A high-safety SF6 fully insulated compact ring main unit

Abstract

The present invention discloses a highly safe SF6 fully insulated compact ring network cabinet, which adopts a common box structure design and includes a circuit breaker unit, a load switch unit, a bus voltage transformer unit and a station terminal. The load switch unit includes a main cabinet and a secondary low-voltage chamber arranged above the main cabinet, and is characterized in that: the main cabinet of the load switch unit is provided with a sealed SF6 gas box, and the SF6 gas box is the bus chamber N1, and the main cabinet space outside the bus chamber N1 is divided into an operating mechanism chamber N2, a fuse chamber N3, a pressure relief channel N4 and a cable chamber N5. The ring network cabinet of the present invention is a medium-voltage switch cabinet series product, which has good sealing and waterproof performance, and the internal structure layout is reasonable, compact distribution, space saving, and sufficient insulation distance can be ensured, and an independent pressure relief channel is provided, which effectively improves the safety and reliability of the equipment, is easy to maintain, and is suitable for popularization and use.

Description

Technical Field

[0001] The present invention relates to a high-security ring network cabinet device, belonging to the technical field of electrical equipment, and specifically to the problems of safety performance, sealing performance, expansion performance and the like of an equipment switch cabinet. Background Art

[0002] With the continuous development of the power system, power users have higher requirements for power quality. At the same time, users' requirements for power supply reliability and safety are also increasing.

[0003] In the power system, the ring main unit is a high-voltage switchgear used for ring network power supply. It undertakes the important function of the power distribution ring network and plays a vital role. With the continuous development of ring main unit technology, its application has become more and more extensive. Therefore, the industry has correspondingly higher and stricter requirements for its safety and flexibility. However, the integration of traditional ring main units is not high enough, and the various components are mixed and fixed without distinction. The flexibility and safety are greatly limited, the insulation performance is low, the floor space is large, and the maintenance cost is high. Once the configuration plan is changed, the layout of the ring network needs to be redesigned.

[0004] SF6 ring main unit is an air-insulated or gas-insulated medium-voltage electrical combination device that can be combined into multiple circuits at will, has the functions of switching, connecting, and protecting the power system, and has load switches as core components. Its main circuit core components are composed of load switches or additional circuit breakers and other primary auxiliary electrical appliances. However, the existing SF6 ring main unit sometimes has the following conditions in actual applications: 1) The ring main unit unit space configuration is unreasonable, occupies a large space, and has low safety; 2) The fuse is blown for no reason, or the faulty transformer / line cannot be powered off, resulting in the expansion of the fault; 3) There are defects in the safety of gas leakage. Summary of the invention

[0005] The technical purpose of the present invention is to provide a highly safe SF6 fully insulated compact ring main unit to improve the deficiencies of the prior art.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A high-safety SF6 fully insulated compact ring main unit adopts a common box structure design, including a circuit breaker unit, a load switch unit, a bus voltage transformer unit and a station terminal. The load switch unit includes a main cabinet and a secondary low-voltage chamber arranged above the main cabinet, and is characterized in that:

[0008] The main cabinet of the load switch unit is provided with a sealed SF6 gas tank, which is the busbar chamber N1. The main cabinet space outside the busbar chamber N1 is divided into an operating mechanism chamber N2, a fuse chamber N3, a pressure relief channel N4 and a cable chamber N5.

[0009] The SF6 gas box and the pressure relief channel N4 are arranged on the side close to the rear cover of the cabinet, and the SF6 gas box is located above the pressure relief channel N4; the operating mechanism chamber N2, the fuse chamber N3 and the cable chamber N5 are arranged on the side close to the cabinet panel, the fuse chamber N3 is located below the operating mechanism chamber N2, and the cable chamber N5 is located below the fuse chamber N3; at the same time, the SF6 gas box is provided with an inwardly recessed groove at the bottom corner close to the cabinet panel; the top of the cable chamber N5 is higher than the top of the pressure relief channel N4, and its top corner close to the rear cover is embedded in the groove, close to the box wall of the SF6 gas box; the inlet and outlet insulating bushings are installed in the cable chamber N5, and the rear ends of the inlet and outlet insulating bushings pass through the groove wall of the groove and extend into the SF6 gas box;

[0010] The SF6 gas tank is provided with a copper busbar, a load switch, a fuse and a grounding switch from top to bottom. The copper busbar is used to connect the busbar and establish an electrical connection between the load switch unit and external equipment. One end of the fuse is connected to the load switch through a copper rod, and the other end is connected to the end of the inlet and outlet insulation sleeve extending into the SF6 gas tank through a copper rod, and is connected to the corresponding grounding switch.

