Organic-silicon electric-insulating water-proof composition for high-voltage insulators
SUBSTANCE: organic-silicon electric-insulating water-proof composition for high-voltage insulators as silicone low-molecular rubber contains rubber of SKTN grade, as low-molecular organic-silicon fluid - organic-silicon fluid of 119-215 grade, as hardener - methyl triacetoxysilan. Per each 100.0 weight parts of rubber this composition contains low-molecular organic-silicon fluid (1.25-2.5) weight parts, aluminium hydrate (5-15.0) weight parts, acetylene black (0.5-2.5) weight parts and hardener (2.5-6.5) weight parts.
EFFECT: improving reliability and increasing service life of cured in coating of electric-insulating construction based on water-proof electric-insulating composition by determining optimum compound and ratio of water-proof composition components.
3 cl, 4 tbl
The invention relates to hydrophobic organosilicon compositions intended for insulating structures, such as high voltage insulators, and can be used to enhance blagorazumnogo voltage and increasing the electric strength of external insulation, working in conditions of pollution.
Known electrically insulating hydrophobic composition in the form of silicone pastes applied to the surface of the insulating structures and used to improve blagorazumnyi voltage high-voltage insulation [Kim Yong-Boon, P.E. Ponomarev. Operating experience of the silicone coating of cold hardening on the substations of the power systems of Ukraine//Electrical networks and systems. - 2006. No. 3. - P.32-35].
A disadvantage of known composition in the form of hydrophobic pastes is that during operation hydrophobic paste layer is saturated with pollutants and loses its hydrophobic properties, which results in low values withstand operating voltages, as well as the need for periodic replacement of the insulating structure.
How similar is selected hydrophobic insulating composition in the form of silicone elastomers that form on the surface of the solid insulator protective film [Ravi S.G. RTV Silicone Rubber Coatings or Ceramic Insulators: Present Knowledge and Future Requirements // 2001 Insulator World Congress, Shanghai, China, November 18-21 - Shanghai. - 2001. - P.361-368].
The disadvantage of the composition of the analogue is not a high performance properties and lifetime of damage on the basis of the hydrophobic coating, which results in low values withstand operating voltages, as well as the need for periodic replacement of the insulating structure.
As the closest analogue (prototype) of the selected insulating hydrophobic composition based on silicone compound (COCS) cold hardening with a solid filler in the form of titanium dioxide and a hydroxide of aluminum, and with a liquid filler in the form of low molecular weight silicone fluids, and organic solvent grade "oil Solvent". Thus the weight ratio between the compound and the low molecular weight silicone fluid is 1:(0,015-0,02), and the weight ratio between the compound and the hydrate of aluminum oxide is 1:(0,07-0,1) [Method of increasing blagorazumnogo high-voltage isolation. Patent UA №77628. IASC (2006) H01B 17/50 (2006.01) H01B 19/00, publ. 15.12.2006, bull. No. 12].
The disadvantages of the composition closest analogue are not high maintenance (electrical insulating) properties and lifetime of damage on the basis of hydrophobic coatings (SE) due to the lack of optimal composition of sootnoshenia components of the composition, the consequences of which are not high enough values withstand operating voltages, as well as the need for periodic replacement of the insulating structure.
An object of the invention is to improve the reliability and longer service life vulcanized coating insulating structure based on the hydrophobic insulating composition by establishing the optimal composition and component ratio of the hydrophobic composition that will also lead to higher blagorazumnyi voltage high-voltage insulation throughout the long period of its use.
The technical problem is solved by the fact that in the silicone insulating hydrophobic composition for high-voltage insulators on the basis of one or dvuhpilonnogo organosilicon compound cold-curing, liquid or pasty in the initial state, containing low-molecular silicone rubber, solid filler in the form of a hydrate of aluminum oxide, liquid filler in the form of low molecular weight silicone fluid, a hardener or catalyst, and an organic solvent as the solvent of the brand "oil solvent", what's new is that as the low-molecular silicone rubber composition comprises the couch is brand SCTN, as a low molecular weight silicone fluid composition contains a silicone fluid brand 119-215, as a solid filler composition further comprises carbon black acetylene, as a hardener composition contains methyltriacetoxysilane, and 100.0 parts by weight of rubber composition contains a low molecular weight silicone fluid in number (1,25-2,5) parts by weight of the hydrate of aluminum oxide in the amount of (5-15,0) parts by weight, acetylene soot in the amount of (0,5-2,5) parts by weight and the curing agent in the amount of (2,5-6,5) parts by weight of
The weight ratio between the polyurethane resin and an organic solvent in the composition at a 100.0 parts by weight of rubber varies depending on the ambient temperature and is (0,85-1,0) parts by weight at ambient temperatures up to 25°C, and (of 1.05 to 1.4) parts by weight when the ambient temperature is over 25°C.
