A steam turbine in situ terminal box

Abstract

A local junction box for steam turbines is disclosed. This invention relates to the field of steam turbine junction boxes. Currently, there are no reliable isolation measures between different circuits or between the circuit and the junction box, posing safety hazards to the normal operation of the unit. This invention includes a junction box body, comprising a cabinet door and a cabinet. Inside the cabinet, there is an insulating plate and extended cylindrical nuts. A set of extended cylindrical nuts is installed on the back plate inside the cabinet. The insulating plate has a number of circular holes equal to the number of extended cylindrical nuts. The insulating plate is fixedly connected to the set of extended cylindrical nuts on the back plate of the junction box body via a connecting assembly, making the insulating plate serve as a terminal block mounting plate and a preamplifier mounting plate inside the junction box body. A grounding copper busbar is installed on the junction box body. Two grounding copper busbars are connected using one yellow-green grounding wire, and another yellow-green grounding wire is connected to the power plant grounding grid. This invention is applied to the field of local junction boxes for steam turbines.

Description

Technical Field

[0001] This utility model relates to the field of turbine junction boxes, specifically to a local junction box for a turbine. Background Technology

[0002] The turbine junction box of Harbin Turbine Power Plant's thermal power units is constructed entirely of ordinary steel plate, including the box body, internal terminal block mounting plate, and preamplifier mounting plate. Analog or digital signals such as thermocouples, RTDs, solenoid valves, pressure switches, and limit switches are directly connected to the terminals. The TSI preamplifier is also directly mounted on the metal mounting plate. There is no reliable isolation between different circuits or between the circuits and the box body, and the box body lacks a grounding copper busbar, making it impossible to connect to the power plant's grounding grid. All of this poses safety hazards to the normal operation of the unit.

[0003] Steel plates offer advantages such as high strength, low cost, and protection against electromagnetic interference. However, since steel plates are conductive, incomplete isolation between the junction box interior and the box body, or poor grounding, can cause the junction box to become energized. This introduces external voltage or current interference, leading to measurement errors in thermocouple or RTD signals connected to the internal terminal blocks, affecting temperature calculation accuracy. An energized junction box can also introduce noise through electromagnetic coupling, affecting the TSI preamplifier's signal amplification and conditioning functions, resulting in abnormal TSI monitoring data. Furthermore, the high temperature and humidity environment of thermal power plants makes steel plates susceptible to moisture, rust, and corrosion, leading to a decrease in the junction box's strength. Utility Model Content

[0004] To address the lack of reliable isolation measures between different circuits and between the circuit and the box, and the absence of a grounding copper busbar on the box, which prevents the box from being connected to the power plant's grounding grid and poses a safety hazard to the normal operation of the unit, this utility model provides a local junction box for steam turbines.

[0005] The technical solution of this utility model is:

[0006] A local junction box for a steam turbine comprises a junction box body, the junction box body including a cabinet door and a cabinet, and the cabinet of the junction box body including an insulating plate and an extended cylindrical nut.

[0007] A set of extended cylindrical nuts is installed on the back plate inside the cabinet of the junction box. The insulating plate has a number of circular holes equal to the set of extended cylindrical nuts. The insulating plate is fixedly connected to the set of extended cylindrical nuts on the back plate of the junction box through a connecting assembly, so that the insulating plate serves as the terminal block mounting plate and preamplifier mounting plate inside the junction box. The junction box is equipped with a grounding copper busbar. The grounding copper busbar is connected to two grounding copper busbars by a yellow-green grounding wire, and the other yellow-green grounding wire is connected to the power plant grounding grid.

[0008] Furthermore, the insulating board also includes a 35mm DIN rail, a first groove, and a second groove;

[0009] The insulating plate has three sets of threaded holes for mounting preamplifiers at the upper right position. Each set of threaded holes has a corresponding preamplifier mounted on it.

[0010] The 35mm DIN rail, the first groove, and the second groove are mounted on the insulating plate with self-tapping screws.

[0011] Furthermore, the insulating board is a rectangular insulating board with the upper and lower plates longer than the left and right plates, and the insulating board is made of electrical phenolic laminated cloth, so that the wiring terminals and preamplifiers are insulated from the metal of the junction box body.

