Ring main unit

Abstract

The invention discloses a ring main unit, which comprises a high-pressure gas tank, a low-pressure instrument chamber and a vacuum circuit breaker, and is characterized in that the ring main unit drives a corrugated pipe and a reflecting plate to be linked by using the pressure difference between the environment of the high-pressure gas tank and the interior of the circuit breaker, and realizes signal transmission through an optical fiber assembly crossing the gas tank and the instrument chamber. And the pressure difference change drives the reflecting plate to displace so as to change the light intensity received by the low-voltage side monitoring module. According to the ring main unit, a cross-regional passive monitoring framework is constructed, so that the problems that a sensor in a closed gas tank is difficult to supply power and is easily interfered are effectively solved, passive on-line monitoring and high-low voltage electrical isolation of a high-voltage side core component are realized, and the operation reliability of power distribution network equipment is remarkably improved.

Description

Technical Field

[0001] This application relates to the field of smart grid distribution equipment technology, and in particular to a gas-insulated ring main unit with passive real-time online monitoring function applied to a large-scale power grid security system. Background Technology

[0002] With the rapid development of smart grids and distribution automation technologies, ring main units (RNBs), as core node equipment in urban power distribution networks, are gradually evolving towards "primary and secondary integration" (i.e., deep integration of primary high-voltage equipment and secondary intelligent monitoring equipment). Especially in fully insulated and enclosed gas-insulated switchgear or environmentally friendly gas switchgear, real-time sensing of the operating status of core components has become an industry necessity to ensure the safety and intelligent dispatch of large-scale power grids. As a core component of RNBs, the vacuum circuit breaker's high-vacuum environment inside its arc-extinguishing chamber is crucial for interrupting load current and short-circuit current; its insulation performance and arc-extinguishing capability directly determine the safe operation level of the entire power distribution system.

[0003] In existing ring main unit (RMM) technology systems, to achieve full insulation protection, high-voltage components such as circuit breakers and busbars are typically sealed within gas-filled compartments (gas boxes), while control and monitoring equipment is placed in a separate low-voltage instrument room. While this structure improves safety, it also presents significant challenges for internal condition monitoring. In current technologies, monitoring the vacuum level of the vacuum circuit breaker within the gas box often requires deploying active electronic sensors inside the high-voltage gas box.

[0004] However, because the gas chamber is a closed, black-box environment, powering the sensors becomes a challenge (batteries cannot be replaced, and inductive power is greatly affected by load current fluctuations). Furthermore, the high-pressure gas chamber is filled with strong electric and magnetic fields, making sensitive electronic components highly susceptible to electromagnetic interference, leading to false alarms or damage. In addition, if an internal sensor malfunctions, the entire gas chamber often needs to be disassembled for repair, significantly increasing maintenance costs. Therefore, there is an urgent need to propose a new type of ring main unit to solve these problems. Summary of the Invention

[0005] The purpose of this invention is to provide a ring main unit with cross-regional passive monitoring capabilities. Without compromising the sealing structure and overall insulation performance of the ring main unit's gas box, it aims to overcome the physical isolation barrier between the high-voltage gas box and the low-voltage instrument room. This constructs a passive monitoring system that does not require active electronic components within the gas box and can be driven by the gas box's own environmental pressure characteristics. This solves the insulation coordination problem and electromagnetic interference issues in signal transmission between high and low voltage areas during the intelligent transformation of existing power distribution equipment, thereby achieving highly reliable sensing of the vacuum circuit breaker's status.

[0006] The technical solution adopted by this invention to solve the above problems is: a ring main unit, comprising a high-pressure gas box, a low-pressure instrument room independent of the high-pressure gas box, a vacuum circuit breaker body installed inside the high-pressure gas box and including a stationary end and a moving end, and a solid-sealed pole covering the outside of the vacuum circuit breaker body; the ring main unit is equipped with a vacuum degree detection system based on the environmental pressure difference of the high-pressure gas box, including: A first bellows is disposed on one side of the solid-sealed pole corresponding to the stationary end of the vacuum circuit breaker body. The interior of the first bellows is connected to the interior of the vacuum circuit breaker body, and the exterior of the first bellows is subjected to the ambient gas pressure of the high-pressure gas box. The first bellows is configured to be driven by the pressure difference between the vacuum degree inside the vacuum circuit breaker body and the insulating gas environment inside the high-pressure gas box. A reflector is movably disposed on the side of the solid-sealed pole where the first corrugated tube is located, and is linked to the telescopic end of the first corrugated tube to be configured to move with the telescopic extension of the first corrugated tube; one side of the reflector is provided with a first reflecting surface and a first absorbing surface that are distributed along its own direction of movement and have different optical reflection characteristics. An optical fiber assembly is arranged across the high-pressure gas box and the low-pressure instrument room. Part of the optical fiber assembly is embedded in the solidified pole. One end of the optical fiber assembly extends into the low-pressure instrument room, and the other end of the optical fiber assembly extends to the side of the solidified pole where the reflector is located. The end face of the optical fiber assembly near the reflector is directly opposite the movement path of the reflector. A monitoring module is installed in the low-pressure instrument room and connected to the fiber optic assembly. The monitoring module is configured to emit light through the fiber optic assembly and receive reflected light reflected back by the reflector.

[0007] When the vacuum level inside the vacuum circuit breaker body is within the normal range, the light emitted by the optical fiber assembly engages with the first reflective surface; when the vacuum level inside the vacuum circuit breaker body is disrupted, causing the internal air pressure to rise, the first corrugated tube extends and drives the reflector to move, so that the light emitted by the optical fiber assembly engages with the first absorption surface, thereby changing the intensity of the reflected light received by the monitoring module.

[0008] Preferably, the optical fiber assembly includes a transmitting optical fiber for emitting light and a receiving optical fiber for receiving light, which are coaxially arranged.

[0009] The solid-sealed pole has a limiting structure on the stationary side near the body of the vacuum circuit breaker for positioning the end of the optical fiber assembly. The end face of the transmitting optical fiber is exposed outside the limiting structure, and the end faces of several receiving optical fibers are arranged around the end face of the transmitting optical fiber.

[0010] The solid-sealed pole is also provided with a first base. The first base has a reflective window that is aligned with the end of the optical fiber assembly on the side near the optical fiber assembly. The reflective plate is movably disposed in the first base, and the reflective plate interacts with the light emitted from the optical fiber assembly through the reflective window.

[0011] Preferably, the first base is provided with a first movable groove extending along the telescoping direction of the first corrugated pipe, and the reflector is slidably disposed in the first movable groove.

[0012] The first movable groove is provided with a guide post whose axis is parallel to the extension and retraction direction of the first corrugated pipe. The reflector plate is provided with a guide groove that penetrates itself, and the guide post passes through the guide groove.

[0013] Preferably, the first movable groove is further provided with a first elastic element, the two ends of the first elastic element abutting against the inner wall of the first movable groove away from the solidified pole and the side of the reflector away from the solidified pole, respectively.

[0014] Preferably, the vacuum level inside the vacuum circuit breaker body is a standard vacuum level.

[0015] The ring main unit further includes a differential compensation mechanism, which includes: The second bellows is disposed on the side of the solid-sealed pole close to the first bellows. The interior of the second bellows is a sealed chamber with a preset standard vacuum degree and is not connected to the vacuum circuit breaker body. The exterior of the second bellows is subjected to the same ambient air pressure of the high-pressure gas box as the exterior of the first bellows. A connecting assembly is provided between the first bellows and the second bellows. The connecting assembly is configured such that when the ambient air pressure change of the high-pressure gas box causes the first bellows and the second bellows to expand and contract synchronously and equally, the connecting assembly drives the reflector to make a translational movement along the expansion and contraction direction of the first bellows; when the air pressure change inside the vacuum circuit breaker body causes a difference in the expansion and contraction of the first bellows and the second bellows, the connecting assembly tilts and drives the reflector to make a deflection movement.

[0016] Preferably, the connection component includes: A first connecting shaft rotatably connected to the first bellows; A second connecting shaft rotatably connected to the second bellows; The outer tube has a first connecting shaft and a second connecting shaft movably inserted into the two ends of the outer tube, and a second elastic element is provided between the first connecting shaft and the outer tube, and a third elastic element is provided between the second connecting shaft and the outer tube, so that the connecting assembly can adapt to the change in the distance between the first corrugated tube and the second corrugated tube when tilting.

[0017] Preferably, the ring main unit is characterized in that it comprises: The second base is disposed on the solid-sealing pole and located between the first corrugated pipe and the second corrugated pipe; the second base is provided with a second moving groove, and the reflector is disposed in the second moving groove; the second base is provided with a connecting groove communicating with the second moving groove, and the connecting groove extends along the extension and contraction direction of the first corrugated pipe. The second connector is fixedly installed at the midpoint of the outer tube, and the second connector passes through the connecting groove and connects to the reflector.

[0018] The reflector is configured to rotate within the second moving slot as the connecting assembly tilts.

[0019] Preferably, the second base has a second reflective surface with the same optical reflection characteristics as the first reflective surface on the side near the optical fiber assembly. At least one groove is formed on the second reflective surface that connects to the second moving groove. The extension direction of the groove is parallel to the extension direction of the first corrugated pipe.

[0020] The first reflective surface is configured such that when the reflective plate moves with the connecting assembly, the groove moves within the range of its orthographic projection on the first reflective surface, so as to form a complete light reflection path together with the second reflective surface; when the reflective plate moves with the connecting assembly, the first reflective surface deflects at an angle relative to the groove, thereby disrupting the integrity of the light reflection path.

[0021] Preferably, the first reflective surface is a striped structure disposed on the reflective plate, and the position of the first reflective surface corresponds to the groove.

[0022] Preferably, the first absorbing surface is disposed in the area outside the first reflecting surface on the reflector.

[0023] The beneficial effects of the embodiments of the present invention are as follows: 1. By employing a vacuum detection system based on the pressure difference of the high-pressure gas box environment within the ring main unit, and utilizing the pressure difference between the vacuum circuit breaker body and the insulating gas environment inside the high-pressure gas box to drive the mechanical bellows and reflector in linkage, and using optical fiber components arranged across the high-pressure gas box and the low-pressure instrument room for isolated transmission of optical signals, this technology effectively solves the technical problems encountered in the intelligent transformation of existing fully insulated and enclosed ring main units. These problems include difficulties in powering active electronic sensors due to the black box environment inside the gas box, high maintenance costs, and susceptibility of electronic components to interference and damage due to the high-voltage and strong magnetic field environment, as well as difficulties in the safe transmission of signals between high and low voltage areas. Furthermore, it achieves passive, real-time online sensing of the status of core components inside the high-pressure gas box without damaging the cabinet's sealing structure and insulation performance. The insulation characteristics of optical fiber complete the physical and electrical dual isolation between the high-voltage side detection end and the low-voltage side monitoring end, significantly improving the equipment's anti-interference capability and operational reliability.