Vulcanized coating on its basis is characterized by the following electrical properties: specific volume resistance ρνnot less than 3×1014Ohm×cm surface resistivity ρsnot less than 1.0×1015Ω, the tangent of dielectric loss angle tgδ, not more than 0,008, as well as the possibility of operation at operating voltages 6-750 kV.
These conditions constitute the essence of the invention.
The causal St. the bond between the set of essential features of the invention and achievable technical result is the following.
The various States of the environment on the outer surface of the high-voltage insulation layers are formed of different pollution intensity. Settling out of the air particles build up over time on the surface of the insulator layer pollution. This layer when moisture atmospheric moisture increases its conductivity, which further reduces the insulating ability of the insulation structures. This creates conditions for flashover of insulators not only when the overvoltage, but under normal operational mode.
Therefore, to improve the reliability of high-voltage insulation in polluted areas is an urgent task of strengthening the outer insulation to ensure the highest bit of stress in adverse conditions. The solution to this problem is the use of silicone SE-based COCS.
It was found that silicone SE is most appropriate to apply in areas where pollution in the atmosphere are mainly gaseous and fog-like components. At the same time, the main technical problem is the choice of the optimal proportions of the components of the applied hydrophobic insulating composition. This, in turn, should provide the highest possible bit values of stresses at such elec is reisolation structures in terms of pollution of various degrees and moisture.
One should dwell on the rationale for the optimization of the hydrophobic insulating composition.
It is known that odnoupakovochnye compositions consist, as a rule, polymer with silanol groups and taken in excess with respect to silanol groups methyltriacetoxysilane, which is well soluble in the polymer. This pre-prepared in the absence of water, the mixture is relatively stable in dry environments, and the process of structuring it occurs only under the influence of moisture in the air. That is, odnoupakovochnye hydrophobic composition can be used only on air for relatively thin coatings.
The disadvantages of such compositions include the inability to apply them in a confined space, in systems with limited access of air, to obtain a thick-walled products, as well as the allocation during curing carboxylic acid.
In the process of curing compositions formed film of cross-linked polymer, which hinders the diffusion of moisture air in the polymer mass, which affects the characteristics of the cured material. Dilution of odnoupakovochnye compositions solvents allows you to adjust the viscosity of the mixture, to slow down the polymerization in its entirety and get on the surface of insulators method of spraying a uniform coating of the desired thickness.
As Hydra is tobitatsu the outer insulation is in most cases carried out at existing facilities, that is, in the field, the process of preparing a hydrophobic composition should be as simple and at the same time provide with sufficient accuracy the ratio of the components (i.e., the optimal composition is determined by examining the optimality of the resulting operational properties utverzhdenii composition).
Studies have shown that with the introduction of a composition component (substance) to improve one of the characteristics of the obtained polymer coating can deteriorate the performance of his other characteristics. In this regard, the optimization of the composition is a complex task, the complexity of which depends on the number of components included in the coating composition. She is the definition of the parameter optimization and affecting factors, the choice of model and experiment plan testing, the analysis of the results and decision making. Parameter optimization should be universal and effective from the point of view of the description of the final result, to be a quantitative value, which has a physical meaning. This should be fairly easily measured or calculated.
The main properties of polymer coatings on the basis of insulating compositions intended for the reduction of the service or enhance blagorazumnyi characteristics of the outer insulation, is its hydrophobicity. Hydrophobic properties of the vulcanized coating directly characterized by the value of the wetting angle of the surface α. However, the measurement of α characterizes the hydrophobicity at small surface area, so determining the average hydrophobicity of the whole object rather time-consuming task. However, studies have shown that hydrophobicity is directly related to the change in the wetting of the surface coverage of a number of physical (electrical insulating) properties.
When wetting the actual insulation constructions (insulators) coated depending on the hydrophobicity of the past (and still in operation and pollution) reduced surface resistivity ρsand increases the leakage current Iut. In addition, it is known that for the detection of defects in the insulation (dielectric materials) in some cases, measurement of the tangent of dielectric loss angle tgδ.
Siloxane coatings of cold hardening can be in the form of a layer of polymer material, within which there are many air pockets, formed by evaporation of the solvent. The volume of these inclusions are much less than the volume of polymeric material. When humidification portion inclusions near the surface are filled with water.
PQS is LCU distribution and orientation of pores and voids in the coating, filled with moisture, can greatly fluctuate under the influence of such factors as the mode of coating application, environmental conditions, etc. when the same amount of water uptake values of dielectric permittivity ε samples of the same material can vary considerably. In addition, changes to the e of the samples with moisture less significant than tgδ, and for their determination requires accurate measurement of the coating thickness, which imposes special requirements to measuring instruments and quality samples.
