipment. Summary of the Invention

[0005] The purpose of this invention is to provide a shielded voltage transformer with temperature measurement function to solve the problems in the prior art.

[0006] The objective of this invention can be achieved through the following technical solutions: A shielded voltage transformer with temperature measurement function, preferably comprising a metal support frame, a sealed housing, a high-voltage insulating tube sealed and installed through the outer wall of the sealed housing, a meter box, and a secondary junction box. A primary conductive rod is installed inside the high-voltage insulating tube, with one end extending into the sealed housing to receive high-voltage current and transmit it to the voltage transformer body. Its sealed through-hole design effectively prevents SF6 insulating gas leakage, ensuring insulation performance. The sealed housing is filled with SF6 insulating gas and houses the voltage transformer body and shielding cylinder drive mechanism. The sealed housing adopts a closed metal tank structure, providing a stable sealed environment for the internal components, preventing external impurities from entering. Simultaneously, in conjunction with the SF6 insulating gas, it achieves excellent insulation protection, avoiding partial discharge under strong electric fields and ensuring the safe operation of the equipment. The voltage transformer body includes a horizontal U-shaped closed iron core, a primary winding, a secondary winding, and a double-layer telescopic shielding cylinder. The iron core consists of an iron core column and two yokes on both sides. The primary and secondary windings are wound around the outer circumference of the iron core column. The structural design of the horizontal U-shaped closed iron core enables closed transmission of the magnetic circuit, reduces magnetic field leakage, improves magnetic field transmission efficiency, and provides a stable carrier for the electromagnetic induction of the primary and secondary windings. The primary winding is used to pass high-voltage current to generate an alternating magnetic field, and the secondary winding is used to induce a corresponding voltage to realize metering and protection functions. The two are wound around the outer circumference of the iron core column, which is a reasonable layout and avoids mutual interference. The double-layer telescopic shielding cylinder is fitted around the outer perimeter of the iron core column. It consists of a grounded outer shielding cylinder and an axially telescopic inner shielding cylinder, both made of non-magnetic conductive material. An SF6 insulating air gap is reserved between the layers. A guide cylinder fitted onto the iron core column is fixed inside the outer shielding cylinder. The selection of non-magnetic conductive material can effectively avoid the shielding cylinder interfering with the magnetic field transmission, ensuring the metering accuracy of the current transformer. The reliable grounding of the outer shielding cylinder can form a basic electric field barrier, avoiding strong electric field interference with the normal operation of the secondary winding. The axial telescopic inner shielding cylinder, together with the reserved SF6 insulating air gap between the layers, achieves a balance between electric field protection and eddy current loss, solving the drawbacks of existing fixed shielding structures. The shielding cylinder drive mechanism includes a temperature-sensitive mechanism, a pneumatic drive unit, and a pressure equalizing wing unit, which can drive the inner shielding cylinder to extend or retract when the temperature or SF6 pressure is abnormal. This drive mechanism adopts a dual-trigger design, capable of responding to both temperature and SF6 pressure anomalies separately, ensuring timely action of the inner shielding cylinder under abnormal operating conditions, and improving the fault tolerance and safety of the equipment. The inner shielding cylinder is equipped with a linkage monitoring unit on its front inner side, which is used to monitor the temperature of the primary winding end and the integrity of the insulation layer in real time, and trigger the corresponding module in the meter box for early warning. The linkage monitoring unit can realize the integration of temperature monitoring and insulation monitoring, detect equipment abnormalities in advance, prevent the fault from escalating, and provide timely signal support for equipment maintenance.

[0007] Preferably, the guide cylinder is made of insulating material to achieve insulation isolation between the inner shielding cylinder and the iron core column, preventing eddy currents from being generated through conduction between the two. It also provides guidance and limitation for the expansion and contraction of the inner shielding cylinder, preventing deviation or jamming during its expansion and contraction. The insulating guide cylinder can effectively suppress eddy current generation, reduce energy loss, and ensure smooth expansion and contraction of the inner shielding cylinder, preventing damage to the winding insulation layer due to jamming and extending the service life of the equipment.

[0008] Preferably, the temperature-sensitive mechanism includes a positioning ring fixedly sleeved in the middle section of the guide cylinder and an abutment ring fixedly sleeved at one end of the inner shielding cylinder. A thermosensitive expansion chamber is formed between the positioning ring and the abutment ring. A solid temperature-sensitive expansion core is disposed within the thermosensitive expansion chamber, and the guide cylinder is fixedly connected to the inner side of the inner shielding cylinder. The positioning ring and the abutment ring provide a stable installation space for the solid temperature-sensitive expansion core, and the thermosensitive expansion chamber ensures that the solid temperature-sensitive expansion core is not disturbed by external factors, ensuring the accuracy of its temperature response and realizing the temperature-triggered expansion and contraction of the inner shielding cylinder.

[0009] Preferably, an insulating ring is provided between the solid-state temperature-sensitive expansion core and the contact ring; a reset chamber is formed between the end of the outer shielding cylinder and the contact ring, and a reset spring and a limiting ring fixed to the inner side of the outer shielding cylinder are provided in the reset chamber. One end of the reset spring is fixed to the contact ring, and the other end abuts against the limiting ring. The insulating ring can achieve insulation isolation between the solid-state temperature-sensitive expansion core and the contact ring, avoiding conductive interference; the reset spring and the limiting ring cooperate to achieve automatic reset of the inner shielding cylinder, ensuring that the equipment returns to normal after the temperature returns to normal. The structure is simple and highly reliable.

