CN113024873B - Power cable insulation aging repair liquid with electrical tree resistance and preparation method and application thereof - Google Patents
Power cable insulation aging repair liquid with electrical tree resistance and preparation method and application thereof Download PDFInfo
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- CN113024873B CN113024873B CN202110517166.0A CN202110517166A CN113024873B CN 113024873 B CN113024873 B CN 113024873B CN 202110517166 A CN202110517166 A CN 202110517166A CN 113024873 B CN113024873 B CN 113024873B
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G1/00—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines
- H02G1/16—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines for repairing insulation or armouring of cables
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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- C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
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Abstract
The invention discloses a power cable insulation aging repair liquid with electrical tree resistance, a preparation method and application thereof, wherein the repair liquid comprises the following components in parts by weight: 88-99.6 parts of siloxane; 0.3-2 parts of a catalyst; 0.1-10 parts of antioxidant, wherein the antioxidant is at least one of 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6-di-tert-butylphenol, antioxidant 1010, antioxidant 1076 and antioxidant 168. The preparation method comprises the following steps: adding the components in parts by weight into a mixing container with a stirrer, introducing inert gas into the mixing container, and stirring and mixing the mixture at room temperature for at least 10min to obtain the power cable insulation aging repair liquid with the electrical tree resistance. The repair liquid is applied to the insulation aging repair of the power cable in an injection mode. The repair liquid provided by the invention can repair the aged area of the water tree, inhibit insulation deterioration and electric tree initiation, improve the electric tree resistance of the aged cable and prolong the service life of the cable.
Description
Technical Field
The invention belongs to the technical field of cable repair, and particularly relates to a power cable insulation aging repair liquid with electrical tree resistance, and a preparation method and application thereof.
Background
Crosslinked polyethylene (XLPE) cables are widely used due to their excellent electrical and mechanical properties, but due to the limitation of modern processes, the cables inevitably leave some microscopic defects such as air gaps, cracks and the like in the insulating layer during the manufacturing, laying and running processes, and the cracks are further developed under the action of an electric field to form electric branches, which can cause irreversible damage to the insulation and finally cause insulation breakdown. Researchers at home and abroad carry out a great deal of research on the initiation and growth of the electrical tree, and the current electrical tree initiation theory mainly comprises an electro-mechanical theory, a photodegradation theory caused by electroluminescence and a charge injection and extraction theory. The electro-mechanical theory considers that under the action of an alternating electric field, a material is continuously subjected to electro-mechanical stress (Maxwell stress), molecular chains in a polymer are broken due to stress fatigue to form micropores and cracks, partial discharge is generated in the micropores under the action of a strong electric field, and the micropores and the cracks are further developed to form electric branches. Researchers carry out electric tree initiation experiments on Polyethylene (PE) samples, an electroluminescence phenomenon is observed at a needle point during the incubation period of electric trees, the electroluminescence generates ultraviolet light, molecular chains of polymers are subjected to high-energy radiation under the action of the ultraviolet light to be changed into an excited state, free radicals are decomposed from the excited state and react with oxygen to generate an automatic oxidation chain reaction, a large number of molecular chains are broken to form micropores, and the micropores are developed into the electric trees under the action of a strong electric field. The theory of charge injection and extraction is thought that in the incubation period of the electric tree, electrons are accelerated to form 'hot electrons' in the injection and extraction processes, molecular chains are broken due to collision of the electrons with molecular chains of the polymer, free radicals are generated, the free radicals generate autoxidation chain reaction under the action of oxygen, a large number of molecular chains are broken to form micropores in the polymer, and the micropores are further developed under the action of an electric field to finally form the electric tree. Researchers find the phenomenon that electrical branches are caused by water branches in industrial operation cables, the water branches grow out of the cables in a humid operation environment, local electric field force is concentrated in a water tree area, and the electrical branches grow out of the water tree area finally.