[0011] The operating mechanism chamber N2 is provided with a spring operating mechanism for controlling the load switch at a position corresponding to the load switch; the fuse is installed in a fuse sealing chamber, the main body of which is arranged in the SF6 gas tank, and the front end of which is provided with an end cover extends into the fuse chamber N3;

[0012] A plurality of pressure relief devices are installed at the bottom of the SF6 gas box, and a pressure relief plate is provided in the pressure relief device. The pressure relief device separates the inner cavity of the SF6 gas box from the pressure relief channel N4 through the pressure relief plate;

[0013] The cable chamber N5 and the pressure relief channel N4 are separated by a metal grounding busbar.

[0014] On the basis of the above scheme, further improved or preferred schemes also include:

[0015] Furthermore, the load switch and the grounding switch are made of silver-graphite alloy material.

[0016] Furthermore, the ring main unit of the present invention is provided with a circuit breaker unit, wherein the circuit breaker unit is provided with a series anti-tripping circuit;

[0017] For a three-phase line, the series anti-tripping circuit includes three sets of identical circuit breaker protection control circuits, the circuit breaker protection control circuit includes a tripping coil, an anti-tripping coil, a switch device K1 and a switch device S, the switch device K1 is connected in series with the tripping coil and in parallel with the anti-tripping coil; the switch device S is arranged between the switch device K1 and the tripping coil;

[0018] The switch device K1 and the switch device S are auxiliary contacts of the relay:

[0019] When the load circuit connected to the circuit breaker works normally, the switch device K1 is in the normally open state;

[0020] The switch device S is simultaneously connected in the closing circuit and is in a closed state when closing;

[0021] The resistance of the anti-tripping coil is greater than that of the tripping coil. When the switch device K1 is in the open state and the switch device S is in the closed state, the voltage division of the anti-tripping coil keeps the voltage of the tripping coil below the action voltage threshold;

[0022] When a faulty closing occurs, the ring main unit terminal sends a tripping signal to energize the relay coil corresponding to the switch device K1, closing the switch device K1 and short-circuiting the anti-tripping coil. After the tripping coil voltage rises to the action voltage threshold, the tripping action is triggered, driving the switch device S to trip and disconnecting the closing circuit.

[0023] Furthermore, the circuit breaker protection control circuit also includes a detection unit for monitoring the open / closed state of the switch device S, and a switch device K2; the switch device K2 is connected in parallel at both ends of the switch device K1, and the switch device K2 is a relay auxiliary contact in a normally open state; when the detection unit feeds back that the states of the switch devices S on the three-phase lines are inconsistent, the ring network cabinet terminal sends a control signal to energize the relay corresponding to the switch device K2, short-circuit the anti-tripping coil, and re-trip the switch device S, so that the switch devices S on the three-phase lines are all in a disconnected state.

[0024] Furthermore, the switch device K2 corresponds to a time delay relay. When the detection unit feedbacks that the state of the switch device S on the three-phase line is inconsistent, the time delay relay delays t seconds to re-trip the switch device S. The t seconds can generally be set to 2 seconds.

[0025] Furthermore, the resistance of the tripping coil is 90Ω, and the resistance of the anti-tripping coil is in the kilo-ohm level.

[0026] Furthermore, the anti-tripping coil is provided with an anti-parallel freewheeling diode.