[0012] Furthermore, the connecting assembly includes a cross-head pan screw, a spring washer, and a flat washer;

[0013] The circular holes on the insulating plate are fixedly connected to the extended cylindrical nuts on the back plate of the junction box body by cross-grooved pan head screws, spring washers, and flat washers.

[0014] Furthermore, a set of nine extended cylindrical nuts are vertically fixed to the cabinet panel of the junction box by welding.

[0015] Furthermore, the bottom of the junction box cabinet is evenly provided with 6 φ30 sockets, the distance between two adjacent sockets is 100mm, and the diameter of the sockets is compatible with the sealing connector.

[0016] Furthermore, a sealing connector is installed inside the socket to seal the bottom of the junction box.

[0017] Furthermore, the junction box also includes hinges and a label;

[0018] The junction box cabinet door and the cabinet body are connected by hinges, and a nameplate is installed on the junction box cabinet door.

[0019] Furthermore, the cabinet door and cabinet body of the junction box are made of 5A02 aluminum alloy plate.

[0020] Furthermore, a sealing strip is installed at the junction box door where it meets the cabinet.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] The junction box of this invention uses 5A02 aluminum alloy plate for its body, which has advantages such as light weight and corrosion resistance. The internal terminal block mounting plate and preamplifier mounting plate use electrical phenolic laminate insulation material to ensure that the terminals and preamplifier are insulated from the metal of the box body. A grounding copper busbar is installed on the junction box body, and the junction box is connected to the power plant's grounding grid through the grounding copper busbar. This new type of turbine local junction box is simple to manufacture, has a robust structure, and high safety performance, meeting the requirements of thermal power plant local junction boxes for corrosion resistance, insulation performance, and grounding safety, and can significantly improve the operational safety of thermal power units.

[0023] The terminal block mounting plate and preamplifier mounting plate of this invention are not directly fixed to the steel plate, but are mounted on an insulating phenolic laminated cloth, achieving complete isolation between the terminal block, TSI preamplifier, and junction box, thus avoiding the adverse effects of the conductive metal casing on the measurement results. Simultaneously, the junction box grounding system has been optimized to ensure reliable grounding of the junction box, improving the safety of the entire system. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the internal structure of the junction box cabinet;

[0025] Figure 2 This is a structural diagram of the cabinet door;

[0026] Figure 3 for Figure 1 A schematic diagram of the structure along direction A;

[0027] Figure 4 for Figure 3 A partial sectional view;

[0028] Figure 5 Diagram showing the welding location for the elongated cylindrical nut on the back panel of the junction box;

[0029] Figure 6 This is a schematic diagram of the insulating board structure;

[0030] Figure 7 This is a schematic diagram of the grounding copper busbar connection;

[0031] Figure 8 Schematic diagram of the opening for a screw-mounted preamplifier;

[0032] Figure 9 A schematic diagram showing the process of installing a preamplifier in a junction box.

[0033] In the diagram: 1. Junction box body, 2. Insulation board, 3. 35mm DIN rail, 4. Terminal block, 5. Phillips head pan head screw, 6. Spring ring, 7. Flat washer, 8. Extended cylindrical nut, 9. Self-tapping screw, 10. First wire groove, 11. Second wire groove, 12. Sealing joint, 13. Grounding copper busbar, 14. Yellow-green grounding wire, 15. Preamplifier, 16. Socket;

[0034] 1-1 Cabinet door, 1-2 Cabinet body, 1-3 Hinges, 1-4 Signs. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this utility model, but are not intended to limit the scope of this utility model. Specific implementation method one:

[0037] Combination Figure 1 — Figure 9 This embodiment describes a local junction box for a steam turbine, comprising a junction box body 1, wherein the junction box body 1 includes a cabinet door 1-1 and a cabinet 1-2, and the cabinet 1-2 of the junction box body 1 includes an insulating plate 2 and an extended cylindrical nut 8.