In order to suppress the generation of electrical tree branches in the cable and prolong the service life of the cable, a large number of methods are adopted, such as a method for improving the cable manufacturing process, a method for adding a voltage stabilizer in a cable material and the like. With the application of the dry crosslinking technology and the three-layer co-extrusion technology, the number of micropores in the XLPE insulating layer is reduced by 99 percent, and the diameter of the micropores is reduced by 90 percent. Further, the insulation performance of the cable is difficult to effectively improve by improving the manufacturing process of the cable, and the cost is high. Therefore, people began to increase the electrical dendrite initiation voltage of cables by adding a voltage stabilizer to the cable material, wherein the voltage stabilizer mainly acts to inhibit the electrical aging of the cables, the electrical aging in the cables is mainly expressed in the form of generation of electrical dendrites, namely, the voltage stabilizer mainly acts to increase the electrical dendrite initiation voltage of XLPE cables. From the twentieth sixties to the present, researchers at home and abroad have conducted a great deal of research on voltage stabilizers, and the research shows that the addition of the voltage stabilizers in the cable can greatly improve the voltage induced by the electrical tree of the cable, inhibit the electrical aging of polymers and prolong the service life of the cable. Different types of voltage stabilizers act at different stages of XLPE electrical tree initiation, for example: (1) the voltage stabilizer with higher electron affinity can capture thermal electrons, weaken the energy of the thermal electrons, reduce the damage of the thermal electrons to polymer molecular chains and inhibit the generation of electrical branches; (2) the free radical scavenging voltage stabilizer can scavenge free radicals in polymers, inhibit automatic oxidation chain reaction and further inhibit generation of electric tree branches, such as an antioxidant or a light stabilizer.
With the further research on voltage stabilizers by researchers, small-molecule voltage stabilizers were found to migrate out of polymers relatively easily, and in order to solve this weakness, the mainstream solution was High molecular weight method (engung V, Huuva R, gubanki S M, et al. High efficiency voltage stabilizers for XLPE cable Insulation [ J ]. Polymer degradation and Stability, 2009, 94 (5): 823 833), solid support method (kah, Maekawa N, Inoue S, e al. impact and mechanism of the new voltage stabilization for linking Insulation [ C ]// polymerization Insulation, preparation of Electrical Insulation material with Electrical properties of IEEE 20120-polystyrene, 2016, and Electrical Insulation material with Electrical properties of IEEE 2019, etc. a polymer antioxidant [ P ] with supermolecular intercalation structure, Chinese patent: CN201210312887.9, 2012-11-28)). The high molecular weight method is to increase the relative molecular mass of the voltage stabilizer and slow down the migration of the voltage stabilizer out of the polymer; the immobilization method is to react the micromolecular voltage stabilizer with inorganic particles to generate a nano-voltage stabilizer, so as to improve the dispersibility and the mobility resistance of the voltage stabilizer; the grafting method is that the voltage stabilizer is grafted to the molecular chain of the polymer through reaction to slow down the migration of the voltage stabilizer out of the polymer; the intercalation assembly technology is to use antioxidant molecules as objects to construct a macromolecular composite antioxidant.
However, in all of the above methods, the voltage stabilizer is mixed with the polyethylene particles in the cable manufacturing process, and then the cross-linking process is performed to obtain the molded cable for inhibiting the generation of electrical dendrites, and after the cable is put into operation, the voltage stabilizer can achieve a good effect in a medium-short period. And the temperature in the crosslinking process can reach 280 ℃, and many high-efficiency voltage stabilizers are difficult to put into practical application due to the reasons that the high temperature is easy to decompose or volatilize and the like. The voltage stabilizer is supplemented aiming at the cable after being put into operation to inhibit insulation deterioration and electrical tree initiation, so that the service life of the cable can be effectively prolonged, and the manpower, material resources and financial resources required for replacing the cable are reduced.
Disclosure of Invention
Aiming at the problem that the voltage stabilizer can be supplemented to the cable after operation in the prior art temporarily without technology, the invention aims to provide the power cable insulation aging repair liquid with the anti-tree electric performance and the preparation method thereof, wherein the repair liquid can repair the water tree aging area, supplement the voltage stabilizer which is lost in the insulation layer, improve the electric tree initiation voltage and the insulation breakdown voltage, inhibit the insulation degradation and the initiation of electric branches, enhance the electric resistance performance of the cable, improve the anti-tree electric performance of the aging cable, remarkably repair the long-term performance and prolong the service life of the cable; meanwhile, the repairing liquid has the advantages of simple preparation, safety, stability, good effect, low cost, convenient construction and the like.
The invention also aims to provide application of the power cable insulation aging repair liquid with the electrical tree resistance in power cable insulation aging repair.
