RU2798212C1 - Hybrid post insulator - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to hybrid insulators of the support-rod type of high voltage electrical apparatus. The hybrid support-rod insulator includes a porcelain rod with an outer ribbed shell of tracking and weather-resistant polymeric insulating material reinforced at the ends with metal flanges mounted on cement, at least two nuts and two washers. The porcelain rod is made with a through axial hole, into which a means of prestressing by compression of the specified rod is introduced, comprising an insulating fiberglass rod, the ends of which are reinforced with metal end caps with an external thread. In this case, the porcelain rod is enclosed between the washers and nuts, and the cavity between the fiberglass rod and the wall of the hole in the porcelain rod is filled with a polymeric elastic insulating material.

EFFECT: increased mechanical bending strength of hybrid post-rod insulators.

2 cl, 1 dwg

Description

The invention relates to electrical engineering, in particular to hybrid insulators of the support-rod type of high voltage electrical apparatus.

High-voltage post-rod insulators are designed for insulation and fastening of current-carrying parts in electrical apparatus, complete switchgears, current conductors, switchgears of power stations and substations.

Known porcelain support rod insulator [1] high voltage. The active use of porcelain insulation in high-voltage technology is explained by its special properties, such as hardness and mechanical strength, heat resistance, variability of electrical properties from an insulator to a semiconductor, high corrosion resistance, and resistance to climatic influences. Insulating porcelain has a high electrical breakdown strength (E _pr \u003d 100 ÷ 250 kV / cm), _high mechanical compressive strength (F compressive \u003d 4500 kg / cm ² ), relatively low bending strength (F _bend \u003d 700 kg / cm ² ) and stretching (F _dist =300 kg/cm ² ). For higher voltage classes, single columns of porcelain insulators are very high and do not provide the necessary mechanical bending strength. Therefore, at these voltages, support structures are most often used in the form of a cone-shaped tripod of three columns of insulators. Under bending forces, insulators in such structures work not only in bending, but also in compression.

An analysis of the operating experience of electrical devices shows that the share of their failures due to failures of porcelain insulators is up to 40% of the total number of damages. Moreover, with an increase in the voltage class, this percentage increases. This is facilitated mainly by the hidden factory defects on the insulators and the development of these defects during operation. The disadvantages of porcelain insulators include their large mass, fragility, the possibility of being struck by foreign objects, complex manufacturing technology due to the developed shape of the surface of the insulating part and the associated technological defects, insufficient surface dielectric strength of insulators in conditions of intense pollution due to the inability to technically ensure sufficiently long creepage distances, as well as the susceptibility of porcelain to contamination.

The above disadvantages of the support insulators of electrical apparatus are largely devoid of insulators made of polymeric materials. So, known [2] supporting rod polymer insulators for outdoor installation. The main bearing element of polymer insulators is a fiberglass rod, protected from external atmospheric influences by a silicone ribbed coating. The structure is closed on both sides with metal flanges.

It should be noted that the production of large-diameter fiberglass rods used for the manufacture of insulators for a mechanical load class of 10 kN and above is problematic due to a number of technological difficulties. The issue of using fiberglass pipes instead of rods has not yet been completely resolved due to the lack of an economic and effective way to prevent the possibility of electrical breakdown of the insulator inside the pipe. In addition, under high static and dynamic mechanical loads, fiberglass has a significantly larger deflection than porcelain. This negatively affects the reliability of the switching devices due to the low rigidity of the insulating columns, for example, on disconnectors.

Below are the main electrical and physical-mechanical characteristics of the insulating elements of polymer insulators.

For fiberglass rod:

- electric strength along the fiber E _pr =35÷60 kV/cm (depending on the diameter);

- mechanical tensile strength F _rast =17000 kg/cm ² ;

- tensile modulus E _control =45000 MPa.

For silicone elastomer:

- electric strength E _pr =22 kV/mm;

- density P _t =1.30÷1.65 g/cm ³ ;

- tracking and erosion resistance U _t =4.5 kV.

Analysis of the given data of porcelain and polymeric insulating materials, as well as structures based on them, shows the possibility of creating new types of insulators with a combination of porcelain and polymer. The main of these characteristics are: the rigidity of porcelain and its high mechanical compressive strength, hydrophobicity and high tracking and erosion resistance of the silicone coating. It is also necessary to take into account the high mechanical tensile strength of the fiberglass rod, which is widely used on high voltage suspension / tension insulators.

In this regard, one of the best ways to solve the issue of providing the electric power industry with reliable support-rod insulators is the creation of hybrid insulators, which are a combined design of a smooth porcelain rod and an outer (ribbed) shell of tracking and weather-resistant organosilicon elastomer with metal flanges at the ends [ 3].

