UA68544A - Solid-cast polymer casing of an insulator - Google Patents

Abstract

The proposed solid-cast polymer casing of an insulator is designed as a cylindrical workpiece with annular ribs and a cone-shaped recess at the lower part.

Description

Description of the invention

The invention relates to the field of electrical engineering, in particular, to polymer insulators, and can be used in the manufacture of structures of high-voltage external devices.

The insulating element of the polymer insulator is known, which contains an electrically insulating fiberglass rod connected to the polymer insulator by means of a binder, as well as metal tips. At the same time, the sought-after insulating element is made in the form of a solid shell, namely in the form of a body and annular ribs, which have a cone-shaped recess in the lower part. The angle of inclination 70 forming the cone-shaped recess to the plane of its base o, in degrees, and the radius of rounding at the point where the surface of the recess adjoins the body of the insulating element K, in millimeters, is selected from the following ratio: 0 /K 0 -2.5 -- 4.0 . At the same time, the insulating element is made of silicone rubber of rapid/additive vulcanization (11.

The disadvantage of the known design of the insulating element, made in the form of a solid polymer 15 shell, is the lack of effective ratios of the geometric dimensions of its component elements, which does not allow achieving high reliability of the insulator in harsh operating conditions.

As a prototype, a one-piece polymer shell with annular ribs, which is part of the polymer insulator (21.

The disadvantage of the prototype device is the lack of effective ratios of the geometric dimensions of its constituent 20 elements, which does not allow to achieve an increase in the operational reliability of the polymer insulator, a decrease in energy consumption, labor intensity and an increase in the manufacturability of its manufacture, as well as an increase in the electrical and mechanical strength of the boundary layer between the electrical insulating rod and the insulating element.

The basis of the invention is the task of increasing the operational reliability of the polymer insulator, reducing the energy consumption, labor intensity and increasing the manufacturability of its manufacture, as well as increasing the electrical and mechanical strength of the boundary layer between the electrical insulating rod and the insulating element "by improving the design and establishing effective ratios of the geometric dimensions of the components of the solid-cast polymer shell of the insulator.

This goal is achieved by the fact that in the one-piece polymer shell of the insulator, made in the form of a cylindrical body with annular ribs having a cone-shaped recess in the lower part, the diameter t 30 of the ribs of the cylindrical insulator shell lies in the range from 80 to 160 mm, the pitch between adjacent ribs lies It ranges from 20 to 60 mm, the width of the annular rib at its base is from 5 to 21 mm, and the ratio of the length of the element's leakage path to the step between adjacent ribs is from 2.35 to 3.5. what

The listed features of the appendix make up the essence of the invention. ee)

The presence of a causal relationship between the set of essential features of the invention and the technical result, which

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Features of operation of insulators in contact networks and power transmission lines put forward increased requirements for their reliability. Based on many years of operational experience, today it can be affirmed that polymer insulators best meet these requirements. "

Currently, the use of polymer insulating structures is a qualitatively new direction in the development of high-voltage insulator construction. Polymer structures are highly resistant to surface electric discharges, solar radiation, dust, pollution, temperature changes, shocks, operational electrical and mechanical influences.

In addition, polymer insulators have high hydrophobicity and low contamination of insulating surfaces, do not require washing, cleaning, defecting, preventive work.

The specified properties of polymer insulating structures ensure their high reliability and durability,

Ф and, therefore, a reduction in costs during their installation, transportation and operation, as well as an increase in the reliability (o) of power supply to objects.

The novelty of the proposed design in the manufacture of insulators consists in the use of insulators with a one-piece protective shell, which does not have joints between individual ribs. t» 50 The execution of the insulating element in the form of a solid shell allows to increase the operational reliability of the polymer insulator, as well as to increase the electrical and mechanical strength of the boundary layer between

T" with an electrically insulating rod and an insulating element, to eliminate depressurization of the insulator between the annular ribs by eliminating connectors, to reduce energy consumption, labor intensity, and to increase the manufacturability of its manufacture by eliminating installation operations. 99 In turn, the effective ratios of the geometric parameters of the ribs and the shell make it possible to achieve optimal operational and technological characteristics of polymer insulators.

The main operational characteristics of polymer insulators include: E vrr - electric field strength at which a discharge occurs on the surface of the insulator in a contaminated and moistened state (kV/cm); t -- tracking and erosion resistance. This is the time from the start of operation to the moment of the formation of a conductive track (track), into which carbon was introduced, or the erosion of the shell surface to a critical depth.

The track and erosion are formed under the simultaneous influence of an electric field and fog formed by spraying salt water of a given electrical conductivity (hours). Greking-erosion resistance of insulator models was determined in a salt fog chamber according to the GOST 28856-90 method.

The technological characteristics of polymer insulators include: resistance (ability) to pull out 62 shells (ribs) from a casting mold without tearing off the ribs and tearing the rubber at the junction of the rib and the barrel of the shell.