The basic idea of the invention is as follows: the voltage stabilizer is added on the basis of the existing siloxane repairing liquid, so that on one hand, moisture in an aged cable is eliminated, and the micro holes generated by aging are filled to improve the local electric field distribution and mitigate the electric field distortion, so that the aged area of a water tree is repaired, the insulation degradation and the initiation of electric branches are inhibited, on the other hand, the lost voltage stabilizer is supplemented, and the electric tree resistance of the aged cable is further improved. Aiming at the above purpose of the invention, based on the above basic ideas, the power cable insulation aging repair liquid with electrical tree resistance provided by the invention comprises the following components in parts by weight:
88-99.6 parts of siloxane;
0.3-2 parts of a catalyst;
0.1-10 parts of an antioxidant;
the antioxidant is at least one of 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6 di-tert-butylphenol, antioxidant 1010, antioxidant 1076 and antioxidant 168.
Most of the voltage stabilizer is a low-molecular substance which is easy to migrate and separate out, and the voltage stabilizer is easy to migrate and separate out under the action of higher working temperature and field intensity in the long-term working process of the cable, so that the effect of improving the electric resistance of the polymer is gradually lost, and the migration resistance of the voltage stabilizer is always a research focus. Further, according to the theory of electrical tree induced traps, the mechanism of action of voltage stabilizers can be roughly classified into four categories: voltage stabilizers to withstand partial discharge and to moderate strong electric fields, voltage stabilizers to trap energetic electrons, radical scavengers, and light stabilizers. Different kinds of voltage stabilizers have different inhibiting effects on XLPE insulated tree, and the concentration of the voltage stabilizer is also closely related to the initiation voltage of the tree. The stabilizer used in the invention belongs to a (free radical scavenger) type voltage stabilizer, and researches show that after the repair liquid is diffused, the highest concentration and the lowest concentration are both in a certain effective concentration range, so that even if the phenomenon of uneven diffusion exists, the injection method can still play a remarkable role, and the initiation voltage of the whole XLPE insulation electric tree is improved. The power cable insulation aging repair liquid with the electrical tree resistance preferably comprises the following components in percentage by weight: 97.5-99.5 parts of siloxane; 0.4-1.5 parts of catalyst; 0.1-1 part of antioxidant; more preferably: 98.3-99.1 parts of siloxane (98.0-98.6 parts of siloxane is shown in the examples of the invention); catalyst 0.5-1.0 parts (catalyst 1.0 part is shown in the examples of the present invention); 0.4-0.7 part of antioxidant (0.4-1.0 part of antioxidant is shown in the embodiment of the invention).
The molecular weight of the selected antioxidant is more than 500, and the antioxidant has better migration resistance and better long-term effect because the diffusion speed of the antioxidant in the insulating layer is lower.
In particular, 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6-di-tert-butylphenol, which has not only antioxidant and voltage stabilizing effects but also 2 hydrolyzable groups and is capable of generating condensation reaction, is the best antioxidant for long-term performance in the present invention, and its mechanism of action is as follows.
In water tree restoration, studies have been made on organic-inorganic nanocomposite filler restorations formed by condensation of nanogels and silane coupling agents (siloxanes) generated in water tree cavities through chemical reactions, but the silane coupling agents have a small molecular weight and have limited life span because the addition of a voltage stabilizer to suppress water trees and electric trees is not considered. The principle of hydrolysis-condensation reaction of the silane coupling agent is shown in formula (1) and formula (2), and dimer or polymer is gradually generated under acidic or basic catalyst.
In a nano composite repair, the surface of nano gel particles formed by hydrolysis-condensation of inorganic metal alkoxide (titanate in catalyst) often contains abundant hydroxyl groups, and can be condensed with silanol hydroxyl groups in the formula (2) to form organic-inorganic nano composite filling, and the repair reaction principle is shown in fig. 1.
Using antioxidants containing phenol and hydrolysable groups, e.g. BHTPrSi (MeO)2Me (4- [3- (dimethoxymethylsilyl) propyl group]2, 6-di-tert-butylphenol), which has not only antioxidant and voltage stabilizing effects, but also 2 hydrolyzable groups and can undergo condensation reaction with the product of formula (2) to form oligomers, thereby not being easily lost. The reaction principle of the phenolic antioxidant containing hydrolytic groups is shown as a formula (3), wherein R represents an active functional group with affinity with polymer molecules, and OMe (methoxyl) is a hydrolytic group.