[0024] 2. By employing a limiting structure on the solid-sealed pole and a first base with guide posts and elastic elements, the technical problems of difficult alignment between optical fibers and moving parts and easy optical path deviation due to vibration during long-term operation in existing technologies are effectively solved. This enables high-precision self-alignment installation between the optical fiber assembly and the reflector. The guide posts restrict the degree of freedom of movement of the reflector, and the elastic elements eliminate mechanical transmission gaps, ensuring that the monitoring optical path remains stable when the ring main unit experiences mechanical vibration or thermal expansion and contraction, further improving the accuracy of monitoring data and the mechanical life of the device.

[0025] 3. Because this application employs a differential compensation mechanism, a second bellows, internally encapsulated in a standard vacuum and not connected to the main body of the vacuum circuit breaker, serves as an environmental reference. This allows the second bellows to withstand the same high-pressure gas chamber ambient pressure as the first bellows. A connecting assembly, including an outer tube and an elastic telescopic structure, connects the two bellows. A second base with grooves parallel to the telescopic direction forms a grating-type detection structure with the reflector. This transforms the synchronous and equal telescopic movement of the two bellows caused by ambient pressure fluctuations into a translational movement of the reflector within the optical path projection range that maintains the integrity of the optical path. Conversely, differential telescopic movement caused only by vacuum disruption is transformed into a disruption of the reflector's optical path integrity. The deflection motion technique effectively solves the technical problem in existing single-corrugated pipe monitoring schemes where pressure fluctuations in the insulating gas (such as SF6 or dry air) inside the high-voltage gas box of the ring main unit cause the first corrugated pipe to malfunction, leading to false triggering of the monitoring device. Furthermore, it enables automatic filtering of interference caused by environmental pressure fluctuations through logical operations of a purely mechanical structure. Without the need for complex electronic algorithm compensation, it accurately distinguishes between normal physical deformation caused by environmental factors and fault deformation caused by vacuum degree destruction, significantly reducing the false alarm rate of the system and greatly improving the detection accuracy and operational reliability of the online vacuum degree monitoring device under complex working conditions. Attached Figure Description

[0026] Figure 1 A schematic diagram of the structure of a vacuum circuit breaker body according to an embodiment of the present invention is shown.

[0027] Figure 2 A partial schematic diagram of the main body of a vacuum circuit breaker according to an embodiment of the present invention is shown.

[0028] Figure 3 This diagram illustrates a structure in which the first corrugated pipe, the first connector, the reflector, and the first base are connected according to an embodiment of the present invention.

[0029] Figure 4 A cross-sectional view of the structure of the first bellows, the first connector, the reflector and the first base in connection according to an embodiment of the present invention is shown.

[0030] Figure 5 A schematic structural diagram of a reflector according to an embodiment of the present invention is shown.

[0031] Figure 6 A schematic diagram of the structure of a vacuum circuit breaker body according to another embodiment of the present invention is shown.

[0032] Figure 7 A partial schematic diagram of the body of a vacuum circuit breaker according to another embodiment of the present invention is shown.

[0033] Figure 8 This diagram illustrates a structure in which a first corrugated pipe, a connecting assembly, a second corrugated pipe, a reflector, and a second base are connected according to an embodiment of the present invention.

[0034] Figure 9 This diagram illustrates the structure of a connecting component and a reflector in a connected state according to an embodiment of the present invention. Figure 1 .

[0035] Figure 10 This diagram illustrates the structure of a connecting component and a reflector in a connected state according to an embodiment of the present invention. Figure 2 .

[0036] Figure 11 This diagram shows a side sectional view of the connecting assembly and the reflector in a connected state according to an embodiment of the present invention. Figure 1 .

[0037] Figure 12 This diagram shows a side sectional view of the connecting assembly and the reflector in a connected state according to an embodiment of the present invention. Figure 2 .

[0038] Figure 13A schematic diagram of the structure of a vacuum circuit breaker main ring network cabinet according to an embodiment of the present invention is shown.

[0039] The components include: 1. Vacuum circuit breaker body; 2. Solid-sealed pole; 3. Limiting structure; 4. Optical fiber assembly; 410. Transmitting optical fiber; 420. Receiving optical fiber; 5. First corrugated tube; 6. First base; 610. First moving groove; 7. First connector; 8. Reflector; 810. First reflecting surface; 820. First absorbing surface; 830. Guide groove; 9. Guide post; 10. First elastic element; 11. Second corrugated tube; 12. Connecting assembly; 1210. First connecting shaft; 1220. Second connecting shaft; 1230. Appearance; 1240. Second elastic element; 1250. Third elastic element; 13. Second base; 1310. Second moving groove; 1320. Connecting groove; 1330. Second reflecting surface; 1331. Cable groove; 14. Second connector. Detailed Implementation

[0040] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0041] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0042] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0043] Existing vacuum circuit breakers are difficult to detect in a timely manner when the vacuum level is compromised during use.

[0044] To address the aforementioned issues, a preferred embodiment of this application provides a ring main unit with online vacuum monitoring capabilities, aiming to solve the problem that vacuum level deterioration in existing vacuum circuit breakers is difficult to detect in a timely manner.

[0045] Figure 1 A schematic diagram of the structure of a vacuum circuit breaker body 1 according to an embodiment of the present invention is shown. Figure 2 A partial schematic diagram of the vacuum circuit breaker body 1 according to an embodiment of the present invention is shown. Figure 3 This diagram illustrates a structure in which the first corrugated pipe 5, the first connector 7, the reflector 8, and the first base 6 are connected according to an embodiment of the present invention. Figure 4 A cross-sectional view of the structure of the first corrugated pipe 5, the first connector 7, the reflector 8 and the first base 6 in an embodiment of the present invention is shown. Figure 5 A schematic structural diagram of a reflector 8 according to an embodiment of the present invention is shown. Figure 13 A schematic diagram of the structure of a vacuum circuit breaker main ring network cabinet according to an embodiment of the present invention is shown.

[0046] Please see Figures 1 to 5 and Figure 13 The ring main unit structurally achieves passive sensing and optical signal transmission across high and low pressure compartments. The ring main unit includes a sealed high-pressure gas chamber, a low-pressure instrument compartment independent of the high-pressure gas chamber, a vacuum circuit breaker body 1 installed inside the high-pressure gas chamber and containing stationary and moving ends, and a solid-sealed pole 2 covering the outside of the vacuum circuit breaker body. The ring main unit is equipped with a vacuum degree detection system based on the environmental pressure difference of the high-pressure gas chamber, including a first bellows 5, a reflector 8, an optical fiber assembly 4, and a monitoring module.

[0047] The first bellows 5 is disposed on one side of the solid-sealed pole 2 corresponding to the stationary end of the vacuum circuit breaker body 1. The interior of the first bellows 5 is in communication with the interior of the vacuum circuit breaker body 1, and the exterior of the first bellows 5 is subjected to the ambient gas pressure of the high-pressure gas box. The first bellows 5 is configured to expand and contract using the pressure difference between the interior of the vacuum circuit breaker body 1 and the high-pressure gas box. The first bellows 5 is configured to be driven by the pressure difference between the vacuum level inside the vacuum circuit breaker body 1 and the insulating gas environment inside the high-pressure gas box.

[0048] The reflector 8 is movably disposed on the side of the solid-sealed pole 2 where the first corrugated tube 5 is located, and is linked with the telescopic end of the first corrugated tube 5 so as to be displaced as the first corrugated tube 5 telescopically extends; one side of the reflector 8 is provided with a first reflective surface 810 and a first absorptive surface 820 distributed along its own direction of movement and having different optical reflective properties.

[0049] The optical fiber assembly 4 is partially embedded in the solidified pole 2. One end of the optical fiber assembly 4 extends into the low-pressure instrument room, and the other end of the optical fiber assembly 4 extends into the side of the solidified pole 2 where the reflector 8 is located. The end face of the optical fiber assembly 4 near the reflector 8 is directly opposite the movement path of the reflector 8.

[0050] The monitoring module is located in the low-pressure instrument room and connected to the optical fiber assembly 4. The monitoring module is configured to emit light through the optical fiber assembly 4 and receive reflected light reflected back by the reflector 8.

[0051] When the vacuum level inside the vacuum circuit breaker body 1 is within the normal range, the light emitted by the optical fiber assembly 4 engages with the first reflective surface 810; when the vacuum level inside the vacuum circuit breaker body 1 is disrupted, causing the internal air pressure to rise, the first bellows 5 extends and drives the reflector 8 to move, so that the light emitted by the optical fiber assembly 4 engages with the first absorption surface 820, thereby changing the intensity of the reflected light received by the monitoring module.

[0052] Specifically: The main structure of the ring main unit is a cabinet. The interior of the cabinet is physically divided into a fully enclosed high-voltage gas chamber and an openable low-voltage instrument compartment by metal or insulating partitions. The high-voltage gas chamber is typically a gas-filled compartment filled with insulating gases such as sulfur hexafluoride or dry air, used to install high-voltage live components. The low-voltage instrument compartment is independent of the high-voltage gas chamber, located in a safe ground potential environment, and is used to install secondary instruments, relay protection devices, and the monitoring module in this embodiment. This compartmentalized layout design ensures physical and electrical isolation between high-voltage and low-voltage electrical systems, conforming to the structural standards of gas-insulated metal-enclosed switchgear (C-GIS).

[0053] The core component located inside the high-voltage gas chamber is the vacuum circuit breaker body 1, which includes a stationary end and a moving end. To improve insulation strength and environmental adaptability, the vacuum circuit breaker body 1 is completely encapsulated within a solid-sealed pole 2. The solid-sealed pole 2 is molded using epoxy resin through an automated pressure gel casting process, encapsulating the vacuum circuit breaker body 1 into a single insulating unit.

[0054] On the side of the solid-sealed pole 2 corresponding to the stationary end of the vacuum circuit breaker body 1, a first bellows 5 is integrated. The first bellows 5 is a pressure-sensitive elastic metal element. Its installation structure is unique: the internal space of the first bellows 5 is directly connected to the internal vacuum interrupter chamber of the vacuum circuit breaker body 1 through a gas guide channel, ensuring that its internal pressure is always the same as that of the interrupter chamber; while the external surface of the first bellows 5 is directly exposed to the environment of the high-pressure gas box, bearing the ambient gas pressure inside the ring main unit gas box. Therefore, the first bellows 5 is configured to generate axial expansion and contraction deformation by utilizing the pressure difference between the internal gas pressure of the interrupter chamber and the ambient gas pressure of the high-pressure gas box.

