An embedded fold-back water-cooled generator outlet bushing and cooling method

Abstract

This invention discloses an embedded, folding-back, water-cooled generator output bushing, belonging to the technical field of steam turbine generators. It includes a conductive rod, which is fitted with a ceramic sleeve. A gap exists between the conductive rod and the ceramic sleeve, filled with sealant. An inner copper tube is fitted inside the conductive rod. One end of the conductive rod is connected to a first connector, and the other end is connected to a second connector. One end of the inner copper tube extends into the first connector, and the other end extends into the second connector. The first connector has an inlet and an outlet. An annular gap for cooling water flow is provided between the inner copper tube and the conductive rod. An outlet channel is formed on the inner copper tube. The inlet is connected to the annular gap, and the outlet is connected to the outlet channel. The annular gap and the outlet channel form a U-shaped cooling water path. This invention can actively prevent airlocking, effectively reduce the temperature rise of the generator output bushing, and improve current carrying capacity.

Description

Technical Field

[0001] This invention relates to the field of steam turbine generator technology, and in particular to an embedded folding-back water-cooled generator output bushing and cooling method. Background Technology

[0002] The stator current of a large-capacity steam turbine generator is transmitted through a sealed high-voltage outgoing bushing. The generator outgoing bushing is equipped with a bushing-type current transformer. The generator outgoing bushing is a high-voltage, high-current power carrying and transmission component.

[0003] The generator's output bushings are connected to the stator ring leads, and the generator ring lead water cooling system is a core component for ensuring the electrical performance and safe operation of the high-voltage generator. It uses circulating cooling water to remove heat generated by conductive components, such as the copper ring leads. Preventing airlocks is a critical design requirement, as airlocks can easily cause numerous problems, such as: This can lead to cooling failure and localized overheating: Gases dissolve in water, and when water flows through pipe changes in diameter, bends, narrow areas of equipment, or the top of waterways, the air bubbles rise due to buoyancy and accumulate, forming an airlock. When an airlock occurs, the accumulated gas forms an insulating layer, blocking heat exchange between the cooling water and the conductive copper pipe. The temperature can rise from normal to over 200°C within seconds, far exceeding the temperature resistance limit of the insulation material, causing insulation carbonization and breakdown.

[0004] Inducing mechanical stress and damaging equipment structure: When air blockage leads to localized overheating, the expansion of the annular lead is much greater than that of the insulating tube, generating radial compressive stress, which may cause the annular lead to crack and cooling water leakage. Localized overheating may also cause fretting wear, leading to material fatigue fracture under long-term operation, affecting the safe operation of the generator.

[0005] Accelerating electrical performance degradation and shortening lifespan: High temperatures accelerate the thermal aging of insulation materials; for every 10°C increase in temperature, the lifespan of insulation materials is halved. Copper ring leads will recrystallize at high temperatures, and the coarsening of grains leads to an increase in resistivity, increasing generator operating losses.

[0006] The most significant characteristic of existing straight-through water-cooled generator bushings is that the cooling water flows directly through the generator, with the inlet located inside the generator and the outlet outside. This straight-through water system relies on external piping connections, resulting in complex piping layouts on the outside of the generator. This increases the risk of mechanical interface failure and leakage. Furthermore, the airlock problem is not addressed at the structural design level, relying solely on post-installation control. Human error during installation can easily lead to excessive flow resistance and insufficient flow, causing airlocks, localized overheating of the water system, and ultimately, burnt-out of the generator's ring leads.

[0007] Chinese patent application document with publication number CN203416088U and publication date January 29, 2014 discloses a generator outlet bushing sealing structure, including a conductive rod and an insulating sleeve. The insulating sleeve is fitted onto the conductive rod and locked by a locking nut. There is an annular space gap between the inner wall of the insulating sleeve and the outer wall of the conductive rod. The annular space gap is filled with high-temperature resistant insulating sealant.