Wherein, BHT: 2,6 di-tert-butylphenol; me: a methyl group; OMe: a methoxy group; pr: and (4) propyl.
Since the silanol formed in the reactions of the two formulae (2) and (3) is unstable, it may eventually undergo further dehydrocondensation with hydroxyl groups to form oligomeric silanes. In this case, since the surface of the nanoparticle is hydrolyzed to form more hydroxyl groups, and the XLPE matrix is aged to form hydroxyl groups, the generated silanol in formula (2) and formula (3) may be combined in several ways: the principle of the method is shown in fig. 2 (a), wherein the method is to combine hydroxyl on the surface of the nano-particles with the surface of an XLPE matrix, and the method is to combine two products with each other. Through further condensation reaction, a product combination form shown in fig. 2 (b) is formed, silanol and a voltage stabilizer molecule are condensed and then anchored, so that the silanol and the voltage stabilizer molecule are not easy to lose, and meanwhile, partial hydroxyl on the silanol and the voltage stabilizer can be connected with covalent bonds formed after dehydration of hydroxyl on nano particles or an XLPE matrix, so that stable chemical bond combination is formed. No matter which condensation mode is adopted, the voltage stabilizer and the nano particles or the matrix can form chemical bonding action to form anchoring or immobilization, so that the migration resistance of the voltage stabilizer is improved, and the long-term performance of the repair effect is enhanced.
The antioxidant adopted by the invention has an inhibiting effect on the oxidation chain reaction in the polymer, so the antioxidant has a certain inhibiting effect on the initiation of the electric tree. The antioxidant adopted by the invention is a phenol main antioxidant and has a free radical capture function. The phenol structure in the antioxidant can provide hydrogen atoms with lower bond energy, and the hydrogen atoms are preferentially combined with ROO & to generate hydroperoxide ROOH, so that chain reaction is stopped, and the effect of protecting polymer molecules is achieved. Antioxidant 1010 is a high molecular weight hindered phenolic antioxidant and has good compatibility with most polymers. The volatility is low, the migration is not easy, and the thermal oxidative degradation of the polymer material in the long-term aging process can be effectively prevented.
The catalyst of the power cable insulation aging repair liquid with electrical tree resistance can be at least one of titanate, dodecyl benzene sulfonic acid, sodium hydroxide, potassium hydroxide, hydrochloric acid and nitric acid. The titanate is preferably at least one of tetraisopropyl titanate, tetraisobutyl titanate, isopropyl trititanate or isopropyl dioctyl pyrophosphate acyloxy titanate. The siloxane has one or more alkoxy groups, and can be at least one of dodecyl trimethoxy silane, methyl phenyl dimethoxy silane, triethoxy ethyl silane, diisopropyl dimethoxy silane and 3-phenylpropyl methyl dimethoxy silane. After the poly-alkoxy siloxane is subjected to hydrolysis reaction, the poly-alkoxy siloxane is subjected to polymerization reaction under the action of a catalyst to generate an oligomer with a longer molecular chain, and the oligomer has a slower diffusion speed in the crosslinked polyethylene insulating layer and is less prone to loss. The siloxane, catalyst and voltage stabilizer are all commercially available.
The invention further provides a preparation method of the power cable insulation aging repair liquid with the electrical tree resistance, which comprises the following steps: adding 88-99.6 parts of siloxane, 0.3-2 parts of catalyst and 0.1-10 parts of voltage stabilizer into a mixing container with a stirrer, introducing inert gas into the mixing container, and uniformly stirring and mixing at room temperature to obtain the power cable insulation aging repair liquid with the electrical tree resistance. The inert gas may be nitrogen, argon, or the like. The stirring and mixing time is at least 10min, generally 10 min-20 min. The room temperature is generally 10 ℃ to 30 ℃.