Possessing the advantages of rod porcelain and polymeric materials, hybrid insulators, at the same time, are largely devoid of the main disadvantages of both. The use of a smooth porcelain rod of a smaller diameter reduces the likelihood of hidden structural defects that reduce the strength of the insulator, and greatly simplifies the process of reinforcing with metal flanges. It is known that mechanical treatment of the surface of a porcelain rod when cutting ribs on it contributes to the exposure of a relatively low-quality, internal porous structure with microcracks in the area between the ribs and, thereby, reducing its bending strength by 30–35%. Whereas the manufacture of a porcelain rod of a relatively smaller diameter and without mechanical surface treatment contributes to a significant increase in its specific mechanical bending strength and weight reduction.

The use of a polymer shell makes it possible to significantly improve the discharge characteristics of insulators, both due to the hydrophobic properties of the elastomer and due to the technical possibility to significantly increase the length of the creepage path.

However, it is impossible to exclude fracture of porcelain products. It is clear that a break in the central porcelain insulator rod will cause high-voltage electrical equipment to fall to the ground with serious consequences. This equipment can be a power or instrument transformer, a high-voltage circuit breaker, a disconnector, a surge arrester, an arrester, a separator, a short circuiter, a reactor, a busbar, etc.

The purpose of the proposed technical solution is to increase the mechanical bending strength of hybrid support-rod insulators, increase the reliability of their operation by eliminating the fall to the ground in case of possible fractures of the central porcelain rod.

The essence of the invention lies in the fact that the hybrid support-rod insulator includes a porcelain rod with an outer ribbed shell made of tracking and weather-resistant polymeric insulating material, reinforced at the ends with metal flanges mounted on cement, the porcelain rod is made with a through axial hole into which the agent is introduced prestressing said rod, wherein the cavity between the means and the wall of the hole is filled with a polymeric insulating material. The prestressing means may include an insulating fiberglass rod, the ends of which are reinforced with metal end caps with an external thread, two nuts and four washers.

The technical result of applying the design solutions proposed in the claimed technical solution is to increase the mechanical bending strength of the hybrid support-rod insulators, increase the reliability of their operation by eliminating falling to the ground in case of possible fractures of the central porcelain rod and thereby reducing the accident rate of power facilities, increasing their service life. services.

In FIG. 1 shows:

1. Porcelain rod with a central axial hole for installing a high tensile fiberglass rod;

2. Metal flanges for mounting electrical apparatus on the insulator;

3. Ribbed coating of polymeric insulating material, such as silicone elastomer, to protect the structure from weathering;

4. High tensile strength fiberglass insulating rod to apply compressive loads to the porcelain rod;

5. Polymeric insulating material, such as elastic silicone compound, to fill the internal cavity of the porcelain rod;

6. Terminations, reinforcing the ends of the fiberglass rod;

7. Nut;

8. Steel washer;

9. Plastic or soft metal washer;

10. Cement filling.

The inventive high-voltage hybrid support-rod insulator is a combined design of a smooth porcelain rod 1 with metal flanges 2 at the ends and an outer ribbed shell 3 made of a polymeric insulating material, for example, tracking and weather-resistant silicone elastomer. The cavity between the porcelain rod 1 and the flanges 2 is filled with cement 10. The specified porcelain rod 1 is made with a through axial hole in which a high-strength insulating fiberglass rod 4 is placed. The cavity between the rod 4 and the wall of the hole in the rod 1 is filled with polymer insulating material, for example, elastic compound 5. The ends of the rod 4 are reinforced with metal ends 6 with external thread. Porcelain rod 1 is enclosed between washers 9, 8 and nuts 7. To prevent chipping on fragile porcelain rod 1 during compression between metal nuts 7, between rod 1 and metal washer 8 an additional washer 9 made of plastic or soft metal is installed.

A significant increase in the mechanical bending strength of the hybrid support-rod insulator, eliminating its fall in case of possible fractures, is carried out due to the axial compressive load applied to the porcelain rod 1, by means of prestressing, including a fiberglass rod 4 of small cross section (no more than 1 cm ² ), end fittings 6, nuts 7, as well as washers 8 and 9. The compression force is adjusted by turning the nuts 7.

Analogues

1. Patent RU 2172034.

2. Patents RU 2074425 and RU 2233493. Insulator OSK-6-110-V-4 UHL1 http://www.em.dn.ua/iz/polymer/ster/osk-6-110-v4.htm.

3. Hybrid post insulators

https://www.ppcinsulators.com/ru/products/hybrid-line-post-insulators/

Hybrid Insulator http://ctcinsulator.com/en/products.php?sortid=11.

Claims (2)

1. A hybrid support-rod insulator, including a porcelain rod with an outer ribbed shell of tracking and weather-resistant polymeric insulating material, reinforced at the ends with metal flanges mounted on cement, characterized in that the porcelain rod is made with a through axial hole into which the agent is introduced prestressing by compression of the specified rod, containing an insulating fiberglass rod, the ends of which are reinforced with metal end caps with an external thread, at least two nuts and two washers, while the porcelain rod is enclosed between the washers and nuts, and the cavity between the fiberglass rod and the wall of the hole in the porcelain rod is filled polymeric elastic insulating material. 2. An insulator according to claim 1, characterized in that the fiberglass rod has a cross section of not more than 1 cm ² .

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