[0008] The generator bushing sealing structure disclosed in this patent application, without altering the original installation structure and dimensions of the bushing, achieves an absolute and tight seal by filling the annular space between the inner wall of the insulating bushing and the outer wall of the conductive rod with high-temperature resistant insulating sealant. This sealant provides excellent sealing regardless of the expansion and extension of the conductive rod due to heat, effectively preventing leakage of the generator's cooling medium—hydrogen—thus reducing generator operating costs and improving generator safety and stability. However, the conductive rod relies on indirect heat dissipation from the external environment, which cannot effectively reduce the temperature rise of the generator bushing, affecting its current-carrying capacity. Summary of the Invention

[0009] To overcome the shortcomings of the prior art, this invention provides an embedded folding-back water-cooled generator outlet bushing and a cooling method. This invention constructs a U-shaped folding-back cooling water circuit through the annular gap between the inner copper tube and the conductive rod, and the water outlet channel inside the inner copper tube. This actively guides the water flow direction and hydrodynamic characteristics, fundamentally eliminating the key physical conditions and space for the formation of stagnant air bubbles and air blockage within the cooling water system. The cooling water circulates within the conductive rod, achieving active anti-air blockage and directly carrying away the heat generated by the conductive rod, effectively reducing the temperature rise of the generator outlet bushing and improving its current-carrying capacity.

[0010] This invention is achieved through the following technical solution: An embedded folding-back water-cooled generator output bushing includes a conductive rod, an outer sleeve of which is covered by a ceramic sleeve. A gap exists between the ceramic sleeve and the conductive rod, filled with sealant. An inner copper tube is fitted inside the conductive rod. One end of the conductive rod is connected to a first connector, and the other end is connected to a second connector. One end of the inner copper tube extends into the first connector, and the other end extends into the second connector. The first connector has an inlet and an outlet. An annular gap for cooling water flow is provided between the inner copper tube and the conductive rod. An outlet channel is formed on the inner copper tube. The inlet is connected to the annular gap, and the outlet is connected to the outlet channel. The annular gap and the outlet channel form a U-shaped cooling water path.

[0011] The width of the annular gap between the conductive rod and the inner copper tube is 0.5mm-2mm.

[0012] The ceramic sleeve is provided with a flange, and the ceramic sleeve and the conductive rod are fixed by the flange.

[0013] A current transformer is mounted on the porcelain bushing.

[0014] The wall thickness of the inner copper tube is 1mm-3mm.

[0015] The water inlet is vertically mounted on the first connector.

[0016] The water outlet is horizontally positioned on the first connector, and the central axis of the water outlet coincides with the central axis of the inner copper pipe.

[0017] Both the water inlet and outlet are located inside the generator.

[0018] The sealant is an epoxy resin sealant.

[0019] A cooling method for the output bushing of a generator with an embedded foldback water-cooled structure includes the following steps: Step S1: Cooling water is introduced into the water inlet, and the cooling water flows into the annular gap between the inner copper tube and the conductive rod. Step S2: After the cooling water cools the conductive rod, it flows back into the outlet channel of the inner copper tube at the second joint. Step S3: Cooling water flows out through the outlet interface along the water outlet channel of the inner copper pipe, completing the cooling work of the generator outlet bushing.

[0020] In step S1, the flow velocity of cooling water in the annular gap is not less than 0.7 m / s.

[0021] In step S1, the cooling water is deionized water.

[0022] The beneficial effects of this invention are mainly reflected in the following aspects: 1. Compared with the prior art, the present invention constructs a U-shaped zigzag cooling water circuit by forming an annular gap between the inner copper tube and the conductive rod and the water outlet channel inside the inner copper tube. This actively guides the direction of water flow and hydrodynamic characteristics, fundamentally eliminating the key physical conditions and space for the formation of stagnant air bubbles and causing air blockage in the cooling water system. The cooling water completes circulation inside the conductive rod, achieving active anti-air blockage and directly carrying away the heat generated by the conductive rod, effectively reducing the temperature rise of the generator outlet bushing and improving the current carrying capacity.

[0023] 2. In this invention, the width of the annular gap is specifically 0.5mm-2mm. This narrow gap can increase the cooling water flow rate and heat transfer coefficient, thereby enhancing the cooling efficiency, while avoiding excessive water resistance or processing difficulties caused by too small a gap.

