CN115286998B - Conductive repair liquid for ablation fault of cable buffer layer and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the technical field of cable buffer layer repair, and discloses a conductive repair liquid for ablation faults of a cable buffer layer, and a preparation method and application thereof. The invention adopts bi-component AB addition type silica gel as a base material of the repair liquid, fills proper nano conductive filler, and uniformly disperses the nano conductive filler in the repair liquid of the curing agent B in a high-speed stirring and super dispersion technology mode. This can reduce the bulk material volume resistivity. And reacting the prepared solution B with the prepared solution A in a proper proportion, and curing to form a conductive shielding repair liquid layer with stable chemical properties. The repair liquid is injected into the cable with the buffer layer defect, so that the release amount of the cable under the laboratory condition can be reduced. After the cables containing white spot defects are injected, the release amount of the defective cables can be 1.5U ₀ (U ₀ =64 kV) was decreased by 20pC.

Description

Conductive repair liquid for ablation fault of cable buffer layer and preparation method and application thereof

Technical Field

The invention belongs to the technical field of cable buffer layer repair, and particularly relates to a conductive repair liquid for ablation faults of a cable buffer layer, and a preparation method and application thereof.

Background

In recent years, a large number of domestic high-voltage XLPE (cross-linked polyethylene) cables have suffered from bulk failures, which are mainly manifested as large-area "spark-over" between the metal sheath and the outer semiconducting layer. Unlike the conventional cable fault (i.e. occurring at the cable accessories or main insulation) discharge of 110kV and above, such large-area discharge is concentrated between the cable metal sheath and the insulation shielding layer, and the discharge point position of the buffer layer region is schematically shown in fig. 1. A large number of ablation points exist on the insulation shielding layer, some ablation points even damage the main insulation, and the ablation defect of the buffer layer causes great trouble for cable operation and maintenance personnel.

It is reported that cable failure caused by ablation of the cable buffer layer accounts for about 30-60% of the failure of the high-voltage cable body. By 2018, the total length of the high-voltage cables of 110kV and above of national grid companies is 14423, the total length is almost thirty kilometers, if most of the cables have the defect of ablation of a buffer layer, on one hand, the cost for replacing the cables is too high, and on the other hand, a large number of hidden danger defective cables cannot be replaced immediately, so that a large number of cables can be operated in a 'sick' manner, and great risk is brought to the safe operation of a power grid.

In the polymer field, because of having good conductivity and stable chemical properties, the liquid conductive silicone rubber is widely applied to the fields of electromagnetic shielding, wave absorption, sensing and the like, and the presently disclosed preparation method of the conductive silicone rubber specifically discloses a preparation method of the conductive silicone rubber, which comprises vinyl silicone oil, a platinum catalyst, hydrogen-containing silicone oil, an inhibitor, conductive carbon black, conductive carbon fibers, a tackifier, a dispersant, fumed silica and a volatile solvent, and the obtained conductive silicone rubber has good conductivity and mechanical properties.

The reason for the ablation of the cable buffer layer is that the cable enters water to cause the non-conductive white spots on the contact surface between the buffer layer and the aluminum sheath, so that the buffer layer and the aluminum sheath cannot be well electrically connected. However, the prior art has the following defects:

1. no corresponding improvement of compatibility is carried out aiming at the internal operating environment of the cable body, if the conductive silicon rubber is injected into the cable body, other serious results (generation of corrosion products is accelerated, or the cable body is punctured due to water trees and the like) are probably caused;

2. the thermal conductivity of the internal structure of the cable body is not improved, and the air gap between the metal sheath and the buffer layer of most defective cables is large (the schematic diagram of the air gap layer of the high-voltage cable is shown in fig. 2), so that the thermal conductivity of the repair liquid itself needs to be considered;

3. similar documents disclosed so far are all directed to accessories of cables with the voltage class of 35kV and below, and do not have materials developed for high-voltage (110 kV) cable bodies, nor do they have related improvements for reducing the partial discharge of the cable bodies.

Disclosure of Invention

In order to overcome the defects and shortcomings of the prior art, the invention mainly aims to provide a conductive repair liquid for ablation faults of a cable buffer layer.

The invention also aims to provide a preparation method of the conductive repair liquid for the ablation fault of the cable buffer layer.