[0010] Preferably, the pneumatic drive unit includes a pressure transformer chamber and a metal bellows. The pressure transformer chamber is formed by a positioning ring on the side away from the thermosensitive expansion chamber, a guide cylinder, and an outer shielding cylinder. The metal bellows is located inside the pressure transformer chamber and has a built-in disc spring. The internal pressure of the metal bellows is evacuated to a low-pressure state. The pressure transformer chamber provides a stable installation and working environment for the metal bellows. Evacuating the internal pressure of the metal bellows ensures stable compression of the bellows by SF6 high-pressure gas under normal operating conditions, avoiding interference with the expansion and contraction of the inner shielding cylinder. The disc spring provides a stable driving force in case of abnormal gas pressure, ensuring that the inner shielding cylinder extends in time to respond to potential SF6 leakage.

[0011] Preferably, the pneumatic drive unit further includes a transmission assembly, which comprises a transmission ring fixedly connected to the end of the metal bellows, and a first transmission groove and a second transmission groove formed on the guide cylinder. The transmission ring can transmit the extension and retraction of the metal bellows to subsequent components, and the first and second transmission grooves provide stable sliding guidance for the transmission components, ensuring smooth transmission and avoiding jamming.

[0012] Preferably, the transmission assembly further includes an L-shaped slide rod slidably disposed inside a transmission groove. One end of the L-shaped slide rod extends into the transformer chamber and is fixedly connected to the transmission ring, while the other end has a follower groove. The L-shaped slide rod enables the steering transmission of power, and the design of the follower groove provides a basis for the parallel linkage of the temperature-sensitive mechanism and the pneumatic drive unit, ensuring that their actions do not interfere with each other.

[0013] Preferably, the transmission assembly further includes a transmission slider fixed inside the inner shielding cylinder and passing through the second transmission groove. One end of the transmission slider is fixedly connected to an abutment wheel located inside the follower groove. The abutment wheel can slide freely within the follower groove, enabling the temperature-sensitive mechanism and the pneumatic drive unit to operate in parallel without interference. The cooperation between the abutment wheel and the follower groove ensures that the temperature-sensitive mechanism is not interfered with by the pneumatic drive unit when driving the inner shielding cylinder to extend or retract. At the same time, the pneumatic drive unit can effectively drive the inner shielding cylinder to extend or retract when it operates, achieving dual-drive without interference and improving the reliability of the equipment response.

[0014] Preferably, the equalizing wing unit includes an arc-shaped equalizing wing hinged to the outer side of the front end of the inner shielding cylinder via a hinge shaft. The outer shielding cylinder has a receiving groove corresponding to the arc-shaped equalizing wing at one end facing the primary winding. A stretching spring connects the inner side of the arc-shaped equalizing wing to the outer wall of the inner shielding cylinder, and the arc-shaped equalizing wing and the inner shielding cylinder are reliably grounded. The arc-shaped equalizing wing can form a 360° annular grounding conductive surface when extended, smoothing out the spike electric field at the end of the primary winding, suppressing partial discharge, and enhancing the electric field shielding effect. The receiving groove can store the equalizing wing under normal conditions, reducing space occupation and eddy current losses. The stretching spring provides a stable driving force for the deployment of the equalizing wing, ensuring reliable operation.

[0015] Preferably, the linkage monitoring unit includes a PT100 temperature probe installed on the inner side of the front end of the inner shielding cylinder 11 and several miniature conductive contacts, which are arranged at intervals in the circumferential direction. The PT100 temperature probe is electrically connected to the internal and external temperature measurement modules of the meter box. The miniature conductive contacts are made of copper and are insulated from the inner shielding cylinder through insulating bushings. They can form a conductive circuit when the primary winding insulation layer is damaged, triggering an early warning from the insulation monitoring module inside the meter box. The PT100 temperature probe has high temperature measurement accuracy and good stability, and can monitor the temperature at the end of the primary winding in real time, issuing a temperature warning in a timely manner. The copper miniature conductive contacts have excellent conductivity, and the insulating bushings avoid short circuit hazards. They can accurately detect the integrity of the winding insulation layer and detect potential insulation damage in advance.

[0016] The beneficial effects of this invention are: 1. This invention adopts a parallel linkage design of a temperature-sensitive mechanism and a pneumatic drive unit. By utilizing the thermal expansion and contraction characteristics of the solid temperature-sensitive expansion core, it accurately responds to abnormal winding temperature and triggers shielding protection. The pneumatic drive unit relies on the pressure difference between SF6 gas pressure and the metal bellows. When SF6 leakage leads to a decrease in insulation capacity, it can trigger shield extension without manual intervention, replacing part of the SF6 insulation effect with a strong shielding effect, and eliminating electric field concentration and partial discharge.

[0017] 2. This invention employs a double-layer telescopic shielding cylinder structure. The outer shielding cylinder is fixedly grounded to achieve basic electric field isolation, preventing strong electric field interference from the primary winding to the secondary winding and ensuring measurement accuracy. The inner shielding cylinder is designed as a telescopic structure, retracting under normal conditions to only cover the iron core column, minimizing eddy current losses caused by the alternating magnetic field cutting the conductive shield. Simultaneously, in conjunction with the deployment of the equalizing wing unit, a dual-protection structure is formed under abnormal operating conditions, combining double-layer shielding with peak electric field flattening, further enhancing the shielding effect and achieving the dual goals of low loss under normal conditions and strong protection under abnormal conditions.