Thus, to ensure the effective conduct of operations in the field composition designed to produce a hydrophobic coating of cold hardening, should be primarily resistant to the possible ingress of impurities and possess vitality, providing work in a wide range of temperatures. Therefore, we can conclude that the best basis for applying silicone hydrophobic coating of cold hardening, in spite of the limitations, is still tropicabana composition (compound).
Well-known currently, compounds of this type include "Sylgard"(USA), KLT-30A (Russia), RPC-102 (Ukraine). The dielectric characteristics of the sample coatings (solid is limernyh films), obtained by condensation of these compounds are shown in table 1.
|Dielectric characteristics of hydrophobic coatings obtained on the basis of single-component compounds of cold hardening|
|Composition||The specific volume resistance ρν, Ohm×cm||Surface resistivity ρsOhms||The tangent of dielectric loss tgδ||The relative dielectric permittivity, ε|
|"Sylgard"||2,03×1014||of 1.2×1015||0,0029||is 3.08|
|RPC 102||4,63×1014||of 1.9×1015||0,0020||1,88|
Since the optimized object is hydrophobic silicone coating is cold-curing, the main factors influencing the process of its formation and define its properties, are components included in the composition, and their number.
Select the desired components was due to both their advantages and their disadvantages from the point of view of electrical properties and processability of the obtained composition (see table 2).
From the above table it follows that one of these components for further consideration as optimizing factors it is advisable to investigate the following:
|Advantages and disadvantages of substances introduced into the composition of a hydrophobic composition|
|Carbon black (C)||Getting painted coating, the formation of additional bonds (increasing the mechanical strength and colonoscopist)||Reduced arcing and ρνincrease tgδ and ε|
|Titanium dioxide (TiO2)||Increases resistance to arcing||At Loznitsa the process of making the composition. With equal dielectric characteristics, to increase durastanti much lower than the hydrate of aluminum oxide|
|Iron oxide (II) (FeO)||Increases resistance to arcing. Getting painted coating, the formation of additional bonds (increasing the mechanical strength and colonoscopist)||Decreasing ρνincrease tgδ and ε. With equal dielectric characteristics, to increase durastanti inferior to the hydrate of aluminum oxide|
|Aluminum oxide (Al2O3)||Increases resistance to arcing||Decreasing ρvincrease tg δ and ε|
|The hydrate of aluminum oxide A1 g (Al2O3×3H2O)||Increases resistance to arcing. In comparison with aluminum oxide at equal durastanti coating has better dielectric characteristics||Decreasing ρvincrease tgδ and ε|
|Low molecular weight organic silicon liquid 119-215 (K)||Increases the rate of recovery of hydrophobicity after exposure to corona discharge. Reduced water absorption. Improve dial kricheskii features||Reduced arcing. When the content is 10% or more of the compound significantly slows down the polymerization of coating|
|Silicone fluid PMS-100||Reduced water absorption. Improved dielectric characteristics. Possible partial replacement used when applying easy-flammable liquids (solvents)||Reduced arcing (especially when the content is more than 5% by weight of the compound). Inferior liquid 119-215 speed recovery of hydrophobicity after exposure to corona discharge|
1. The hydrate of aluminum oxide (the main purpose to increase durastanti).
2. Iron oxide (II) (increase durastanti and colonoscopist).
3. Low molecular weight silicone fluid 119-215 (increase the speed of recovery of hydrophobicity after exposure to corona, reduced water absorption).
4. Carbon black is acetylene (staining of the coating, increasing colonoscopist).
The main purpose of the hydrate of aluminum oxide and iron oxide (II) in the composition is the same.
The properties (primarily dielectric), no doubt influenced by the environmental conditions during coating (temperature and relative humidity), elm is the outer coat of the composition and the amount of applied per unit area (indicates the thickness of the coating).
In accordance with the decision on the metal samples (5 specimens of 100 mm diameter for measuring dielectric properties and water absorption, and 5 rectangular samples of 70 mm×35 mm to determine durastanti) spray application method were applied following water composition (here KOK abbreviated marked organosilicon compound, numbers (100)% of the content in KOC):
composition No. 1: KOK (100)+FeO(26)+K(1)+s(0);
composition No. 2: KOK (100)+Alg(5)+(1,25)+C(1);
composition No. 3: KOK (100)+FeO(14)+K(1)+C(4);
composition No. 4: KOK (100)+Alg(13)+K(1,5)+C(2,5);
composition No. 5: KOK (100)+FeO(26)+K(3,5)+C(3);
composition No. 6: KOK (100)+Alg(7)+(5)+C(4);
composition No. 7: KOK (100)+FeO(14)+(3,0)+(1);
composition No. 8: KOK (100)+Alg(20)+(5)+(5);
composition No. 9: KOK (100)+Alg(11)+(2,0)+s(0.5);
composition No. 10: KOK (100)+Alg(10)+K(2,5)+C(3,5);
composition No. 11: KOK (100)+Alg(18)+(4)+(5);
composition No. 12 (control): KOK (100)+C(1).