The invention further provides an application of the power cable insulation aging repair liquid with the electrical tree resistance in power cable insulation aging repair, which specifically comprises the following steps:
(1) installing an adapter: removing cable terminals at two ends of a power cable to be repaired, and respectively installing a front end adapter and a rear end adapter;
(2) and (3) testing the penetration: the front-end adapter is connected with nitrogen injection equipment, 0.1-0.2 MPa of nitrogen is injected into the power cable to be repaired from the rear-end adapter, and meanwhile, the connectivity of the power cable to be repaired is detected by using a barometer of the nitrogen injection equipment; if the power cable to be repaired has good connectivity, the step (3) is carried out, otherwise, injection repair is not recommended;
(3) injecting a repairing liquid: removing the nitrogen injection equipment connected with the adapter, connecting the nitrogen injection equipment with the repair equipment, injecting the repair liquid into the power cable core to be repaired from the front end adapter under the pressure of 0.15-0.8 MPa, stopping injecting the repair liquid after the repair liquid overflows from the outlet of the rear end adapter, and keeping the pressure for 2-6 hours to ensure that the repair liquid fully permeates into the cable insulation layer;
(4) filling and repairing: and (3) sealing the inlet of the front-end adapter and the outlet of the rear-end adapter, enabling the repair liquid to fully react with the moisture in the cable power tree area, generating oligomers in the process of the repair liquid to fill and repair the aged micropores, wherein the repair time is at least 2 h, opening the adapters at the two ends of the cable after the repair is finished, and removing the residual repair liquid and the waste liquid from the outlet of the rear-end adapter to finish the repair of the aged cable.
And after the repair is finished, the adapter is detached, the cable terminal is manufactured again, and the insulation of the terminal is recovered.
The invention is characterized in that on the basis of the existing siloxane repairing liquid, a voltage stabilizer which is good in compatibility with polymers and difficult to migrate out is selected, in order to ensure that good electrical tree resistance is achieved, the addition concentration of the voltage stabilizer is strictly limited, in the effective concentration range, even if the phenomenon of uneven diffusion exists, the injection method can still play a remarkable role, and the electrical tree initiation voltage of the XLPE insulation whole body is effectively improved.
The power cable insulation aging repair liquid with the tree resistance and the preparation method and application thereof provided by the invention have the following beneficial effects:
(1) the power cable insulation aging repair liquid provided by the invention mainly comprises siloxane, a catalyst and an antioxidant, wherein the siloxane component can effectively remove moisture in a cable insulation layer and generate oligomers to fill aging micropores, the repair effect on a damp cable and a water tree aging cable is particularly better, and the insulation performance of the aging cable can be greatly improved; the added antioxidant can effectively supplement the voltage stabilizer which runs off or is consumed in the early-stage cable operation, can remove free radicals, enhances the oxidation resistance of cable insulation, improves the voltage caused by the electrical tree, further improves the breakdown strength, enhances the electrical tree resistance and prolongs the cable operation life.
(2) The voltage stabilizer component of the power cable insulation aging repair liquid provided by the invention can be combined with a free radical ROO generated in an aging process, so that the insulation aging is prevented from being aggravated, and polymer molecules of a power cable are protected.
(3) The power cable insulation aging repair liquid provided by the invention has the advantages of low raw material price, simple and feasible preparation process and convenient application and construction, and can save a large amount of cost and resources compared with the method of directly replacing an aged power cable.
(4) The antioxidant 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6 di-tert-butylphenol selected by the invention can generate hydrolysis reaction and is condensed with silanol and hydroxyl formed by aging of insulating layer molecules, so that the diffusion loss speed is greatly slowed down, and the long-acting property of the repair effect is improved.
Drawings
FIG. 1 is a model of the interaction of inorganic materials with an XLPE matrix/coupling agent in accordance with the present invention, wherein (a) is the interaction model of inorganic materials with the matrix and (b) is the interaction principle of inorganic materials with the coupling agent;
FIG. 2 is the immobilization principle of the voltage stabilizer, the coupling agent and the nanogel in the invention; wherein (a) is a schematic diagram of hydrolysis of methoxyl group to form hydroxyl group, and (b) is a schematic diagram of condensation between hydroxyl groups to form covalent bond;
FIG. 3 is a schematic view of an injective repair of a cross-linked polyethylene power cable;
FIG. 4 is a graph of electrical tree initiation voltage versus initiation probability;
fig. 5 is a graph of breakdown voltage versus breakdown probability.
Description of reference numerals: 1. a front end adapter inlet; 2. a rear end adapter outlet; 3. a front end adapter; 4. a back end adapter; 5. the cable is to be repaired.