At the same time, the set of parameters of the rib and the shell should be such as to ensure obtaining the highest possible operational and technological characteristics.

It was established that the aforementioned geometric parameters of the protective ribbed shell of the polymer insulator are interrelated. The need to observe the above-mentioned ratios is due to the elastic-strength properties of the material of the solid shell (such as conditional strength, relative elongation and residual deformation).

The invention is illustrated by graphic material, where fig. 1 shows the general view of the integrally cast 7/0 polymer insulator shell; in fig. 2 shows experimental graphs of the dependence of the electric field strength Е врр, during which a discharge occurs on the surface of the insulator in a contaminated and wet state, on the ratio of the diameters of the edge of the shell 0 and the insulator stem 4, i.e. О/4, at different diameters of the insulator stem a; in fig. C schematically depicts an element of a ring rib of a solid polymer shell; in fig. 4 shows a graphical dependence showing the influence of the angle of inclination of the rib Ж on the tracking-erosion resistance T and on the coefficient of safety margin for separation Kr when pulling the insulator from the casting mold.

The one-piece polymer shell of the insulator is made in the form of one-piece structure 1, which has a cylindrical body 2 with annular ribs 3, which have a cone-shaped recess 4 in the lower part.

The diameter of the rib of the cylindrical shell of the ХО insulator ranges from 80 to 160 mm, the step between the adjacent ribs H" (or H.) ranges from 20 to 60 mm, the width of the annular rib Z at its base AP ranges from 5 to 21 mm, and the ratio of the length of the leakage path of the element (I 5) to the step between the adjacent edges of H, i.e. the ratio of B - I //H lies in the range from 2.35 to 3.5.

The angle of inclination Ж of the annular rib C of the insulator lies in the range from 13 to 25", the angle of inclination 9 of the top 5 of the annular rib of the insulator lies in the range from b to 7", and the angle of inclination of the lower surface of the ring rib C to the horizontal plane lies in the range of 6 to 18" (see Fig. 1). "

The radii of connection (r, and gv) of the annular rib of the insulator with the upper 6 and lower 7 parts of the cylindrical shell 2 of the insulator are in the ranges of r, - 01 5 C mm and gv - 5 5 6 mm, respectively. The thickness of the wall A of the cylindrical shell 1 is between 5 and 7 mm (see Fig. 1).

A polymer insulator based on a protective ribbed shell is made in this way. -

The binder is applied to the surface of the electrically insulating fiberglass rod (not shown in Fig. 1-4) along its entire length, then the electrically insulating rod is placed in a casting mold, the inner surface of which determines the ribbed configuration of the outer surface of the shell. at

To form an insulating element, an elastomer is fed into the mold under pressure, and it is processed with a certain temperature-time dependence and pressure. As an elastomer, as a rule, silicone rubber of additive vulcanization is used, containing both vinyl and hydrogen-containing siloxanes, which are cross-linked under the influence of a platinum catalyst.

As it was established, the above-mentioned geometric parameters of the edge of the cylindrical shell of the insulator affect its operational and technological characteristics. "

It should be noted that the effective values of the angle of inclination of the rib were found under the condition of simultaneous provision of high values of tracking-erosion resistance (T) and margin of mechanical strength of the rib against tearing and separation. Dependence of HT - (5) was determined experimentally. The Ku factor, the margin of strength for separation when pulling » the insulator from the casting mold (Кр - Н/Пр, where Н is the breaking strength, Гр is the tearing force) was determined by calculation.

The effective (optimal) value of the ratio between the length of the rib leakage path (I 3) and the interrib distance, or the height of the insulating element (Не), was also determined experimentally.

Me. In fig. 2 shows experimental graphs of the dependence of the electric field strength E vrn, at which

Go! a discharge occurs on the surface of the insulator in a contaminated and moistened state, from a ratio of 0/4 at different diameters of the insulator barrel: a -12 mm (1); a - 20 mm (2) and a - 36 mm (3). o The tests were carried out when the insulators were contaminated with kaolin with a specific surface conductivity of 5 and 20 MμS. From the graphs in fig. 2 it follows that the effective (optimal) diameter of the rib O lies in the range of 80 - 160 mm.

The maximum intensity of the electric field E vrn, at which a discharge occurs on the surface of the insulator v

T" in a contaminated and moistened state, in the range of Ю - 80 - 160 mm is explained by the fact that at Ю " 80 mm, the ribs do not effectively protect the insulator from continuous wetting of the shell during rain.

At the same time, at О » 160 mm, due to a decrease in the required number of ribs, the number of leakage zones dried by 29 currents in the space between the ribs decreases, which leads to an increase in the surface conductivity of the insulator and a decrease in the overlap stress (surface breakdown).