[0027] The beneficial effects of the present invention are:

[0028] 1) The invented ring main unit is a medium voltage switch cabinet series product with good sealing and waterproof performance, and the internal structure layout is reasonable, compact, and space-saving, while ensuring sufficient insulation distance and leaving an independent pressure relief channel to ensure the safety and reliability of the equipment;

[0029] 2) The circuit breaker unit of the ring main unit of the present invention can effectively solve the problem of fault tripping and closing through the design of a series anti-tripping circuit, and avoid damage to electrical equipment caused by continuous closing and switching of the circuit breaker, such as abnormal melting of the fuse, thereby extending the service life of the equipment;

[0030] 3) The ring main unit of the present invention is easy to maintain and suitable for popularization and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Attached Figure 1 This is the overall front view of the ring main unit of the present invention;

[0032] Attached Figure 2 This is a schematic diagram of the internal structure of the main part of the ring main unit of the present invention;

[0033] Attached Figure 3 This is a schematic diagram of the internal structure of the terminal unit of the ring main unit station of the present invention;

[0034] Attached Figure 4 It is a schematic diagram of the spatial layout of the side direction of the main part of the load switch unit of the ring main unit of the present invention;

[0035] Attached Figure 5 This is the circuit diagram of the series anti-tripping circuit. DETAILED DESCRIPTION

[0036] The following is a further detailed description with reference to the accompanying drawings and specific implementation examples:

[0037] like Figure 1 As shown, this embodiment is a high-safety SF6 fully insulated compact ring main unit 1, which adopts a modular design and includes a whole cabinet consisting of three functional units arranged side by side and a station terminal 5 located next to the whole cabinet;

[0038] The whole cabinet is composed of bus voltage transformer unit 2, load switch unit 3 and circuit breaker unit 4 from left to right. The electrical connection between each functional unit is isolated from each other by an insulated bus channel. The station terminal 5 is connected to the cable room of each unit of the whole cabinet through an aviation plug cable.

[0039] The busbar voltage transformer unit 2, load switch unit 3 and circuit breaker unit 4 are all provided with a main cabinet and a secondary low-voltage room 6 (low-voltage distribution room) located above the main cabinet. Circuit components such as relays (such as SPAJ140C, etc.) and live locking control units are installed in the secondary low-voltage room 6, and instruments and equipment such as ammeters, signal indicator lights, fault indicators, live displays, etc. are installed on the panel of the secondary low-voltage room 6.

[0040] The following is a detailed introduction to each unit in conjunction with the accompanying drawings:

[0041] 1) Bus voltage transformer unit

[0042] like Figure 1 , Figure 2 As shown, the main cabinet of the bus voltage transformer unit 2 is provided with an operating hole (10, 11) for the disconnecting / grounding switch opening and closing mechanism and a local / remote control switch on the side close to the panel, and a gas pressure gauge 9 is installed on the cabinet wall panel to display the gas pressure inside the cabinet. The cable chamber 7 and the pressure relief channel of the bus voltage transformer unit 2 are both arranged at the lower part of the main cabinet, with the cable chamber 7 located at the front side and the pressure relief channel located at the rear side, and a pressure relief channel warning sign 8 is affixed to the corresponding position of the cabinet door panel.

[0043] 2) Load switch unit

[0044] The main cabinet of the load switch unit 3 is provided with a load switch mechanism operating hole 12, a grounding switch mechanism operating hole 13, a fuse chamber 14 and a cable chamber 7 on one side close to the panel. The load unit adopts a combination of a load switch and a fuse, uses a spring energy storage mechanism, and the mechanism can be triggered by the fuse striker; it is equipped with a phase current transformer and a zero-sequence current transformer, and is equipped with voltage, current and pressure indicators to clearly detect the internal conditions of the device, and is installed with a local / remote control switch and a fuse alarm device to ensure the safe operation and good operability of the device.

[0045] Specific as Figure 4 As shown, the main cabinet of the load switch unit adopts a common box structure design, and a sealed SF6 gas tank is provided in the cabinet, and the SF6 gas tank is the busbar chamber N1. The main cabinet space outside the busbar chamber N1 is divided into an operating mechanism chamber N2, a fuse chamber N3, a pressure relief channel N4 and the cable chamber N5.