The invention further aims to provide application of the conductive repair liquid for the cable buffer layer ablation fault in repairing the cable buffer layer.

The purpose of the invention is realized by the following scheme:

a conductive repair liquid for ablation faults of a cable buffer layer comprises an A component and a B component which are 3:7-7:3 (preferably 1:1) in mass ratio, wherein the A component comprises the following raw materials in parts by mass:

the component B comprises the following raw materials in parts by mass:

the vinyl silicone oil is at least one of vinyl-terminated polydimethylsiloxane and vinyl-terminated polymethylvinylsiloxane.

The conductive filler is a blend of nano copper silicide and at least one of nano conductive filler carbon nanotube, graphene and carbon black, wherein the mass ratio of the nano copper silicide to the at least one of carbon nanotube, graphene and carbon black is 6:1-100, and preferably is 20;

more preferably, the conductive filler is a blend of carbon nanotubes and nano copper silicide with a mass ratio of 25:1, wherein the carbon nanotubes are selected from SCC-8 produced by Jiaxing new nano material Co., ltd, the nano copper silicide is selected from Cuke produced by Zhongke, and the mixing of the nano copper silicide and the carbon nanotube powder not only improves the conductivity of the carbon nanotubes, but also can prevent the agglomeration phenomenon of the carbon nanotube powder.

The catalyst is a platinum compound, preferably chloroplatinic acid.

The surfactant is at least one of fatty glyceride, polyhydric alcohol and triethanolamine.

The waterproof emulsion is vinyl acetate-ethylene copolymer emulsion, preferably with pH of 7 and viscosity of not more than 600mpa.s at 25 ℃. The addition of the water-proof emulsion can neutralize the penetration of water vapor in the air.

The addition of the nano boron nitride can effectively improve the thermal conductivity of the cured silica gel and improve the strength of the cured silica gel.

The hydrogen-containing silicone oil is at least one of methyl siloxane, ethyl siloxane and methyl phenyl siloxane. The hydrogen-containing silicone oil used preferably has a viscosity of 1000 to 3000.

The thickening agent is acrylic acid, preferably anionic acrylic acid. The thickening agent is added into the component B to adjust the viscosity of the liquid, so that the viscosity of the component B is similar to that of the component A after the conductive filler is added.

The defoaming agent is selected from one of non-silicon type, polyether type, organic silicon type and polyether modified organic silicon type.

The preparation method of the conductive repair liquid for the ablation fault of the cable buffer layer comprises the following steps:

(1) Adding the raw materials of the component A into a stirrer with a heat and pressure reduction system, and uniformly stirring and mixing to obtain a component A;

(2) Adding the raw materials of the component B into a stirrer with a heat and pressure reduction system, and uniformly stirring and mixing to obtain a component B;

(3) When in use, the component A and the component B are mixed according to the mass ratio and are solidified.

The stirring and mixing in the step (1) refers to stirring for 1-3 hours at 50-70 ℃ under reduced pressure;

the stirring and mixing in the step (2) means stirring at 50 to 70 ℃ under reduced pressure for 1 to 3 hours.

The conductive repairing liquid can be cured at room temperature and can be cured by heating, the higher the temperature is, the faster the curing is, and the conductive repairing liquid does not generate any by-product in the curing reaction.

The preparation method does not add water in any step. If moisture is introduced into the cable, under the combined action of electricity and heat during long-time operation of the cable, a water tree defect occurs on an insulating layer of the cable, and the defect can cause the electric field concentration on the surface of the insulating layer, so that the performance of the insulating layer can be directly damaged in severe cases, and the cable is punctured. The influence of water on the effect of the invention is minimized by strict control in the preparation process and addition of the waterproof emulsion.

The conductive repair liquid for the cable buffer layer ablation fault is applied to the cable buffer layer repair. In particular for the repair of cable buffer layers for high voltage (110 kV) cables.