Based on this, it was established that the effective diameter of the rib О of the cylindrical insulator shell is between 80 and 160 mm.

Determination of the optimal ratio of the length of the edge leakage path | from to the inter-rib distance Hn, 60 i.e. the ratio V - I 8/Nh, was carried out on the basis of measurements of the electric field strength, during which a discharge occurs on the surface of the insulator in a contaminated and moistened state E vry - 7 (V) at an alternating voltage T - 50 Hz and when contaminated with salt fog and kaolin.

The effective range of the B - I //H ratio was determined on the basis of the data given in the table. 1, where 1 μSm of current (microsiemens) - 1 cm'1075 --- the specific surface conductivity of a contaminated and moistened insulator.

MEvvioViem pollution G

Coil with a specific surface conductivity of 17 mem 09 12113525 2.28 2.25/2.09 208 1.84

It follows from Table 1 that the desired effective ratio is В - | 3/Nh lies in the range from 2.35 to 3.5. 7/0 Deviation from this range leads to deterioration of operational and technological characteristics of insulator shells.

The thickness of the edge of the shell Ai at its base, that is, at the point of connection with the cylindrical part of the shell, was determined based on the following considerations.

When pulling out the insulator from the casting mold, the rib must not break away from the body of the shell and there must be no tearing of the rubber at the point of contact A of the base of the rib with the cylindrical body of the shell (see Fig. 3), i.e. at the point where the annular rib of the insulator meets the lower part cylindrical shell.

The resistance of the silicone rib to separation and tearing was determined experimentally and computationally, that is, the obtained calculated values were subsequently verified experimentally. Below is the calculation sequence. 1) The force E needed to pull the rib out of the casting half-form is calculated based on the following ratio:

There was 8 INTO), 2 where "7 is the friction pair coefficient "rubber - metal"; taking into account the use of an anti-adhesive "-0.1; 85 - internal pressure of vulcanized rubber in the mold before opening, MPa; the value of Z is taken as equal to the elastic modulus of rubber under compression E r szh, which is equal to E rszh - 5 MPa - « 5105 n/me;

Z - the area of the lower surface of the insulator rib: zv lira) m?) Z 4 ' « 2) The Hud force is calculated per unit length of the semicircle at the point of contact of the rib with the cylindrical part of the shell (trunk):

KE ,INI (Z) p

Ed. - pt (Ce) where r - a/2-- the radius of the protective polymer shell.

C) Calculate the force of separation of the rib from the insulator E o when pulling it out of the mold, as well as the tearing force Er in the corner part of the connection (point A, see Fig. 3):

Ra - ud sov8, N/mm (4) « vu - Bud. Vipa, N/mm (5) - s 4) The required thickness Ai is calculated: хз» m- МО)

I-I where |gr) is the strength limit of rubber at tear (stretching); for rubber НМ1760/65 the value |в»| x 4.5 N/mm7.

Ф The auxiliary parameters Ii (thickness of the rib near the surface of the cylindrical part of the shell) and Г are determined:

Ge | 1: AnNovip I (7) tya sl K- where o is the radius of the rib. n-- th 2

Thus, the thickness of the rib near the surface of the cylindrical part of the shell y, while maintaining the same stiffness of the ribs with an increase in their diameter ОО, is proportional to the departure of the rib s and is calculated using the empirical expression: iv -i) ; (8) where 7 is 0.2-0.25. » 5) The coefficient of the margin of rubber tear strength at the point of connection of the rib with the shell trunk is determined: kr) 6o Re de N - rubber tear strength, N/mm.

Table 2 shows the calculated and verified experimental values of E and Rud for the annular ribs of the solid polymer insulator shell with effective dimensions. vv

O, MmmMm 8, m2 g H Ore, N/mm vo Irosaztrovav| 2519.

It should be noted that the force of separation of the rib from the insulator and the tearing force of the rubber material in the zone of the base of the rib 3, lying between positions 6 and 7, depend on the angle of inclination of the lower surface of the rib 5, which, in turn, is related to the angle 5. Therefore, the indicated ratios must be found experimentally and/or by calculation.

In fig. 4 shows the graphical dependence obtained by experimental and computational methods, which shows the effect of the angle of inclination of rib 2 on the tracking-erosion resistance T and on the coefficient of safety margin for separation when pulling the insulator from the casting mold Kr (Kr - Н/Пр, where Н -- breaking strength, N/mm, which for rubber НМ1760/65 is H - 4.5 N/mm; 1-1;2-- Kr).

From the graphs shown in fig. 4, it follows that in the case of small angles of inclination of the ribs (Ж « 8"), the tracking-erosion resistance T decreases significantly below the norm (norm - 182 hours). On the other hand, an increase in the angle 2 leads to a decrease in the margin of tear strength.