[0046] The SF6 gas box and the pressure relief channel N4 are arranged on a side close to the rear cover plate 43 of the cabinet, and the SF6 gas box is located above the pressure relief channel N4; the operating mechanism chamber N2, the fuse chamber N3 and the cable chamber N5 are arranged on a side close to the cabinet panel, the fuse chamber N3 is located below the operating mechanism chamber N2, and the cable chamber N5 is located below the fuse chamber N3; at the same time, the SF6 gas box is provided with an inwardly recessed groove at the bottom corner close to the cabinet panel, so that its cross-section is "P"-shaped; the top of the cable chamber N5 is higher than the top of the pressure relief channel N4, and its top corner close to the rear cover plate is embedded in the groove, close to the box wall of the SF6 gas box; the cable chamber N5 is installed with an inlet and outlet insulating sleeve 38, and the rear end of the inlet and outlet insulating sleeve 38 passes through the groove wall of the groove and extends into the SF6 gas box.

[0047] The SF6 gas box is a fully enclosed stainless steel shell, which is made by laser cutting and welding technology controlled by a robot and has good sealing performance. The gas box is filled with SF6 gas in a vacuum state to ensure that the switch devices such as the load switch 31, the grounding switch 32 and the busbar 33 are permanently and hermetically integrated in the gas box and are not affected by external conditions. The shell of the SF6 gas box is assembled with the cabinet part by bolts.

[0048] The copper busbar 34, the load switch 31, the fuse and the grounding switch 32 are installed in the SF6 gas box from top to bottom.

[0049] The copper busbar 34 is used to connect the busbars to establish electrical connection between the load switch unit and external devices. The top of the copper busbar 34 can reserve a busbar expansion space, and the installation space of the expansion connector can be reserved on both sides.

[0050] One end of the fuse is connected to the load switch 31 upward through a copper rod, and the other end is connected to the end of the inlet and outlet line insulating sleeve 38 extending into the SF6 gas tank through a copper rod 37, and is connected to the corresponding grounding switch 32, which is used for the combination and expansion of switch cabinets with different functions.

[0051] The load switch 31 is a three-position switch unit, which is used to control the opening, closing and grounding of the ring network line, and can form various functional circuits with the corresponding grounding switch 32. The grounding switch 32 can only be operated manually, while the load switch 31 can also be operated by an electric operating mechanism in addition to manual operation. The operating mechanism chamber N2 is equipped with a spring operating mechanism 35 for controlling the load switch 31 at the position corresponding to the load switch 31, including a load switch / isolating switch operating shaft and a grounding switch operating shaft. At the same time, the load switch unit 2 is equipped with an interlocking device for the load switch 31 and the grounding switch 32 to improve the reliability of the equipment.

[0052] The fuse with the striker is installed in the fuse sealed compartment 36, with the striker pointing to the front of the cabinet. Under normal conditions, the fuse pulls the fuse striker tight. When the fuse blows, the striker loses the fuse and is pushed out by the spring that was originally pulled in, triggering the spring energy storage mechanism of the load switch 31, which plays a tripping role. In order to avoid the possibility of the SF6 gas tank being more or less exposed to moisture during the equipment maintenance process, the main body of the fuse sealed compartment 36 is set in the SF6 gas tank, and the front end part of the fuse sealed compartment 36 with the end cover is extended into the fuse chamber N3. The tripping mechanism of the fuse is placed in front of the SF6 gas tank N1, behind the independent locking shell of the cabinet, that is, the position indicated by the arrow of the fuse chamber N5. After the maintenance personnel open the cabinet panel, they can directly remove the sealed compartment shell of the fuse chamber N5 part through the operating handle to replace the fuse, so as to ensure the waterproof performance of the entire system.

[0053] The fuse and the load switch 31 form a load switch-fuse combination unit. A plurality of pressure relief devices 42 are installed at the bottom of the SF6 gas tank, and a metal pressure relief plate is provided in the pressure relief device 42. The pressure relief device 42 separates the inner cavity of the SF6 gas tank from the pressure relief channel N4 through the metal pressure relief plate.

[0054] The cable chamber N5 and the pressure relief channel N4 are separated by a metal grounding busbar 42. In the cable chamber N5, a bolted outlet bushing 40 connected to the inlet and outlet insulating bushing 38 is provided with a current / voltage / temperature sensor.

[0055] The present invention opens an independent pressure relief channel N4 at the rear bottom of the cabinet to play a buffering and pressure relief role. When the high-temperature gas pressure inside the SF6 gas tank N1 rises sharply, the metal pressure relief plate of the pressure relief device is opened to form a pressure relief passage from top to bottom. The gas is discharged through the pressure relief channel N4 to release the pressure into the cable trench 1000mm deep.

