Conductive filler for breakdown resistance of power transmission cable and application method of conductive filler

Abstract

The invention relates to an anti-breakdown conductive filler for a power transmission cable and an application method of the anti-breakdown conductive filler, and belongs to the technical field of methods for repairing cable insulation. The filling agent is prepared by mixing and stirring the following components in percentage by mass: 15 to 25 percent of phosphorus-based imidazole bromide, 2 to 5 percent of tetraethylenepentamine, 10 to 16 percent of amino polar silicone oil, 13 to 17 percent of vinyl silicone oil, 3 to 7 percent of styrene and 40 to 50 percent of ethyl acetate. In practical application, phosphorus-based imidazole bromide is obtained through synthesis, then the phosphorus-based imidazole bromide, tetraethylenepentamine, amino polar silicone oil, vinyl silicone oil and styrene are added into ethyl acetate to be mixed, and the filling agent is obtained; a high-pressure pump and a pipeline are arranged outside, the two ends of a required power transmission cable filling section are stripped to a corrugated aluminum sheath and punched, benzoyl peroxide is added into a filling agent, the filling agent is rapidly injected into a gap between the corrugated aluminum sheath and a buffer layer, and finally the two holes are sealed; a conductive path is formed between the corrugated aluminum sleeve and the buffer layer, accumulated charges are conducted out, and therefore ablation of the buffer layer is avoided.

Description

Technical Field

[0001] The invention relates to a conductive filler for preventing breakdown of a power transmission cable and a method for applying the conductive filler to a power transmission cable, belonging to the technical field of methods for repairing cable insulation (H02G1 / 16). Background Art

[0002] In recent years, the "ablation" and "white spot" phenomena of the buffer layer and insulating shielding layer (generally corrugated aluminum) of cross-linked polyethylene high-voltage transmission cables have appeared in many areas of China, seriously endangering the safe and stable operation of the power system. Analysis of the causes of surface ablation shows that most of them are related to the conductive properties of the gap layer between the buffer layer and the corrugated aluminum. The poor conductivity in the gap layer leads to excessive local resistance and the "ablation" phenomenon. Since the national standard does not clearly stipulate the conductive properties of the gap layer of the buffer layer / corrugated aluminum, some gap layer resistivity data obtained in engineering vary greatly. Therefore, preventing and repairing the ablation of the buffer layer / corrugated aluminum gap layer of the transmission cable is the key to the reliable operation of the power system, and is of great significance to the maintenance and management of the power system and ensuring the reliable operation of the power system. Summary of the invention

[0003] The technical problem to be solved by the present invention is: how to effectively increase the conductivity of the gap layer between the buffer layer and the insulating shielding layer of the transmission cable in use, so as to avoid breakdown and ablation caused by poor conductivity of the gap layer.

[0004] The present invention proposes a technical solution to solve the above technical problems. The first one is: a conductive filler for anti-penetration of power transmission cables, comprising the following components mixed and stirred with each other: (1) 15% to 25% by weight of phosphorus-based imidazole bromide; (2) 2% to 5% by mass of tetraethylenepentamine; (3) 10% to 16% by mass of amino polar silicone oil; (4) 13% to 17% by mass of vinyl silicone oil; (5) 3% to 7% by mass of styrene; (6) 40% to 50% by mass of ethyl acetate; The synthesis process of the phosphorus-based imidazole bromide salt is as follows: First, 1,3-dibromopropane and triisopropyl phosphite were added to a container in a molar mass ratio of 4:1, and then connected to a distillation device after being fully stirred, and reacted at 120°C for 6 hours; then, excess dibromopropane was removed by reduced pressure distillation to obtain an intermediate product, diisopropyl (3-bromopropyl) phosphonate; Secondly, take methylimidazole and dichloromethane in a molar mass ratio of 1:8 and add them into a container. Under the protection of nitrogen and magnetic stirring under an ice-salt bath condition, gradually add the intermediate product of diisopropyl (3-bromopropyl) phosphonate dropwise into the container using a constant-pressure funnel, react for 24 h, and then raise the temperature to 40 °C and continue to react for 40 h; Finally, remove the remaining solvent by vacuum distillation, wash the product three times repeatedly with a mixed solution of n-hexane and diethyl ether mixed in a volume ratio of 2:1, and dry it under vacuum at 40 °C for 12 h to obtain a phosphorus-based imidazole bromide salt.