[0024] 3. The present invention uses a flange to fix the porcelain bushing to the conductive rod, which can ensure the structural stability and sealing of the entire generator outlet bushing, while facilitating installation, disassembly and maintenance.

[0025] 4. This invention, by installing a current transformer on the outside of the porcelain bushing, enables real-time monitoring of the generator output current while simultaneously achieving water cooling of the conductive rod.

[0026] 5. In this invention, the copper tube wall thickness is specifically adopted to be 1mm-3mm, which can ensure that the inner copper tube has sufficient mechanical strength and water pressure resistance, and is also conducive to heat transfer, avoiding the effect of excessive wall thickness affecting the cooling effect.

[0027] 6. In this invention, the water inlet is vertically set on the first connector, which facilitates the vertical access of cooling water from the external pipeline, reduces the resistance of the bend, and at the same time helps the water flow to enter the annular gap evenly.

[0028] 7. In this invention, the water outlet is set horizontally and the central axis of the water outlet coincides with the inner copper pipe, so that the water flow channel is straight and without abrupt changes, reducing water resistance, avoiding turbulence, and ensuring smooth operation of the return water path.

[0029] 8. In this invention, both the water inlet and outlet interfaces are located inside the generator. By integrating the water inlet and outlet interfaces of the generator outlet bushing into the generator, the relevant water interfaces can be integrated and sealed during the generator production stage. This significantly reduces the number of complex water pipes that need to be connected on site, greatly simplifies the on-site installation process, and effectively avoids the risk of assembly errors caused by on-site operations, making on-site installation more convenient and safer.

[0030] 9. In this invention, the sealant is an epoxy resin sealant. Epoxy resin has excellent insulation, adhesion and heat resistance, and can reliably seal and withstand the temperature and vibration during generator operation.

[0031] 10. The present invention adopts a cooling method with an embedded folding water cooling structure, which realizes cyclic cooling through three steps: water inlet, folding, and water outlet. The whole method is simple and reliable, and can use the U-shaped water channel to uniformly cool the entire length of the conductive rod, significantly reducing the working temperature of the generator outlet bushing and ensuring operational reliability.

[0032] 11. In this invention, the flow velocity of cooling water in the annular gap is not less than 0.7 m / s, which can ensure heat exchange efficiency, prevent local overheating, and avoid water resistance caused by excessive flow velocity. It eliminates the conditions for air blockage from the physical mechanism level and ensures the stability of cooling water circulation. Attached Figure Description

[0033] The present invention will now be further described in detail with reference to the accompanying drawings and specific embodiments, wherein: Figure 1 This is a schematic diagram of the structure of the present invention; The markings in the diagram are: 1. Conductive rod, 2. Porcelain sleeve, 3. Sealant, 4. Inner copper tube, 5. First connector, 6. Second connector, 7. Water inlet, 8. Water outlet, 9. Annular gap, 10. Water outlet channel, 11. Handle flange, 12. Current transformer. Detailed Implementation

[0034] Example 1 See Figure 1 An embedded folding-back water-cooled generator output bushing includes a conductive rod 1, an outer sleeve of a ceramic sleeve 2, a gap between the ceramic sleeve 2 and the conductive rod 1 filled with sealant 3, an inner copper tube 4 inside the conductive rod 1, one end of the conductive rod 1 connected to a first connector 5, and the other end of the conductive rod 1 connected to a second connector 6, one end of the inner copper tube 4 extending into the first connector 5, and the other end of the inner copper tube 4 extending into the second connector 6, the first connector 5 having an inlet 7 and an outlet 8, an annular gap 9 for cooling water flow between the inner copper tube 4 and the conductive rod 1, and an outlet channel 10 on the inner copper tube 4, the inlet 7 communicating with the annular gap 9, and the outlet 8 communicating with the outlet channel 10, forming a U-shaped cooling water path.