[0056] 3) Circuit breaker unit

[0057] The main cabinet of the circuit breaker unit 4 is provided with a circuit breaker opening and closing button switch mechanism operating hole 15, an energy storage switch mechanism operating hole 16, an isolating switch mechanism operating hole 17, a grounding switch mechanism operating hole 18 and a cable chamber 7 below on one side close to the panel.

[0058] The circuit breaker unit is provided with a series anti-tripping circuit. For a three-phase line, the series anti-tripping circuit includes three sets of identical circuit breaker protection control circuits. The circuit breaker protection control circuit includes a tripping coil, an anti-tripping coil, a switch device K1, a switch device K2 and a switch device S. The switch device K1 is connected in series with the tripping coil, in parallel with the anti-tripping coil, and in parallel with the switch device K2; the switch device S is arranged between the switch device K1 and the tripping coil. Figure 5As shown, the switching devices S in the three-phase circuit are SA, SB, and SC; the tripping coils are YA, YB, and YC; and the anti-tripping coils are K31, K32, and K33.

[0059] The switch devices K1, K2 and switch device S are all auxiliary contacts of the relay. The relay corresponding to the switch device K1 is controlled by the ring network cabinet terminal (station terminal 5, the same below). When the load circuit connected to the circuit breaker works normally, the switch devices K1\K2 are both in the normally open state. The switch device S is also connected to the closing circuit and is in the closed state when closing.

[0060] The resistance of the anti-tripping coil is much greater than the circuit of the tripping coil. When the switch device K1 is in the open state and the switch device S is in the closed state, the voltage division of the anti-tripping coil keeps the voltage of the tripping coil below the action voltage threshold. For example, when the resistance of the tripping coil is about 90Ω, the anti-tripping coil adopts a coil with a resistance of kilo-ohm level.

[0061] When a faulty closing occurs, the ring main unit terminal sends a tripping signal to energize the relay coil corresponding to the switch device K1, closing the switch device K1 and short-circuiting the anti-tripping coil. After the tripping coil voltage rises to the action voltage threshold, the tripping action is triggered, driving the switch device S to trip and disconnecting the closing circuit.

[0062] The circuit breaker protection control circuit also includes a detection unit for monitoring the open / closed state of the switch device S. The switch device K2 is connected in parallel to both ends of the switch device K1, and the switch device K2 is a relay auxiliary contact in a normally open state;

[0063] When the detection unit feeds back that the states of the switch devices S on the three-phase lines are inconsistent, the ring main unit terminal sends a control signal to energize the relay corresponding to the switch device K2, close the switch device K2, short-circuit the anti-tripping coil, and re-trip the switch device S, so that the switch devices S on the three-phase lines are all in the disconnected state.

[0064] As a preferred embodiment, the relay corresponding to the switch device K2 can be a time-delay relay. When the detection unit feedbacks that the state of the switch device S on the three-phase line is inconsistent, the time-delay relay delays 2 seconds to re-trip the switch device S.

[0065] The anti-jump coil is provided with an anti-parallel freewheeling diode, such as Figure 5 As shown, the anti-parallel freewheeling diode can provide a freewheeling path to release the coil current after the anti-trip coil (K31, K32, K33) is short-circuited, preventing the instantaneous high voltage from damaging the circuit itself and playing a protective role for other circuit components.

[0066] The present invention adopts the design of a series anti-tripping circuit to permanently disconnect the closing state of the line when a fault occurs, thereby ensuring the effective disconnection of the faulty line and avoiding damage to electrical equipment due to erroneous reclosing caused by persistent closing.

[0067] The load switch-fuse combination unit provided by the load switch unit 3 is used for transformer protection, which can clear the fault within 10ms, and the required action time is much shorter than the circuit breaker protection method. However, the circuit breaker unit 4 adopts a vacuum switch / vacuum circuit breaker module and can also be used for transformer or line protection, which can be used selectively or together with the load switch unit 3 in the circuit protection system, further ensuring the safety of the equipment.