[0018] 3. This invention uses a PT100 temperature probe to collect winding temperature in real time, enabling early warning of excessively high temperatures and alarms to detect potential overheating hazards in advance. It also uses miniature conductive contacts to monitor the winding insulation layer in real time, triggering an early warning at the initial stage of insulation damage, thus addressing faults proactively. Furthermore, all drive and protection actions are automatically triggered without manual intervention, significantly reducing the workload of maintenance personnel.

[0019] 4. This solution, through the independent triggering design of the temperature-sensitive mechanism and the pneumatic drive unit, combined with the temperature monitoring of the PT100 temperature probe, can automatically distinguish between two core faults: winding overheating and SF6 gas pressure leakage. The meter box outputs differentiated early warning information, and maintenance personnel can directly judge the root cause of the fault by the warning type, thereby achieving accurate fault location and rapid repair, and greatly improving the operation and maintenance efficiency of the intelligent power distribution system. Attached Figure Description

[0020] The invention will now be further described with reference to the accompanying drawings.

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a top view of the sealed housing in this invention; Figure 3 yes Figure 2 A cross-sectional view along the AA direction; Figure 4 This is a schematic diagram of the overall internal structure of the sealed housing in this invention; Figure 5 This is a schematic diagram of the overall structure of the outer shielding cylinder in this invention; Figure 6 This is a top view of the outer shielding cylinder in this invention. Figure 7 yes Figure 6 A sectional view along the BB direction; Figure 8 This is a top side view of the outer shielding cylinder in this invention; Figure 9 yes Figure 8 A sectional view along the CC direction; Figure 10This is a schematic diagram showing the connection relationship between the guide tube and the inner shielding tube in this invention; Figure 11 This is a schematic diagram of the overall structure of the transmission slider in this invention; Figure 12 This is a schematic diagram of the overall structure of the L-shaped slide bar in this invention.

[0022] Explanation of reference numerals in the attached drawings: 1. Metal support frame; 2. Sealed housing; 3. High-voltage insulating tube; 4. Meter box; 5. Secondary junction box; 6. Iron core column; 7. Yoke; 8. Primary winding; 9. Secondary winding; 10. Outer shielding cylinder; 11. Inner shielding cylinder; 12. Guide cylinder; 13. Positioning ring; 14. Contact ring; 15. Thermosensitive expansion chamber; 16. Reset chamber; 17. Reset spring; 18. Limiting ring; 19. 20. Solid-state temperature-sensitive expansion core; 21. Insulating ring; 22. Transformer chamber; 23. Metal bellows; 24. Disc spring; 25. Transmission ring; 26. Transmission slide groove one; 27. Transmission slide groove two; 28. L-shaped slide rod; 29. ​​Transmission slider; 30. Abutment wheel; 31. Follower groove; 32. Arc-shaped equalizing wing; 33. Storage groove; 34. Extension spring; 35. PT100 temperature probe; 36. Miniature conductive contact. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] A shielded voltage transformer with temperature measurement function is mainly designed for high-voltage insulation metering equipment used in the metering and protection of high-voltage power systems in the smart grid industry and intelligent distribution systems. It adapts to the application requirements of shielded voltage transformers in intelligent distribution scenarios. Through the coordinated operation of a temperature-sensitive mechanism, a pneumatic drive unit, a double-layer telescopic shielding cylinder, and a linkage monitoring unit, it solves the problems of traditional shielded voltage transformers, such as a single shielding trigger mode, lack of adaptive protection against SF6 leakage, difficulty in balancing eddy current loss and electric field protection, disconnect between temperature measurement and shielding protection, and prominent partial discharge hazards at the winding ends. This shielded voltage transformer with temperature measurement function belongs to the field of high-voltage power system metering and protection technology. Through pure mechanical linkage combined with linkage monitoring, it achieves synchronous adaptive triggering of temperature and pressure factors, shielding cylinder telescopic adjustment, real-time monitoring of winding temperature and insulation status, and peak electric field suppression. This meets the requirements of the smart grid industry and intelligent distribution systems for automated adaptive protection of high-voltage metering equipment, reduced eddy current loss, improved metering accuracy, enhanced insulation performance, and stable improvement in operational safety.