[0055] The reflector 8 is movably mounted on the side of the solid-sealed pole 2 where the first bellows 5 is installed, and is mechanically linked to the telescopic end (movable end) of the first bellows 5. This linkage allows the reflector 8 to precisely move in sync with the telescopic movement of the first bellows 5. A key feature of the reflector 8 is that its surface facing the detection side has two regions with distinctly different optical properties, which are distributed sequentially along the direction of movement of the reflector 8: The first reflective surface 810 is made of a high-reflectivity material, such as a mirrored metal sheet or a reflective coating, for efficient reflection of light signals.

[0056] The first absorbing surface 820 is made of a light-absorbing material, such as a black matte coating or a light-absorbing velvet surface, to absorb light signals and make the reflectivity extremely low.

[0057] The fiber optic assembly 4 acts as a bridge for signal transmission across the high and low voltage instrument rooms. Its main body is embedded in the epoxy resin medium of the solidified pole 2, utilizing the resin's excellent insulation properties to achieve high-voltage isolation. One end of the fiber optic assembly 4 extends into the safe low-voltage instrument room and connects to the monitoring module; the other end extends to the side of the solidified pole 2 where the reflector 8 is installed, with the end face perpendicular to the movement path of the reflector 8. This fiber optic assembly 4 can be a single fiber with a beam splitter, or a coaxial fiber bundle (center transmitter, peripheral receiver) used for both light transmission and reception.

[0058] The monitoring module, housed in the low-voltage instrument room, includes a light source driving circuit and a photoelectric signal processing circuit. Connected to fiber optic assembly 4, it is configured to transmit continuous or pulsed light signals into the fiber and to receive and analyze the intensity of the light signals transmitted back from the fiber in real time. Specifically, the monitoring module, acting as the brain of the entire online monitoring system, is integrated within the low-voltage instrument room. To achieve the transmission, reception, and intelligent processing of light signals, the monitoring module specifically includes a controlled light source (transmitting module), a photoelectric receiver (receiving module), and a microcontroller (MCU).

[0059] The controlled light source is connected to the transmitting fiber 410, and the controlled light source is typically a high-stability light-emitting diode (LED) or laser diode (LD). To ensure the constant intensity of the emitted light, a constant current driver chip is integrated into the light source circuit. The transmitting fiber 410 (located at the center of the coaxial structure) in the fiber optic assembly 4 is coupled to the optical output port of the controlled light source at one end in the low-voltage instrument compartment via a standard fiber optic connector (such as FC, ST, or SMA connector). The microcontroller sends a drive signal (such as a pulse modulation signal) to the controlled light source, controlling the light source to emit a probe beam according to a preset frequency or timing, which is transmitted to the reflector 8 on the high-voltage side via the transmitting fiber 410.

[0060] The photodetector is connected to the receiving optical fiber 420, which employs a high-sensitivity photodiode (PD) or photomultiplier tube (PMT). The receiving optical fiber 420 (located on the periphery of the coaxial structure) in the optical fiber assembly 4 is bundled at one end of the low-voltage instrument compartment and coupled to the optical input port of the photodetector via an optical fiber connector. The photodetector converts the weak optical signal returned from the receiving optical fiber 420 into an electrical signal (current or voltage). This electrical signal is then conditioned by a preamplifier circuit and a filter circuit to remove noise interference, ultimately outputting an analog voltage signal whose amplitude is directly proportional to the intensity of the received reflected light.

[0061] The microcontroller (such as the STM32 series, DSP, or FPGA) has a built-in analog-to-digital converter (ADC). It connects to the output of the photodetector, acquires the analog voltage signal in real time, and digitizes it to accurately obtain the current received light intensity value. The microcontroller internally stores a preset safe light intensity threshold. The microcontroller compares the real-time acquired light intensity value with the safe threshold. If the real-time light intensity is higher than the threshold, it is determined to be "normal," and the microcontroller sends a normal status code to the background monitoring system via a communication interface (such as RS485 or CAN bus), or drives the green indicator light to remain constantly lit. If the real-time light intensity is lower than the threshold (a step drop occurs), it is determined to be an abnormal vacuum level, and the microcontroller immediately sends an alarm signal, drives the red alarm light to flash, and can output a relay dry contact signal to lock the circuit breaker's operating circuit.

[0062] For example, the controlled light source uses an infrared LED with a center wavelength of 850nm and an emission power set to the mW level. The photodetector uses a PIN photodiode that is sensitive to the 850nm band. The microcontroller sets a safety threshold of 50% of full scale. When the vacuum level is normal, the reflected light intensity is 80% of full scale (above 50%), and the system displays normally. When the vacuum level is disrupted, causing the reflector 8 to deflect or shift, the reflected light intensity drops to 10% of full scale (below 50%). After several consecutive sampling cycles, the microcontroller triggers the alarm logic. Because the monitoring module includes a controlled light source, a photoelectric receiver, and a microcontroller, and is coupled to the transmitting fiber optic cable 410 and the receiving fiber optic cable 420 respectively via fiber optic connectors, and utilizes the microcontroller to perform analog-to-digital conversion and threshold comparison of the received light intensity, it effectively solves the technical problems in existing technologies where relying solely on visual observation or simple switch detection cannot accurately quantify light intensity changes, and is susceptible to misjudgments due to light source aging or transmission loss. Furthermore, it achieves precise digital demodulation of reflected light signals, can compensate for optical path attenuation through software algorithms, flexibly set alarm thresholds, and provides a standardized data communication interface, significantly improving the intelligence and environmental adaptability of the monitoring system.

[0063] In this embodiment, based on the aforementioned structural layout, a mechanical-optical linkage system is cleverly constructed inside the cabinet, utilizing the environmental pressure of the high-pressure gas box as the driving source. This design not only avoids the power supply and maintenance difficulties associated with arranging active electronic sensors within a closed gas box, but more importantly, it utilizes the insulation transmission characteristics of fiber optic components across the gas box partition to completely solve the signal transmission insulation coordination problem in high and low voltage areas at the physical structure level. Compared to traditional circuit breaker online monitoring solutions, this solution deeply integrates the monitoring device with the ring main unit's cabinet structure, achieving intrinsically safe monitoring of core components even in environments with strong electromagnetic interference.

[0064] When the vacuum circuit breaker body 1 is in a good vacuum state, its internal air pressure is extremely low (high vacuum), while the first bellows 5 is subjected to the relatively high pressure (usually slightly positive pressure) of the ring main unit's gas box. At this time, the huge internal and external pressure difference overcomes the elastic resistance of the first bellows 5, compressing it into a contracted state. Driven by the first bellows 5, the reflector 8 is in the normal position. At this time, the end face of the fiber optic assembly 4 on the side of the solidified pole 2 faces the first reflective surface 810 on the reflector 8. The light emitted by the monitoring module is transmitted through the optical fiber and then shines on the first reflective surface 810. Most of the light energy is reflected back to the fiber optic assembly 4 along the original path or in a directional manner, and is finally received by the monitoring module in the low-pressure instrument room. The monitoring module detects the high-intensity reflected light signal and determines that the equipment is in a normal state.

[0065] When the vacuum circuit breaker body 1 experiences a vacuum failure due to ceramic cracking or seal failure, external gas seeps in, and the internal pressure gradually increases, approaching the ambient pressure. At this time, the pressure difference acting on the inside and outside of the first bellows 5 significantly decreases or even disappears. Due to the loss of the pressure difference restraint force, the first bellows 5 undergoes axial elongation (springback) under the action of its own material elasticity. The elongation of the first bellows 5 directly drives the reflector 8 to shift, causing it to slide from the normal position to the fault position.

[0066] As the reflector 8 shifts, the area facing the end face of the fiber optic assembly 4 changes from the first reflecting surface 810 to the first absorbing surface 820. At this time, the light emitted by the monitoring module shines on the light-absorbing material, and a large amount of light energy is absorbed, causing a sharp drop in the intensity of the light reflected back into the fiber. The monitoring module detects that the reflected light intensity is below a preset safety threshold, immediately determines that the vacuum circuit breaker has failed, and outputs an alarm signal or drives the control circuit to lock out the malfunction, preventing operation while faulty.

[0067] The technical solution in this embodiment is applicable to gas-insulated ring main units (C-GIS) or solid-insulated cabinets of various voltage levels, and is particularly suitable for power distribution sites with high insulation requirements, compact space, and where frequent manual inspections are not feasible. Furthermore, since the detection components located in the high-voltage gas box (first corrugated pipe 5, reflector 8, fiber optic assembly 4) are all composed of metal mechanical parts or insulating materials and contain no active electronic components, this solution can operate stably for extended periods in strong electric and magnetic field environments, completely immune to electromagnetic interference and radio frequency interference. Moreover, this solution relies on the ambient air pressure inside the ring main unit's gas box as a reference pressure. Therefore, it is suitable for environments with relatively stable air pressure inside the gas box.

[0068] In another embodiment, the positions of the first reflecting surface 810 and the first absorbing surface 820 on the reflector 8 can be interchanged. That is, it is set so that the optical fiber faces the absorbing surface (low light intensity) under normal conditions, and moves to the reflecting surface (high light intensity) under fault conditions. This light alarm logic is also feasible. The first bellows 5 can be made of corrosion-resistant and highly elastic alloy materials such as stainless steel or phosphor bronze to ensure operational reliability after long-term static placement. The linkage between the reflector 8 and the first bellows 5 can be directly rigidly connected by a connecting rod, or it can be driven by a gear and rack mechanism to adjust the transmission ratio of the displacement.

[0069] Furthermore, in this embodiment, a first bellows 5 is installed at the stationary end of the vacuum circuit breaker corresponding to the solid-sealed pole 2. This utilizes the pressure difference between the inside of the vacuum circuit breaker body 1 and the external high-pressure gas box to generate mechanical expansion and contraction deformation, thereby driving the displacement of the reflector 8 with different optical characteristic regions. The optical path change is then transmitted to the monitoring module in the independent low-voltage instrument room for judgment through the pre-embedded insulated optical fiber assembly 4. Therefore, this effectively solves the technical problems in the prior art, such as the difficulty in real-time detection of vacuum circuit breaker vacuum degree failure, and the susceptibility of traditional online monitoring schemes to false alarms due to strong electromagnetic interference when electronic sensors are placed on the high-voltage side, as well as the significant insulation risks. This achieves passive, real-time, and intrinsically safe monitoring of vacuum circuit breaker vacuum degree under high-voltage and strong magnetic field operating conditions. The pure optical and mechanical principles completely eliminate the influence of electromagnetic interference and achieve electrical isolation between the high and low voltage sides, significantly improving the operational safety and intelligent maintenance efficiency of the ring main unit.