Detailed Description
So that the technical solutions of the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings, it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, belong to the present invention.
The cable aging repair mechanism of the power cable insulation aging repair liquid with electrical tree resistance provided by the invention is explained by taking 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6-di-tert-butylphenol as an example.
Example 1
The power cable insulation aging repair liquid with electrical tree resistance provided by the embodiment is prepared according to the following method: adding 98.6 parts of methyl phenyl dimethoxy silane (PMDMS) (the concentration of the PMDMS is 98.6 wt%), 1 part of tetraisopropyl titanate (the concentration of the tetraisopropyl titanate is 1 wt%), and 0.4 part of 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6 di-tert-butylphenol (the concentration of the 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6 di-tert-butylphenol is 0.4 wt%) into a mixing container with a stirrer, introducing nitrogen into the mixing container, and stirring and mixing the mixture at room temperature for about 20min to obtain the power cable insulation aging repair liquid with the electrical tree resistance.
Example 2
The power cable insulation aging repair liquid with electrical tree resistance provided by the embodiment is prepared according to the following method: adding 98.3 parts of methyl phenyl dimethoxy silane (PMDMS) (the concentration of the PMDMS is 98.3 wt%), 1 part of tetraisopropyl titanate (the concentration of the tetraisopropyl titanate is 1 wt%), and 0.7 part of 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6 di-tert-butylphenol (the concentration of the 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6 di-tert-butylphenol is 0.7 wt%) into a mixing container with a stirrer, introducing nitrogen into the mixing container, and stirring and mixing the mixture at room temperature for about 20min to obtain the power cable insulation aging repair liquid with the electrical tree resistance.
Example 3
The power cable insulation aging repair liquid with electrical tree resistance provided by the embodiment is prepared according to the following method: adding 98 parts of methyl phenyl dimethoxy silane (PMDMS) (the concentration of the PMDMS is 98 wt%), 1 part of tetraisopropyl titanate (the concentration of the tetraisopropyl titanate is 1 wt%), and 1 part of 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6 di-tert-butylphenol (the concentration of the 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6 di-tert-butylphenol is 1 wt%) into a mixing container with a stirrer, introducing nitrogen into the mixing container, and stirring and mixing the mixture at room temperature for about 20min to obtain the power cable insulation aging repair liquid with the electrical tree resistance.
Application example
1. Subject acquisition
In order to research the repairing effect of the power cable aging repairing liquid provided by the invention on an aged cable, a batch of new cables are selected for accelerated thermo-oxidative aging to obtain an aged sample for a repairing experiment, and the preparation method of the aged sample comprises the following steps:
(1) YJLV-8.7/10-1X 95 mm is selected2The model number of the cable is 25, the cable is made into a short cable sample with the length of 400 mm, the short cable sample is divided into 3 groups, the number of the groups is A, B, C, and the groups are respectively 5, 5 and 15;
(2) stripping the outer sheath, the copper strip and the water blocking tape of the short cable sample to expose the outer semi-conducting layer of the cable;
(3) stripping 100 mm of the outer semi-conducting layers on the left side and the right side of the short cable sample respectively;
(4) stripping the insulating layer and the inner semi-conducting layer from one side of the short cable sample to expose a cable core with the thickness of 10 mm, so as to facilitate subsequent electrical performance test;
(5) and (3) putting the stripped and cut short cable sample into a temperature and humidity control box for accelerated thermo-oxidative aging, setting the aging temperature to be 150 ℃, opening the control box once every 30 min, keeping the opening time for 5 min, ensuring sufficient oxygen in the thermo-oxidative aging process, and aging for 132 h to obtain an aged power cable sample.
The obtained aged power cable samples were used for microscopic observation and breakdown voltage test respectively for test samples in which no repair liquid (sample a) was injected, a siloxane repair liquid (pure siloxane repair liquid without added voltage stabilizer (antioxidant) and catalyst, sample B) of the prior art and the power cable insulation aging repair liquid with electrical tree resistance (sample C) of the present invention were injected, as shown in table 1.
TABLE 1 setting of thermo-oxidative aged samples
Note: TIPT is tetraisopropyl titanate, PMDMS is methyl phenyl dimethoxy silicon, and antioxidant A is 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6-di-tert-butylphenol.