[0035] This embodiment is the most basic implementation method. Compared with the prior art, a U-shaped zigzag cooling water circuit is constructed through the annular gap 9 formed between the inner copper tube 4 and the conductive rod 1 and the water outlet channel 10 inside the inner copper tube 4. This actively guides the water flow direction and hydrodynamic characteristics, fundamentally eliminating the key physical conditions and space for the formation of stagnant air bubbles and causing air blockage in the cooling water system. The cooling water completes circulation inside the conductive rod 1, realizing active anti-air blockage. It can directly remove the heat generated by the conductive rod 1, effectively reducing the temperature rise of the generator outlet bushing and improving the current carrying capacity.

[0036] Example 2 See Figure 1An embedded folding-back water-cooled generator output bushing includes a conductive rod 1, an outer sleeve of a ceramic sleeve 2, a gap between the ceramic sleeve 2 and the conductive rod 1 filled with sealant 3, an inner copper tube 4 inside the conductive rod 1, one end of the conductive rod 1 connected to a first connector 5, and the other end of the conductive rod 1 connected to a second connector 6, one end of the inner copper tube 4 extending into the first connector 5, and the other end of the inner copper tube 4 extending into the second connector 6, the first connector 5 having an inlet 7 and an outlet 8, an annular gap 9 for cooling water flow between the inner copper tube 4 and the conductive rod 1, and an outlet channel 10 on the inner copper tube 4, the inlet 7 communicating with the annular gap 9, and the outlet 8 communicating with the outlet channel 10, forming a U-shaped cooling water path.

[0037] Preferably, the width of the annular gap 9 between the conductive rod 1 and the inner copper tube 4 is 0.5 mm.

[0038] The ceramic sleeve 2 is provided with a handle flange 11, and the ceramic sleeve 2 and the conductive rod 1 are fixed by the handle flange 11.

[0039] This embodiment is a preferred implementation method. The porcelain bushing 2 and the conductive rod 1 are fixedly connected by the flange 11, which can ensure the structural stability and sealing of the entire generator outlet bushing, and at the same time facilitates installation, disassembly and maintenance.

[0040] Example 3 See Figure 1 An embedded folding-back water-cooled generator output bushing includes a conductive rod 1, an outer sleeve of a ceramic sleeve 2, a gap between the ceramic sleeve 2 and the conductive rod 1 filled with sealant 3, an inner copper tube 4 inside the conductive rod 1, one end of the conductive rod 1 connected to a first connector 5, and the other end of the conductive rod 1 connected to a second connector 6, one end of the inner copper tube 4 extending into the first connector 5, and the other end of the inner copper tube 4 extending into the second connector 6, the first connector 5 having an inlet 7 and an outlet 8, an annular gap 9 for cooling water flow between the inner copper tube 4 and the conductive rod 1, and an outlet channel 10 on the inner copper tube 4, the inlet 7 communicating with the annular gap 9, and the outlet 8 communicating with the outlet channel 10, forming a U-shaped cooling water path.

[0041] The width of the annular gap 9 between the conductive rod 1 and the inner copper tube 4 is 1 mm.

[0042] The ceramic sleeve 2 is provided with a handle flange 11, and the ceramic sleeve 2 and the conductive rod 1 are fixed by the handle flange 11.

[0043] A current transformer 12 is mounted on the porcelain bushing 2.

[0044] The inner copper tube 4 has a wall thickness of 1 mm.

[0045] This embodiment is a preferred implementation. By installing a current transformer 12 outside the porcelain bushing 2, the generator output current can be monitored in real time while the conductive rod 1 is water-cooled.

[0046] Example 4 See Figure 1 An embedded folding-back water-cooled generator output bushing includes a conductive rod 1, an outer sleeve of a ceramic sleeve 2, a gap between the ceramic sleeve 2 and the conductive rod 1 filled with sealant 3, an inner copper tube 4 inside the conductive rod 1, one end of the conductive rod 1 connected to a first connector 5, and the other end of the conductive rod 1 connected to a second connector 6, one end of the inner copper tube 4 extending into the first connector 5, and the other end of the inner copper tube 4 extending into the second connector 6, the first connector 5 having an inlet 7 and an outlet 8, an annular gap 9 for cooling water flow between the inner copper tube 4 and the conductive rod 1, and an outlet channel 10 on the inner copper tube 4, the inlet 7 communicating with the annular gap 9, and the outlet 8 communicating with the outlet channel 10, forming a U-shaped cooling water path.