[0070] For further information, please refer to [link / reference]. Figure 2 In some embodiments, the optical fiber assembly 4 includes a transmitting optical fiber 410 for emitting light and a receiving optical fiber 420 for receiving light, coaxially arranged. The solid-sealed pole 2 has a limiting structure 3 for positioning the end of the optical fiber assembly 4 on the stationary side near the vacuum circuit breaker body 1. The end face of the transmitting optical fiber 410 is exposed outside the limiting structure 3, and the end faces of several receiving optical fibers 420 are arranged around the end face of the transmitting optical fiber 410. The solid-sealed pole 2 is also provided with a first base 6. The first base 6 has a reflective window aligned with the end of the optical fiber assembly 4 on the side near the optical fiber assembly 4. A reflector 8 is movably disposed within the first base 6, and the reflector 8 interacts with the light emitted from the optical fiber assembly 4 via the reflective window.

[0071] Specifically: The fiber optic assembly 4 abandons the traditional dual-strand parallel arrangement and innovatively adopts a coaxial structure. Specifically, the fiber optic assembly 4 is divided into two functional areas from the inside out: at the center is a single or bundled transmitting fiber 410 for emitting light, serving as the core of the optical signal output; around the radial periphery of the transmitting fiber 410, several receiving fibers 420 are tightly arranged for receiving light. From the end face, the transmitting fiber 410 is located at the center, and the receiving fibers 420 form a ring-shaped receiving band surrounding the transmitting fiber 410, constituting a bullseye-like optical end face structure. This structure is typically encapsulated in a uniform sheath, forming the appearance of a single cable 1230.

[0072] On one side of the solid-sealed pole 2 corresponding to the stationary end of the vacuum circuit breaker body 1, a limiting structure 3 is integrally formed using an epoxy resin casting process. This limiting structure 3 is specifically manifested as a blind hole, slot, or stepped mounting base extending into the solid-sealed pole 2. The inner diameter of this limiting structure 3 precisely matches the size of the end of the optical fiber assembly 4, used for radial fixing and axial positioning of the end of the optical fiber assembly 4. The end of the optical fiber assembly 4 is inserted into the limiting structure 3, so that the end face of the transmitting optical fiber 410 and the end face of the receiving optical fiber 420 are exposed outside the limiting structure 3 (or flush with the port of the limiting structure 3), directly facing the detection area. At this time, several end faces of the receiving optical fibers 420 are evenly distributed in space around the end face of the transmitting optical fiber 410, forming a wide-angle signal receiving aperture.

[0073] A first base 6 is also fixedly installed on the solidified pole 2. This base is located outside the limiting structure 3 and serves as the moving carrier for the reflector 8. The first base 6 has a through hole or a window with a transparent medium embedded on the side near the optical fiber assembly 4, which is the reflective window. The central axis of the reflective window is collinear with the axis of the transmitting optical fiber 410 of the optical fiber assembly 4, realizing the alignment of the optical fiber end face, the reflective window, and the reflector 8.

[0074] The reflector 8 is movably installed in the internal cavity of the first base 6, with its side having a reflective surface and an absorptive surface facing the reflective window. Light emitted from the fiber optic assembly 4 must pass through this reflective window to illuminate the reflector 8, and similarly, light reflected back from the reflector 8 must also pass through the reflective window to be captured by the receiving fiber optic cable 420.

[0075] During operation, the central transmitting fiber 410 emits a divergent or parallel beam of light, which passes through the reflection window on the first base 6 and is projected onto the surface of the reflector 8. Because light undergoes scattering and diffraction during transmission and reflection, the reflected beam's spot typically expands. Traditional parallel dual-fiber structures are prone to signal loss at the receiver (a dead zone) due to reflected beam spot offset. However, in this embodiment, since the receiving fiber 420 surrounds the transmitting fiber 410, regardless of the slight offset of the reflected beam in any direction, as long as the beam falls within the annular receiving band formed by the receiving fiber 420, the optical signal can be effectively captured. This significantly improves the coupling efficiency and anti-jitter capability of optical energy.

[0076] The limiting structure 3 ensures the positional stability of the fiber optic assembly 4, preventing displacement or detachment of the fiber optic end. When the reflector 8 moves within the first base 6 with the corrugated tube, the reflective window acts as an optical stop, defining the effective detection area and reducing stray light interference. When light shines onto the reflector 8 through the reflective window, if it encounters the first reflecting surface 810, the strongly reflected light passes through the reflective window and is collected by the peripheral receiving fiber 420; if it encounters the first absorbing surface 820, the light is absorbed, and the intensity of the light collected by the receiving fiber 420 drops sharply.

[0077] In some alternative embodiments and solutions, the limiting structure 3 can be an integrally cast resin groove, and the reflective window can be an open through-hole, or it can be embedded with high-transmittance quartz glass or sapphire glass to protect the fiber end face from contamination. The receiving fiber 420 can be arranged in a single tightly packed loop, or in a multi-loop stacked loop, or even in an integral annular receiving surface formed by fused taper of multiple fibers to further increase the light-receiving area.

[0078] In this embodiment, by employing the technical means of coaxially setting the transmitting and receiving optical fibers 420 with the optical fiber assembly 4, constructing a precision limiting structure 3 on the solidified pole 2, and cooperating with the first base 6 with a reflective window, the technical problems of difficult installation and alignment of split optical fibers, easy optical path deviation leading to signal loss under strong equipment vibration, and poor signal-to-noise ratio due to low reflected light collection efficiency in the prior art are effectively solved. This achieves efficient optical signal coupling in a compact space, significantly improves the optical path stability and detection sensitivity of the online monitoring device under long-term operation and mechanical shock, and reduces the risk of false alarms caused by installation errors or environmental vibrations.

[0079] Furthermore, to ensure the stability and accuracy of the reflector 8 during displacement, please refer to [link / reference needed]. Figure 4 In some embodiments, the first base 6 is provided with a first movable groove 610 extending along the telescopic direction of the first corrugated pipe 5, and the reflector 8 is slidably disposed within the first movable groove 610. The first movable groove 610 is provided with a guide post 9 whose axial direction is parallel to the telescopic direction of the first corrugated pipe 5, and the reflector 8 is provided with a through guide groove 830, in which the guide post 9 passes. The first movable groove 610 is also provided with a first elastic member 10, the two ends of which abut against the inner wall of the first movable groove 610 away from the solidified pole 2 and the side of the reflector 8 away from the solidified pole 2, respectively.

[0080] To provide a stable trajectory for the reflector 8, a first moving groove 610 is constructed inside the first base 6 fixed on the sealing pole 2. This first moving groove 610 is a cavity or channel of a certain depth, and its extension direction is strictly consistent with the extension direction of the first bellows 5 (i.e., coaxial or parallel). The inner wall surface of the first moving groove 610 is smoothed, serving as the outer boundary for the movement of the reflector 8. The reflector 8 is not suspended but embedded within the first moving groove 610, and the outer contour dimensions of the reflector 8 and the inner cavity dimensions of the first moving groove 610 are fitted with a clearance or sliding fit. This design confines the reflector 8 within the first moving groove 610, allowing it to move linearly back and forth along the groove's extension direction, thus limiting its lateral offset or flipping freedom.

[0081] To further eliminate the risk of swaying or jamming of the reflector 8 during movement, a guide post 9 is integrated inside the first moving groove 610. The guide post 9 is a rigid cylinder or prism, fixed to the bottom or end wall of the first moving groove 610, and its axial direction is strictly parallel to the extension / retraction direction of the first bellows 5. Correspondingly, a guide groove 830 (or guide hole) penetrating the thickness direction is formed on the reflector 8 body. The diameter or width of the guide groove 830 is slightly larger than the cross-sectional dimensions of the guide post 9. In the assembled state, the guide post 9 passes through the guide groove 830 on the reflector 8. At this time, the reflector 8 acts like a slider on a track, with the guide post 9 acting as a central skeleton, ensuring that the reflector 8 slides smoothly along the axis of the guide post 9 when under force, preventing tilting or jamming caused by uneven force.

[0082] The first elastic element 10 is also housed within the internal space of the first moving groove 610. The first elastic element 10 is typically a cylindrical helical compression spring. Its installation position has a specific abutment relationship: one end of the first elastic element 10 abuts against the inner wall of the first moving groove 610 away from the fixed electrode post 2 (i.e., the bottom surface or sealing surface of the groove), and the other end abuts against the surface of the reflector plate 8 away from the fixed electrode post 2. In other words, the first elastic element 10 is located in front of the movement of the reflector plate 8 (assuming the bellows protruding outwards is considered the front). In the initial state, the first elastic element 10 is in a state of free extension or slight pre-compression, using its elastic force to press the reflector plate 8 towards the fixed electrode post 2, making it tightly adhere to the linkage end of the first bellows 5, eliminating mechanical connection gaps.

[0083] When the vacuum level of the vacuum circuit breaker body 1 is disrupted, causing the first bellows 5 to elongate, the bellows pushes the reflector 8 away from the solid-sealed pole 2. At this time, under the thrust, the reflector 8 slides along the inner wall of the first moving groove 610. Simultaneously, the guide groove 830 on the reflector 8 slides along the fixed guide post 9. The guide post 9 restricts all rotational degrees of freedom of the reflector 8, forcing it to only perform precise axial linear translation.

[0084] As the reflector 8 moves away from the fixed end post 2, the first elastic element 10 located in front of the reflector 8 is gradually compressed. The reverse elastic force (resistance) generated by the first elastic element 10 acts on the reflector 8. When the bellows thrust is greater than the elastic force, the reflector 8 continues to move into place. If resetting is required (e.g., bellows retraction after maintenance, or to eliminate vibration effects), the elastic potential energy stored in the first elastic element 10 is released, pushing the reflector 8 to move in the opposite direction to the fixed end post 2, ensuring that the reflector 8 always closely follows the movement of the bellows and preventing lag or disengagement. At the same time, the preload of the spring also prevents the reflector 8 from mis-displaced under normal equipment vibration.