[0005] The second technical solution proposed by the present invention to solve the above technical problems is as follows: The application method of the above conductive filler for high-voltage transmission cable puncture resistance includes the following steps: I. Preparation of the conductive filler Mix the synthesized phosphorus-based imidazole bromide salt with tetraethylenepentamine, amino polar silicone oil, vinyl silicone oil, and styrene in ethyl acetate, and stir well at 25 - 30 °C for 90 minutes to obtain the conductive filler; II. Injection of the conductive filler into the transmission cable 1) Peel open the corrugated aluminum sheath at both ends of the filling section of the required transmission cable, and punch holes in the corrugated aluminum sheaths at both ends of the filling section; 2) Place the conductive filler prepared in step I in a container, equipped with inlet and outlet pipes and a high-pressure pump; at the same time, connect the inlet of the high-pressure pump to the container containing the filler through the inlet pipe, and connect the outlet of the high-pressure pump to the hole in the corrugated aluminum sheath at one end of the filling section through the outlet pipe; 3) Before injection, add 0.2 g of benzoyl peroxide to the container containing the conductive filler, immediately start the high-pressure pump, and inject the filler in the container into the gap between the corrugated aluminum sheath and the buffer layer through the hole in the corrugated aluminum sheath at one end of the filling section. When the corrosion-resistant agent flows out from the hole in the corrugated aluminum sheath at the other end of the filling section, turn off the high-pressure pump; 4) Remove the outlet pipe connected to the hole in the corrugated aluminum sheath at one end of the filling section, tightly cover and wrap the holes in the corrugated aluminum sheaths at both ends of the filling section with non-woven fabric, and then brush an epoxy resin-based adhesive on the surface of the non-woven fabric for curing and sealing.

[0006] The beneficial effects of the conductive filler of the present invention and its application are as follows: 1) The filler uses an ionic solution formed by dissolving phosphonium-based imidazole bromide in polar solutions such as ethyl acetate. After the ionic liquid is injected into the gap between the corrugated aluminum sheath and the buffer layer of the high-voltage transmission cable, it enables the corrugated aluminum and the buffer layer to form all-round contact spatially, providing a good conductive path for the subsequent external transmission of excess induced charges, thereby preventing the buffer layer from being ablated; 2) Since both tetraethylenepentamine and amino silicone oil have good polarity, the solubility of phosphonium-based imidazole bromide in ethyl acetate solution is greatly enhanced, so as to better obtain a phosphonium-based imidazole bromide solution with low viscosity; 3) Since the formed ionic liquid has low viscosity, it is relatively easy to be injected into the gap between the high-voltage transmission cable and the buffer layer through a high-pressure pump, and can effectively and uniformly fill the gap between the corrugated aluminum sleeve and the buffer layer, enabling all-round contact and conductive paths to be formed between the space between the wave crests and wave troughs of the corrugated aluminum sleeve and the buffer layer, and being able to conduct the accumulated charges out well, avoiding the ablation of the contact position between the corrugated aluminum and the buffer layer; 4) Since the vinyl silicone oil and styrene in Technical Solution 1 and benzoyl peroxide in Technical Solution 2 can be uniformly dissolved in the above ionic solution, and over time, the ionic solution will present a semi-cured state, avoiding leakage of the ionic liquid solution in special cases and causing other damages; 5) This corrosion inhibitor will not cause corrosion and other damages to the corrugated aluminum and the buffer layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 FIG. is a schematic diagram of the application process of a conductive filler for preventing breakdown of a power transmission cable in Example 1. DETAILED DESCRIPTION OF THE INVENTION Example 1