[0047] The width of the annular gap 9 between the conductive rod 1 and the inner copper tube 4 is 2 mm.

[0048] The ceramic sleeve 2 is provided with a handle flange 11, and the ceramic sleeve 2 and the conductive rod 1 are fixed by the handle flange 11.

[0049] A current transformer 12 is mounted on the porcelain bushing 2.

[0050] The inner copper tube 4 has a wall thickness of 3 mm.

[0051] The water inlet 7 is vertically mounted on the first connector 5.

[0052] The water outlet 8 is horizontally positioned on the first connector 5, and the central axis of the water outlet 8 coincides with the central axis of the inner copper pipe 4.

[0053] This embodiment is a preferred implementation. The water inlet 7 is vertically set on the first connector 5, which facilitates the vertical access of cooling water from the external pipeline, reduces the resistance of the bend, and at the same time helps the water flow into the annular gap 9 evenly.

[0054] The water outlet 8 is set horizontally and its central axis coincides with the inner copper pipe 4, so that the water outlet channel 10 is straight and without abrupt changes, reducing water outlet resistance, avoiding turbulence, and ensuring smooth operation of the return water path.

[0055] Example 5 See Figure 1 An embedded folding-back water-cooled generator output bushing includes a conductive rod 1, an outer sleeve of a ceramic sleeve 2, a gap between the ceramic sleeve 2 and the conductive rod 1 filled with sealant 3, an inner copper tube 4 inside the conductive rod 1, one end of the conductive rod 1 connected to a first connector 5, and the other end of the conductive rod 1 connected to a second connector 6, one end of the inner copper tube 4 extending into the first connector 5, and the other end of the inner copper tube 4 extending into the second connector 6, the first connector 5 having an inlet 7 and an outlet 8, an annular gap 9 for cooling water flow between the inner copper tube 4 and the conductive rod 1, and an outlet channel 10 on the inner copper tube 4, the inlet 7 communicating with the annular gap 9, and the outlet 8 communicating with the outlet channel 10, forming a U-shaped cooling water path.

[0056] The width of the annular gap 9 between the conductive rod 1 and the inner copper tube 4 is 2 mm.

[0057] The ceramic sleeve 2 is provided with a handle flange 11, and the ceramic sleeve 2 and the conductive rod 1 are fixed by the handle flange 11.

[0058] A current transformer 12 is mounted on the porcelain bushing 2.

[0059] The inner copper tube 4 has a wall thickness of 3 mm.

[0060] The water inlet 7 is vertically mounted on the first connector 5.

[0061] More preferably, the water outlet 8 is horizontally disposed on the first connector 5, and the central axis of the water outlet 8 coincides with the central axis of the inner copper pipe 4.

[0062] Both the water inlet 7 and the water outlet 8 are located inside the generator.

[0063] The sealant 3 is an epoxy resin sealant.

[0064] This embodiment is a preferred implementation. Both the water inlet 7 and the water outlet 8 are located inside the generator. By integrating the water inlet 7 and the water outlet 8 of the generator outlet bushing into the generator, the relevant water interfaces can be integrated and sealed during the generator production stage. This significantly reduces the number of complex water pipes that need to be connected on site, greatly simplifies the on-site installation process, and effectively avoids the risk of assembly errors caused by on-site operations, making on-site installation more convenient and safer.

[0065] Sealant 3 is an epoxy resin sealant. Epoxy resin has excellent insulation, adhesion and heat resistance, and can reliably seal and withstand the temperature and vibration during generator operation.

