Method for improving insulation performance of wall bushing in switch cabinet and improved wall bushing

Abstract

The present invention provides a method for improving the insulation performance inside the wall bushing of a switch cabinet and a lifting type wall bushing, and belongs to the field of high voltage insulation technology. It includes: fluidizing the conductors in the busbar and the wall bushing to obtain a busbar with a fluidized layer and a lifting type wall bushing; using the busbar with a fluidized layer and the lifting type wall bushing to improve the insulation performance inside the wall bushing of the switch cabinet, so as to reduce the flashover on the inner surface of the wall bushing caused when the busbar is energized. The present invention can reduce the flashover on the inner surface of the bushing by coating the surface of the high-voltage inner shield in the bushing structure and the primary busbar placed in the bushing with an insulating coating, and achieves the effect of improving the insulation performance inside the wall bushing of the switch cabinet by improving the insulation strength of the inner shield and the primary busbar.

Description

Technical Field

[0001] The invention relates to the technical field of high voltage insulation, and in particular to a method for improving the insulation performance of a wall bushing in a switch cabinet and a lifting type wall bushing. Background Art

[0002] At present, the typical double-shielded switch cabinet wall bushing on the market is mainly composed of epoxy casting layer, shielding net, primary busbar, equipotential wire and fixing nut. Among them, the main function of the fixing nut is to install and fix the wall bushing on the mounting plate. The epoxy casting layer is an insulating jacket cast and spliced ​​by a special mold. The shielding net is divided into high-voltage shielding and low-voltage shielding. The whole adopts the method of nesting and ambush in the epoxy casting layer. The high-voltage shielding process adopts the structure of exposed metal mesh, which is embedded in the inner diameter side of the bushing wall. The primary busbar and the high-voltage shielding are connected to form an equipotential through an equipotential wire composed of multiple layers of soft copper wire wrapped in a rubber jacket. The air gap discharge between the high-voltage primary busbar and the bushing epoxy casting layer is shielded in the high-voltage body, reducing the inducement to cause discharge. The low-voltage shielding net is installed near the middle of the bushing wall and is reliably grounded through the installation nut. In this double-shielded bushing design, the main function of the double shielding composed of low-voltage shielding and high-voltage shielding is to limit the main electric field distribution to the epoxy casting layer, so as to increase the electric field strength in the epoxy resin and reduce the field strength in the air, so that the electric field distribution is more reasonable. However, due to the intermittent power generation process of the new energy station, the busbar current changes, resulting in changes in the temperature field inside the switch chamber, which is prone to condensation on the busbar and the inner surface of the high-voltage shield, causing rust at the busbar transfer point, and condensation water droplets on the inner surface of the bushing causing insulation discharge, affecting the insulation performance of the switch cabinet. As the discharge time increases, the discharge becomes increasingly serious, eventually leading to the breakdown of the main insulation of the bushing. Summary of the invention

[0003] In view of this, the present invention provides a method for improving the insulation performance inside the wall bushing of a switch cabinet and an improved wall bushing, wherein a layer of insulating coating is applied to the surface of the conductor such as the inner shield of the bushing in the bushing structure and the primary busbar placed in the bushing, and the insulation performance inside the wall bushing of the switch cabinet is improved by improving the insulation strength of the inner shield and the primary busbar.

[0004] The technical solution adopted by the embodiment of the present invention to solve the technical problem is:

[0005] A method for improving the insulation performance of a wall bushing in a switch cabinet, comprising:

[0006] Step S1, fluidizing the busbar and the conductors in the wall bushing to obtain a busbar with a fluidized layer and a lifting type wall bushing, wherein each conductor in the lifting type wall bushing has a fluidized layer;

[0007] Step S2, using the busbar with the fluidized layer and the lifting type wall bushing to improve the insulation performance of the wall bushing of the switch cabinet, specifically adopting one of the schemes 1 to 3, so as to reduce the flashover of the high-voltage shielding on the inner surface of the wall bushing to the ground through the outer surface of the bushing when the busbar is powered on:

[0008] Method 1: two adjacent switch cabinets are connected by ordinary wall bushings, and the busbar with the fluidized layer is inserted into the ordinary wall bushings;

[0009] Method 2: Install the lifting type wall bushing at the connection between two adjacent switch cabinets, and insert the common busbar into the lifting type wall bushing;

[0010] Method three: Install the lifting type wall bushing at the connection between two adjacent switch cabinets, and insert the busbar with the fluidized layer into the lifting type wall bushing.