[0025] like Figures 1-12 As shown, the device includes a metal support frame 1, a sealed housing 2, a high-voltage insulating pipe 3 that is sealed and installed through the outer wall of the sealed housing 2, a meter box 4, and a secondary junction box 5. A primary conductive rod is installed inside the high-voltage insulating pipe 3, with one end of the primary conductive rod extending into the sealed housing 2. This rod is used to connect the high-voltage current and transmit it to the voltage transformer body. Its sealed through-hole design can effectively prevent SF6 insulating gas leakage and ensure insulation performance. The sealed housing 2 is filled with SF6 insulating gas and houses the voltage transformer body and shielding cylinder drive mechanism. The sealed housing 2 adopts a closed metal tank structure, which can provide a stable sealed environment for the internal components, prevent external impurities from entering, and, together with the SF6 insulating gas, achieve good insulation protection, avoid partial discharge under strong electric fields, and ensure the safe operation of the equipment. The voltage transformer body includes a horizontal U-shaped closed iron core, a primary winding 8, a secondary winding 9, and a double-layer telescopic shielding cylinder. The iron core consists of an iron core column 6 and two yokes 7 on both sides. The primary winding 8 and the secondary winding 9 are wound around the outer periphery of the iron core column 6. The horizontal U-shaped closed iron core structure design enables closed transmission of the magnetic circuit, reduces magnetic field leakage, improves magnetic field transmission efficiency, and provides a stable carrier for the electromagnetic induction of the primary and secondary windings. The primary winding 8 is used to pass high-voltage current to generate an alternating magnetic field, and the secondary winding 9 is used to induce a corresponding voltage to realize metering and protection functions. The two are wound around the outer periphery of the iron core column 6, which is a reasonable layout and avoids mutual interference. A double-layer telescopic shielding cylinder is fitted around the outer periphery of the iron core column 6. It consists of a grounded outer shielding cylinder 10 and an axially telescopic inner shielding cylinder 11, both made of non-magnetic conductive material. An SF6 insulating air gap is reserved between the layers. A guide cylinder 12, which is fitted onto the iron core column 6, is fixed inside the outer shielding cylinder 10. The selection of non-magnetic conductive material can effectively avoid the shielding cylinder interfering with the magnetic field transmission and ensure the metering accuracy of the current transformer. The reliable grounding of the outer shielding cylinder 10 can form a basic electric field barrier, avoiding strong electric field interference with the normal operation of the secondary winding 9. The axial telescopic inner shielding cylinder 11, together with the reserved SF6 insulating air gap between the layers, achieves a balance between electric field protection and eddy current loss, solving the drawbacks of the existing fixed shielding structure. The shielding cylinder drive mechanism includes a temperature-sensitive mechanism, a pneumatic drive unit, and a pressure equalizing wing unit, which can drive the inner shielding cylinder 11 to extend or retract when the temperature or SF6 pressure is abnormal. This drive mechanism adopts a dual-trigger design, which can respond to abnormal temperature and SF6 pressure separately, ensuring that the inner shielding cylinder 11 operates in a timely manner under abnormal conditions, thereby improving the fault tolerance and safety of the equipment. The inner shielding cylinder 11 has a linkage monitoring unit on its inner front end, which is used to monitor the temperature and insulation integrity of the primary winding 8 end in real time and trigger the corresponding module in the meter box 4 for early warning. The linkage monitoring unit can realize the integration of temperature monitoring and insulation monitoring, detect equipment abnormalities in advance, avoid the escalation of faults, and provide timely signal support for equipment maintenance. The guide cylinder 12 is made of insulating material to achieve insulation isolation between the inner shielding cylinder 11 and the iron core column 6, preventing eddy currents from being generated through conduction between the two. It also provides guidance and limitation for the extension and retraction of the inner shielding cylinder 11, preventing deviation or jamming during its extension and retraction. The insulating material of the guide cylinder 12 effectively suppresses eddy current generation, reduces energy loss, and ensures smooth extension and retraction of the inner shielding cylinder 11, preventing damage to the winding insulation layer due to jamming and extending the service life of the equipment. Furthermore, the temperature-sensitive mechanism includes a positioning ring 13 fixedly sleeved in the middle section of the guide cylinder 12 and an abutment ring 14 fixedly sleeved at one end of the inner shielding cylinder 11. A thermosensitive expansion chamber 15 is formed between the positioning ring 13 and the abutment ring 14. A solid-state temperature-sensitive expansion core 19 is disposed inside the thermosensitive expansion chamber 15. The guide cylinder 12 is fixedly connected to the inner side of the inner shielding cylinder 11. The positioning ring 13 and the abutment ring 14 provide a stable installation space for the solid-state temperature-sensitive expansion core 19. The thermosensitive expansion chamber 15 ensures that the solid-state temperature-sensitive expansion core 19 is not disturbed by external factors, ensuring the accuracy of its temperature response and realizing the temperature-triggered expansion and contraction of the inner shielding cylinder 11. Furthermore, an insulating ring 20 is provided between the solid-state temperature-sensitive expansion core 19 and the contact ring 14; a reset chamber 16 is formed between the end of the outer shielding cylinder 10 and the contact ring 14. A reset spring 17 and a limiting ring 18 fixed to the inner side of the outer shielding cylinder 10 are provided within the reset chamber 16. One end of the reset spring 17 is fixed to the contact ring 14, and the other end abuts against the limiting ring 18. The insulating ring 20 enables insulation isolation between the solid-state temperature-sensitive expansion core 19 and the contact ring 14, preventing conductive interference. The reset spring 17, in conjunction with the limiting ring 18, enables automatic reset of the inner shielding cylinder 11, ensuring that the equipment returns to normal operation after the temperature recovers. The structure is simple and highly reliable. It is worth noting that the solid-state temperature-sensitive expansion core 19 is the core passive driving element of the temperature-sensitive mechanism of this invention. It uses high-purity refined paraffin wax as the core thermosensitive substrate, and is compounded with boron nitride thermally conductive filler, alumina high-temperature resistant filler, and epoxy resin dimensional stabilizer, mixed in a specific ratio and then molded and cured to form an integrated solid-state composite thermosensitive component. In this solution, it possesses the core characteristics of passive triggering, precise thermal response, reversible deformation, and no electromagnetic interference. It requires no external power supply or control circuit, relying entirely on its own thermal expansion and contraction physical properties to output a stable mechanical driving force. Furthermore, electrical isolation is achieved through the insulating ring 20 and the contact ring 14, which does not interfere with the electromagnetic circuit and metering accuracy of the current transformer. In this scheme, the solid-state temperature-sensitive expansion core 19 is set with a precise action threshold: when the temperature at the end of the primary winding rises to 80°C, the paraffin substrate inside the core undergoes a solid-liquid phase change and generates significant volume expansion, pushing the inner shielding cylinder 11 to extend axially to achieve enhanced shielding; when the temperature drops below 70°C, the paraffin substrate returns to solid state, and the core volume shrinks and resets synchronously, cooperating with the reset spring 17 to drive the inner shielding cylinder 11 to retract to the normal state. Furthermore, the pneumatic drive unit includes a pressure transformer chamber 21 and a metal bellows 22. The pressure transformer chamber 21 is formed by the positioning ring 13 on the side away from the thermosensitive expansion chamber 15, the guide cylinder 12, and the outer shielding cylinder 10. The metal bellows 22 is located inside the pressure transformer chamber 21, and a disc spring 23 is built into the metal bellows 22. The inside of the metal bellows 22 is evacuated to a low-pressure state. The pressure transformer chamber 21 can provide a stable installation and working environment for the metal bellows 22. The low-pressure state inside the metal bellows 22 can ensure that the SF6 high-pressure gas stably compresses the bellows under normal working conditions, avoiding interference with the extension and retraction of the inner shielding cylinder 11. The disc spring 23 can provide a stable driving force when the gas pressure is abnormal, ensuring that the inner shielding cylinder 11 extends in time to respond to potential SF6 leakage. Furthermore, the pneumatic drive unit is also equipped with a transmission assembly, which includes a transmission ring 24 fixedly connected to the end of the metal bellows 22, and a transmission groove 25 and a transmission groove 26 formed on the guide cylinder 12. The transmission ring 24 can transmit the extension and retraction of the metal bellows 22 to subsequent components, and the transmission grooves 25 and 26 provide stable sliding guidance for the transmission components, ensuring smooth transmission and avoiding jamming. Furthermore, the transmission assembly also includes an L-shaped slide rod 27 slidably disposed inside the transmission slide groove 25. One end of the L-shaped slide rod 27 extends into the transformer chamber 21 and is fixedly connected to the transmission ring 24, while the other end has a follower groove 30. The L-shaped slide rod 27 enables the steering transmission of power, and the design of the follower groove 30 provides a basis for the parallel linkage between the temperature-sensitive mechanism and the pneumatic drive unit, ensuring that their actions do not interfere with each other. Furthermore, the transmission assembly also includes a transmission slider 28 fixed inside the inner shielding cylinder 11 and passing through the transmission slide groove 26. One end of the transmission slider 28 is fixedly connected to an abutment wheel 29 located inside the follower groove 30. The abutment wheel 29 can slide freely within the follower groove 30, realizing parallel linkage and non-interference between the temperature-sensitive mechanism and the pneumatic drive unit. The cooperation between the abutment wheel 29 and the follower groove 30 ensures that the temperature-sensitive mechanism is not interfered with by the pneumatic drive unit when driving the inner shielding cylinder 11 to extend or retract. At the same time, when the pneumatic drive unit is activated, it can effectively drive the inner shielding cylinder 11 to extend or retract, realizing dual-drive without interference and improving the reliability of the equipment response. Furthermore, the equalizing wing unit includes an arc-shaped equalizing wing 31 hinged to the outer side of the front end of the inner shielding cylinder 11 via a hinge shaft. The outer shielding cylinder 10 has a receiving groove 32 corresponding to the arc-shaped equalizing wing 31 at one end facing the primary winding 8. A stretching spring 33 connects the inner side of the arc-shaped equalizing wing 31 to the outer wall of the inner shielding cylinder 11, ensuring reliable grounding of the arc-shaped equalizing wing 31 and the inner shielding cylinder 11. The arc-shaped equalizing wing 31 can form a 360° annular grounding conductive surface when extended, smoothing out the spike electric field at the end of the primary winding 8, suppressing partial discharge, and enhancing the electric field shielding effect. The receiving groove 32 can store the equalizing wing under normal conditions, reducing space occupation and eddy current losses. The stretching spring 33 provides a stable driving force for the deployment of the equalizing wing, ensuring reliable operation. Furthermore, the linkage monitoring unit includes a PT100 temperature probe 34 installed on the inner side of the front end of the inner shielding cylinder 11 and several miniature conductive contacts 35, which are arranged at intervals in the circumferential direction. The PT100 temperature probe 34 is electrically connected to the internal and external temperature measurement modules of the meter box 4. The miniature conductive contacts 35 are made of copper and are insulated from the inner shielding cylinder 11 through an insulating bushing. They can form a conductive circuit when the insulation layer of the primary winding 8 is damaged, triggering an early warning from the insulation monitoring module inside the meter box 4. The PT100 temperature probe 34 boasts high temperature measurement accuracy and stability, enabling real-time monitoring of the temperature at the ends of the primary winding 8 and timely temperature warnings. The copper miniature conductive contact 35 exhibits excellent conductivity, and the insulating bushing prevents short-circuit hazards, accurately detecting the integrity of the winding insulation layer and proactively identifying potential insulation damage. Notably, this linkage monitoring unit, combined with the independent triggering characteristics of the shielding cylinder drive mechanism, achieves automatic fault type identification and differentiated warnings: when the PT100 temperature probe 34 detects that the temperature at the ends of the primary winding 8 rises to 80℃ or above, and the inner shielding cylinder 11 is extended by the temperature-sensitive mechanism, the warning module in the meter box 4 outputs a winding overheating fault warning; when the PT100 temperature probe 34 detects that the temperature is within the normal range, and the inner shielding cylinder 11 is extended by the pneumatic drive unit, the warning module in the meter box 4 outputs an SF6 gas leak / abnormal pressure fault warning. Different warning signals directly distinguish the root cause of the fault, assisting maintenance personnel in quickly locating problems and simplifying the repair process.