[0068] In this embodiment, the circuit breaker unit adopts an integrated combination design of an isolating / earthing switch and a circuit breaker, which has a simple structure, low cost, and good protection characteristics. It is equipped with a phase current transformer and a zero-sequence current transformer, and is composed of indicators of voltage, current, and pressure. It is equipped with a local / remote control switch and a fuse alarm device when the fuse is blown. The vacuum switch / vacuum circuit breaker module is equipped with a protection relay and a current transformer to provide transformer or line protection. When used as protection, the relay protection adopts the DMR140 series, ABB-SPAJ140C series or other specified types.

[0069] 4) Station Terminal

[0070] like Figure 3 As shown, the station terminal 5 is arranged in parallel with each functional unit in a separate cabinet. A terminal device 20 is provided in the main cabinet of the station terminal 5, and a communication module 19 is provided above the terminal device 20, so that the station terminal has functions such as remote signaling, remote measurement, and remote adjustment. The terminal device 20 includes a core component 21 and an auxiliary component 22. The core component 21 includes an AC sampling board 23, a main control / auxiliary board 24, an input board 25, and an output / power board 26. The auxiliary component 22 includes a local / remote control switch 27, a switch-on / off button 28, a line nameplate 29, a power module 30, etc.

[0071] In this embodiment, the equipment model of the station terminal is APT-6600, equipped with a D30A-CQ500WD48P24MD power module and a HC730 line loss module. The station terminal is equipped with a triangular socket for convenient external connection and power supply, and is equipped with an incoming cable with a grounding lock to effectively avoid the cabinet being energized and grounded. The equipment can directly collect real-time data of the distribution network and send it to the upper-level master station system, monitor the distribution network status and make decisions at any time, and can also remotely control the distribution network equipment through the master station system, thereby shortening the fault handling time and reducing the labor maintenance cost.

[0072] In the above-mentioned units of this embodiment, the bus voltage transformer unit 1, the load switch unit 2, and the circuit breaker unit 3 are arranged in the same manner with respect to the cable chamber 7, the pressure relief channel, and the pressure relief channel warning sign 8, that is, they will not be described one by one. The height of the entire cabinet of the ring network cabinet is 1363mm, and the side width is 759mm. The cable inlet of the cable chamber 7 is reserved with two different heights of 272mm and 450mm, which are used for the combination and expansion of switch cabinets with different functions. The three-phase outlet bushings 40 in the cabinet are 107mm apart from each phase, and the outlet position is 595mm high from the base. The load switch 31 and the grounding switch 32 are preferably made of silver-graphite alloy material. The switch device has a high melting point and less metal vapor when it is melted. All load switches 31 can be equipped with 2NO+2NC indicating switches for remote signaling, and can be equipped with a tripping coil for remote tripping, which serves to trip the transformer for gas or over-temperature protection.