2. Aged cable repair
According to the setting of the thermo-oxidative aging sample, the power cable insulation aging repair liquid with the electrical tree resistance prepared in the embodiment 1-3 is injected into the group C sample, and the method specifically comprises the following steps:
(1) installing an adapter: as shown in fig. 3, the cable terminations at the two ends of the power cable to be repaired are removed, and a front end adapter and a rear end adapter are respectively installed;
(2) and (3) testing the penetration: the front-end adapter is connected with nitrogen injection equipment, 0.1-0.2 MPa of nitrogen is injected into the power cable to be repaired from the rear-end adapter, and meanwhile, the connectivity of the power cable to be repaired is detected by using a barometer of the nitrogen injection equipment; if the power cable to be repaired has good connectivity, the step (3) is carried out, otherwise, injection repair is not recommended;
(3) injecting a repairing liquid: removing the nitrogen injection equipment connected with the adapter, connecting the nitrogen injection equipment with the repair equipment, injecting the repair liquid into the power cable core to be repaired from the front end adapter under the pressure of 0.15-0.8 MPa, stopping injecting the repair liquid after the repair liquid overflows from the outlet of the rear end adapter, and keeping the pressure for 2-6 hours to ensure that the repair liquid fully permeates into the cable insulation layer;
(4) filling and repairing: and (3) sealing the inlet of the front-end adapter and the outlet of the rear-end adapter, enabling the repair liquid to fully react with the moisture in the cable power tree area, generating oligomers in the process of the repair liquid to fill and repair the aged micropores, keeping for 4 hours, opening the adapters at the two ends of the cable after the repair is finished, and removing the residual repair liquid and waste liquid from the outlet of the rear-end adapter, namely finishing the repair of the aged cable. And after the repair is finished, the adapter is detached, the cable terminal is manufactured again, and the insulation of the terminal is recovered.
In the same manner as described above, a prior art silicone repair fluid (no voltage stabilizing repair fluid added) was injected into the group B samples.
3. Test analysis
(1) Initiation of electric Tree
And (3) performing an electrical tree initiation experiment on the group A sample, the group B sample, the group C sample and the new cable, and processing electrical tree initiation data according to the statistical analysis guide GB/T29310-. For the group A samples which are not repaired, the electric tree initiation voltage is 9.81 kV, and for the group B samples which are repaired by using the pure repairing liquid, the electric tree initiation voltage is 12.81 kV. When the content of 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6-di-tert-butylphenol reached 0.7wt%, the electrical dendron initiation voltage was 15.96 kV, which was increased by 62.69%. When the concentration of 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6-di-tert-butylphenol added was increased to 1.0% by weight, there was a slight supersaturation and the voltage for initiation of the electric tree was lower than that at the time of low addition.
(2) Power frequency breakdown experiment
And performing a power frequency breakdown experiment on the group A sample, the group C sample and the new cable, sorting breakdown data and drawing a two-parameter Weibull distribution curve, as shown in FIG. 5. It can be seen that the breakdown field strength of the new cable sample was 35.19 kV/mm at the highest, the breakdown field strength of the sample of group A which was not repaired was 22.50 kV/mm at the lowest, and the breakdown field strength of the sample of group C which was repaired with the repair liquid containing 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6-di-tert-butylphenol in an amount of 0.7wt% was 29.06 kV/mm. The breakdown field strength of the sample in the group A which is not repaired is greatly reduced by 56.40% compared with that of a new sample. The breakdown field strength of the samples in the group C after being repaired by using the repairing liquid with the content of 0.7wt% of 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6-di-tert-butylphenol is improved by 29.16% compared with the breakdown field strength of the samples aged without being repaired. It can be seen that the injection of the repair liquid of the invention into the aged cable can improve the breakdown field strength of the thermo-oxidative aged sample.
The experiment shows that the loss and consumption of the voltage stabilizer aggravate the oxidation reaction in the insulating layer, the insulating property of the cable sample is greatly reduced after thermal oxidation aging, and after the repairing method is used for repairing, the electric tree initiation voltage and the breakdown voltage are both obviously improved.
It will be appreciated by those of ordinary skill in the art that the embodiments described herein are intended to assist the reader in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited embodiments and examples. Those skilled in the art can make various other specific changes and combinations based on the teachings of the present invention without departing from the spirit of the invention, and these changes and combinations are within the scope of the invention.