[0011] Preferably, the step S1 comprises:

[0012] Step S11, pre-treating the conductors of the busbar and the wall bushing to obtain conductor parts with surfaces that meet coating conditions, wherein the pre-treatment includes cleaning and rust removal;

[0013] Step S12, using a high temperature resistant adhesive tape to cover the overlapping surfaces and equipotential connection points of the conductor parts;

[0014] Step S13, setting fluidization treatment conditions, the fluidization treatment conditions including the insulating powder used for fluidization, preheating temperature control, fluidization thickness, dipping time, curing temperature and curing time;

[0015] Step S14, according to the fluidized treatment conditions, preheating the conductor parts, immersing them in a fluidized bed suspended with insulating powder for fluidized treatment, to obtain a busbar with a fluidized layer, and a conductor part with a fluidized layer required for the lifting wall bushing;

[0016] Step S15, removing the high temperature resistant adhesive tape on the conductor part having the fluidized layer;

[0017] Step S16, assembling the lifting type wall bushing using the conductor parts and non-conductor parts after the fluidization treatment.

[0018] Preferably, the step S14 includes:

[0019] Step S141, using a fluidized bed method, a compressed gas of a certain pressure is input into the bottom chamber of the fluidized bed tank, and the compressed gas is clean air, carbon dioxide or nitrogen. The compressed gas forms a uniform upward blowing airflow in the upper chamber of the tank through the air permeable plate, so that the insulating powder accumulated in the fluidized bed tank is loosened and generates an omnidirectional flow to be suspended. After reaching a certain suspension height, a stable fluidized suspended insulating powder layer is formed;

[0020] Step S142, preheating the conductor part in a preheating furnace so that the temperature of the conductor part as a whole reaches a preheating temperature range to form a heated conductor part;

[0021] Step S143, using a sleeve-type fixture, vertically immersing the heated conductor part into the suspended insulating powder layer in a fluidized state in step S141, and evenly moving the sleeve-type fixture and the heated conductor part through the fixture hook, making the heated conductor part intermittently hit the inner wall of the fluidizing tank and turning the part over multiple times, so that the insulating powder is continuously melted and adheres to the surface of the heated conductor part, and gradually melted into a viscous insulating liquid, which is cast and infiltrated on the surface of the heated conductor part to obtain a conductor part with an insulating surface layer;

[0022] Step S144, transferring the conductor parts with the insulating surface layer into a post-processing baking furnace for curing; after the curing is completed, allowing the conductor parts to cool naturally in a controlled environment, thereby obtaining the busbar with the fluidized layer and the conductor parts with the fluidized layer required in the lifting wall bushing.

[0023] Step S145, checking the uniformity and integrity of the coating, and performing local repair or re-coating treatment on defective or uneven parts.

[0024] Preferably, the conductor of the wall bushing refers to the inner shield of the bushing, the metal fixing buckle, the metal connector and the high-voltage lead, and the high-voltage lead is a bare lead with no insulating wrapping layer on the surface.

[0025] Preferably, the high temperature resistant adhesive tape has Stretch Performance; the material of the insulating powder is epoxy resin powder.

[0026] Preferably, the preheating temperature of the conductor workpiece in the fluidized bed process is higher than the melting temperature of the insulating powder, and the preheating temperature range is 190-195°C.

[0027] Preferably, the dipping time interval of the fluidized bed treatment is 25-45 s; the curing temperature of the fluidized bed treatment is set to 185° C., and the curing time interval is 35-50 min.

[0028] Preferably, the fluidized layer thickness of the conductor part is in the range of 1.2 to 1.7 mm.