The invention adopts bi-component AB addition type silica gel as a base material of the repair liquid, fills proper nano conductive filler, and uniformly disperses the nano conductive filler in the repair liquid of the curing agent B in a high-speed stirring and super dispersion technology mode. This can reduce the bulk material volume resistivity. And reacting the prepared solution B with the prepared solution A in a proper proportion, and curing to form a conductive shielding repair liquid layer with stable chemical properties. The reaction mechanism of A, B liquid is as follows: under the action of Pt catalyst, vinyl silicone oil and hydrogen-containing silicone oil produce hydrosilylation reaction to form cross-linked macromolecule. After the repair liquid permeates into the buffer layer, the potential difference caused by corrosion products can be reduced, and the risk of partial discharge is reduced.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) The introduction of moisture can cause deterioration of the electrical properties of the buffer layer and the insulation layer in the cable body. The reliability of the cable body in operation is deteriorated. Therefore, no water is added in the preparation process, and the compatibility of the conductive repairing liquid and the cable body (particularly the compatibility of the conductive silicon rubber, the cable buffer layer and the aluminum sheath) can be enhanced.

(2) The cured conductive silicone rubber has good dispersibility, and the equivalent resistance between the buffer layer and the aluminum sheath can be effectively reduced after the defect cable is injected.

(3) The nano filling material can effectively reduce the thermal resistance of the repair liquid, and the current-carrying capacity of the cable can be improved after the repair liquid is injected into the cable body. From the perspective of economy and heat conductivity, 0.1-0.5 parts of nano copper silicide and 2-3 parts of boron nitride are added.

(4) The pH value of the repair liquid material is controlled to be 7, so that corrosion to the cable aluminum sheath and the buffer layer in an alkaline or acidic environment is prevented, and good compatibility between the repair liquid and the cable body is ensured;

(5) The repair liquid is injected into the cable with the buffer layer defect, so that the release amount of the cable under the laboratory condition can be reduced. After the cables containing white spots are injected, the release amount of the defective cables can be kept at 1.5U ₀ (U ₀ =64 kV) was decreased by 20pC.

Drawings

FIG. 1 is a schematic diagram of a discharge point position in a buffer layer region.

Fig. 2 is a schematic view of an air gap layer of a high-voltage cable.

Fig. 3 is a schematic diagram of wiring and layout in the partial discharge test.

Fig. 4 is a diagram of a partial discharge signal before repair of a defective cable.

Fig. 5 is a diagram of a partial discharge signal after repair of a defective cable.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the embodiments of the present invention are not limited thereto. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

In the embodiment, the vinyl silicone oil is Shandong Xinglong Da 5846; the conductive filler is a mixture of a carbon nano tube and nano copper silicide mixed according to the mass ratio of 25 to 1, wherein the carbon nano tube is selected from SCC-8 produced by Jiaxing nano new material company Limited; the catalyst is a platinum catalyst produced by Shanghai Aladdin Biotechnology GmbH; the surfactant is triethanolamine produced by Shanghai Aladdin Biotechnology Limited; the waterproof emulsion is Achima ENCOR 5132; the nano copper silicide is produced by adopting the Chinese science excellent; the nanometer boron nitride is produced by Guangzhou Hongwu new material company; the hydrogen-containing silicone oil adopts Zhejiang Jiashan JF-201 silicone oil with the viscosity of 2000; the defoamer selects and uses the chemical PLX-4060 of Bo Te of Quzhou city; viscoat 46 thickener was used as the thickener, and was neutralized with aqueous ammonia to pH =7 before use.

In the examples, parts are by mass.

Examples

Adding 91.2 parts of vinyl silicone oil, 3 parts of conductive filler, 1 part of catalyst, 1 part of surfactant, 1.5 parts of waterproof emulsion, 0.3 part of nano copper silicide and 2 parts of boron nitride into a stirrer with a heating and pressure reducing system, heating to 60 ℃, and stirring under reduced pressure for 1 hour to obtain the component A.

According to requirements, 73.7 parts of vinyl silicone oil, 25 parts of hydrogen-containing silicone oil, 0.3 part of defoaming agent and 1 part of thickening agent are heated to 60 ℃ and stirred under reduced pressure for 1 hour to prepare the component B.

When used, the components A, B were mixed at the mass ratio shown in table 1 and cured.

The product can be cured at room temperature and also can be cured by heating, has the characteristic of faster curing at higher temperature, and does not generate any by-product in the curing reaction.

The following table 1 shows the measurement data of various performance indexes.

