A method for repairing a hole in the insulation of a power cable

Abstract

The application discloses a kind of repair methods for power cable insulation hole, belong to cable repair technical field.The application repair method includes: for the power cable to be repaired, determine the dielectric parameter of the power cable to be repaired, prepare basic repair liquid based on the dielectric parameter;If the load flow is lower, the core temperature is not high or the depth of the hole to be repaired is shallow, the prepared basic repair liquid is used to fill the hole to be repaired, to fill the hole to be repaired;The hole to be repaired filled with basic repair liquid is irradiated using ultraviolet light source, after the basic repair liquid is fully cured, the surface of the hole to be repaired is polished using sandpaper to complete the repair of the power cable insulation hole.The application method can quickly and accurately repair the hole on the surface of the cable without further damaging or peeling the outer structure of the cable.

Description

Technical Field

[0001] This invention relates to the field of cable repair technology, and more specifically, to a method for repairing insulation holes in power cables. Background Technology

[0002] As an indispensable and crucial component of power transmission lines, the reliability of power cables plays a decisive role in the stability and safety of the entire power system. Cross-linked polyethylene (XLPE) power cables, due to their excellent electrical and mechanical properties, are widely used in my country's power system, accounting for a large proportion of the total. However, many cable lines have been in operation for 20 years. To ensure the safe operation of transmission lines, cables with severe insulation problems can be replaced entirely, or hidden defects in the XLPE insulation can be repaired to extend the service life of the cable insulation. However, replacing the entire cable would consume enormous human, material, and financial resources. Repair technology, under limited cost conditions, can effectively repair water treeing in cables, thereby strengthening the insulation of existing aging power cable lines and significantly extending their service life, possessing significant economic and social value.

[0003] During the repair process, it is unavoidable to drill several small holes on the cable surface. Although these holes usually only penetrate the outer sheath and metal sheath of the cable, reaching the buffer layer, and will not damage the cable insulation layer, if these holes are not properly sealed or the seal is inadequate after repair, it may lead to new hidden dangers such as moisture or oxidation. Therefore, it is necessary to choose appropriate sealing measures to ensure the sealing and mechanical strength of these holes after repair. Currently, the main method is welding repair. Welding repair uses high-temperature molten solder to repair the cut metal sheath, which can ensure the sealing of the cable's outer sheath and metal sheath after repair. However, the temperature needs to be precisely controlled during the welding process, as excessively high local temperatures may pose a potential threat to the insulation layer. Summary of the Invention

[0004] To address the above problems, this invention proposes a method for repairing insulation holes in power cables, comprising:

[0005] For the power cable to be repaired, the dielectric parameters of the power cable to be repaired are determined, and a basic repair solution is prepared based on the dielectric parameters;

[0006] For the power cable to be repaired, determine the load current carrying capacity, core temperature and hole depth of the power cable to be repaired. If the load current carrying capacity is low, the core temperature is not high or the hole depth is shallow, then use the prepared basic repair solution to fill the hole.

[0007] The holes to be repaired, filled with the basic repair liquid, are irradiated with an ultraviolet light source. After the basic repair liquid has fully cured, sandpaper is used to polish the surface of the holes to be repaired to complete the repair of the insulation holes in the power cable.

[0008] The load carrying capacity is low, specifically: the load carrying capacity is less than 50%.

[0009] The core temperature is not high, specifically: the core temperature is below 50°C.

[0010] The hole to be repaired is shallow, specifically: the hole depth is such that it penetrates the metal sheath and penetrates the undamaged waterproof layer or penetrates the damaged waterproof layer without affecting normal use.

[0011] Optional dielectric parameters include: dielectric constant and resistivity.

[0012] Optionally, a basic repair solution is prepared based on the dielectric parameters, including:

[0013] Based on the dielectric parameters, adjust the ratio of the raw materials in the basic repair solution;

[0014] Prepare the basic repair solution according to the specified ratio.