[0008] A conductive filler for preventing breakdown of a power transmission cable in this example is prepared by mixing the following components: (1) 15% by mass of phosphonium-based imidazole bromide; (2) 5% by mass of tetraethylenepentamine; (3) 10% by mass of amino polar silicone oil; (4) 13% by mass of vinyl silicone oil; (5) 7% by mass of styrene; (6) 50% by mass of ethyl acetate; The synthesis process of phosphonium-based imidazole bromide is as follows: First, 1,3-dibromopropane (0.4 mol) and triisopropyl phosphite (0.1 mol) are added to a container (such as a test tube) in a molar mass ratio of 4:1, and then connected to a distillation device after being fully stirred, and fully reacted at 120° C. for 6 hours; then, excess dibromopropane is removed by reduced pressure distillation to obtain an intermediate product, diisopropyl (3-bromopropyl) phosphonate; Secondly, methylimidazole (0.1 mol) and 50 mL of dichloromethane (converted to mass according to the density of 1.325 g / ml and then divided by the molecular weight of about 0.8 mol) with the same molar mass ratio as triisopropyl phosphite were added into the container, and the diisopropyl (3-bromopropyl) phosphonate intermediate product was added dropwise into the container under nitrogen protection and magnetic stirring under ice-salt bath conditions using a constant pressure funnel. The reaction was continued for 24 h, and the temperature was raised to 40 °C and the reaction was continued for 40 h. Finally, the remaining solvent was removed by distillation under reduced pressure, and the product was repeatedly washed three times with a mixed solution of n-hexane and ether in a volume ratio of 2:1, and vacuum dried at 40° C. for 12 h to obtain phosphorus-based imidazole bromide.

[0009] An application method of the anti-breakdown conductive filler for a power transmission cable in this embodiment is as follows: 1. Preparation of conductive filler Weigh 15 grams of the synthesized phosphorus-based imidazole bromide salt, add it to 50 grams of ethyl acetate, mix it with 5 grams of tetraethylene pentamine, 10 grams of amino polar silicone oil, 13 grams of vinyl silicone oil and 7 grams of styrene, and stir it at 25-30° C. for 90 minutes to obtain a conductive filler for anti-penetration of power transmission cables in this embodiment. The resistivity of the filler is tested to be 925 Ω•cm.

[0010] 2. Injecting conductive filler into transmission cables 1) If Figure 1 As shown, a section (eg, 2 meters) of high-voltage transmission cable is selected, both ends of the filling section of the cable are peeled off until the corrugated aluminum sheath 2 is exposed, and holes 3 are punched on the corrugated aluminum sheath 2 peeled off at both ends of the filling section.

[0011] 2) If Figure 1 As shown, the conductive filler 8 obtained in step 1 is placed in a container 5, equipped with inlet and outlet pipes and a high-pressure pump 1; at the same time, the inlet of the high-pressure pump 1 is connected to the container 5 where the corrosion-resistant agent 8 is placed through the inlet pipe 4, and the outlet of the high-pressure pump 1 is connected to the hole 3 on the corrugated aluminum sheath 2 at one end of the filling section through the outlet pipe 6.

[0012] 3) If Figure 1As shown, before injection, 0.2 grams of benzoyl peroxide was added to the container 5 containing the conductive filler 8. Immediately, the high-pressure pump 1 was started to inject the corrosion inhibitor 8 in the container 5 from the hole 3 on one end of the corrugated aluminum sheath 2 in the filling section into the gap between the corrugated aluminum sheath 2 and the buffer layer 7. When the corrosion inhibitor 8 flowed out from the hole on the other end of the corrugated aluminum sheath 2 in the filling section, the high-pressure pump 1 was turned off.

[0013] 4) Remove the outlet pipe 6 connected to the hole 3 on one end of the corrugated aluminum sheath 2 in the filling section. Use non-woven fabric to tightly cover and wind around the holes 3 on the corrugated aluminum sheaths 2 at both ends of the filling section. Then, brush the epoxy resin-based adhesive on the surface of the non-woven fabric for curing and sealing.