TABLE 1 measurement data of Performance indicators at different ratios

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Table 2 measurement data of various performance indexes in example 3

The component A and the component B prepared in the embodiment 3 are fully stirred and mixed according to the proportion, and then the mixture is injected into the high-voltage cable with the defect buffer layer, so that the cable laying amount can be effectively reduced. Partial discharge signal test 1.5U of record is carried out according to GB/T11017.1-2014 partial discharge test standard ₀ And (5) a corresponding partial discharge signal is sent down. The background noise of the test site was about 1.22pC, the center frequency of the partial discharge signal filter was set to 205kHz, and the bandwidth of the partial discharge signal filter was 350kHz. Fig. 3 is a schematic of the wiring and layout of the test. Fig. 4 partial discharge measurement diagram before cable repair, where PD:21.97pC HV:96.38kV. Fig. 5 is a partial discharge measurement diagram after cable repair, where PD:1.12pC HV:96.07kV. Namely, after the cables containing white spots are injected, the release amount of the defective cables can be kept at 1.5U ₀ (U ₀ =64 kV) was decreased by 20pC.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such modifications are intended to be included in the scope of the present invention.

Claims (7)

1. A conductive repair liquid for ablation faults of a cable buffer layer is characterized by comprising an A component and a B component which have the mass ratio of 5:5-7:3, wherein,

the component A comprises the following raw materials in parts by mass:

78 to 95.5 portions of vinyl silicone oil;

3 to 10 parts of conductive filler;

1 to 10 parts of a catalyst;

0.5-2 parts of a surfactant;

0.5-2 parts of waterproof emulsion;

0.1-0.5 parts of nano copper silicide;

2-3 parts of boron nitride;

the component B comprises the following raw materials in parts by mass:

44.5 to 78.9 parts of vinyl silicone oil;

20 to 50 parts of hydrogen-containing silicone oil;

1-5 parts of a thickening agent;

0.1-0.5 part of defoaming agent;

the conductive filler is a blend of nano copper silicide and at least one of nano conductive filler carbon nano tube, graphene and carbon black; the mass ratio of at least one of the nano conductive filler carbon nano tube, the graphene and the carbon black to the nano copper silicide is 20:1-30:1;

the waterproof emulsion is vinyl acetate-ethylene copolymer emulsion with pH of 7 and viscosity of not more than 600mpa.s at 25 ℃.

2. The conductive repair liquid for cable buffer layer ablation failure according to claim 1, characterized in that:

the vinyl silicone oil is at least one of vinyl-terminated polydimethylsiloxane and vinyl-terminated polymethylvinylsiloxane.

3. The conductive repair fluid for cable buffer layer ablation failure according to claim 1, characterized in that:

the hydrogen-containing silicone oil is at least one of methyl siloxane, ethyl siloxane and methyl phenyl siloxane;

the catalyst is a platinum compound.

4. The conductive repair liquid for cable buffer layer ablation failure according to claim 1, characterized in that:

the surfactant is at least one of fatty glyceride, polyhydric alcohol and triethanolamine;

the thickening agent is an acrylic thickening agent;

the defoaming agent is selected from one of non-silicon type, polyether type, organic silicon type and polyether modified organic silicon type.

5. A preparation method of the conductive repair liquid for the cable buffer layer ablation fault according to any one of claims 1 to 4, characterized by comprising the following steps:

(1) Adding the raw materials of the component A into a stirrer with a heat and pressure reduction system, and uniformly stirring and mixing to obtain a component A;

(2) Adding the raw materials of the component B into a stirrer with a heat and pressure reduction system, and uniformly stirring and mixing to obtain a component B;

(3) When in use, the component A and the component B are mixed according to the mass ratio and are solidified.

6. The preparation method of the conductive repairing liquid for the cable buffer layer ablation fault, according to claim 5, is characterized in that:

the stirring and mixing in the step (1) refers to stirring for 1-3 hours at 50-70 ℃ under reduced pressure;

the stirring and mixing in the step (2) means stirring at 50 to 70 ℃ under reduced pressure for 1 to 3 hours.

7. Use of the conductive repair liquid for cable buffer ablation failure according to any one of claims 1 to 4 in cable buffer repair.

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