[0026] During use, firstly, under normal operation, the inner shielding cylinder 11 is in a retracted state, only covering the iron core column 6, minimizing eddy current losses. At the same time, the outer shielding cylinder 10 is reliably grounded, effectively blocking the strong electric field of the primary winding 8, avoiding interference with the secondary winding 9, and ensuring accurate metering data. At this time, the arc-shaped equalizing wing 31 is housed in the storage slot 32, which reduces space occupation and energy loss under normal conditions, while protecting the equalizing wing and spring from wear and extending the service life of the components. At this time, SF6 maintains its rated pressure, fully exerting its insulation function, and the linkage monitoring unit operates without interference throughout the process, monitoring the temperature and insulation status in real time. Then, when the end temperature of the primary winding 8 rises to 80°C due to overload, the solid temperature-sensitive expansion core 19 undergoes a phase change after being heated, and its volume expands rapidly. The thrust generated by the expansion is transmitted to the contact ring 14 through the insulating ring 20, which drives the inner shielding cylinder 11 to extend along the guide cylinder 12 towards the end of the primary winding 8. At this time, the equalizing wing unit operates synchronously: the arc-shaped equalizing wing 31 unfolds under the action of the extension spring 33 to form a ring-shaped grounding conductive surface, flattening the end peak electric field, suppressing partial discharge, and avoiding electric field distortion and insulation aging caused by overheating; at the same time, the PT100 temperature probe 34 triggers a high temperature alarm, reminding the staff to check for overload hazards in time. When the temperature drops to 70℃, the paraffin-based material inside the solid temperature-sensitive expansion core 19 returns to solid state, shrinks and resets, and the reset spring 17 pushes the inner shielding cylinder 11 to shrink and reset. The pressure equalizing wing is re-stored in the storage groove 32, returning to normal, ensuring the safe operation of the equipment under abnormal thermal conditions. When SF6 leakage occurs in the sealed housing 2, the insulation capacity of SF6 drops significantly. At this time, the winding temperature remains within the normal range, and traditional temperature-triggered shielding schemes are completely unresponsive, easily leading to electric field breakdown and partial discharge. In this situation, the pneumatic drive unit responds quickly: the pressure difference between the inside and outside of the metal bellows 22 decreases, the disc spring 23 rebounds, pushing the metal bellows 22 to extend, causing the transmission ring 24 and L-shaped slide rod 27 to slide along the first transmission groove 25. The follower groove 30 on the L-shaped slide rod 27 pushes the contact wheel 29 and the transmission slider 28 to move along the second transmission groove 26, thereby causing the inner shielding cylinder 11 to extend. After the inner shielding cylinder 11 extends, it wraps around the end of the primary winding 8, replacing part of the SF6 insulation effect through a strong shielding effect, compensating for the insulation deficiency after SF6 leakage, preventing electric field concentration and partial discharge, and avoiding equipment failure. Simultaneously, the equalizing wings deploy synchronously, further strengthening the shielding effect. Insulation reinforcement can be achieved without manual intervention, significantly improving the fault tolerance and safety of the equipment. If the insulation layer of the primary winding 8 is damaged at this time, the miniature conductive contact 35 will come into contact with the exposed winding conductor to form a conductive circuit, triggering an early warning from the insulation monitoring module in the meter box 4. Staff can then stop the machine for maintenance in time to prevent the fault from escalating.