[0038] A set of extended cylindrical nuts 8 are installed on the back plate inside the cabinet 1-2 of the junction box body 1. The insulating plate 2 has a number of circular holes equal to the number of extended cylindrical nuts 8. The insulating plate 2 is fixedly connected to the set of extended cylindrical nuts 8 on the back plate of the junction box body 1 via a connecting assembly, making the insulating plate 2 serve as the terminal block mounting plate and preamplifier mounting plate inside the junction box body 1. A grounding copper busbar 13 is installed on the junction box body 1. Two grounding copper busbars 13 are connected by a yellow-green grounding wire 14, and another yellow-green grounding wire 14 is connected to the power plant's grounding grid. This new type of turbine local junction box is simple to manufacture, has a robust structure, and high safety performance. It meets the requirements of thermal power plant local junction boxes for corrosion resistance, insulation performance, and grounding safety, and can significantly improve the operational safety of thermal power units. Specific Implementation Method Two:

[0040] Combination Figure 1 — Figure 9 This embodiment describes a local junction box for a steam turbine, wherein the insulating plate 2 further includes a 35mm DIN rail 3, a first wire groove 10, and a second wire groove 11.

[0041] The upper right position of the insulating plate 2 is provided with threaded holes for installing the preamplifier 15. There are three sets of threaded holes, and three preamplifiers 15 are installed in the three sets of threaded holes respectively.

[0042] The 35mm DIN rail 3, the first groove 10, and the second groove 11 are mounted on the insulating plate 2 by self-tapping screws 9.

[0043] The insulation board 2 is at least 5mm thick and uses electrical grade phenolic laminate fabric, which has a variety of excellent properties. It can maintain stable performance in high temperature environments; it has good oil resistance; it can effectively prevent current conduction and prevent leakage and short circuit accidents; it has high mechanical strength and good machinability, and is easy to cut, drill and other processing operations. Specific implementation method three:

[0045] Combination Figure 1 — Figure 9 This embodiment describes a local junction box for a steam turbine. The insulating plate 2 is a rectangular insulating plate with the upper and lower plates longer than the left and right plates. The insulating plate is made of electrical phenolic laminate fabric, so that the terminals 4 and the preamplifier 15 are metal-insulated from the junction box body 1. Specific implementation method four:

[0047] Combination Figure 1 — Figure 9 This embodiment describes a local junction box for a steam turbine, wherein the connection assembly includes a cross-slot pan head screw 5, a spring washer 6, and a flat washer 7.

[0048] The circular hole on the insulating plate 2 is fixedly connected to the extended cylindrical nut 8 on the back plate of the junction box body 1 by a cross-slot pan head screw 5, a spring washer 6, and a flat washer 7.

[0049] The junction box body 1 has a cabinet door 1-1 and a cabinet body 1-2 made of 5A02 aluminum alloy plate. Nine extended cylindrical nuts 8 are welded to the inner side of the back plate of the cabinet body 1-2. The insulating plate 2 has eight corresponding round holes, which are fixed to the extended cylindrical nuts 8 on the back plate of the junction box by cross-slot pan head screws 5, spring washers 6, and flat washers 7. Specific implementation method five:

[0051] Combination Figure 1 — Figure 9 This embodiment describes a local junction box for a steam turbine. A set of nine extended cylindrical nuts 8 are vertically fixed to the cabinet 1-2 panel of the junction box body 1 by welding.

[0052] The insulating plate 2 has eight φ9 circular holes, the size and position of which are consistent with the position of the elongated cylindrical nut 8 on the back plate of the junction box body 1. Additionally, the insulating plate 2 has three sets of openings for screw-mounted preamplifiers. Specific implementation method six:

[0054] Combination Figure 1 — Figure 9 This embodiment describes a local junction box for a steam turbine. The bottom of the cabinet 1-2 of the junction box body 1 is evenly provided with 6 φ30 sockets 16, the distance between two adjacent sockets 16 is 100mm, and the diameter of the sockets 16 is adapted to the sealing joint 12. Specific implementation method seven:

[0056] Combination Figure 1 — Figure 9 This embodiment describes a local junction box for a steam turbine, wherein a sealing joint 12 is installed inside the socket 16 to seal the bottom of the junction box body 1.