After determining the thickness of coatings obtained on all samples was carried out rejection: if the average thickness was less than 150 μm or values of the confidence interval were more than 10% of the average value, then the sample was excluded from testing. The averaged characteristics of the hydrophobic coating compositions No. 1 to 8 are shown in table 3.
|The averaged characteristics of the hydrophobic coating compositions No. 1-8|
|composition||characteristics in the initial state||after 24 h of hydration in distilled water||increment Δtgδ||the arcing|
|ρν, Ohm×cm||tgδ||ε||ρν, Ohm×cm||tgδ||ε|
|No. 1||4.26 deaths×1014||0,0045||3,19||to 2.29×1014||0,0106||3,25||0,0061||-|
|No. 3||3,55×1014||0,0059||3,09||to 2.41×1014||0,0113||3,20||0,0052||to 83.5|
|No. 5||10,14×1014||0,0056||3,03||of 5.06×1014||0,0111||3,21||0,0055||12,5|
|No. 7||of 2.72×1014||0,0036||2,87||1,80×1014||0,0085||2,93||0,0049||36,2|
|No. 8||to 3.41×1014||0,0083||2,49||the 2.46×1014||0,0206||2,80||0,0123||449,2|
During the test for each sample was carried out: external examination and determination of dielectric parameters (ρν, tgδ, ε) with a frequency of 1 time per day during the initial period of the test (up to 4 days) and 1 every 2-3 days thereafter. According to the results of visual observation of the surface condition of the samples was noted the following:
1) after 2 days from the start of the trials the appearance of visible changes of the surface coating on the effects of corona discharge;
2) after 8 days the appearance of darkening the surface (about 50% of the area) at a distance of 4 mm from the edge of the high voltage electrodes and the emergence of signs of the influence of corona discharge (faint rosy hue when observed at an acute angle) at a distance of 7 mm from the edge of the electrodes;
3) for the period through 11-17 days - increased darkening of the surface (100% area) at a distance of 5 mm from the edge of the high voltage electrodes and the distribution after the economical impact (low iridescent shade) to a distance of 8 mm from the edge of the electrodes;
4) after 29 days - increased darkening of the surface and the expansion of this area to a distance of 6 mm from the edge of the electrodes;
5) over the entire period from 31 to 60 days (end of test) - the size of the areas with a visible change in the surface condition remained almost unchanged: the darkened area of the surface was in the form of rings with diameters of 26 mm and 12 mm, and traces from exposure to corona discharge was noted at a distance of 9 mm from the edge of the electrodes.
Throughout the test period ρν, tgδ and ε test pieces were changed slightly. All obtained values were in the range of possible deviations due to the uneven thickness of the samples and variations in the ambient temperature during measurement. Changes in surface conditions in the area affected by the corona discharge indicate the processes of destruction of polymer material.
It was found that after 10 or more days after the start of testing these processes are beginning to stabilize, and the rate of destruction of the coatings with soot content of 3.5-5% (compositions No. 10 and No. 11) is less than that of coatings containing 0.5% and 1% (formulations # 9 and # 12).
Proceeding from the obtained results we can draw the following conclusions:
1) samples of organosilicon compositions with increased to 3.5-5% soot content (compositions No. 10 and 11) are more stable the part to the effects of corona discharge of long duration; the optimal content of carbon black is 0.5 to 2.5%;
2) the increase in the content of carbon black is not lowered water-repellent properties, determined by the increase in mass after hydration in distilled water;
3) samples containing 1,25-2,5% low molecular weight silicone fluids 119-215, by their hydrophobic properties (moisture absorption) are only slightly inferior to samples containing 3.5-4% low molecular weight silicone fluids 119-215.
4) In order to increase tregimeerotike resistance of the coating as antipyrine in its composition is administered and the hydrate of aluminum oxide (A1G. He has a greater solubility in the Solvent oil than titanium dioxide, which greatly facilitates the preparation of water-repelling compositions in "field conditions" (directly on the site of waterproofing).
The presence of chemically bound water allows part of the molecules of the hydrate of aluminum oxide to participate in the polymerization KOK-component cold curing. This increases the rate of polymerization, and some of the aluminum atoms is included in the structure of the polymer chains, which increases their resistance to thermal degradation. In turn, the increase in the number of hydrate of aluminum oxide increases democractically coverage. But this reduces much of the second volume resistivity and increases the tangent of dielectric loss angle, measured on the sample after 24 hours of hydration in distilled water.