[0015] Optional, the base repair solution includes the following raw materials: 74 to 93 parts by weight of UV-curable resin, 0.5 to 10 parts by weight of activator, 5 to 10 parts by weight of wetting agent, 0.5 to 5 parts by weight of thickener, and 0.5 to 1 part by weight of defoamer.

[0016] The total weight of the raw materials for the repair solution is 100 parts.

[0017] Optionally, a basic repair solution is prepared, including:

[0018] The following raw materials are added to a light-proof mixing container equipped with a stirring device according to the following proportions: 74-93 parts by weight of UV-curable resin, 0.5-10 parts by weight of activator, 5-10 parts by weight of wetting agent, 0.5-5 parts by weight of thickener, and 0.5-1 parts by weight of defoamer. Inert gas is introduced into the raw materials in the light-proof mixing container, and the raw materials are stirred evenly. After stirring is completed, the mixture is allowed to stand in the dark at room temperature to obtain the repair solution.

[0019] Optionally, based on the dielectric parameters, the proportion of the raw materials in the basic repair solution is determined, specifically by adjusting the proportion of activator, wetting agent, and thickener in the total raw materials according to the range of node parameters.

[0020] Optionally, the irradiation time is 10 to 30 minutes.

[0021] Optional, the sandpaper is 300 to 2000 grit sandpaper.

[0022] Optionally, filling the hole to be repaired further includes:

[0023] The basic repair solution is injected into the hole to be repaired in small amounts and multiple times. Each injection of basic repair solution does not exceed 3 mm. After each injection, the hole is irradiated with an ultraviolet light source at a rate of 5 to 10 minutes per millimeter until the basic repair solution completely fills the hole to be repaired.

[0024] Optionally, the dielectric constant of the base repair solution ranges from 3.3 to 6, and the resistivity ranges from 10⁻⁶. 6 ~10 10 .

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] This invention provides a method for repairing insulation holes in power cables, characterized in that the repair method includes: determining the dielectric parameters of the power cable to be repaired, and preparing a basic repair fluid based on the dielectric parameters; determining the current carrying capacity, core temperature, and hole depth of the power cable to be repaired; if the current carrying capacity is low, the core temperature is not high, or the hole depth is shallow, then filling the hole with the prepared basic repair fluid; The holes to be repaired, filled with the basic repair fluid, are irradiated with an ultraviolet light source. After the basic repair fluid has fully cured, sandpaper is used to polish the surface of the holes to complete the repair of the insulation holes in the power cable. The load current carrying capacity is low, specifically below 50%. The core temperature is not high, specifically below 50°C. The hole depth is shallow, specifically penetrating the metal sheath and penetrating the undamaged waterproof layer or a damaged waterproof layer without affecting normal use. This invention allows for rapid and accurate repair of holes on the cable surface without further damage or stripping of the cable's outer structure, improving the efficiency of cable injection-type repair construction. Attached Figure Description

[0027] Figure 1 This is a flowchart of the method of the present invention;

[0028] Figure 2 This is a schematic diagram of a power cable according to an embodiment of the method of the present invention;

[0029] Figure 3 This is a schematic cross-sectional view of a power cable in an embodiment of the method of the present invention;

[0030] Figure 4This is a schematic diagram of drilling holes in a power cable according to an embodiment of the method of the present invention;

[0031] Figure 5 This is a schematic diagram of a cross-section of a power cable drilled according to an embodiment of the method of the present invention;

[0032] Figure 6 This is a schematic diagram of the irradiation of power cables according to an embodiment of the method of the present invention. Detailed Implementation

[0033] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0034] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0035] Example 1:

[0036] This invention proposes a method for repairing insulation holes in power cables, such as... Figure 1 As shown, it includes:

[0037] Step 1: For the power cable to be repaired, determine the dielectric parameters of the power cable to be repaired, and prepare a basic repair solution based on the dielectric parameters;

[0038] Step 2: For the power cable to be repaired, determine the load current carrying capacity, core temperature and the depth of the hole to be repaired. If the load current carrying capacity is low, the core temperature is not high or the depth of the hole to be repaired is shallow, then use the prepared basic repair solution to fill the hole to be repaired.