[0029] Preferably, the three solutions are arranged in order from low to high according to the effect of improving the insulation performance: method 1, method 2, and method 3.

[0030] Furthermore, the present invention also provides a lifting type wall bushing, which is installed at the connection between adjacent switch cabinets and is used to place the busbar. It is a lifting type wall bushing made using the above-mentioned method; the conductor in the lifting type wall bushing has a fluidized layer, and the conductor refers to the inner shield of the bushing, the metal fixing buckle, the metal connecting part and the high-voltage lead.

[0031] It can be seen from the above technical scheme that the method for improving the insulation performance of the wall bushing of the switch cabinet provided by the embodiment of the present invention fluidizes the conductors in the busbar and the wall bushing to obtain a busbar with a fluidized layer and a lifting type wall bushing; the busbar with a fluidized layer and the lifting type wall bushing are used to improve the insulation performance of the wall bushing of the switch cabinet, specifically adopting one of the schemes of method one to method three to reduce the flashover of the inner surface of the wall bushing caused when the busbar is energized. The scheme includes: connecting two adjacent switch cabinets with ordinary wall bushings, and inserting the busbar with a fluidized layer into the ordinary wall bushing; or, installing the lifting type wall bushing at the connection between two adjacent switch cabinets, and inserting the ordinary busbar into the lifting type wall bushing; or, installing the lifting type wall bushing at the connection between two adjacent switch cabinets, and inserting the busbar with a fluidized layer into the lifting type wall bushing. The present invention covers the surface of the conductors such as the inner shield of the bushing in the bushing structure and the primary busbar placed in the bushing with an insulating coating, which can reduce the flashover on the inner surface of the bushing and improve the insulation strength of the inner shield and the primary busbar, thereby achieving the effect of improving the insulation performance of the wall bushing of the switch cabinet. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a flow chart of a method for improving the insulation performance of a wall bushing in a switch cabinet.

[0033] Figure 2 This is a schematic diagram of the installation position of the switch cabinet wall bushing.

[0034] Figure 3 This is the structural diagram of the wall bushing and busbar.

[0035] Figure 4 This is a schematic diagram of the connection between the lifting wall bushing and the busbar with a fluidized layer when using Scheme 3.

[0036] In the figure: 1-busbar, 2-wall bushing, 21-high-voltage shielding tube, 22-low-voltage shielding tube, 23-metal fixing buckle, 24-high-voltage lead, 25-epoxy resin, 26-fixing nut, 27-metal connector, 28-high-voltage shielding range. DETAILED DESCRIPTION

[0037] The technical scheme and technical effects of the present invention are further elaborated in detail below in conjunction with the accompanying drawings of the present invention.

[0038] The present invention provides a method for improving the insulation performance of a wall bushing of a switch cabinet. An insulating coating is applied to the surface of a shielding conductor in a bushing structure and a primary busbar in the bushing, thereby reducing flashover on the inner surface of the bushing.

[0039] refer to Figure 1 As shown, the specific implementation steps are:

[0040] Step S1, fluidizing the busbar and the conductors in the wall bushing to obtain a busbar with a fluidized layer and a lifting type wall bushing, wherein each conductor in the lifting type wall bushing has a fluidized layer;

[0041] Step S2, using a busbar with a fluidized layer and a lifting type wall bushing to improve the insulation performance of the wall bushing of the switch cabinet, specifically adopting one of the schemes 1 to 3, so as to reduce the flashover of the inner surface of the wall bushing caused by the busbar being energized:

[0042] Method 1: Two adjacent switch cabinets are connected by ordinary wall bushings, and the busbar with fluidized layer is installed in the ordinary wall bushings;

[0043] Method 2: Install the lifting wall bushing at the connection between two adjacent switch cabinets, and pass the ordinary busbar through the lifting wall bushing;

[0044] Method three: Install the lifting type wall bushing at the connection between two adjacent switch cabinets, and pass the busbar with fluidized layer through the lifting type wall bushing.