5) Increase the proportion of low molecular weight silicone fluids 119-215 (more than 2.5%, i.e. up to 3-5% or more by weight COCS), as shown by the experiments, slows down the polymerization processes. As a result, the surface coating may long remain sticky and particles contaminated particles that fell during this time, saturate the surface layer, reducing its dielectric characteristics.
KOK ensures the formation of a mechanically stable coatings, and low molecular weight silicone fluid 119-215 fills the free spaces formed during solidification, preventing the penetration of water molecules and ions of salts as a result of their diffusion from the environment. This reduces the moisture permeability and water absorption of the coating increases its resistance to surface leakage currents and partial discharges.
After a comprehensive analysis of all the data about the changing characteristics of the test samples (α, ρv, tg δ, ε), together with the available information on the mechanisms of oxidation of organic polymers, it was concluded that the proposed mechanism of physical-chemical "destruction" hydrophobic coatings studied type includes the following steps:
Stage # 1. The oxidation of a metal of groups active the mi atoms of oxygen:
Chemical interaction takes place with a slight increase in mass. Group - OH formed on the surface, easily form hydrogen bonds with water molecules and with the increase in the number of these groups, the surface becomes hydrophilic properties (sharp drop hydrophobic properties after short-term exposure to corona discharge).
Stage # 2. The increase in the "structuring" of the surface is the formation of new Si-O links ("links"):
This chemical interaction takes place with decreasing mass. The result: compacted surface layer is hindered diffusion of oxygen into the coating. The decrease in the number of groups IT on the surface of the coating contributes to the restoration of hydrophobic properties.
Stage # 3. Destruction at both ends of the siloxane chains with the formation of low-molecular siloxanes:
Chemical reactions of this type are no mass change. In the "output" on the surface of low molecular weight siloxanes are recovered hydrophobic properties (increasing the angle of spacian the I surface in the impact zone of corona discharge, as well as the emergence of a rosy hue on the surface of the coating).
Stage # 4. Oxidative degradation:
Chemical transformation takes place with a slight increase in mass. As a result of such processes is the accumulation of silicon dioxide on the surface of the coating (decrease Shine and smoothness of the surface and the appearance of dark hours).
It should be noted that the chemical reaction of step 1 is the "initiator" of the reaction stages # 2 and # 3. When prolonged exposure to corona discharge these reactions (reduction and increasing mass) occur simultaneously, resulting in the destruction mechanism of silicone coating has a very complex character.
Since the results of visual inspection on samples not detected geometric "growth" area of influence of corona discharge, it is possible to make the following assumptions:
- all tested coatings (compositions No. 9 to 12) have coronopifolia sufficient for their successful application for at least 5 years in the insulation of existing high-voltage lines and substations;
- temporary loss of hydrophobicity on separate parts of the surface due to the impact of the crown will not cause a significant reduction blagorazumnyi characteristics of hydrophobizing the data of the insulator as a whole.
The effectiveness of this technical solution is confirmed by the results of comparative tests on the samples and on the real insulators. The samples were tested in the chamber of the fog in continuous flow surface leakage current characteristic of the operation (4-5 mA), and the insulators in the cell salt fog when exposed to the operating voltage and surface partial discharges.
As follows from the results of tests on samples and insulators, the hydrophobic coating " KOK+low molecular weight silicone fluid has a significantly better performance than the well-known floor. The optimum weight ratio between KOC and low molecular weight silicone fluid is 1:(0,0125-0,025).
The composition may be applied to the surface of the insulation spray (mechanized), by immersing the processed product in the composition or brush. To provide the necessary viscosity of the composition when applied mechanically using the device type of spray gun are encouraged to use the solvent-Solvent oil". After application to the surface, the solvent evaporates, without affecting the electrical characteristics of the coating.
The optimum weight ratio between KOC and the hydrate of aluminum oxide for maximum increased the E. mesocestoides, while maintaining the dielectric characteristics of the coating to the relevant regulations of silicone rubber (TU 3.72-00216473-028-2001)is 1:(0.05 to 0.15) by weight of the compound.
In the developed method, the curing KOK is carried out using a catalyst (hardener) methyltriacetoxysilane or To US at room temperature in the presence of moisture in the air. This is because the catalyst-To-10C (methyltriacetoxysilane) has an acidic reaction, because when in contact with moisture in the air it rapidly hydrolyzed with the formation of acetic acid. It is in large quantities is released during the curing of the rubber SCTN the addition of hydrogen atoms of hydroxyl groups of the rubber to the acidic residues of the catalytic Converter.
Vulcanization takes place only in the presence of moisture in the air. If this occurs before the hydrolysis of the acetate groups and then condensation of molecules with crosslinking agents containing three functional groups, resulting in increased molecular weight. Released acetic acid, having a characteristic odor, evaporates from the system.