[0085] In this embodiment, by employing a guide post 9 parallel to the direction of movement within the movable groove of the first base 6, which works in conjunction with the guide groove 830 on the reflector plate 8 for interpenetration and guidance, and by utilizing the first elastic element 10 to apply a reverse abutment pre-tightening force to the reflector plate 8, the technical problems in the prior art that the reflector plate 8 is prone to tilting and jamming due to lateral force when moving with the corrugated pipe, prone to mis-displacement under equipment vibration, and cause lag in action due to mechanical connection gaps are effectively solved. This achieves a high degree of linearity and stability in the movement trajectory of the reflector plate 8, ensures the accuracy of optical detection alignment, and endows the mechanism with the ability to resist vibration interference and automatically eliminate gaps, significantly improving the mechanical reliability of the monitoring device.

[0086] Figure 6 A schematic diagram of the structure of a vacuum circuit breaker body 1 according to another embodiment of the present invention is shown. Figure 7 A partial schematic diagram of the vacuum circuit breaker body 1 according to another embodiment of the present invention is shown. Figure 8 This diagram illustrates a structure in which the first corrugated pipe 5, the connecting component 12, the second corrugated pipe 11, the reflector 8, and the second base 13 are connected according to an embodiment of the present invention. Figure 9 This diagram illustrates the structure of the connecting component 12 and the reflector 8 in a connected state according to an embodiment of the present invention. Figure 1 . Figure 10 This diagram illustrates the structure of the connecting component 12 and the reflector 8 in a connected state according to an embodiment of the present invention. Figure 2 . Figure 11 This figure shows a side sectional view of the connecting assembly 12 and the reflector 8 in a connected state according to an embodiment of the present invention. Figure 1 . Figure 12 This figure shows a side sectional view of the connecting assembly 12 and the reflector 8 in a connected state according to an embodiment of the present invention. Figure 2 .

[0087] Because the SF6 or dry air pressure inside the ring main unit is significantly affected by temperature and the pressure fluctuations in the high-pressure gas box during filling are substantial, please refer to [link to relevant documentation] to prevent false triggering of the monitoring device due to pressure changes in the high-pressure gas box of the ring main unit. Figures 6 to 12 In some embodiments, the ring main unit includes: The system comprises a cabinet, a low-pressure instrument compartment separate from the high-pressure gas box, a vacuum circuit breaker body 1 installed in the high-pressure gas box and including a stationary end and a moving end, a solid-sealed pole 2, a reflector plate 8, an optical fiber assembly 4, and a monitoring module covering the outside of the vacuum circuit breaker body 1. The vacuum level inside the vacuum circuit breaker body 1 is a standard vacuum level.

[0088] The first bellows 5 is disposed on one side of the solid-sealed pole 2 corresponding to the stationary end of the vacuum circuit breaker body 1. The interior of the first bellows 5 is connected to the interior of the vacuum circuit breaker body 1, and the exterior of the first bellows 5 is subjected to the ambient air pressure of the high-pressure gas box. The first bellows 5 is configured to generate expansion and contraction deformation by utilizing the pressure difference between the interior of the vacuum circuit breaker body 1 and the high-pressure gas box.

[0089] The reflector 8 is movably disposed on the side of the solid-sealed pole 2 where the first corrugated tube 5 is located, and is linked with the telescopic end of the first corrugated tube 5 so as to be displaced as the first corrugated tube 5 telescopically extends; one side of the reflector 8 is provided with a first reflective surface 810 and a first absorptive surface 820 distributed along its own direction of movement and having different optical reflective properties.

[0090] The optical fiber assembly 4 is partially embedded in the solidified pole 2. One end of the optical fiber assembly 4 extends into the low-pressure instrument room, and the other end of the optical fiber assembly 4 extends into the side of the solidified pole 2 where the reflector 8 is located. The end face of the optical fiber assembly 4 near the reflector 8 is directly opposite the movement path of the reflector 8.

[0091] The monitoring module is located in the low-pressure instrument room and connected to the optical fiber assembly 4. The monitoring module is configured to emit light through the optical fiber assembly 4 and receive reflected light reflected back by the reflector 8.

[0092] Differential compensation mechanism, wherein the differential compensation mechanism includes: The second bellows 11 is disposed on the side of the solid-sealed pole 2 near the first bellows 5. The interior of the second bellows 11 is a sealed chamber with a preset standard vacuum degree and is not connected to the vacuum circuit breaker body 1. The exterior of the second bellows 11 is subjected to the same ambient air pressure of the high-pressure gas box as the exterior of the first bellows 5. A connecting assembly 12 is connected between the first bellows 5 and the second bellows 11. The connecting assembly 12 is configured such that when the ambient air pressure change of the high-pressure gas box causes the first bellows 5 and the second bellows 11 to expand and contract synchronously and equally, the connecting assembly 12 drives the reflector plate 8 to perform a translational movement along the expansion and contraction direction of the first bellows 5; when the air pressure change inside the vacuum circuit breaker body 1 causes the first bellows 5 and the second bellows 11 to have a difference in expansion and contraction amount, the connecting assembly 12 tilts and drives the reflector plate 8 to perform a deflection movement.

[0093] When the vacuum level inside the vacuum circuit breaker body 1 is within the normal range, the light emitted by the optical fiber assembly 4 engages with the first reflective surface 810; when the vacuum level inside the vacuum circuit breaker body 1 is disrupted, causing the internal air pressure to rise, the first bellows 5 extends and drives the reflector 8 to move, so that the light emitted by the optical fiber assembly 4 engages with the first absorption surface 820, thereby changing the intensity of the reflected light received by the monitoring module.

[0094] This embodiment provides a ring main unit with adaptive compensation function for ambient air pressure, which is specifically optimized for working conditions with large fluctuations in internal air pressure of the gas-filled cabinet.

[0095] The ring main unit mainly consists of a cabinet, which is physically divided into a high-voltage gas chamber and a low-voltage instrument compartment. The high-voltage gas chamber is a sealed, gas-filled compartment filled with sulfur hexafluoride or dry air as the insulating medium, used to install the vacuum circuit breaker body 1, which includes the stationary and moving ends. The low-voltage instrument compartment is completely independent of the high-voltage gas chamber and is located in the atmospheric environment. It is used to install secondary equipment and monitoring modules, achieving physical isolation between high and low voltage. The solid-sealed pole 2 covers the outside of the vacuum circuit breaker body 1, serving both as a supporting insulating component and as a mounting carrier for the monitoring components.

[0096] The first bellows 5 serves as the detection end, and is installed at the position of the solid-sealed pole 2 corresponding to the stationary end of the vacuum circuit breaker body 1. Its key structural feature is that the internal space of the first bellows 5 is directly connected to the internal vacuum chamber of the vacuum circuit breaker body 1, ensuring that its internal pressure is always equal to the pressure inside the arc-extinguishing chamber; while its external surface is directly exposed to the gas-filled environment of the high-pressure gas box. Therefore, the state of the first bellows 5 depends on the pressure difference between the vacuum level of the arc-extinguishing chamber and the ambient gas pressure of the gas box.

[0097] The differential compensation mechanism is the core component of this embodiment. In order to eliminate the influence of ambient air pressure fluctuations, this embodiment introduces a differential compensation mechanism, which includes a second bellows 11 and a connecting component 12.

[0098] The second bellows 11 is positioned as a reference end on the solid-sealed pole 2, adjacent to the first bellows 5. The second bellows 11 maintains the same structural parameters (such as stiffness and dimensions) as the first bellows 5, but its function is entirely different. The interior of the second bellows 11 is a sealed chamber pre-set to a standard vacuum level and is completely isolated from the vacuum circuit breaker body 1 (i.e., it is an independent vacuum reference). Its exterior is also subjected to the ambient pressure of the high-pressure gas chamber. This design ensures that the second bellows 11 is only affected by changes in ambient pressure and not by changes in the circuit breaker's vacuum level.

[0099] The connecting assembly 12 spans between the first bellows 5 and the second bellows 11, physically connecting their telescopic ends. It is configured as a mechanical balancing mechanism (such as a floating rod or bridging frame), and the reflector 8 is mounted on the connecting assembly 12. The design of the connecting assembly 12 allows it to perform two distinct modes of motion: overall translational motion and tilting / deflecting motion.

[0100] The reflector 8 is movably mounted on one side of the first corrugated pipe 5 and is driven by the connecting assembly 12. The side of the reflector 8 facing the detection has a first reflective surface 810 (high reflectivity area) and a first absorptive surface 820 (light absorption area) distributed along the direction of movement. The fiber optic assembly 4 is partially embedded in the solidified pole 2, with one end connected to the monitoring module in the low-voltage instrument room and the other end facing the movement path of the reflector 8.

[0101] The monitoring principle of this embodiment is to use mechanical differential logic to filter out common-mode interference (changes in ambient air pressure) and only respond to differential-mode signals (destruction of vacuum).

[0102] In the initial state, under normal operating conditions, both the vacuum circuit breaker body 1 and the second bellows 11 are under high vacuum, while the outside is under gas box pressure. The pressure difference between them is the same, maintaining the same compression state. The connecting assembly 12 is in a horizontal equilibrium position, and the light emitted from the fiber optic assembly 4 is projected onto the first reflecting surface 810 of the reflector 8. The monitoring module receives the strong reflected light and determines that the system is normal.

[0103] When the pressure of the insulating gas in the high-voltage gas box inside the ring main unit decreases, the pressure acting on the outside of the bellows decreases. At this time, the first bellows 5 and the second bellows 11, due to the same external pressure change and the fact that both are under vacuum, will undergo synchronous and equal elongation deformation. As the two support points rise synchronously, the connecting assembly 12 drives the reflector 8 to make an overall translational movement along the bellows' extension and contraction direction (for example, moving outward a certain distance). The first reflective surface 810 is designed to cover this translational path, so the light still shines on the first reflective surface 810, the reflected light intensity does not change abruptly, and the system will not trigger a false alarm.

[0104] When a leak occurs in the vacuum circuit breaker body 1, causing an increase in internal air pressure (vacuum failure), the pressure difference inside and outside the first bellows 5 decreases, resulting in a significant elongation of the first bellows 5. Meanwhile, the second bellows 11, serving as a reference, maintains a standard vacuum, and the ambient air pressure remains constant; therefore, the second bellows 11 retains its length (or changes very little). At this time, one end of the connecting assembly 12 (the side connected to the first bellows 5) rises significantly, while the other end (the side connected to the second bellows 11) remains stationary. This difference causes the connecting assembly 12 to tilt or rotate. The tilting of the connecting assembly 12 causes the reflector 8 to deflect. This deflection changes the position or angle of the reflector 8, causing the light emitted from the fiber optic assembly 4 to move out of the first reflecting surface 810 and onto the first absorbing surface 820. The light intensity received by the monitoring module decreases sharply, thus determining a vacuum failure and triggering an alarm.