[0027] The working principle of the shielded voltage transformer with temperature measurement function provided by this invention is as follows: First, the sealed housing 2 adopts a closed structure, filled with SF6 insulating gas, which can effectively block the strong electric field at the end of the primary winding 8, avoid partial discharge, and ensure operational safety. At the same time, the closed structure can prevent external impurities from entering and SF6 gas from leaking, preventing oxidation damage to internal components. The high-voltage insulating tube 3 seals through the sealed housing 2, and the primary conductive rod inside it is specifically used to connect external high-voltage current and transmit it to the primary winding 8. The horizontal U-shaped closed iron core of the voltage transformer body consists of an iron core column 6 and two yokes 7 forming a complete magnetic circuit. After a high voltage current is applied to the primary winding 8, an alternating magnetic field is generated. The magnetic field forms a closed transmission through the iron core column 6 and the yokes 7, and acts on the secondary winding 9 wound on the other side of the iron core column 6. The secondary winding 9 generates a low voltage induced voltage with a fixed ratio to the primary winding 8 through electromagnetic induction. The voltage is output to the subsequent metering and protection equipment through the secondary junction box 5, realizing the metering of high voltage power and the transmission of protection signals. The outer shielding cylinder 10 is fixed to the internal support of the sealed shell 2 and reliably grounded. It is specifically used to form a basic electric field barrier to prevent the strong electric field generated by the primary winding 8 from interfering with the secondary winding 9 and to ensure measurement accuracy. The inner shielding cylinder 11 is sleeved between the guide cylinder 12 and the outer shielding cylinder 10. It is designed to be able to extend and retract along the axial direction of the iron core column 6. The core purpose is to adapt to different working conditions. Under normal conditions, it is in a retracted state, only covering the iron core column 6, which minimizes the eddy current loss generated by the alternating magnetic field cutting the conductive shield and reduces energy consumption. The SF6 insulating air gap reserved between the two is to further improve the insulation performance and prevent the inner shielding cylinder 11 from interfering with the iron core column 6 and the outer shielding cylinder 10. It ensures the insulation isolation between the shielding cylinder and the iron core and winding, and at the same time, it works with SF6 gas to achieve double insulation protection. The shielding cylinder drive mechanism adopts a parallel linkage design of temperature-sensitive mechanism and pneumatic drive unit. Relying on the sliding cooperation structure of transmission slider 28, contact wheel 29 and follower groove 30 on L-shaped slide bar 27, the power transmission paths of the two drive units are completely decoupled. The two share the inner shielding cylinder 11 as the execution terminal. Their actions do not interfere with each other and can respond to faults independently, ensuring that the shielding protection can be reliably triggered when any hidden danger occurs. When the temperature at the end of the primary winding 8 rises to 80°C or above, the solid-state temperature-sensitive expansion core 19 expands due to heat. This expansion pushes the contact ring 14 through the insulating ring 20. The insulating ring 20 prevents conductive interference and ensures stable transmission of driving force. This causes the inner shielding cylinder 11 to extend along the guide cylinder 12 towards the end of the primary winding 8. Under the limiting action of the limiting ring 18, it perfectly wraps around the high field strength area, suppressing partial discharge. When the temperature drops to 70°C or below, the solid-state temperature-sensitive expansion core 19 contracts and resets. The reset spring 17 in the reset chamber 16 pushes the contact ring 14 and the inner shielding cylinder 11 to retract to their normal position. During this process, the pneumatic drive unit remains in place and does not generate any mechanical obstruction. The metal bellows 22 has a built-in disc spring 23 and is evacuated to a low-pressure state. This design aims to create a stable pressure difference with the high-pressure SF6 gas inside the sealed housing 2. Under normal conditions, the high-pressure SF6 gas continuously compresses the metal bellows 22, keeping the disc spring 23 in a contracted state. This does not interfere with the normal contraction action of the inner shielding cylinder 11, ensuring low losses during normal equipment operation. When SF6 leaks from the sealed housing 2, the internal gas pressure decreases, the pressure difference between the inside and outside of the metal bellows 22 decreases, and the disc spring 23 rebounds, pushing the metal bellows 22 to extend. This, in turn, drives the transmission ring 24 and the L-shaped slide rod 27 to slide along the first transmission groove 25. The follower groove 30 on the L-shaped slide rod 27 pushes the contact wheel 29 and the transmission slider 28 to move along the second transmission groove 26, ultimately causing the inner shielding cylinder 11 to extend. Throughout the transmission process, through the coordinated operation of the transmission components, the change in SF6 gas pressure is converted into the extension and contraction of the shielding cylinder. The strong shielding effect of the shielding cylinder replaces part of the insulation effect of SF6, compensating for insufficient insulation, electric field concentration, and partial discharge after SF6 leakage. Furthermore, when the inner shielding cylinder 11 extends, the arc-shaped equalizing wing 31, under the elastic force of the extension spring 33, detaches from the receiving groove 32 at the end of the outer shielding cylinder 10, unfolds around the hinge axis, and forms a 360° annular grounding conductive surface, smoothing out the spike electric field at the end of the primary winding 8, further suppressing partial discharge, forming a double shield with the shielding cylinder, and improving the reliability of insulation protection; when the inner shielding cylinder 11 retracts, the arc-shaped equalizing wing 31 is brought into the receiving groove 32, squeezing the extension spring 33 to retract and reset, reducing the space occupation under normal conditions, while reducing eddy current loss, avoiding collision and wear of the equalizing wing and spring, and extending the service life of the components; Meanwhile, the PT100 temperature probe 34 and the miniature conductive contact 35 are spaced apart and arranged on the inner front side of the inner shielding cylinder 11, avoiding direct contact with the primary winding 8 to prevent interference with the normal operation of the winding and to ensure the accuracy of monitoring. The PT100 temperature probe 34 is specifically used to collect the temperature signal at the end of the primary winding 8 in real time and transmit it to the external temperature measurement module in the meter box 4. When the temperature reaches 75℃, a high temperature warning is triggered, and when it reaches 80℃, a high temperature alarm is triggered, reminding maintenance personnel to check for overheating hazards in advance and to prevent equipment damage caused by continuous temperature rise. It is also temperature sensitive. The mechanism's action provides a temperature reference, ensuring the accuracy of the temperature-sensitive drive; the miniature conductive contact 35 is made of copper with excellent conductivity, which can quickly form a conductive circuit. It is insulated and connected to the inner shielding cylinder 11 through an insulating bushing. When the inner shielding cylinder 11 extends, it fits against the insulation layer of the primary winding 8. If the insulation layer is damaged, the miniature conductive contact 35 contacts the exposed winding conductor to form a conductive circuit, triggering an early warning from the insulation monitoring module in the meter box 4. This allows for early detection of potential insulation damage and reminds maintenance personnel to shut down for repairs before electric field breakdown or equipment failure occurs, thus reducing losses from failures. Meanwhile, this solution leverages the parallel, independently triggered structure of the temperature-sensitive mechanism and the pneumatic drive unit, combined with real-time temperature data from the PT100 temperature probe 34, to form a clear fault diagnosis logic: if the inner shielding cylinder 11 extends and its temperature is ≥80℃, it is determined to be a winding overheating fault; if the inner shielding cylinder 11 extends and its temperature is within the normal range of 70℃ or below, it is determined to be an SF6 gas pressure leakage fault. The meter box 4 outputs corresponding differentiated warnings, allowing maintenance personnel to identify the cause of the fault and accurately carry out maintenance work without disassembling the machine for troubleshooting.