Aggressive concentrated acetic acid, as shown by tests, causes corrosion damage of carbon steel. Acid secretion is accompanied by shrinkage of the water-repellent. Shrinkage of water-repellent, KORRO the Oia steel are the main causes of insufficient adhesive strength of the connection surface konstruktivnih elements insulator with a wetting agent, resulting in breaking of water-repellent surface of the insulator and the penetration of moisture to the surface of the insulator and the interface of the insulator-coated".
Attempt to use other catalysts for the curing of rubber SCTN not forming acetic acid, did not produce positive results. Thus, the use of well-known catalyst For-18 (tetraethoxysilane) has considerably complicated the technology of waterproofing, increased curing time and did not improve quality insulators.
The complexity of the technology was that the water-repellent agent with a catalyst K-18 is a two and require mixing before application. The vulcanization reaction proceeds very slowly, so it requires acceleration corresponding catalysts are acidic or alkaline in nature. These are metal salts or ORGANOMETALLIC compounds: Sn, Pb, Ti, Zn. Mainly used octoate tin Sn(OOCC7H15)2.
The curing reaction with catalyst K-18 is also accompanied by the release of by-product (in this case alcohol) and, as a result, the shrinkage of the sealant (water-repellent). In addition, the use of water-repellent with catalyst K-18 requires pre-priming the surface of metals.
The above analysis of the mechanisms of curing water-repellent agent showed that Hermetica the Oia insulators should be substances, curing which occurs without shrinkage and without allocation of by-products, i.e. using K-10C (methyltriacetoxysilane).
Preparation and application of a developed hydrophobic composition is implemented as follows.
The desired hydrophobic composition is prepared on the basis of low-molecular silicone rubber, filler, hardener and solvent. Moreover, as the low-molecular silicone rubber using rubber stamps SCTN, as filler is used as a solid filler in the form of a hydrate of aluminum oxide and carbon black acetylene and liquid filler in the form of low molecular weight silicone fluids 119-215, and as a hardener use methyltriacetoxysilane, and the solvent is an organic solvent brand oil solvent.
Preparation of a solution of a hydrophobic coating desired consistency is as follows. In KOK before mixing with low molecular weight silicone fluid 119-215 impose additional solid filler in the form of acetylene soot. Then in the tank for mixing and pouring the solvent, and then add the fillers in the form of a hydrate of aluminum oxide, and the resulting solution is stirred to form a homogeneous mixture.
Moreover, the weight ratio between KOC and the solvent is chosen depending the spine from the ambient temperature, when the desired weight ratio by 100.0 parts by weight of rubber is (0,85-1,0) parts by weight at ambient temperatures up to 25°C and (1,05-1,4) parts by weight when the ambient temperature is over 25°C. At the same time applying a hydrophobic coating is carried out at an ambient temperature not lower than minus 10°C and the absence of precipitation, and dew.
In the prepared homogeneous mixture KOK, diluted silicone liquid and containing a solid filler in the form of acetylene soot, then the obtained liquid composition is thoroughly mixed before the formation of the desired homogeneous mixture.
This hydrophobic coating contains a 100.0 parts by weight of rubber hydrate of aluminum oxide in the amount of 5.0 to 15.0 parts by weight, acetylene soot in the amount of 0.5 to 2.5 parts by weight, of low molecular weight silicone fluid 119-215 in the amount of 1.25 to 2.5 parts by weight, methyltriacetoxysilane in the amount of 2.5 to 6.5 parts by weight of
After that make cleaning gidrofobiziruyuschey surface from the existing dirt and put a layer (or several layers) prepared hydrophobic composition. Approximately 30 min after the application of the hydrophobic coating is cured and gidrofobizirovannym insulating design may be used.
Thus, the advantage of the developed composition in comparison with analogues and the prototype of the m is increased reliability and longer service life caused vulcanized hydrophobic coating, the optimization of its structure, which also leads to the increase blagorazumnyi voltage high-voltage insulation throughout the long period of its use.
For example, the results of testing electrical insulating structures obtained using the proposed technical solution, the permissible operating voltage and the electric field is confirmed by the reduction of the probability of overlapping chains of insulators due to contamination by at least 15-20%.
All tested hydrophobizated insulators tested on takingemotional resistance (the duration of the test is not less than 500 hours) and can be operated in areas with a high level of serrazanetti atmosphere to the 4th be inclusive, the relative humidity of the atmosphere within 20-100%, the value of the maximum allowable operating voltage is supplied to the insulating structure, within 6-750 kV.
In addition, the amplitude of the main leakage currents through hydrophobizated insulators were 1.5-2 times less than through insulators without coating. In actual use, this value will be even greater, since the surface of the silicone polymer coating significantly less polluted.