[0014] The high-voltage power cable with the anti-breakdown filler for the buffer layer of the power cable in this embodiment was left standing for 3 hours after the above injection was completed. Then, a power-on experiment was carried out. After 3.5 hours of power-on, it could be seen that the strip-shaped white spots and dot-shaped distributed white spots on the surface of the buffer layer decreased, the original rust spots became loose and fell off, a new conductive path was formed, and the corrosion pits on the surface of the corrugated aluminum decreased. Example Two

[0015] A conductive filler for anti-breakdown of a power cable in this embodiment is composed of the following components in the following contents, which are mixed and stirred with each other: (1) Phosphorus-based imidazole bromide with a mass percentage of 15%; (2) Tetraethylenepentamine with a mass percentage of 5%; (3) Amino polar silicone oil with a mass percentage of 10%; (4) Vinyl silicone oil with a mass percentage of 17%; (5) Styrene with a mass percentage of 3%; (6) Ethyl acetate with a mass percentage of 50%.

[0016] The synthesis method of the phosphorus-based imidazole bromide in this embodiment is the same as that in Example One and will not be elaborated here.

[0017] The application method of the corrosion inhibitor for the buffer layer of a high-voltage power cable in this embodiment is basically the same as that in Example One, with the slight difference being: I. Preparation of the conductive filler Weigh 15 grams of the synthesized phosphorus-based imidazole bromide, and add 5 grams of tetraethylenepentamine, 10 grams of amino polar silicone oil, 17 grams of vinyl silicone oil and 3 grams of styrene to 50 grams of ethyl acetate for mixing. Stir well at 25 - 30 °C for 90 minutes to obtain a conductive filler for anti-breakdown of a power cable in this embodiment. The resistivity of this filler is 652 Ω•cm.

[0018] The other steps are the same as those in Example One and will not be elaborated here.

[0019] An anti-corrosion agent for the buffer layer of high-voltage transmission cables in this embodiment is injected into the high-voltage transmission cables to conduct a power-on experiment. After 3.5 hours of power-on, it can be seen that the strip-shaped white spots and dot-distributed white spots on the surface of the buffer layer decrease, the original rust spots become loose and fall off, a conductive path is re-formed, and the corrosion pits on the surface of the corrugated aluminum decrease. Example 3

[0020] A conductive filler for anti-breakdown of transmission cables in this embodiment is composed of the following components with the following contents mixed and stirred: (1) Phosphorus-based imidazole bromide with a mass percentage of 25%; (2) Tetraethylenepentamine with a mass percentage of 5%; (3) Amino polar silicone oil with a mass percentage of 10%; (4) Vinyl silicone oil with a mass percentage of 15%; (5) Styrene with a mass percentage of 5%; (6) Ethyl acetate with a mass percentage of 40%.

[0021] The synthesis method of the phosphorus-based imidazole bromide in this embodiment is the same as that in Example 1 and will not be elaborated here.

[0022] The application method of the conductive filler for anti-breakdown of transmission cables in this embodiment is basically the same as that in Example 1, with the slight difference being: I. Preparation of the conductive filler Weigh 25 grams of the synthesized phosphorus-based imidazole bromide, and add 5 grams of tetraethylenepentamine, 10 grams of amino polar silicone oil, 15 grams of vinyl silicone oil, and 5 grams of styrene to 40 grams of ethyl acetate and mix them. Stir well at 25 - 30 °C for 90 minutes to obtain a conductive filler for anti-breakdown of transmission cables in this embodiment.

[0023] The other steps are the same as those in Example 1 and will not be elaborated here.

[0024] The conductive filler for anti-breakdown of transmission cables in this embodiment is injected into the high-voltage transmission cables to conduct a power-on experiment. After 1.5 hours of power-on, it can be seen that the strip-shaped white spots and dot-distributed white spots on the surface of the buffer layer decrease, the original rust spots become loose and fall off, a conductive path is re-formed, and the corrosion pits on the surface of the corrugated aluminum decrease. Example 4

[0025] A conductive filler for anti-breakdown of transmission cables in this embodiment is composed of the following components with the following contents mixed and stirred: (1) Phosphorus-based imidazole bromide with a mass percentage of 19%; (2) Tetraethylenepentamine with a mass percentage of 5%; (3) Amino polar silicone oil with a mass percentage of 10%; (4)Vinyl silicone oil with a mass percentage of 13%; (5)Styrene with a mass percentage of 7%; (6)Ethyl acetate with a mass percentage of 46%.