[0039] Step 3: Irradiate the hole to be repaired with an ultraviolet light source to fill the basic repair liquid. After the basic repair liquid has fully cured, use sandpaper to polish the surface of the hole to be repaired with the cured basic repair liquid to complete the repair of the insulation hole of the power cable.

[0040] The load carrying capacity is low, specifically: the load carrying capacity is less than 50%.

[0041] The core temperature is not high, specifically: the core temperature is below 50°C.

[0042] The hole to be repaired is shallow, specifically: the hole depth is such that it penetrates the metal sheath and penetrates the undamaged waterproof layer or penetrates the damaged waterproof layer without affecting normal use.

[0043] Among them, dielectric parameters include dielectric constant and resistivity.

[0044] The preparation of the basic repair solution based on the dielectric parameters includes:

[0045] Based on the dielectric parameters, adjust the ratio of the raw materials in the basic repair solution;

[0046] Prepare the basic repair solution according to the specified ratio.

[0047] The basic repair solution includes the following raw materials: 74-93 parts by weight of UV-curable resin, 0.5-10 parts by weight of activator, 5-10 parts by weight of wetting agent, 0.5-5 parts by weight of thickener, and 0.5-1 parts by weight of defoamer.

[0048] The total weight of the raw materials for the repair solution is 100 parts.

[0049] The preparation of the basic repair solution includes:

[0050] The following raw materials are added to a light-proof mixing container equipped with a stirring device according to the following proportions: 74-93 parts by weight of UV-curable resin, 0.5-10 parts by weight of activator, 5-10 parts by weight of wetting agent, 0.5-5 parts by weight of thickener, and 0.5-1 parts by weight of defoamer. Inert gas is introduced into the raw materials in the light-proof mixing container, and the raw materials are stirred evenly. After stirring is completed, the mixture is allowed to stand in the dark at room temperature to obtain the repair solution.

[0051] Specifically, the ratio of the raw materials for the basic repair solution is determined based on the dielectric parameters, which involves adjusting the ratio of activator, wetting agent, and thickener in the total raw materials according to the range of node parameters.

[0052] The irradiation time is 10 to 30 minutes.

[0053] The sandpaper used is 300-2000 grit sandpaper.

[0054] The process of filling the hole to be repaired also includes:

[0055] The basic repair solution is injected into the hole to be repaired in small amounts and multiple times. Each injection of basic repair solution does not exceed 3 mm. After each injection, the hole is irradiated with an ultraviolet light source at a rate of 5 to 10 minutes per millimeter until the basic repair solution completely fills the hole to be repaired.

[0056] The dielectric constant of the base repair solution ranges from 3.3 to 6, and the resistivity ranges from 10⁻⁶. 6 ~10 10 .

[0057] Example 2:

[0058] The structure of a common high-voltage power cable sample is as follows: Figure 2 As shown, the main structure of a high-voltage cable typically includes 1. an outer sheath, 2. a metallic sheath, 3. a water-blocking buffer layer, 4. main insulation, and 5. a cable core. A further longitudinal cross-sectional structure of a high-voltage cable is shown below. Figure 3 As shown, the 4 main insulation layers can be further divided into 41 insulation shielding layer, 42 cross-linked polyethylene layer, and 43 conductor shielding layer.

[0059] Cable repair work typically involves injecting repair into the cable, which requires drilling holes in the cable surface. A schematic diagram of the cable sample to be repaired after drilling is shown below. Figure 4 As shown, its longitudinal cross-sectional structure is as follows Figure 5 As shown. Repair work usually requires drilling holes to be repaired on the cable surface, typically in the range of 10-30mm in diameter, and the depth of the holes needs to penetrate through 1. the outer sheath, 2. the metal sheath, and 3. the water-blocking buffer layer.

[0060] This invention proposes a method for repairing insulation holes in power cables, comprising:

[0061] (1) Measurement of dielectric parameters of each layer of cable: The dielectric parameters of the main materials of the outer sheath, metal sheath and water-blocking buffer layer of the cable sample to be repaired and the collected samples were measured. The main test parameters include conductivity, dielectric constant and so on.