[0105] The technical solution proposed in this embodiment is specifically designed for gas-insulated switchgear, and is particularly suitable for applications with large outdoor temperature differences or where the internal air pressure of the gas box fluctuates with load heating. Furthermore, the first corrugated pipe 5 and the second corrugated pipe 11 must be arranged adjacent to each other to ensure that the local ambient temperature and pressure of the two are as consistent as possible, thereby guaranteeing the accuracy of compensation.

[0106] In some alternative embodiments, the first reflecting surface 810 and the first absorbing surface 820 on the reflector 8 can be interchanged according to the monitoring logic, for example, designed so that when deflected, the reflected light enters the receiving optical fiber 420 (bright signal alarm).

[0107] In this embodiment, a second bellows 11 with a preset standard vacuum level is used as an environmental reference. The first bellows 5 and the second bellows 11 are connected by a connecting component 12 to form a differential compensation mechanism. This transforms the synchronous expansion and contraction caused by ambient air pressure fluctuations into the translational movement of the reflector 8, while the differential expansion and contraction caused by vacuum level disruption is transformed into the deflection movement of the reflector 8. The technical means of changing the intensity of reflected light through the coordination of different optical characteristic areas on the reflector 8 effectively solves the technical problem in the prior art where the pressure of the insulating gas in the high-voltage gas box of the ring main unit fluctuates greatly due to temperature, leading to frequent false triggering of a single differential pressure monitoring device. Furthermore, it achieves automatic filtering of purely mechanical environmental interference, accurately distinguishing between environmental factors and fault factors without the need for electronic sensor compensation, and significantly improving the detection accuracy and anti-interference capability of the online vacuum monitoring device in complex environments.

[0108] To eliminate mechanical interference caused by changes in geometric position while transmitting displacement signals, please refer to [link / reference]. Figures 10 to 12 In some embodiments, the connecting assembly 12 is designed as a telescopic rod structure with automatic telescopic compensation function. The connecting assembly 12 includes a first connecting shaft 1210 rotatably connected to the first corrugated pipe 5, a second connecting shaft 1220 rotatably connected to the second corrugated pipe 11, and an outer tube. The first connecting shaft 1210 and the second connecting shaft 1220 are respectively movably inserted into the two ends of the outer tube, and a second elastic element 1240 is provided between the first connecting shaft 1210 and the outer tube, and a third elastic element 1250 is provided between the second connecting shaft 1220 and the outer tube, so that the connecting assembly 12 adapts to changes in the distance between the first corrugated pipe 5 and the second corrugated pipe 11 when tilting.

[0109] The main structure of the connecting assembly 12 consists of three parts: a first connecting shaft 1210, a second connecting shaft 1220, and an outer tube located in the middle. The outer tube is a hollow tubular component with openings at both ends. The first connecting shaft 1210 and the second connecting shaft 1220 are respectively inserted into the internal cavities of the outer tube from both ends. The outer diameters of the first connecting shaft 1210 and the second connecting shaft 1220 are clearance-fitted with the inner diameter of the outer tube, allowing the two connecting shafts to slide freely back and forth axially within the outer tube (i.e., telescopic movement), thereby changing the overall length of the connecting assembly 12.

[0110] Both ends of the connecting assembly 12 are connected to the bellows. Specifically, the end of the first connecting shaft 1210 away from the outer tube is provided with a hinge hole or ball joint structure, which is rotatably connected to the telescopic end (movable end) of the first bellows 5; similarly, the end of the second connecting shaft 1220 away from the outer tube also adopts a similar structure and is rotatably connected to the telescopic end of the second bellows 11. This rotatable connection means that the connecting shaft can not only move up and down with the bellows, but also deflect or swing at a certain angle relative to the axis of the bellows, similar to a joint structure.

[0111] An elastic element is integrated within the connecting assembly 12 to maintain structural stability and return capability. A second elastic element 1240 is disposed between the first connecting shaft 1210 and the outer tube, and a third elastic element 1250 is disposed between the second connecting shaft 1220 and the outer tube. These two elastic elements are typically cylindrical helical springs, encapsulated inside the outer tube. One end of the elastic element abuts against the inner wall limit (or constriction) of the outer tube, and the other end abuts against the stepped surface or end face of the connecting shaft. The elastic elements are configured to apply an axial preload or restoring force to the connecting shaft, such that, without external force, the connecting shaft tends to remain in a specific extended or retracted position, eliminating connection gaps and preventing slippage of the connecting shaft.

[0112] When changes in ambient air pressure cause the first bellows 5 and the second bellows 11 to expand and contract synchronously and equally, the tops of the two bellows are on the same horizontal plane and move synchronously. At this time, the connecting assembly 12 moves as a whole, and the first connecting shaft 1210 and the second connecting shaft 1220 do not undergo relative displacement (or only slight adjustment) relative to the outer tube. The connecting assembly 12 maintains a horizontal posture and accurately transmits the translation signal.

[0113] When the vacuum level of the vacuum circuit breaker body 1 is disrupted, causing the first bellows 5 to elongate more than the second bellows 11, the top of the first bellows 5 is higher than that of the second bellows 11. At this time, the connecting assembly 12 is forced to tilt. According to geometric principles, the straight-line distance (hypotenuse) between the connection points of the tilted connecting assembly 12 is greater than the distance (right-angle side) in the horizontal state. During this process, the first connecting shaft 1210 and the second connecting shaft 1220 slide outward within the outer tube, causing the total length of the connecting assembly 12 to automatically elongate to match the aforementioned hypotenuse distance. Simultaneously, the rotating connection structure at the end allows the connecting shaft to deflect at an angle relative to the bellows. The second elastic element 1240 and the third elastic element 1250 are compressed (or stretched) during this process, not only providing damping during extension and contraction to prevent abrupt changes in action, but also using elastic force to pull the connecting shaft back to its initial position during fault clearing or bellows reset, ensuring that the connecting assembly 12 returns to its standard length.

[0114] In some alternative embodiments and solutions, in addition to using a pin hinge, the rotating connection can also be designed as a universal ball joint at the end of the connecting shaft, working in conjunction with the ball socket at the top of the bellows to provide more degrees of freedom of rotation and accommodate possible minor lateral installation errors. To prevent the connecting shaft from completely detaching from the outer tube, a limiting pin can be provided at the end of the connecting shaft, and a long, narrow limiting groove can be formed on the outer tube to limit both rotation and maximum travel. Furthermore, the elastic element can also be a tension spring, directly hooked between the inner ends of the two connecting shafts, tightening them inwards through tension.

[0115] In this embodiment, the connecting component 12 is designed as a split telescopic structure comprising a first connecting shaft 1210, a second connecting shaft 1220, and an outer tube. Axial telescopic buffering is achieved through end-rotation connections with the internally installed second elastic element 1240 and third elastic element 1250. Therefore, this effectively solves the technical problem in the prior art where rigid connecting rods, when connecting two bellows with a difference in telescopic range, experience mechanical jamming due to changes in geometric distance, or damage to the bellows due to lateral forces. Furthermore, the connecting component 12 automatically adapts to the increased distance at both ends when the differential action tilts, ensuring the smoothness and flexibility of the monitoring mechanism's operation and significantly improving the mechanical lifespan of the device and the reliability of the detection action.

[0116] For further information, please refer to [link / reference]. Figure 7 In some embodiments, the ring main unit further includes a second base 13 and a second connector 14. The second base 13 is disposed on the solid-sealing pole 2 and located between the first corrugated pipe 5 and the second corrugated pipe 11. A second moving groove 1310 is provided in the second base 13, and the reflector 8 is disposed in the second moving groove 1310. A connecting groove 1320 communicating with the second moving groove 1310 is opened on the second base 13, and the connecting groove 1320 extends along the extension and retraction direction of the first corrugated pipe 5. The second connector 14 is fixedly disposed at the midpoint of the outer pipe, and the second connector 14 passes through the connecting groove 1320 and is connected to the reflector 8. The reflector 8 is configured to rotate within the second moving groove 1310 as the connecting assembly 12 tilts.

[0117] This embodiment focuses on describing the core transmission and support assembly located between the two bellows, which is responsible for converting the expansion and contraction of the bellows into a specific motion trajectory of the reflector 8.

[0118] The second base 13 serves as a support housing, mounted on the surface of the solidified pole post 2, and precisely positioned in the middle region between the installation positions of the first bellows 5 and the second bellows 11. The second base 13 is typically made of insulating material (such as high-strength engineering plastic or epoxy resin) and functions as a separate mounting box or support frame. The second base 13 has a second moving groove 1310 inside. This is a cavity with sufficient space, its shape and size designed to accommodate the reflector 8 and allow it to move and rotate within a specified range. The reflector 8 is not exposed but is encapsulated or semi-encapsulated within the second moving groove 1310 of the second base 13, providing dust protection and physical protection.

[0119] A connecting groove 1320 is provided on the side wall or surface of the second base 13, connecting the external and internal second moving groove 1310. The geometry of this groove is crucial: it is an elongated through hole or slide, and its extension direction is strictly parallel to the extension and contraction direction (i.e., the vertical direction) of the first bellows 5. This connecting groove 1320 not only serves as a channel for the connector but also acts as a vertical guide rail, restricting the horizontal displacement freedom of the connector.

[0120] The second connector 14 is a pin, screw, or similar connecting rod. It is fixedly positioned at the geometric midpoint (i.e., the center of the outer tube along its length) of the outer tube of the connecting assembly 12. Since the outer tube connects two bellows, this midpoint is the fulcrum or equilibrium point of the differential lever. One end of the second connector 14 is fixed to the outer tube, and the other end passes through the connecting groove 1320 on the second base 13, extends into the interior of the second moving groove 1310, and is firmly connected to the reflector 8 placed there. Through this structure, the motion state (translation or tilt) of the outer tube is directly transmitted to the reflector 8 via the second connector 14.

[0121] When changes in ambient air pressure cause the bellows on both sides to expand and contract synchronously, the outer tube of the connecting assembly 12 maintains a horizontal posture and moves up and down as a whole. The second connecting piece 14, fixed at the midpoint of the outer tube, moves up and down vertically accordingly. At this time, the second connecting piece 14 slides smoothly within the connecting groove 1320 of the second base 13. Since the connecting piece does not rotate, it drives the internal reflector 8 to perform a simple vertical translational movement within the second moving groove 1310. This translational movement keeps the angle of the reflector 8 constant.