[0026] The synthesis method of the phosphorus-based imidazole bromide salt in this example is the same as that in Example 1 and will not be elaborated here.

[0027] The application method of the conductive filler for anti-breakdown of power transmission cables in this example is basically the same as that in Example 1, with the slight difference being: I. Preparation of the conductive filler Weigh 19 grams of the synthesized phosphorus-based imidazole bromide salt, and add it to 46 grams of ethyl acetate together with 5 grams of tetraethylenepentamine, 10 grams of amino polar silicone oil, 13 grams of vinyl silicone oil, and 7 grams of styrene, and mix them. Stir well at 25 - 30 °C for 90 minutes to obtain a conductive filler for anti-breakdown of power transmission cables in this example. The resistivity of this filler is 905 Ω•cm. Other steps are the same as those in Example 1 and will not be elaborated here.

[0028] After the conductive filler for anti-breakdown of power transmission cables in this example is injected into the high-voltage power transmission cable for a power-on experiment, after 2.5 hours of power-on, it can be seen that the strip-shaped white spots and dot-distributed white spots on the surface of the buffer layer decrease, the original rust spots become loose and fall off, a new conductive path is formed, and the corrosion pits on the surface of the corrugated aluminum decrease. Example 5

[0029] A conductive filler for anti-breakdown of power transmission cables in this example is composed of the following components mixed and stirred together: (1)Phosphorus-based imidazole bromide salt with a mass percentage of 15%; (2)Tetraethylenepentamine with a mass percentage of 2%; (3)Amino polar silicone oil with a mass percentage of 13%; (4)Vinyl silicone oil with a mass percentage of 13%; (5)Styrene with a mass percentage of 7%; (6)Ethyl acetate with a mass percentage of 50%.

[0030] The synthesis method of the phosphorus-based imidazole bromide salt in this example is the same as that in Example 1 and will not be elaborated here.

[0031] The application method of the conductive filler for anti-breakdown of power transmission cables in this example is basically the same as that in Example 1, with the slight difference being: I. Preparation of the conductive filler Weigh 15 g of the synthesized phosphorus-based imidazole bromide salt, and add 2 g of tetraethylenepentamine, 13 g of amino polar silicone oil, 13 g of vinyl silicone oil, and 7 g of styrene to 50 g of ethyl acetate and mix them. Stir well at 25 - 30 °C for 90 minutes to obtain a conductive filler for anti-breakdown of power transmission cables in this example. The resistivity of this filler is 949 Ω•cm.

[0032] The other steps are the same as those in Example 1 and will not be elaborated here.

[0033] The conductive filler for anti-breakdown of power transmission cables in this example is injected into the high-voltage power transmission cable for a power-on experiment. After 3.5 hours of power-on, it can be seen that the strip-shaped white spots and dot-distributed white spots on the surface of the buffer layer decrease, the original rust spots become loose and fall off, a new conductive path is formed, and the corrosion pits on the surface of the corrugated aluminum decrease. Example Six

[0034] A conductive filler for anti-breakdown of power transmission cables in this example is composed of the following components in the following contents, which are mixed and stirred with each other: (1) 15% by mass of phosphorus-based imidazole bromide salt; (2) 4% by mass of tetraethylenepentamine; (3) 16% by mass of amino polar silicone oil; (4) 13% by mass of vinyl silicone oil; (5) 7% by mass of styrene; (6) 50% by mass of ethyl acetate.

[0035] The synthesis method of the phosphorus-based imidazole bromide salt in this example is the same as that in Example 1 and will not be elaborated here.

[0036] The application method of a conductive filler for anti-breakdown of power transmission cables in this example is basically the same as that in Example 1, with the slight difference being: I. Preparation of the conductive filler Weigh 15 g of the synthesized phosphorus-based imidazole bromide salt, and add 4 g of tetraethylenepentamine, 16 g of amino polar silicone oil, 13 g of vinyl silicone oil, and 7 g of styrene to 50 g of ethyl acetate and mix them. Stir well at 25 - 30 °C for 90 minutes to obtain a conductive filler for anti-breakdown of power transmission cables in this example. The resistivity of this filler is 937 Ω•cm.