[0057] The sealing joint 12 is located at the bottom of the junction box 1 and is used to seal the cable passing through the junction box. The grounding copper busbar 13 is installed on the lower inner side of the cabinet door 1-1 and the cabinet body 1-2, and is connected to the power plant grounding grid through the yellow-green grounding wire 14. Detailed implementation method eight:

[0059] Combination Figure 1 — Figure 9 This embodiment describes a local junction box for a steam turbine. The junction box body 1 further includes hinges 1-3 and nameplates 1-4.

[0060] The cabinet door 1-1 and cabinet 1-2 of junction box 1 are rotatably connected by hinge 1-3, and a nameplate 1-4 is installed on the cabinet door 1-1 of junction box 1.

[0061] The cabinet door 1-1 and cabinet body 1-2 are made of 5A02 aluminum alloy plate, a rust-resistant aluminum alloy material with high fatigue strength and corrosion resistance. The hinge 1-3 is made of stainless steel, which also has good corrosion resistance and strength. The nameplate 1-4, made of stainless steel with a brushed finish, is installed in a suitable position on the cabinet door 1-1 and has good wear resistance. A sealing strip is installed on the cabinet door 1-1. Specific implementation method nine:

[0063] Combination Figure 1 — Figure 9 This embodiment describes a local junction box for a steam turbine. The cabinet door 1-1 and cabinet body 1-2 of the junction box body 1 are made of 5A02 aluminum alloy plate.

[0064] The junction box body 1 is made of 5A02 aluminum alloy plate, which has the advantages of being lightweight and corrosion resistant;

[0065] The internal terminal block mounting plate and preamplifier mounting plate use electrical phenolic laminate insulation material to ensure that the wiring terminals and preamplifier are insulated from the metal of the box. Specific Implementation Method Ten:

[0067] Combination Figure 1 — Figure 9 This embodiment describes a local junction box for a steam turbine. A sealing strip is installed at the closing point between the cabinet door 1-1 and the cabinet body 1-2 of the junction box body 1.

[0068] Installation steps:

[0069] After the insulating board 2 is processed, align the round hole of the insulating board 2 with the extended cylindrical nut 8 on the back plate of the junction box, and press the insulating board 2 to check for any obvious bending. If there is bending, continue to weld extended cylindrical nuts 8 at appropriate positions on the back plate of the junction box body 1 until the insulating board 2 is no longer obviously bent. Then, use cross-slot pan head screws 5, spring washers 6, and flat washers 7 to fix the insulating board 2 to the extended cylindrical nuts 8 of the junction box body 1, for a total of 8 installations.

[0070] Refer to the following: three 35mm DIN rails 3 with terminals 4 installed, one empty 35mm DIN rail 3, wire trough 10, and wire trough 11. Figure 1 After placing the terminal 4 in a suitable position on the insulating board 2, ensuring its even distribution and sufficient wiring space on both sides of the terminal 4 to the wire grooves 10 and 11, use self-tapping screws 9 to fix it to the insulating board 2. Use self-tapping screws 9 as needed, ensuring the guide rail and wire groove are securely installed. After installation, there should be some space between the length of the self-tapping screws 9 and the back plate of the junction box body 1.

[0071] Press the grounding copper busbar 13. Figure 7 As shown, the grounding copper busbars 13 are installed on the bottom inner sides of cabinet door 1-1 and cabinet body 1-2 respectively. After connecting the two grounding copper busbars 13 using a yellow-green grounding wire 14, they are then connected to the power plant's grounding grid via another yellow-green grounding wire 14. Using this connection method, even if the electrical equipment inside the junction box 1 experiences insulation damage and current leakage to the equipment casing, the leakage current will be conducted to the ground through the grounding copper busbar 13, avoiding safety hazards caused by energized equipment. Simultaneously, because the metal junction box 1 has the function of preventing electromagnetic interference, the grounding copper busbar 13 can also introduce electromagnetic interference generated during the operation of the electrical equipment to the ground, thereby reducing the impact of electromagnetic interference on the normal operation of the equipment and components.

[0072] Finally, install the sealing connector 12 in the six φ30 sockets 16 at the bottom of the junction box.