[0045] In the present invention, the conductor of the wall bushing refers to the inner shielding of the bushing (high-voltage shielding tube, low-voltage shielding tube), metal connectors, metal fixing buckles and high-voltage leads; the overlapping surfaces and equipotential connections of the high-voltage shielding tube and the low-voltage shielding tube do not have a fluidized layer; the high-voltage leads here are bare leads, which are different from ordinary leads with an easily peelable insulating wrapping layer on the surface.

[0046] Furthermore, the specific implementation steps of step S1 for preparing the busbar with a fluidized layer and the lifting type wall bushing include:

[0047] Step S11, pre-treating the conductors of the busbar and the wall bushing to obtain conductor parts with coating conditions on the surface, the pre-treatment includes cleaning and rust removal. Surface cleaning refers to dust removal, oil removal, rust removal and other pollutants to ensure that the surface is free of oil and rust. Chemical cleaning and physical methods (such as sandblasting) can be used to increase the surface roughness to improve the adhesion of the coating;

[0048] Step S12, using a high temperature resistant adhesive tape to cover the overlapping surfaces and equipotential connection points of the conductor parts;

[0049] Step S13, setting fluidization treatment conditions, the fluidization treatment conditions including the insulating powder used for fluidization, preheating temperature control, fluidization thickness, dipping time, curing temperature and curing time;

[0050] Step S14, preheating the conductor parts according to the fluidized treatment conditions, and immersing them in a fluidized bed in which insulating powder is suspended for fluidized treatment, so as to obtain a busbar with a fluidized layer and a conductor part with a fluidized layer required for the lifting wall bushing;

[0051] Step S15, removing the high temperature resistant adhesive tape on the conductor part with the fluidized layer;

[0052] Step S16, assembling the lifting type wall bushing using the conductor parts and non-conductor parts after the fluidization treatment.

[0053] In the present invention, the selected high temperature resistant adhesive tape has tensile properties, certain tensile strength and moderate viscosity. Before fluidized treatment, the purpose of coating the overlapping surfaces and equipotential connection points of the conductor parts is to retain the conductivity of these positions.

[0054] The material of insulating powder is epoxy resin powder, which is mainly composed of epoxy resin, curing agent, pigment, additives, etc.

[0055] Fluidization conditions:

[0056] The preheating temperature of the conductor workpiece in the fluidized bed treatment is higher than the melting temperature of the insulating powder, and the preheating temperature range is 190~195℃.

[0057] The dipping time interval of the fluidized bed treatment is 25~45s; the curing temperature of the fluidized bed treatment is set to 185°C, and the curing time interval is 35~50min.

[0058] The thickness of the fluidized layer of the conductor parts ranges from 1.2 to 1.7 mm.

[0059] Step S14 is a metal fluidization process for the busbar and the metal conductor, which is a surface treatment technology for improving shielding effect and corrosion resistance, and is specifically implemented as follows:

[0060] Step S141, using a fluidized bed method, a compressed gas of a certain pressure is input into the bottom chamber of the fluidized bed tank, and the compressed gas forms a uniform upward blowing airflow in the upper chamber of the tank through the air permeable plate, so that the insulating powder accumulated in the fluidized bed tank is loosened and generates an omnidirectional flow to be suspended. After reaching a certain suspension height, a stable fluidized suspended insulating powder layer is formed; the compressed gas is clean air, carbon dioxide or nitrogen;

[0061] Step S142, preheating the conductor part in a preheating furnace so that the temperature of the conductor part as a whole reaches a preheating temperature range to form a heated conductor part; preheating helps to improve the adhesion and uniformity of the coating;

[0062] Step S143, using a sleeve-type fixture, vertically immerse the heated conductor part into the suspended insulating powder layer in the fluidized state in step S141, and evenly move the sleeve-type fixture and the heated conductor part through the fixture hook, so that the heated conductor part intermittently hits the inner wall of the fluidizing tank and turns the part over many times, so that the insulating powder is continuously melted and adheres to the surface of the heated conductor part, and gradually melts into a viscous insulating liquid, which is cast and infiltrated on the surface of the heated conductor part, so as to obtain a conductor part with an insulating surface layer;

[0063] Step S144, transfer the conductor parts with the insulating surface layer into a post-processing baking furnace for curing; after the curing is completed, allow the conductor parts to cool naturally in a controlled environment to obtain a busbar with a fluidized layer and a conductor part with a fluidized layer required for the lifting type wall bushing.