[0062] (2) Based on the measured dielectric parameters, select the formula ratio of the repair solution (basic repair solution) to prepare the repair solution, and determine the temperature load of the power cable, etc.

[0063] (3) Pour an appropriate volume of repair solution into the 6 holes to be repaired, and irradiate the 6 holes to be repaired with a UV light source. The irradiation time can be controlled within the range of 10 to 30 minutes depending on the depth of the repair solution, so as to ensure that the repair solution is fully cured.

[0064] (4) Figure 6 As shown, the root is infused with a base repair solution of appropriate thickness, and step (3) is repeated to ensure the repair effect of each layer of structure.

[0065] (5) After the outer sheath is repaired, use 300-2000 grit sandpaper to properly polish the surface of the 6 holes to be repaired to ensure that the surface of the cable outer sheath is flat and smooth.

[0066] Among them, dielectric parameters mainly include conductivity and dielectric constant. The conductivity and dielectric constant of different cable structures: shielding layer material, metal sheath, outer sheath, the main materials and parameters of the cable structural layers involved in the repair process are shown in Table 1. The dielectric parameter range of the basic repair fluid (basic formula) and the adjustment ratio method are shown in Table 2.

[0067] Table 1

[0068]

[0069] Table 2

[0070]

[0071] For cables with low load (load current less than 50% of rated current carrying capacity) or low overall operating temperature (core temperature below 50℃), a basic repair fluid (basic formula) should be used. Additionally, if the hole to be repaired is shallow and penetrates the metal sheath without damage or with only minor damage to the water-blocking buffer layer, the basic formula of the repair fluid can also be used for repair.

[0072] For full curing, it is recommended that the thickness of a single injection of repair fluid should not exceed 3mm, and the curing time can be selected according to the curing time of 5 to 10 minutes per millimeter of thickness.

[0073] The appropriate thickness is as follows: If the base formula of the repair fluid is used, it is recommended that the thickness of a single injection should not exceed 3mm, and that small amounts be filled multiple times until the hole is completely filled. (The thickness of each structural layer of the cable can usually be found directly in the purchased and accepted materials, or it can be measured using the depth scale of a vernier caliper after drilling.)

[0074] The basic repair solution, by weight, has the following raw material composition and content:

[0075] 74-93 parts of UV-curable resin (photosensitive resin);

[0076] Surfactant 0.5–10 parts;

[0077] 5-10 parts of wetting agent;

[0078] Thickener 0.5-5 parts;

[0079] Defoamer 0.5 to 1 part;

[0080] The total amount of each component is 100 portions.

[0081] The UV-curable resin includes, but is not limited to, at least one or any combination of polyurethane acrylate, epoxy acrylate, polyether acrylate, and polyester acrylate in any mass ratio.

[0082] The active agents include, but are not limited to, at least one or any combination of hydroxyethyl methacrylate, acrylomorpholine, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, ethoxyethoxyethyl acrylate, and polyhexyl acrylate in any mass ratio.

[0083] The wetting agent includes, but is not limited to, at least one or any combination of polysiloxane compounds, polydimethylsiloxane compounds, or polyethers, or acrylate-modified polydimethylsiloxanes, or polyether-modified polysiloxane compounds in any mass ratio.

[0084] The thickener includes, but is not limited to, at least one or any combination of water-based nonionic associative rheology modifiers, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0085] The defoamer includes, but is not limited to, at least one or any combination of polysiloxanes, dipropylene glycol butyl ether, dodecyl alcohol ester, hydroxyanisole, p-tert-butylcatechol, 2,6-di-tert-butyl-4-methylphenol, and tert-butyl-p-hydroxyanisole in any mass ratio.