[0066] Example 6 See Figure 1 A cooling method for the output bushing of a generator with an embedded foldback water-cooled structure includes the following steps: Step S1: Cooling water is introduced into the water inlet 7, and the cooling water flows into the annular gap 9 between the inner copper pipe 4 and the conductive rod 1; Step S2: After cooling the conductive rod 1, the cooling water flows back into the outlet channel 10 of the inner copper pipe 4 at the second connector 6. Step S3: Cooling water flows out through the outlet port 8 along the outlet channel 10 of the inner copper pipe 4, completing the cooling work of the generator outlet bushing.

[0067] This embodiment is a preferred implementation method, which adopts a cooling method with an embedded folding water cooling structure. It achieves cyclic cooling through three steps: water inlet, folding, and water outlet. The whole method is simple and reliable, and can use the U-shaped water channel to uniformly cool the entire length of the conductive rod 1, significantly reducing the working temperature of the generator outlet bushing and ensuring operational reliability.

[0068] Example 7 See Figure 1 A cooling method for the output bushing of a generator with an embedded foldback water-cooled structure includes the following steps: Step S1: Cooling water is introduced into the water inlet 7, and the cooling water flows into the annular gap 9 between the inner copper pipe 4 and the conductive rod 1; Step S2: After cooling the conductive rod 1, the cooling water flows back into the outlet channel 10 of the inner copper pipe 4 at the second connector 6. Step S3: Cooling water flows out through the outlet port 8 along the outlet channel 10 of the inner copper pipe 4, completing the cooling work of the generator outlet bushing.

[0069] In step S1, the flow rate of cooling water in the annular gap 9 is not less than 0.7 m / s.

[0070] In step S1, the cooling water is deionized water.

[0071] This embodiment is a preferred implementation. The flow velocity of cooling water in the annular gap 9 is not less than 0.7 m / s, which can ensure heat exchange efficiency, prevent local overheating, and avoid water resistance caused by excessive flow velocity. It eliminates the conditions for air blockage from the physical mechanism level and ensures the stability of cooling water circulation.

[0072] The basic principle of this invention is as follows: Based on an embedded zigzag water-cooling structure: an inner copper tube 4 is installed inside the conductive rod 1, forming an annular gap 9 with a width of 0.5mm-2mm between them. The inner copper tube 4 also serves as an independent outlet channel 10. Cooling water is vertically introduced from the inlet port 7 on the first connector 5, first flowing into the annular gap 9 and then along the axial direction of the conductive rod 1. Due to the narrowness of the annular gap 9 and the forced guidance of the water flow direction, the cooling water can uniformly and rapidly sweep across the inner wall of the conductive rod 1, directly absorbing the heat generated by the conductive rod 1. When the cooling water flows to the other end of the conductive rod 1, i.e., the second connector 6, it is naturally zigzag due to structural constraints, entering the outlet channel 10 inside the inner copper tube 4, and flowing back horizontally to the outlet port 8 at the first connector 5. Thus, the annular gap 9 and the outlet channel 10 of the inner copper tube 4 together construct a U-shaped zigzag cooling water circuit, allowing the cooling water to complete a complete cooling cycle inside the conductive rod 1.

[0073] The U-shaped reversible cooling water circuit design actively eliminates the risks of air bubble retention and air blockage. In traditional water-cooling structures, cooling water channels often have local expansion, corners, or abrupt cross-sectional changes, easily creating low-velocity water flow zones. Once air bubbles enter, they cannot be carried away by the water flow, gradually accumulating to form air blockage and blocking cooling water circulation. In this invention, the reversal point of the U-shaped reversible cooling water circuit is located at the end of the annular gap 9. The entire water circuit cross-section is continuous without sharp corners, and the water flow direction is strictly limited to axial forward and reverse flow, eliminating local low-pressure or stagnant areas where air bubbles can remain. Even if tiny air bubbles enter, they will be continuously flushed away by a high-speed water flow of at least 0.7 m / s and carried to the outlet 8 for discharge, thus fundamentally preventing air bubble accumulation and air blockage, ensuring long-term stable cooling water circulation.