[0064] Step S145, checking the uniformity and integrity of the coating, and performing local repair or re-coating treatment on defective or uneven parts.

[0065] According to the treatment process and the actual installation schemes of the three methods, the three methods are arranged in order from low to high according to the improvement effect of insulation performance: method 1, method 2, and method 3. Figure 2 and Figure 3 As shown, it can be installed according to the selected installation method.

[0066] Further, refer to Figure 3 As shown, the present invention provides a lifting type wall bushing for utilizing Figure 1 The lifting wall bushing made by the method shown in the figure is shown in the figure. Figure 2 The lifting wall bushing is installed at the connection of adjacent switch cabinets, and the hollow structure is used to place the busbar. The difference between the lifting wall bushing and the ordinary wall bushing is that the conductor in the lifting wall bushing has a fluidized layer, and the conductor refers to the inner shield of the bushing, the metal fixing buckle, the metal connector and the high-voltage lead.

[0067] As an optional embodiment, refer to Figure 4The bushing structure shown in the figure, the lifting type wall bushing includes a bushing body, a high-voltage shielding tube, a low-voltage shielding tube, a high-voltage lead, a metal connector and a group of metal fixing buckles. The high-voltage shielding tube is arranged in the middle side wall of the bushing body, and the low-voltage shielding tube is coaxially arranged outside the high-voltage shielding tube. The bushing body is provided with a high-voltage lead terminal and a grounding terminal. The high-voltage lead terminal is connected to the high-voltage shielding tube. The two ends of the metal connector are connected to the grounding terminal and the low-voltage shielding tube. A mounting hole is provided on the outer wall of the bushing body, and a fixing nut is fixedly installed on the mounting hole. The busbar copper bar is passed through the hollow tube of the wall bushing, and the high-voltage lead is connected to the high-voltage lead terminal and the busbar copper bar; the high-voltage lead is fixed by a group of metal fixing buckles and is all placed within the cylindrical high-voltage shielding area formed by the high-voltage shielding tube and does not touch the edge of the cylindrical high-voltage shielding area. Referring to the example in the attached figure, the positions of the metal fixing buckles are respectively located at the busbar and the high-voltage lead terminal.

[0068] The present invention covers the surface of the conductors such as the inner shield of the bushing in the bushing structure and the primary busbar placed in the bushing with an insulating coating, which can reduce the flashover on the inner surface of the bushing and improve the insulation strength of the inner shield and the primary busbar, thereby achieving the effect of improving the insulation performance of the wall bushing of the switch cabinet.

[0069] What is disclosed above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for improving the insulation performance of a wall bushing in a switch cabinet, characterized in that: include: Step S1, fluidizing the busbar and the conductors in the wall bushing to obtain a busbar with a fluidized layer and a lifting type wall bushing, wherein each conductor in the lifting type wall bushing has a fluidized layer; Step S2, using the busbar with the fluidized layer and the lifting type wall bushing to improve the insulation performance of the wall bushing of the switch cabinet, specifically adopting one of the schemes of the second method to the third method, so as to reduce the flashover of the high-voltage shielding on the inner surface of the wall bushing to the ground through the outer surface of the bushing when the busbar is energized: Method 2: Install the lifting type wall bushing at the connection between two adjacent switch cabinets, and insert the common busbar into the lifting type wall bushing; Method three: installing the lifting type wall bushing at the connection between two adjacent switch cabinets, and inserting the busbar with the fluidized layer into the lifting type wall bushing; The step S1 comprises: Step S11, pre-treating the conductors of the busbar and the wall bushing to obtain conductor parts with surfaces that meet coating conditions, wherein the pre-treatment includes cleaning and rust removal; Step S12, using a high temperature resistant adhesive tape to cover the overlapping surfaces and equipotential connection points of the conductor parts; Step S13, setting fluidization treatment conditions, the fluidization treatment conditions including the insulating powder used for fluidization, preheating temperature control, fluidization thickness, dipping time, curing temperature and curing time; Step S14, according to the fluidized treatment conditions, preheating the conductor parts, immersing them in a fluidized bed suspended with insulating powder for fluidized treatment, to obtain a busbar with a fluidized layer, and a conductor part with a fluidized layer required for the lifting wall bushing; Step S15, removing the high temperature resistant adhesive tape on the conductor part having the fluidized layer; Step S16, assembling the lifting type wall bushing using the conductor parts and non-conductor parts after the fluidization treatment.