[0122] When the vacuum level is disrupted, causing inconsistent expansion and contraction of the bellows on both sides, the outer tube of the connecting assembly 12 tilts. The second connecting member 14, located at the midpoint of the outer tube, then deflects at an angle (i.e., rotates about its own axis or a vertical plane). Since the second connecting member 14 is fixedly connected to the reflector 8, the tilting torque of the connecting member is directly transmitted to the reflector 8. At this time, the reflector 8 rotates (deflects) about the second connecting member 14 within the internal space of the second moving slot 1310. This rotation changes the angle or position of the reflector 8 relative to the incident light.

[0123] The structure in this embodiment is specifically designed for the narrow space between the two corrugated pipes, utilizing the gap between them for arrangement. This results in a compact structure that does not increase the additional volume of the ring main unit. It is suitable for applications with strict requirements on motion trajectory. The width of the connecting groove 1320 must be precisely matched with the diameter of the second connector 14 to eliminate lateral sway gaps and ensure the stability of the optical path alignment.

[0124] In this embodiment, a second base 13 with a second moving groove 1310 and a vertically extending connecting groove 1320 is set between the two corrugated pipes, and a second connector 14 fixed at the midpoint of the outer pipe passes through the connecting groove 1320 to connect with the reflector 8. Therefore, the technical problems of the differential mechanism's reflector component lacking a stable support point, resulting in uncontrollable motion trajectory and difficulty in effectively physically separating the overall displacement caused by the environment from the tilting action caused by the fault, are effectively solved in the prior art. This provides a stable mechanical support and guiding protection for the reflector 8, ensuring that the reflector 8 only moves horizontally without false alarms when the ambient air pressure fluctuates, and can sensitively respond to the tilting torque and rotate when there is a vacuum fault, greatly improving the mechanical stability of the monitoring device and the accuracy of signal recognition.

[0125] For further information, please refer to [link / reference]. Figure 6 and Figure 8 In some embodiments, the second base 13 has a second reflective surface 1330 with the same optical reflection characteristics as the first reflective surface 810 on the side near the optical fiber assembly 4. The second reflective surface 1330 has at least one groove 1331 connecting to the second moving groove 1310, and the extension direction of the groove 1331 is parallel to the extension / retraction direction of the first corrugated pipe 5. The first reflective surface 810 is configured such that when the reflective plate 8 moves with the connecting assembly 12, the groove 1331 moves within the range of its orthographic projection on the first reflective surface 810, forming a complete light reflection path together with the second reflective surface 1330; when the reflective plate 8 moves with the connecting assembly 12, the first reflective surface 810 deflects at an angle relative to the groove 1331, thereby disrupting the integrity of the light reflection path.

[0126] This embodiment focuses on describing a high-precision optical differential filter structure, which is integrated on the interface between the second base 13 and the internal reflector 8, and is used to directly distinguish environmental interference and fault signals at the optical level.

[0127] The second base 13 and the second reflective surface 1330 are fixed grating masks. The surface of the second base 13 near the fiber optic assembly 4 is processed or coated with a highly reflective mirror, i.e., the second reflective surface 1330. The optical reflection characteristics (such as reflectivity and spectral response) of this surface are specifically designed to be completely consistent with the first reflective surface 810 on the reflector 8. One or more grooves 1331 connecting the internal cavity are formed on the second reflective surface 1330. These grooves 1331 are not only light-transmitting holes, but also optical filtering gratings. The key geometric feature is that the extension direction of the grooves 1331 is strictly parallel to the extension and contraction direction of the first corrugated tube 5 (usually vertical). This means that the grooves 1331 form a vertical slit window. At this time, the surface of the second base 13 facing the fiber optic assembly 4 presents a shape composed of a large-area mirror and a vertical slit.

[0128] The first reflective surface 810 is a movable patch. The first reflective surface 810 is provided on the reflector 8 located inside the second base 13. The shape of the first reflective surface 810 is typically designed as a stripe or band shape to match the groove 1331. In the initial assembly state, the reflector 8 is located inside the second base 13, and the first reflective surface 810 on it is exposed through the groove 1331. Since the first reflective surface 810 and the second reflective surface 1330 have the same optical characteristics, and the first reflective surface 810 precisely fills the projection area of ​​the groove 1331, from the perspective of the fiber optic assembly 4, the gap at the groove 1331 is perfectly filled by the rearward first reflective surface 810. At this time, the fixed second reflective surface 1330 and the movable first reflective surface 810 seen through the groove 1331 visually merge into one, together forming a complete, continuous, and flawless large light spot reflective surface.

[0129] When changes in ambient air pressure cause the connecting component 12 to move the reflector 8 in a translational motion, the reflector 8 moves up and down along the extension direction (vertical direction) of the first corrugated pipe 5. Since the groove 1331 on the second base 13 also extends vertically and its length covers the movement stroke of the reflector 8, no matter how the reflector 8 slides up and down, its first reflective surface 810 always slides within the projection range of the vertical groove 1331. This is similar to the slider of a zipper moving along the zipper track, with the slider always remaining within the track. During this process, the light emitted by the fiber optic component 4 always hits the first reflective surface 810 (through the groove 1331) or the second reflective surface 1330 (base surface), the entire light reflection path remains intact, the light intensity is maintained at a high level, the system determines it as environmental interference, and does not alarm.

[0130] When the vacuum level is breached, causing the connecting component 12 to tilt, which in turn causes the reflector 8 to deflect (rotate), a drastic change occurs. The reflector 8 twists at an angle or shifts laterally relative to the vertical groove 1331. At this point, the first reflective surface 810 on the reflector 8 is no longer aligned with the vertical groove 1331, but instead crosses at an angle or moves out of the groove 1331's range. It's like a wooden board that was originally blocking a window has become crooked, revealing the gap behind it. The light from the fiber optic assembly 4 directed towards the groove 1331 is no longer reflected by the first reflective surface 810 (it may hit the non-reflective area of ​​the reflector 8 or pass directly through it), causing the originally intact reflective surface to be destroyed. The integrity of the reflected light path is disrupted, and the received light intensity changes drastically, thereby triggering an alarm.

[0131] The structural design in this embodiment is suitable for applications requiring extremely high detection accuracy. The narrower the groove 1331, the higher the sensitivity to angular deflection, enabling the detection of even minute vacuum leaks. Furthermore, since the groove 1331 is parallel to the main vibration direction (the bellows' expansion and contraction direction), this structure is inherently insensitive to axial mechanical vibrations, exhibiting excellent noise reduction performance.

[0132] In some alternative embodiments and solutions, to increase signal contrast, a set of parallel groove arrays 1331 (gratings) can be formed on the second base 13, and a set of striped reflective surfaces can be correspondingly provided on the reflector 8. This will produce a moiré fringe effect when deflection occurs, making the change in light intensity more significant. Furthermore, the first reflective surface 810 does not need to be perfectly elongated; it only needs to ensure that its projection on the translation path covers the grooves 1331.

[0133] In this embodiment, a second reflective surface 1330 with a groove 1331 parallel to the telescopic direction is set on the second base 13, and an optical splicing structure is formed with the first reflective surface 810 on the reflector 8. The reflector 8 maintains the integrity of the optical path when it is translated and destroys the integrity of the optical path when it is deflected by using geometric projection relationship. Therefore, it effectively solves the technical problem in the prior art that it is difficult to distinguish between the normal environmental thermal expansion and contraction and abnormal fault deformation of the bellows by a single sensor. It also realizes the direct filtering of environmental interference signals at the optical physical level and only responds to the rotational action caused by vacuum destruction, which greatly reduces the false alarm rate. Furthermore, it uses the destruction of the integrity of the optical path (brightness turning dark) as the fault criterion, which is in line with the principle of fault-oriented safety.

[0134] For further details, please refer to Figures 9 to 10 In some embodiments, the first reflective surface 810 is a striped structure disposed on the reflective plate 8, and the position of the first reflective surface 810 corresponds to the groove 1331.

[0135] In this embodiment, the optical functional area on the reflector 8 is precisely designed, and a rasterized stripe structure is adopted to match the groove 1331 on the second base 13 to form a highly sensitive optical geometric lock.

[0136] The surface of the reflector 8 facing the detection side is not designed as a single, solid mirror, but rather divided into regions. The first reflective surface 810 specifically presents as a long, thin striped structure. This striped structure is composed of a high-reflectivity material (such as a mirror silver coating, a high-reflectivity film, or polished metal strips), and is elongated with clearly defined width and length boundaries. On the surface of the reflector 8, apart from the striped first reflective surface 810 area, the remaining areas (especially those adjacent to the sides of the stripes) are treated as light-absorbing areas (i.e., the first absorption surface 820), forming a high-contrast optical pattern of black background and bright stripes. The spatial position of this striped first reflective surface 810 has a strict geometric correspondence with the groove 1331 on the second base 13. The width of the first reflective surface 810 is designed to be slightly greater than, equal to, or slightly less than the width of the groove 1331 (depending on the sensitivity adjustment requirements) to ensure that light passing through the groove 1331 accurately covers the reflective stripes.

[0137] In the initial installation state and when only translational movement occurs, the extension axis of the striped first reflective surface 810 coincides with the extension axis of the groove 1331 on the second base 13 in spatial projection. That is to say, if viewed from the perspective of the fiber optic assembly 4 through the groove 1331, the bright reflective stripes behind it can be clearly seen through the gap of the groove 1331.

[0138] When ambient air pressure fluctuations cause the reflector 8 to move along the direction of the bellows extension and retraction, the first reflective surface 810 is a long strip structure extending along the direction of movement, and the groove 1331 also extends in the same direction. Therefore, the up-and-down movement of the reflector 8 merely allows the reflective stripes to slide longitudinally within the field of view of the groove 1331. Geometrically, the stripes never leave the opening range of the groove 1331. The light emitted from the fiber optic assembly 4 passes through the groove 1331, always hitting the reflective stripes and being reflected back. The monitoring module continuously receives high-intensity light signals, the system determines that the optical path is intact, confirms it as environmental interference, and does not trigger an alarm.

[0139] When the vacuum is disrupted, causing the connecting assembly 12 to tilt, which in turn causes the reflector 8 to deflect (i.e., rotate or twist in the plane), the striped first reflective surface 810 intersects the fixed groove 1331 at an angle. As the deflection angle increases, the slender reflective stripes quickly form an "X" shape intersection with the groove 1331, or completely move out of the projection range of the groove 1331. At this point, what is seen through the groove 1331 is no longer a highly reflective stripe, but rather the light-absorbing background (first absorption surface 820) on both sides of the stripe. The light reflection path is physically interrupted, and the reflected light intensity drops abruptly. This structure amplifies a small angular change into a significant light intensity change signal.