In addition, the resulting hydrophobic coating of the composition in the vul is Anisimovna condition has improved performance properties compared with the known coatings (see table 4).
|The dielectric characteristics of the coatings obtained on the basis of the developed composition based on KOK-component cold curing|
|Composition||the specific volume resistance ρνnot less than||surface resistivity ρsnot less than||the tangent of dielectric loss tgδ, no more than||the relative dielectric permittivity, ε, of not less than|
|according to the formula||4,82×1014||of 2.0×1015||0,008||3,11|
Optimization of the composition and ratio of the components of the composition, in turn, minimizes the loss of consumables when the hydrophobization of the surface of the insulating structures.
The effectiveness of the developed composition when it is used in the technology of applying a hydrophobic coating mechanized method is confirmed by more than 15-year positive experience of its application in substations located the x in areas with heavy industrial pollution.
At the same time, the optimal composition of the hydrophobic coating, and improved cleaning and self-cleaning" get gidrofobiziruyuschey surface high-voltage insulation allow preventive measures to exclude work on the removal of the "old" layer coating before applying "new" and ensure the effective operation of the coating without additional preventive measures for at least 10 years.
The obtained results of the research can also be used in the manufacture of the outer polymeric insulation of the other high-voltage electrical equipment: surge arresters, bearing and bushings, current transformers and voltage.
1. Silicone insulating hydrophobic composition for high-voltage insulators on the basis of one or dvuhpilonnogo organosilicon compound cold-curing, liquid or pasty in the initial state, containing low-molecular silicone rubber, solid filler in the form of a hydrate of aluminum oxide, liquid filler in the form of low molecular weight silicone fluid, a hardener or catalyst, and an organic solvent as the solvent of the brand "solvent oil, characterized in that the quality of low molecular weight silicone rubber composition contains a rubber stamps SCTN, as a low molecular weight silicone fluid composition contains a silicone fluid brand 119-215, as a solid filler composition further comprises carbon black acetylene, as a hardener composition contains methyltriacetoxysilane, and 100.0 parts by weight of rubber composition contains a low molecular weight silicone fluid in number (1,25-2,5) parts by weight of the hydrate of aluminum oxide in the amount of (5-15,0) parts by weight, acetylene soot in the amount of (0,5-2,5) parts by weight and the curing agent in the amount of (2,5-6,5) parts by weight of
2. The composition according to claim 1, characterized in that the weight ratio between the polyurethane resin and an organic solvent in the composition at a 100.0 parts by weight of rubber varies depending on the ambient temperature and is (0,85-1,0) parts by weight at ambient temperatures up to 25°C, and (of 1.05 to 1.4) parts by weight when the ambient temperature is over 25°C.
3. The composition according to claim 1, wherein the vulcanized coating on its basis is characterized by the following electrical properties: specific volume resistance ρνnot less than 3·1014Ohm·cm surface resistivity ρsnot less than 1.0·1015Ω, the tangent of dielectric loss angle tgδ not more than 0,008, as well as the possibility of operation at operating voltages 6-750 kV.
SUBSTANCE: invention relates to insulation materials used in the cable industry, which are radiation cross-linked fluoropolymer compositions based on an ethylene-tetrafluoroethylene copolymer. The method involves adding a cross-linking agent - trialyl isocyanurate - to a polymer base which contains a granular ethylene-tetrafluoroethylene copolymer (brand - Tefzel). Said agent is added in form of its 20% concentrate which is obtained by mixing molten trialyl isocyanurate with granules of the ethylene-tetrafluoroethylene copolymer (Tefzel), wherein the concentrate is added to the polymer base in ratio of 1 part concentrate to 4-7 parts granules of the polymer base.
EFFECT: high uniformity of distribution of the cross-linking agent in the composition without formation of gel-like inclusions.
2 cl, 2 tbl
SUBSTANCE: surface modified electric insulation system used for electric insulation of an external plant, which makes it possible for garbage and contaminants deposited on the surface to be removed by rain, i.e. self-cleaned, has a superhydrophobic surface containing a composition of a hardened or a cured synthetic polymer, which contains at least one filler and other additives, if required, in which at least one filler is selected from the group containing inorganic oxides, inorganic hydroxides and inorganic metahydroxides, and the surface of the electric insulation system represents a structured surface with its micro- and nano-size characteristics, besides, the specified surface is coated with a liquid hydrophobic compound; a method is also described how to manufacture an electric insulation system.
EFFECT: production of highly resistant and durable electric insulation.
SUBSTANCE: disconnecting switch for interruption of current circuit under voltage which is at least 100 kV relative to the ground includes two groups (14, 15) of elongated bar-shaped support insulators (16) provided with possibility of being installed on the ground and supporting each of ends (19, 20) of wire at high altitude above the ground. Blade (21) of disconnecting switch is connected to one or both of the above wire ends and has the possibility of being moved for connection and disconnection of those ends. Support insulator is made from insulating water-proof composite material on the basis of rubber, containing rubber introduced to fire-resistant filler which is resistant to corona discharge. Disconnecting switch and support insulator can be used in converter station of transfer system of high voltage on direct current.