2. The method for improving the insulation performance of the wall bushing of a switch cabinet according to claim 1, characterized in that: The step S14 comprises: Step S141, using a fluidized bed method, compressed gas is input into the bottom chamber of the fluidized bed tank, and the compressed gas is clean air, carbon dioxide or nitrogen. The compressed gas passes through the air permeable plate to form a uniform upward blowing airflow in the upper chamber of the tank body, so that the insulating powder accumulated in the fluidized bed tank is loosened and generates non-directional flow to be suspended. After reaching the suspension height, a stable fluidized suspended insulating powder layer is formed; Step S142, preheating the conductor part in a preheating furnace so that the temperature of the conductor part as a whole reaches a preheating temperature range to form a heated conductor part; Step S143, using a sleeve-type fixture, vertically immersing the heated conductor part into the suspended insulating powder layer in a fluidized state in step S141, and evenly moving the sleeve-type fixture and the heated conductor part through the fixture hook, making the heated conductor part intermittently hit the inner wall of the fluidizing tank and turning the part over multiple times, so that the insulating powder is continuously melted and adheres to the surface of the heated conductor part, and gradually melted into a viscous insulating liquid, which is cast and infiltrated on the surface of the heated conductor part to obtain a conductor part with an insulating surface layer; Step S144, transferring the conductor parts with the insulating surface layer into a post-processing baking furnace for curing; after the curing is completed, allowing the conductor parts to cool naturally in a controlled environment, so as to obtain the busbar with the fluidized layer and the conductor parts with the fluidized layer required for the lifting wall bushing; Step S145, checking the uniformity and integrity of the coating, and performing local repair or re-coating treatment on defective or uneven parts.

3. The method for improving the insulation performance of the wall bushing of a switch cabinet according to claim 2, characterized in that: The conductor of the wall bushing refers to the inner shield of the bushing, the metal fixing buckle, the metal connector and the high-voltage lead. The high-voltage lead is a bare lead and has no insulating wrapping layer on the surface.

4. The method for improving the insulation performance of the wall bushing of a switch cabinet according to claim 3, characterized in that: The high temperature resistant adhesive tape has Stretch Performance; the material of the insulating powder is epoxy resin powder.

5. The method for improving the insulation performance of the wall bushing of a switch cabinet according to claim 4, characterized in that: The preheating temperature of the conductor workpiece in the fluidized bed process is higher than the melting temperature of the insulating powder, and the preheating temperature range is 190-195°C.

6. The method for improving the insulation performance of the wall bushing of a switch cabinet according to claim 5, characterized in that: The dipping time interval of the fluidized bed treatment is 25-45 seconds; the curing temperature of the fluidized bed treatment is set to 185° C., and the curing time interval is 35-50 minutes.

7. The method for improving the insulation performance of the wall bushing of a switch cabinet according to claim 6, characterized in that: The thickness of the fluidized layer of the conductor parts ranges from 1.2 to 1.7 mm.

8. A lifting wall bushing installed at the connection between adjacent switch cabinets for placing busbars, characterized in that: A lifting type wall bushing made by the method of any one of claims 1 to 7; the conductor in the lifting type wall bushing has a fluidized layer, and the conductor refers to the inner shield of the bushing, a metal fixing buckle, a metal connector and a high-voltage lead.

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