[0140] In this embodiment, by employing a technique where the first reflective surface 810 is designed as a striped structure on the reflector plate 8 and its position corresponds to the groove 1331 on the second base 13 in spatial projection, the technical problem of the prior art—that it is difficult to sensitively distinguish between the translational motion and slight deflection motion of the reflector plate 8 at the optical level by simply relying on a large-area reflective surface, resulting in incomplete filtering of environmental interference or delayed fault response—is effectively solved. Furthermore, by utilizing the geometric grating effect, the integrity of the optical path is rapidly destroyed when the reflector plate 8 undergoes a slight angular deflection, greatly improving the signal-to-noise ratio and fault identification sensitivity of the differential monitoring mechanism and ensuring the accuracy of alarm triggering.

[0141] For further details, please refer to Figure 9 In some embodiments, the first absorption surface 820 is disposed on the reflector plate 8 in an area other than the first reflective surface 810.

[0142] This embodiment focuses on the optical partitioning layout of the surface of the reflector 8, particularly the light absorption design for non-reflective areas. On the side of the reflector 8 facing the fiber optic assembly 4, all blank areas, except for the first reflective surface 810 which is designed for high reflectivity, are defined and set as the first absorption surface 820. From a microstructural perspective, the first reflective surface 810 and the first absorption surface 820 together constitute the complete front surface of the reflector 8. They are complementary and mutually exclusive in spatial distribution, with no intermediate ambiguous zone that neither reflects nor absorbs. The first absorption surface 820 is typically made of materials or processes with high absorption rates for the monitored light wavelength, such as being coated with carbon-based black matte paint, covered with black light-absorbing velvet, or subjected to surface roughening and blackening treatment. In terms of structural layout, the first absorption surface 820 acts as the background color of the first reflective surface 810. If the first reflective surface 810 is striped, then the first absorption surface 820 fills the spaces between and around the stripes, forming a high-contrast optical pattern with bright stripes on a black background.

[0143] This embodiment utilizes the presence or absence of an optical signal to determine the state. During operation, when the reflector 8 is in a specific position (such as a translational position caused by environmental interference) so that the fiber optic assembly 4 is aligned with the first reflective surface 810, the system receives a high-intensity optical signal. However, if the reflector 8 deflects or excessively displaces due to vacuum disruption, causing the beam projection point emitted from the fiber optic assembly 4 to move outside the boundary of the first reflective surface 810, the beam will immediately fall within the range of the first absorption surface 820. The first absorption surface 820 quickly absorbs most of the incident light energy, or uses the principle of diffuse reflection to scatter a very small amount of residual light to the non-receiving direction, preventing the light from returning to the receiving fiber optic 420. Through this mechanism, the first absorption surface 820 ensures that as soon as the light spot leaves the reflection area, the feedback signal intensity will immediately drop sharply, generating a clear logic zero level, eliminating the trailing or noise interference of the optical signal in the transition region.

[0144] In an alternative implementation, the first absorption surface 820 does not necessarily have to be achieved by coating with a light-absorbing material; an equivalent absorption effect can also be achieved by changing the surface geometry. For example, the area outside the first reflective surface 810 can be designed as an inclined light-guiding surface, mirror-reflecting the incident light to an ineffective area outside the fiber optic receiving aperture (such as reflecting it to the inner wall of the base). This also appears as a loss of light energy at the receiving end, achieving the same technical effect as a light-absorbing material. Furthermore, the first absorption surface 820 can also directly utilize the dark color of the reflector 8 substrate itself. If the substrate is black engineering plastic, it can be used as an absorption surface without additional processing.

[0145] In this embodiment, by employing a technique of setting a high-absorbency first absorption surface 820 as an optical background on the area of ​​the reflector 8 other than the first reflective surface 810, the technical problem of low optical signal contrast and blurred signal threshold boundary between fault and normal states caused by background stray light interference or reflection from non-detection areas in the prior art is effectively solved. This results in a significant improvement in the signal-to-noise ratio of the optical monitoring signal, ensuring that the received light intensity can produce a steep step change when the reflector 8 moves and the optical path deviates from the reflection area, providing a clear and definite fault judgment basis for the monitoring module and greatly improving the detection accuracy of the system.

[0146] The above description is merely illustrative of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not depart from the content of this specification or exceed the scope defined by the claims, all of which should fall within the protection scope of this invention.

Claims

1. A ring main unit, comprising a high-voltage gas box, a low-voltage instrument compartment independent of the high-voltage gas box, a vacuum circuit breaker body installed inside the high-voltage gas box and including a stationary end and a moving end, and a solid-sealed pole covering the outside of the vacuum circuit breaker body; characterized in that, The ring main unit is equipped with a vacuum degree detection system based on the environmental pressure difference of the high-pressure gas box, including: A first bellows is disposed on one side of the solid-sealed pole corresponding to the stationary end of the vacuum circuit breaker body. The interior of the first bellows is connected to the interior of the vacuum circuit breaker body, and the exterior of the first bellows is subjected to the ambient gas pressure of the high-pressure gas box. The first bellows is configured to be driven by the pressure difference between the vacuum degree inside the vacuum circuit breaker body and the insulating gas environment inside the high-pressure gas box. A reflector is movably disposed on the side of the solid-sealed pole where the first corrugated tube is located, and is linked to the telescopic end of the first corrugated tube to be configured to move with the telescopic extension of the first corrugated tube; one side of the reflector is provided with a first reflecting surface and a first absorbing surface that are distributed along its own direction of movement and have different optical reflection characteristics. An optical fiber assembly is arranged across the high-pressure gas box and the low-pressure instrument room. Part of the optical fiber assembly is embedded in the solidified pole. One end of the optical fiber assembly extends into the low-pressure instrument room, and the other end of the optical fiber assembly extends to the side of the solidified pole where the reflector is located. The end face of the optical fiber assembly near the reflector is directly opposite the movement path of the reflector. A monitoring module is installed in the low-pressure instrument room and connected to the fiber optic assembly. The monitoring module is configured to emit light through the fiber optic assembly and receive reflected light reflected back by the reflector. When the vacuum level inside the vacuum circuit breaker body is within the normal range, the light emitted by the optical fiber assembly matches the first reflective surface; when the vacuum level inside the vacuum circuit breaker body is disrupted, causing the internal air pressure to rise, the first corrugated pipe extends and drives the reflector to move, so that the light emitted by the optical fiber assembly matches the first absorption surface, thereby changing the intensity of the reflected light received by the monitoring module.

2. The ring main unit according to claim 1, characterized in that: The optical fiber assembly includes a transmitting optical fiber for emitting light and a receiving optical fiber for receiving light, which are coaxially arranged. The solid-sealed pole has a limiting structure on the stationary side near the body of the vacuum circuit breaker for positioning the end of the optical fiber assembly. The end face of the transmitting optical fiber is exposed outside the limiting structure, and the end faces of a plurality of receiving optical fibers are arranged around the end face of the transmitting optical fiber. The solid-sealed pole is also provided with a first base. The first base has a reflective window that is aligned with the end of the optical fiber assembly on the side near the optical fiber assembly. The reflective plate is movably disposed in the first base, and the reflective plate interacts with the light emitted from the optical fiber assembly through the reflective window.

3. The ring main unit according to claim 2, characterized in that: The first base is provided with a first movable groove extending along the telescopic direction of the first corrugated pipe, and the reflector is slidably disposed in the first movable groove; The first movable groove is provided with a guide post whose axis is parallel to the extension and retraction direction of the first corrugated pipe. The reflector plate is provided with a guide groove that penetrates itself, and the guide post passes through the guide groove.

4. The ring main unit according to claim 3, characterized in that, The first movable groove is further provided with a first elastic element, the two ends of which abut against the inner wall of the first movable groove away from the solidified pole and the side of the reflector away from the solidified pole, respectively.

5. The ring main unit according to claim 1, characterized in that: The vacuum level inside the main body of the vacuum circuit breaker is the standard vacuum level; The ring main unit further includes a differential compensation mechanism, which includes: The second bellows is disposed on the side of the solid-sealed pole close to the first bellows. The interior of the second bellows is a sealed chamber with a preset standard vacuum degree and is not connected to the vacuum circuit breaker body. The exterior of the second bellows is subjected to the same ambient air pressure of the high-pressure gas box as the exterior of the first bellows. A connecting assembly is provided between the first bellows and the second bellows. The connecting assembly is configured such that when the ambient air pressure change of the high-pressure gas box causes the first bellows and the second bellows to expand and contract synchronously and equally, the connecting assembly drives the reflector to make a translational movement along the expansion and contraction direction of the first bellows; when the air pressure change inside the vacuum circuit breaker body causes a difference in the expansion and contraction of the first bellows and the second bellows, the connecting assembly tilts and drives the reflector to make a deflection movement.

6. The ring main unit according to claim 5, characterized in that, The connection component includes: A first connecting shaft rotatably connected to the first bellows; A second connecting shaft rotatably connected to the second bellows; The outer tube has a first connecting shaft and a second connecting shaft movably inserted into the two ends of the outer tube, and a second elastic element is provided between the first connecting shaft and the outer tube, and a third elastic element is provided between the second connecting shaft and the outer tube, so that the connecting assembly can adapt to the change in the distance between the first corrugated tube and the second corrugated tube when tilting.

7. The ring main unit according to claim 6, characterized in that, include: The second base is disposed on the solid-sealing pole and located between the first bellows and the second bellows; The second base is provided with a second movable groove, and the reflector is disposed in the second movable groove; the second base is provided with a connecting groove communicating with the second movable groove, and the connecting groove extends along the extension and contraction direction of the first corrugated pipe; The second connector is fixedly installed at the midpoint of the outer tube, and the second connector passes through the connecting groove and is connected to the reflector. The reflector is configured to rotate within the second moving slot as the connecting assembly tilts.

8. The ring main unit according to claim 7, characterized in that, The second base has a second reflective surface with the same optical reflection characteristics as the first reflective surface on the side near the optical fiber assembly. At least one groove is formed on the second reflective surface that connects to the second moving groove. The extension direction of the groove is parallel to the extension direction of the first corrugated pipe. The first reflective surface is configured such that when the reflective plate moves with the connecting assembly, the groove moves within the range of its orthographic projection on the first reflective surface, so as to form a complete light reflection path together with the second reflective surface; when the reflective plate moves with the connecting assembly, the first reflective surface deflects at an angle relative to the groove, thereby disrupting the integrity of the light reflection path.

9. The ring main unit according to claim 8, characterized in that, The first reflective surface is a striped structure disposed on the reflective plate, and the position of the first reflective surface corresponds to the groove.

10. The ring main unit according to claim 8 or 9, characterized in that, The first absorbing surface is disposed in the area outside the first reflecting surface on the reflector plate.

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