[0037] The other steps are the same as those in Example 1 and will not be elaborated here.

[0038] The conductive filler for withstanding breakdown of the power transmission cable in this embodiment is injected into the high-voltage power transmission cable for a power-on experiment. After 3.5 hours of power-on, it can be seen that the strip-shaped white spots and dot-distributed white spots on the surface of the buffer layer decrease, the original rust spots become loose and fall off, a new conductive path is formed, and the corrosion pits on the surface of the corrugated aluminum decrease.

[0039] The above are only the preferred embodiments of the present invention, but the present invention is not limited thereto. All equivalent substitutions or equivalent changes made according to the concept and technical solution of the present invention should be covered within the protection scope of the present invention.

Claims

1. A conductive filler for anti-penetration of power transmission cables, comprising the following components mixed and stirred together: (1) 15% to 25% by weight of phosphorus-based imidazole bromide; (2) 2% to 5% by mass of tetraethylenepentamine; (3) 10% to 16% by mass of amino polar silicone oil; (4) 13% to 17% by mass of vinyl silicone oil; (5) 3% to 7% by mass of styrene; (6) 40% to 50% by mass of ethyl acetate; The synthesis process of the phosphorus-based imidazole bromide salt is as follows: First, 1,3-dibromopropane and triisopropyl phosphite were added to a container in a molar mass ratio of 4:1, and then connected to a distillation device after being fully stirred, and reacted at 120°C for 6 hours; then, excess dibromopropane was removed by reduced pressure distillation to obtain an intermediate product, diisopropyl (3-bromopropyl) phosphonate; Secondly, methylimidazole and dichloromethane were added into the container in a molar mass ratio of 1:8, and the diisopropyl (3-bromopropyl) phosphonate intermediate was added dropwise into the container using a constant pressure funnel under nitrogen protection and magnetic stirring under ice-salt bath conditions. The reaction was continued for 24 h, and the temperature was raised to 40 °C for a further 40 h. Finally, the remaining solvent was removed by distillation under reduced pressure, and the product was repeatedly washed three times with a mixed solution of n-hexane and ether in a volume ratio of 2:1, and vacuum dried at 40° C. for 12 h to obtain phosphorus-containing imidazole bromide.

2. According to claim 1, a method for applying a conductive filler for anti-penetration of a power transmission cable comprises the following steps:

1. Preparation of conductive filler The synthesized phosphorus-based imidazole bromide salt, tetraethylenepentamine, amino polar silicone oil, vinyl silicone oil, and styrene are added to ethyl acetate and mixed, and stirred at 25-30° C. for 90 minutes to obtain the conductive filler; 2. Injecting conductive filler into transmission cables 1) Strip the corrugated aluminum sheath at both ends of the required transmission cable filling section, and punch holes in the corrugated aluminum sheath at both ends of the filling section; 2) placing the conductive filler obtained in step 1 in a container, equipped with inlet and outlet pipes and a high-pressure pump; at the same time, the inlet of the high-pressure pump is connected to the container in which the filler is placed through the inlet pipe, and the outlet of the high-pressure pump is connected to the hole on the corrugated aluminum sheath at one end of the filling section through the outlet pipe; 3) Before injection, add 0.2 grams of benzoyl peroxide into the container containing the conductive filler, and immediately start the high-pressure pump to inject the filler in the container into the gap between the corrugated aluminum sheath and the buffer layer from the hole on the corrugated aluminum sheath at one end of the filling section. When the corrosion-resistant agent flows out of the hole on the corrugated aluminum sheath at the other end of the filling section, turn off the high-pressure pump; 4) Remove the outlet pipe connected to the hole on the corrugated aluminum sheath at one end of the filling section, tightly cover and wrap the holes on the corrugated aluminum sheath at both ends of the filling section with non-woven fabric, and then brush epoxy resin-based adhesive on the surface of the non-woven fabric for curing and sealing.

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