[0086] Its preparation method is as follows:

[0087] Add 74-93 parts of UV-curable resin (photosensitive resin), 0.5-10 parts of activator, 5-10 parts of wetting agent, 0.5-5 parts of thickener, and 0.5-1 parts of defoamer to a light-proof mixing container equipped with a stirring device. Introduce nitrogen inert gas into the mixture and stir at a speed of 60-300 rpm until homogeneous. Maintain stirring at room temperature for at least 30 minutes. After stirring, allow the mixture to stand at room temperature in the dark for at least 30 minutes to obtain the basic formula for UV-curable high-voltage power cable buffer layer and sheath repair solution.

[0088] The method of this invention can quickly and accurately repair holes on the cable surface without further damaging or stripping the outer layer structure of the cable, thus improving the construction efficiency of cable injection repair construction.

[0089] It should be noted that the above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention.

[0090] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0091] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for repairing insulation holes in power cables, characterized in that, The repair method includes: For the power cable to be repaired, the dielectric parameters of the power cable to be repaired are determined, and a basic repair solution is prepared based on the dielectric parameters; For the power cable to be repaired, determine the load current carrying capacity, core temperature and hole depth of the power cable to be repaired. If the load current carrying capacity is low, the core temperature is not high or the hole depth is shallow, then use the prepared basic repair solution to fill the hole. The holes to be repaired, filled with the basic repair liquid, are irradiated with an ultraviolet light source. After the basic repair liquid has fully cured, sandpaper is used to polish the surface of the holes to be repaired to complete the repair of the insulation holes in the power cable. The low load capacity specifically means that the load capacity is less than 50%. The core temperature is not high, specifically: the core temperature is below 50°C. The hole to be repaired is shallow, specifically: the hole has penetrated the metal sheath, and the penetration of the undamaged waterproof layer or the penetration of the damaged waterproof layer does not affect normal use. The basic repair solution comprises the following raw materials: 74 to 93 parts by weight of UV-curable resin, 0.5 to 10 parts by weight of activator, 5 to 10 parts by weight of wetting agent, 0.5 to 5 parts by weight of thickener, and 0.5 to 1 part by weight of defoamer; The total weight of the raw materials for the repair solution is 100 parts; The filling of the hole to be repaired also includes: The basic repair solution is injected into the hole to be repaired in small amounts and multiple times. Each injection of basic repair solution should not exceed 3 mm. After each injection, the hole is irradiated with an ultraviolet light source at a rate of 5 to 10 minutes per millimeter until the basic repair solution completely fills the hole to be repaired.

2. The method for repairing holes according to claim 1, characterized in that, The dielectric parameters include: dielectric constant and resistivity.

3. The method for repairing holes according to claim 1, characterized in that, The basic repair solution is prepared based on the dielectric parameters, including: Based on the dielectric parameters, the ratio of the raw materials in the basic repair solution is adjusted; Prepare the basic repair solution according to the specified ratio.

4. The method for repairing holes according to claim 3, characterized in that, The preparation of the basic repair solution includes: The following raw materials are added to a light-proof mixing container equipped with a stirring device according to the following proportions: 74-93 parts by weight of UV-curable resin, 0.5-10 parts by weight of activator, 5-10 parts by weight of wetting agent, 0.5-5 parts by weight of thickener, and 0.5-1 parts by weight of defoamer. Inert gas is introduced into the raw materials in the light-proof mixing container, and the raw materials are stirred evenly. After stirring is completed, the mixture is allowed to stand in the dark at room temperature to obtain the repair solution.

5. The method for repairing holes according to claim 3, characterized in that, The determination of the proportion of raw materials for the basic repair solution based on the dielectric parameters specifically involves adjusting the proportions of activator, wetting agent, and thickener in the total raw materials according to the range of dielectric parameters.

6. The method for repairing holes according to claim 1, characterized in that, The irradiation time is 10~30 min.

7. The method for repairing holes according to claim 1, characterized in that, The sandpaper is 300-2000 grit sandpaper.

8. The method for repairing holes according to claim 1, characterized in that, The dielectric constant of the basic repair solution ranges from 3.3 to 6, and the resistivity ranges from 10⁻⁶ to 10⁻⁶. 6 ~10 10 .

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