[0073] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back", etc. cited in the invention are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments in their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0074] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A high-safety SF6 fully insulated compact ring main unit, adopting a common box structure design, including a circuit breaker unit, a load switch unit, a bus voltage transformer unit and a station terminal, wherein the load switch unit includes a main cabinet and a secondary low-voltage chamber arranged above the main cabinet, characterized in that: The main cabinet of the load switch unit is provided with a sealed SF6 gas tank, which is the busbar chamber N1. The main cabinet space outside the busbar chamber N1 is divided into an operating mechanism chamber N2, a fuse chamber N3, a pressure relief channel N4 and a cable chamber N5. The SF6 gas box and the pressure relief channel N4 are arranged on a side close to the rear cover of the cabinet, and the SF6 gas box is located above the pressure relief channel N4; the operating mechanism chamber N2, the fuse chamber N3 and the cable chamber N5 are arranged on a side close to the cabinet panel, the fuse chamber N3 is located below the operating mechanism chamber N2, and the cable chamber N5 is located below the fuse chamber N3; at the same time, the SF6 gas box is provided with an inwardly recessed groove at the bottom corner close to the cabinet panel; the top of the cable chamber N5 is higher than the top of the pressure relief channel N4, and its top corner close to the rear cover is embedded in the groove and closely adheres to the box wall of the SF6 gas box; the cable chamber N5 is installed with an inlet and outlet insulating bushing (38), and the rear end of the inlet and outlet insulating bushing (38) passes through the groove wall of the groove and extends into the SF6 gas box; A copper busbar (34), a load switch (31), a fuse and a grounding switch (32) are installed in the SF6 gas box from top to bottom. The copper busbar (34) is used to connect the busbars and establish an electrical connection between the load switch unit and external equipment. One end of the fuse is connected to the load switch (31) through a copper rod, and the other end is connected to the end of the inlet and outlet line insulating sleeve (38) extending into the SF6 gas box through a copper rod (37), and is connected to the corresponding grounding switch (32). The operating mechanism chamber N2 is provided with a spring operating mechanism (35) for controlling the load switch (31) at a position corresponding to the load switch (31); the fuse is installed in a fuse sealing chamber (36); the main body of the fuse sealing chamber (36) is arranged in the SF6 gas tank, and the front end portion thereof provided with an end cover extends into the fuse chamber N3; A plurality of pressure relief devices (42) are installed at the bottom of the SF6 gas box, wherein a pressure relief plate is provided in the pressure relief device (42), and the pressure relief device (42) separates the inner cavity of the SF6 gas box from the pressure relief channel N4 through the pressure relief plate; The cable chamber N5 and the pressure relief channel N4 are separated by a metal grounding busbar; A circuit breaker unit is provided, wherein a series anti-tripping circuit is provided in the circuit breaker unit; For a three-phase line, the series anti-tripping circuit includes three sets of identical circuit breaker protection control circuits, the circuit breaker protection control circuit includes a tripping coil, an anti-tripping coil, a switch device K1 and a switch device S, the switch device K1 is connected in series with the tripping coil and in parallel with the anti-tripping coil; The switch device S is arranged between the switch device K1 and the trip coil; The switch device K1 and the switch device S are auxiliary contacts of the relay: When the load circuit connected to the circuit breaker works normally, the switch device K1 is in the normally open state; The switch device S is simultaneously connected in the closing circuit and is in a closed state when closing; The resistance of the anti-tripping coil is greater than the resistance of the tripping coil. When the switch device K1 is in the open state and the switch device S is in the closed state, the voltage division of the anti-tripping coil keeps the voltage of the tripping coil below the action voltage threshold; When a faulty closing occurs, the ring main unit terminal sends a tripping signal to energize the relay coil corresponding to the switch device K1, closing the switch device K1 and short-circuiting the anti-tripping coil. After the tripping coil voltage rises to the action voltage threshold, the tripping action is triggered, the switch device S is tripped, and the closing circuit is disconnected.

2. A high-safety SF6 fully insulated compact ring main unit according to claim 1, characterized in that: The load switch (31) and the grounding switch (32) are made of silver-graphite alloy material.

3. A high-safety SF6 fully insulated compact ring main unit according to claim 1, characterized in that: The circuit breaker protection control circuit also includes a detection unit for monitoring the open / closed state of the switch device S, and a switch device K2; The signal output of the detection unit controls the on / off of the relay corresponding to the switch device K2; The switch device K2 is connected in parallel to both ends of the switch device K1, and the switch device K2 is a relay auxiliary contact in a normally open state; When the detection unit feeds back that the states of the switch devices S on the three-phase lines are inconsistent, the ring main unit terminal sends a control signal to energize the relay corresponding to the switch device K2, close the switch device K2, short-circuit the anti-tripping coil, and re-trip the switch device S, so that the switch devices S on the three-phase lines are all in the disconnected state.

4. A high-safety SF6 fully insulated compact ring main unit according to claim 3, characterized in that: The switch device K2 corresponds to a time delay relay. When the detection unit feedbacks that the state of the switch device S on the three-phase line is inconsistent, the time delay relay delays t seconds to close the switch device K2.

5. A high-safety SF6 fully insulated compact ring main unit according to claim 4, characterized in that: The t seconds is 2 seconds.

6. The high-safety SF6 fully insulated compact ring main unit according to claim 1 is characterized in that: The resistance of the tripping coil is 90Ω, and the resistance of the anti-tripping coil is in the kilo-ohm level.

7. The high-safety SF6 fully insulated compact ring main unit according to claim 1 is characterized by: The anti-jump coil is provided with an anti-parallel freewheeling diode.

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