[0028] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A shielded voltage transformer with temperature measurement function, comprising a metal support frame (1), a sealed housing (2), a high-voltage insulating pipe (3) that is sealed and installed through the outer wall of the sealed housing (2), a meter box (4), and a secondary junction box (5), characterized in that: A primary conductive rod is inserted inside the high-voltage insulating tube (3), with one end of the primary conductive rod extending into the sealed housing (2); The sealed housing (2) is filled with SF6 insulating gas and has a voltage transformer body and a shielding cylinder drive mechanism inside. The voltage transformer body includes a horizontal U-shaped closed iron core, a primary winding (8), a secondary winding (9) and a double-layer telescopic shielding cylinder. The iron core is composed of an iron core column (6) and two yokes (7) on both sides. The primary winding (8) and the secondary winding (9) are respectively wound around the outer periphery of the iron core column (6). The double-layer telescopic shielding cylinder is sleeved on the outer periphery of the iron core column (6). It consists of an outer shielding cylinder (10) that is grounded and an inner shielding cylinder (11) that can be axially telescopic. Both are made of non-magnetic conductive materials, with SF6 insulation air gap reserved between the layers. A guide cylinder (12) that is sleeved on the iron core column (6) is fixed inside the outer shielding cylinder (10). The shielding cylinder driving mechanism includes a temperature-sensitive mechanism, a pneumatic driving unit and a pressure equalization wing unit, and a linkage monitoring unit is provided on the inner side of the front end of the inner shielding cylinder (11).