[0074] Building upon this foundation, the cooling method further ensures cooling efficiency and reliability through parameter optimization and medium selection. Specifically: the width of the annular gap 9 is limited to 0.5mm-2mm, which can improve flow rate and heat transfer coefficient without excessively increasing water resistance; deionized water is used for cooling to avoid insulation failure caused by leakage of conductive media; the inlet port 7 is vertical and the outlet port 8 is horizontal and coaxial with the inner copper pipe 4, respectively optimizing the uniformity of inflow and the smoothness of outflow. In actual operation, cooling water continuously flows in from the inlet port 7, flows out from the outlet port 8 after a U-shaped return, and the heat generated by the conductive rod 1 is directly carried away by the circulating water, significantly reducing the temperature rise of the generator outlet bushing and improving the current carrying capacity. At the same time, both the inlet port 7 and the outlet port 8 are integrated inside the generator, simplifying on-site piping connections and further ensuring the system's sealing reliability and ease of installation.

Claims

1. An embedded folding-back water-cooled generator output bushing, comprising a conductive rod (1), characterized in that: The conductive rod (1) is covered with a ceramic sleeve (2), and there is a gap between the ceramic sleeve (2) and the conductive rod (1). The gap is filled with sealant (3). The conductive rod (1) is fitted with an inner copper tube (4). One end of the conductive rod (1) is connected to a first connector (5), and the other end of the conductive rod (1) is connected to a second connector (6). One end of the inner copper tube (4) extends into the first connector (5), and the other end of the inner copper tube (4) extends into the second connector (6). The first connector (5) is provided with a water inlet (7) and a water outlet (8). An annular gap (9) for cooling water to flow is provided between the inner copper tube (4) and the conductive rod (1). A water outlet channel (10) is opened on the inner copper tube (4). The water inlet (7) is connected to the annular gap (9), and the water outlet (8) is connected to the water outlet channel (10). The annular gap (9) and the water outlet channel (10) form a U-shaped cooling water circuit.

2. The embedded folding-back water-cooled generator output bushing according to claim 1, characterized in that: The width of the annular gap (9) between the conductive rod (1) and the inner copper tube (4) is 0.5mm-2mm.

3. The embedded folding-back water-cooled generator output bushing according to claim 1, characterized in that: The ceramic sleeve (2) is provided with a flange (11) for fixing the ceramic sleeve (2) and the conductive rod (1).

4. The embedded folding-back water-cooled generator output bushing according to claim 1, characterized in that: A current transformer (12) is fitted onto the porcelain bushing (2).

5. The embedded folding-back water-cooled generator output bushing according to claim 1, characterized in that: The wall thickness of the inner copper tube (4) is 1mm-3mm.

6. The embedded folding-back water-cooled generator output bushing according to claim 1, characterized in that: The water inlet (7) is vertically mounted on the first connector (5).

7. The embedded folding-back water-cooled generator output bushing according to claim 1, characterized in that: The water outlet (8) is horizontally positioned on the first connector (5), and the central axis of the water outlet (8) coincides with the central axis of the inner copper pipe (4).

8. The embedded folding-back water-cooled generator output bushing according to claim 1, characterized in that: Both the water inlet (7) and the water outlet (8) are located inside the generator.

9. The embedded folding-back water-cooled generator output bushing according to claim 1, characterized in that: The sealant (3) is an epoxy resin sealant.

10. A cooling method for the output bushing of a generator with an embedded foldback water-cooled structure, characterized in that, Includes the following steps: Step S1: Cooling water is introduced into the water inlet (7), and the cooling water flows into the annular gap (9) between the inner copper pipe (4) and the conductive rod (1). Step S2: After cooling the conductive rod (1) with cooling water, the water flows back into the outlet channel (10) of the inner copper tube (4) at the second connector (6). Step S3: Cooling water flows out through the outlet port (8) of the inner copper pipe (4) via the outlet channel (10), completing the cooling work of the generator outlet bushing.

11. The cooling method for the output bushing of an embedded folding-back water-cooled generator according to claim 10, characterized in that: In step S1, the flow rate of cooling water in the annular gap (9) is not less than 0.7 m / s.

12. The cooling method for the output bushing of an embedded folding-back water-cooled generator according to claim 10, characterized in that: In step S1, the cooling water is deionized water.

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