[0073] For the final use of the junction box, see Figure 8 In actual use, the analog or digital measurement points of the junction box 1 are connected to the terminals. The TSI preamplifier is installed in a suitable location depending on whether it is screw-mounted or rail-mounted. The internal cables pass through the sealing connector 12, which also ensures the sealing of the junction box. Using this implementation method ensures the safety and reliability of the turbine monitoring system.

[0074] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present utility model's technical solution. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present utility model's technical solution, based on the technical essence of the present utility model and within the spirit and principles of the present utility model, shall still fall within the protection scope of the present utility model's technical solution.

Claims

1. A local junction box for a steam turbine, comprising a junction box body (1), wherein the junction box body (1) includes a door (1-1) and a cabinet (1-2), characterized in that, The junction box body (1) includes an insulating plate (2) and an extended cylindrical nut (8) inside the cabinet (1-2). A set of extended cylindrical nuts (8) is installed on the back plate inside the cabinet (1-2) of the junction box body (1). The insulating plate has a number of round holes equal to the set of extended cylindrical nuts (8). The insulating plate (2) is fixedly connected to the set of extended cylindrical nuts (8) on the back plate of the junction box body (1) through the connecting assembly, so that the insulating plate (2) serves as the terminal block mounting plate and preamplifier mounting plate inside the junction box body (1). The junction box body (1) is equipped with a grounding copper busbar (13). The grounding copper busbar (13) is connected to two grounding copper busbars (13) using a yellow-green grounding wire (14). Another yellow-green grounding wire (14) is connected to the power plant grounding grid.

2. The turbine local junction box according to claim 1, characterized in that, The insulating plate (2) also includes a 35mm DIN rail (3), a first groove (10), and a second groove (11); The insulating plate (2) has a threaded hole for installing a preamplifier (15) at the upper right position. There are three sets of threaded holes, and three preamplifiers (15) are installed in the three sets of threaded holes respectively. The 35mm DIN rail (3), the first groove (10) and the second groove (11) are mounted on the insulating plate (2) by self-tapping screws (9).

3. The turbine local junction box according to claim 2, characterized in that, The insulating board (2) is a rectangular insulating board (2) with the upper and lower plate lengths being greater than the left and right plate lengths. The insulating board is made of electrical phenolic laminate fabric, so that the wiring terminals (4) and the preamplifier (15) are metal insulated from the junction box body (1).

4. The turbine local junction box according to claim 1, characterized in that, The connecting assembly includes a cross-shaped pan head screw (5), a spring washer (6), and a flat washer (7). The circular hole on the insulating plate (2) is fixedly connected to the elongated cylindrical nut (8) on the back plate of the junction box body (1) by a cross-groove pan head screw (5), a spring washer (6), and a flat washer (7).

5. The turbine local junction box according to claim 4, characterized in that, A set of nine extended cylindrical nuts (8) are vertically fixed to the cabinet (1-2) panel of the junction box (1) by welding.

6. The turbine local junction box according to claim 5, characterized in that, The bottom of the cabinet (1-2) of the junction box (1) is evenly provided with 6 φ30 sockets (16), the distance between two adjacent sockets (16) is 100mm, and the diameter of the sockets (16) is compatible with the sealing joint (12).

7. The turbine local junction box according to claim 6, characterized in that, A sealing connector (12) is installed inside the socket (16) to seal the bottom of the junction box body (1).

8. The turbine local junction box according to claim 1, characterized in that, The junction box body (1) also includes hinges (1-3) and a nameplate (1-4). The cabinet door (1-1) and cabinet (1-2) of the junction box body (1) are rotatably connected by a hinge (1-3), and a nameplate (1-4) is installed on the cabinet door (1-1) of the junction box body (1).

9. The turbine local junction box according to claim 8, characterized in that, The cabinet door (1-1) and cabinet body (1-2) of the junction box body (1) are made of 5A02 aluminum alloy plate.

10. The turbine local junction box according to claim 8 or 9, characterized in that, A sealing strip is installed at the junction of the cabinet door (1-1) and the cabinet body (1-2) of the junction box body (1).

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