2. A shielded voltage transformer with temperature measurement function according to claim 1, characterized in that: The guide cylinder (12) is made of insulating material to achieve insulation isolation between the inner shielding cylinder (11) and the iron core column (6), so as to avoid the two from conducting and generating eddy currents. At the same time, it provides guidance and limit for the extension and retraction of the inner shielding cylinder (11) to prevent it from deviating or jamming during the extension and retraction process.

3. A shielded voltage transformer with temperature measurement function according to claim 1, characterized in that: The temperature-sensitive mechanism includes a positioning ring (13) fixedly sleeved in the middle section of the guide cylinder (12) and an abutment ring (14) fixedly sleeved at one end of the inner shielding cylinder (11). A thermosensitive expansion chamber (15) is formed between the positioning ring (13) and the abutment ring (14). A solid temperature-sensitive expansion core (19) is provided inside the thermosensitive expansion chamber (15). The guide cylinder (12) is fixedly connected to the inside of the inner shielding cylinder (11).

4. A shielded voltage transformer with temperature measurement function according to claim 3, characterized in that: An insulating ring (20) is provided between the solid temperature-sensitive expansion core (19) and the contact ring (14). A reset chamber (16) is formed between the end of the outer shielding cylinder (10) and the abutment ring (14). The reset chamber (16) is provided with a reset spring (17) and a limiting ring (18) fixed to the inner side of the outer shielding cylinder (10). One end of the reset spring (17) is fixed to the abutment ring (14), and the other end abuts against the limiting ring (18).

5. A shielded voltage transformer with temperature measurement function according to claim 1, characterized in that: The pneumatic drive unit includes a pressure chamber (21) and a metal bellows (22). The pressure chamber (21) is formed by the positioning ring (13) on the side away from the thermosensitive expansion chamber (15), the guide cylinder (12) and the outer shielding cylinder (10). The metal bellows (22) is located inside the pressure chamber (21) and has a built-in disc spring (23). The inside of the metal bellows (22) is drawn to a low pressure state.

6. A shielded voltage transformer with temperature measurement function according to claim 4, characterized in that: The pneumatic drive unit is also provided with a transmission assembly, which includes a transmission ring (24) fixedly connected to the end of the metal bellows (22), and a transmission groove one (25) and a transmission groove two (26) opened on the guide cylinder (12).

7. A shielded voltage transformer with temperature measurement function according to claim 6, characterized in that: The transmission assembly also includes an L-shaped slide rod (27) that is slidably disposed inside the transmission slide groove (25). One end of the L-shaped slide rod (27) extends into the transformer chamber (21) and is fixedly connected to the transmission ring (24), and the other end is provided with a follower groove (30).

8. A shielded voltage transformer with temperature measurement function according to claim 7, characterized in that: The transmission assembly also includes a transmission slider (28) fixed inside the inner shielding cylinder (11) and passing through the transmission slide groove (26). One end of the transmission slider (28) is fixedly connected to an abutment wheel (29) located inside the follower groove (30). The abutment wheel (29) can slide freely in the follower groove (30) to realize the parallel linkage and non-interference between the temperature-sensitive mechanism and the pneumatic drive unit.

9. A shielded voltage transformer with temperature measurement function according to claim 1, characterized in that: The equalizing wing unit includes an arc-shaped equalizing wing (31) hinged to the outer side of the front end of the inner shielding cylinder (11) via a hinge shaft. The outer shielding cylinder (10) has a receiving groove (32) corresponding to the arc-shaped equalizing wing (31) at one end facing the primary winding (8). An extension spring (33) is connected between the inner side of the arc-shaped equalizing wing (31) and the outer wall of the inner shielding cylinder (11). The arc-shaped equalizing wing (31) and the inner shielding cylinder (11) are reliably grounded.

10. A shielded voltage transformer with temperature measurement function according to claim 1, characterized in that: The linkage monitoring unit includes a PT100 temperature probe (34) installed on the inner side of the front end of the inner shielding cylinder (11) and several miniature conductive contact pieces (35), which are arranged at intervals in the circumferential direction. The PT100 temperature probe (34) is electrically connected to the internal and external temperature measurement modules of the meter box (4). The miniature conductive contact (35) is made of copper and is insulated from the inner shielding cylinder (11) through an insulating bushing. It can form a conductive circuit when the insulation layer of the primary winding (8) is damaged, triggering an early warning from the insulation monitoring module inside the meter box (4).

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