It is known that the norm of tracking-erosion resistance according to GOST 28856-90 is 182 hours, which, as can be seen from fig. 2, corresponds to the angle of inclination of the rib 5 - 13", The ratio of the tear strength of rubber to the force Er, equal to

M corresponds to the angle of inclination of the rib, which is 25" (see Fig. 4).

Thus, the following ranges of changes in the angle of inclination of the annular rib of the insulator were established: "those - 19",

Section U 297. These angles correspond to the angles of inclination of the lower surface of the battle rib - 67 degrees from 18".

It was established that in order to increase the margin of safety of the rib against tearing (E p) and tear (Ро) forces, the connection point of the rib З with the cylindrical part of the shell (barrel 2 of the shell 1) must be made with the following radii: in the lower part гн-» 2 mm; in the upper part of ha 2» 5 MM. "

Practice has shown that increasing the radii гу - 2 mm and гв - 5 mm is impractical, since the margin of strength at these values of the radii is quite sufficient, and the further increase of г and ге leads to an increase in rubber consumption.

Thus, the ranges of change of the radii of the connection of the rib with the upper (r,) and lower (gv) parts of the cylindrical shell of the insulator were established, namely: гу - 1 3 mm; in - 57 6 mm. "AND

It was experimentally confirmed that these dimensions allow to exclude the deformation of the ribs when the mold is opened and to avoid the possible detachment of the ring-shaped rib from the body of the insulating element and the shell. (se)

If the upper values of these parameters are exceeded, the edge may detach from the shell body, and if the values are lower than the lower limit values, the cost of the casting mold increases significantly and the strength of the finished shell significantly deteriorates.

The thickness of the shell (A was chosen from the condition of ensuring moisture protection of the fiberglass electrical insulating rod (not shown in Fig. 1-4) and the erosion resistance of the shell 1, and was 5 mm; "

Atakh 7 7 MM. From c Thus, the values of Dpdip and Aitach were determined for a shell with a rib diameter of OO - 100 mm. In this » case, Andip - 8 MM; Ai tah - 8.4 MM

For a shell with a rib diameter of 80 mm, the following was determined:

ANtip - B. Passovu sova Zla sov, 4b'mmy mm b br sr 45 o For a shell with a rib diameter of О groin- 160 mm we got: sl Aptyaye s 0 - вЕ0ВЕ 109 СО sd tyme: lMM sr abr 4.5 - Thus , it was established by calculation and experiment that the effective size of the foundation

T" of the Ap rib for angles 2-13 and 25", respectively, is: Andir - 5 MM; tah - 21 mm.

The step between the edges of Н was also determined by calculation and experiment. The corresponding calculation ratio for determining Ne has the following form: во0б-ф-нав) 5ип пе 7 viпе(В-) С where 8 is the angle of inclination of the upper plane of the rib (not shown in Fig. 1-4), which is equal to 85 - 90 - 5, hail; because в - the angle of inclination of the lower plane of the rib (not shown in Fig. 1-4), which is determined as follows: в'- anything else. Itvadi (11) p2 de po -- the height of the inner cone of the rib, which is determined as follows: vBo pu sosdv- TMM zipe de s-- the protrusion of the rib Z (see Fig. 3).

The effective range of H 5 values determined by calculation and experiment turned out to be as follows: Notepipe U 20 mm; Natach - 60 mm.

The one-piece polymer shell of the insulator of the specified sizes, which are declared, has successfully passed experimental tests in high voltage laboratories, including in the EEZ named after Paton, and documentation is currently being prepared for its industrial use at nominal voltages from З5 to 110 kV (at lightning impulse voltages that can withstand, according to the requirements of the standard, from 220 to 450 kV).

Sources of information 70 1. Polymer insulator and method of ego production. IPC 7 H 01 V 17/00. Patent Ukrainyi (SHA) Mo 52084А, 2002. 2. Insulator, overvoltage limiter and method of manufacturing a polymer shell. IPC 7 H 01 B 17/50, H 01 B 19/04, H 01 C 17/12. Patent of the Russian Federation (Ky) Mo2203514, 2003. p

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Claims (1)

The formula of the invention " - c Solid-cast polymer shell of the insulator, which is made in the form of a cylindrical body with annular ribs having a conical recess in the lower part, which is distinguished by the fact that the diameter of the ring "" rib of the cylindrical insulator shell lies in the range from 80 to 160 mm , the step between adjacent ring ribs is in the range from 20 to 60 mm, the width of the ring rib at its base is in the range from 5 to 21 mm, and the ratio of the length of the path of the coil of the element to the step between the adjacent ring ribs is in the range of Ge») 2 .35 to 3.5. Me Official Bulletin "Industrial Property". Book 1 "Inventions, useful models, topographies of integrated microcircuits", 2004, M 8, 15.08.2004. State Department of Intellectual Property of the Ministry of Education and Science of Ukraine. 50 of them In the city of 60 b5