Claims (9)
1. The utility model provides a power cable insulation aging repair liquid with anti electrical tree performance which characterized in that: the repairing liquid comprises the following components in parts by weight:
88-99.6 parts of siloxane;
0.3-2 parts of a catalyst;
0.1-10 parts of an antioxidant;
the antioxidant is 4- [3- (dimethoxymethylsilyl) propyl ] -2, 6 di-tert-butylphenol.
2. The power cable insulation aging repair liquid with electrical tree resistance as claimed in claim 1, wherein: the repairing liquid comprises the following components in parts by weight:
97.5-99.5 parts of siloxane;
0.4-1.5 parts of catalyst;
0.1-1 part of antioxidant.
3. The power cable insulation aging repair liquid with electrical tree resistance as claimed in claim 2, wherein: the repairing liquid comprises the following components in parts by weight:
98.3-99.1 parts of siloxane;
0.5-1.0 part of catalyst;
0.4-0.7 part of antioxidant.
4. A power cable insulation aging repair liquid with electrical tree resistance according to any one of claims 1 to 3, characterized in that: the catalyst is at least one of titanate, dodecyl benzene sulfonic acid, sodium hydroxide, potassium hydroxide, hydrochloric acid and nitric acid.
5. The power cable insulation aging repair liquid with electrical tree resistance as claimed in claim 4, wherein: the titanate is at least one of tetraisopropyl titanate, tetraisobutyl titanate, isopropyl trititanate or isopropyl dioctyl pyrophosphato acyloxy titanate.
6. A power cable insulation aging repair liquid with electrical tree resistance according to any one of claims 1 to 3, characterized in that: the siloxane is at least one of dodecyl trimethoxy silane, methyl phenyl dimethoxy silane, triethoxy ethyl silane, diisopropyl dimethoxy silane and 3-phenylpropyl methyl dimethoxy silane.
7. The preparation method of the power cable insulation aging repair liquid with electrical tree resistance of claim 1 is characterized by comprising the following steps: adding 88-99.6 parts of siloxane, 0.3-2 parts of catalyst and 0.1-10 parts of antioxidant into a mixing container with a stirrer, introducing inert gas into the mixing container, and stirring and mixing for at least 10min at room temperature to obtain the power cable insulation aging repair liquid with the electrical tree resistance.
8. Use of a power cable insulation aging repair liquid having electrical tree resistance properties according to any one of claims 1 to 6 in power cable insulation aging repair.
9. The application of the power cable insulation aging repair liquid with the electrical tree resistance performance in power cable insulation aging repair according to claim 8 is characterized in that: the method comprises the following steps:
(1) installing an adapter: removing cable terminals at two ends of a power cable to be repaired, and respectively installing a front end adapter and a rear end adapter;
(2) and (3) testing the penetration: the front-end adapter is connected with nitrogen injection equipment, 0.1-0.2 MPa of nitrogen is injected into the power cable to be repaired from the rear-end adapter, and meanwhile, the connectivity of the power cable to be repaired is detected by using a barometer of the nitrogen injection equipment; if the power cable to be repaired has good connectivity, the step (3) is carried out, otherwise, injection repair is not recommended;
(3) injecting a repairing liquid: removing the nitrogen injection equipment connected with the adapter, connecting the nitrogen injection equipment with the repair equipment, injecting the repair liquid into the power cable core to be repaired from the front end adapter under the pressure of 0.15-0.8 MPa, stopping injecting the repair liquid after the repair liquid overflows from the outlet of the rear end adapter, and keeping the pressure for 2-6 hours to ensure that the repair liquid fully permeates into the cable insulation layer;
(4) filling and repairing: and (3) sealing the inlet of the front-end adapter and the outlet of the rear-end adapter, enabling the repair liquid to fully react with the moisture in the cable power tree area, generating oligomers in the process of the repair liquid to fill and repair the aged micropores, opening the adapters at two ends of the cable after the repair is finished, and discharging the residual repair liquid and the waste liquid from the outlet of the rear-end adapter.
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| WO2016170952A1 (en) * | 2015-04-21 | 2016-10-27 | 日東電工株式会社 | Self-repairing electrical insulation resin composition and electrical wire using same |
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