EFFECT: decreasing the height of support insulators and due to this the height of disconnecting switch.
19 cl, 2 dwg
SUBSTANCE: insulating materials are radiation-cross linked composition based on hydrogen-containing fluoropolymers with polyallyl ethers of polycarboxylic acids acting as cross linking agents. The radiation-cross linked composition based on fluorocarbon polymer contains a hydrogen-containing fluorocarbon polymer with a cross linking agent which is triallyl isocyanurate, and zinc oxide. The fluorocarbon polymeer is an alternating modified copolymer of tetrafluoroethylene and ethylene of equimolar composition, which is such a mixture of two modified copolymers of tetrafluoroethylene and ethylene with different melt flow indices, where the first copolymer of tetrafluoroethylene and ethylene has melt flow index of 60-90 g/10 min in a prepared mixture with CuI2 and with content of the latter between 0.1 and 1.0 wt %, and the other copolymer of tetrafluoroethylene and ethylene is part of the composition with melt flow index of 20-35 g/10 min.
EFFECT: composition has high manufacturability during extrusion and provides high mechanical strength, hardness, wear resistance of the insulation material made from the composition.
FIELD: electrical engineering.
SUBSTANCE: invention relates to electrical engineering, particularly to insulation materials, namely to silicon rubber material containing mix of poly alkylsiloxane (A) and poly arylsiloxane (B). Said mix comprises 3 to 30 weight parts of arylsiloxane (B) per 100 weight parts of poly alkylsiloxane (A). Invention relates also to the method of producing such material. Proposed material can be used for various applications at low temperatures, one of them pertaining to electric insulation.
EFFECT: reduced viscosity factor at minus 50°C and lower costs.
SUBSTANCE: invention concerns low-viscosity siloxane compositions which can be solidified at room temperature and form elastomer materials applicable as dielectrics and insulators. Invention claims low-viscosity siloxane composition including, weight parts: polyorganosiloxanediol - polydimethylsiloxanediol or polydimethyl(methylphenyl) siloxanediol or their mix at the molar weight ratio of (2÷1):1, 15÷100 thousand - 100, partial tetraethoxysilane hydrolysis product - 4.0÷7.2, amonisilane selected out of group including γ-aminopropyltriethoxysilane or its mix with (3-aminoisopropyltriethoxysilane or diethylamonipropyltetraethoxysilane - 0.5÷1.0. Composition can include fine-dispersed filler quartz, silicon dioxide or dolomite powder, iron, titanium, aluminium, chrome or zinc oxides or their mixes, boron or aluminium nitrides, or mixes of carbon black with metal oxides, oligodimethylsiloxane.
EFFECT: low-viscosity siloxane composition for obtainment of elastic dielectric material without corrosion effect on non-ferrous metals, with high dielectric properties, enhanced substrate adhesion and reduced toxicity, at room temperature.
8 cl, 2 tbl, 2 ex
FIELD: electrical engineering.
SUBSTANCE: silicon rubber based insulating material proposed for insulating cables and wires has polyethylene, target dope in the form of ethylene copolymer with vinyl acetate, and heat regulator. This insulating material for cables and wires is distinguished by desired hardness and flexibility.
EFFECT: enhanced speed of composition radiation cross-linking.
1 cl, 1 tbl
SUBSTANCE: shaping method of electrical insulator of spring terminal of rail fastening consists in the fact that front section of spring terminal is installed in process frame, rear and internal sections of spring terminal are installed and fixed on centring faces of the frame of device. After that, elements of seals are fixed along the rod diameter of front section of spring terminal, and process frame is filled with electrical insulating material using dosing device.
EFFECT: reducing labour intensity of manufacture and erection works, improving reliability and life time exploitation of rail fastening, providing reliable electrical insulation of fastening from rail.
FIELD: electrical engineering; insulation and surge protection of high-voltage apparatuses and power transmission lines.
SUBSTANCE: proposed surge limiter designed, for instance, to insulate and protect disconnecting switches installed in substations and on distribution networks has insulator body made of polymeric material, two electrodes installed at ends of mentioned insulator, and varistor pile disposed between electrodes inside mentioned body; novelty is that varistor pile is installed inside body so that clearance is formed between body walls and outer surface of varistors; the latter are assembled within pile into separate modules; extreme modules are mechanically and electrically connected to their respective electrodes and to each other by means of spherical joints made of conducting material.
EFFECT: enhanced stability of surge limiter under external bending and torsional mechanical forces.
3 cl, 1 dwg