RU2332740C1 - Pin-type organosilicone insulator with end terminal - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention is attributed to high-voltage pin-type organosilicone insulators for overhead electric transmission lines (OETL) designed for voltages mainly of 6-35 kV. Pin-type insulator contains dielectric body with ribs and place for wire attachment. Dielectric body is made of organosilicone rubber and end terminal for mounting on bridge dowel. End terminal can be performed as heat-shrinkage socket.

EFFECT: improvement of operating reliability, simplification of design and installation, and reduction of insulator manufacturing cost.

2 cl, 3 dwg

Description

Technical field

The invention relates to the electric power industry, and more specifically to linear pin high-voltage insulators designed for insulated fastening of wires to metal, reinforced concrete and wooden supports on overhead power lines and switchgears of stations and substations for voltage up to 35 kV AC of industrial frequency of 50 Hz.

State of the art

Known pin insulator containing an electrical insulating body with ribs, a socket for attaching an insulator containing screw thread with an annular groove for lateral knitting of a wire on the surface of an upper skirt made of porcelain (German Standard DIN 48004-1969. Porcelain pin insulators with internal reinforcement for nominal voltages from 10 to 30 KB for power overhead power lines.Insulators for overhead power lines; pin type insulators St, rated voltages 10 to 30 kV). The insulator of this design is widely used in the electric power industry, but has a number of disadvantages. The insulator is characterized by a large mass (porcelain), since it must have a bending strength of at least 13 kN. Bending loads are applied to the lateral knitting point of the wire and act through the insulator on the metal pin to which the insulator is attached. The insulators are mounted on a pin through a polyethylene cap to compensate for different temperature expansions of porcelain and metal. Typically, the top edge of the pin receptacle is below the side groove for securing the wire. In this case, bending loads occur during the tension of the wires inside the insulator, the greater, the larger the shoulder between the guides of the applied forces of the wire tension and the reaction of the metal pin. In order to increase the strength, the porcelain body of the insulator is made thicker, however, with increasing porcelain thickness, the likelihood of microcracks increases and the breakdown voltage of the insulator decreases. Porcelain insulator when exposed to electrical voltage quickly loses its properties and grow old. In addition, the glassy glaze of the porcelain insulator, when wetted in the rain, conducts electric current quite strongly, and is also very dirty. The disadvantages of this insulator are also the complexity and energy consumption of manufacturing, the need to use intermediate products (polyethylene caps) for attaching the insulator to the bearing pin, the fragility of the insulator, large dimensions, low electrical and mechanical properties. Organosilicon rubber is devoid of these drawbacks, however, it does not have mechanical strength.

Known insulator (US 5945636 Aug. 31.1999), containing an insulating body with skirts, a socket for attaching an insulator containing a screw thread with a groove for lateral knitting of a wire made of a dielectric polymer material and coated with an organosilicon sheath. Organosilicon rubber as the outer shell is the best material for insulators operating in the open air, as it is resistant to ultraviolet, tracking, erosion, atmospheric and pollution, and also has hydrophobic and dirt-repellent properties. These qualities of silicone rubber are used in an insulator to protect a dielectric polymer solid carrying a mechanical load from external influences. Durable polymeric materials, including those used in the specified insulator, are not resistant to adverse atmospheric and other influences, to the action of which silicone rubber is resistant. A contradiction can be identified: rubber is resistant to atmospheric and current effects, but does not have mechanical strength, solid polymers have mechanical strength, but are not resistant to tracking, erosion, ultraviolet, etc.

The disadvantage of this insulator is also the high consumption of expensive polymeric material, since it is necessary to ensure high mechanical properties of the insulator, the complexity of manufacturing, the need for intermediate products for fastening the insulator to the bearing pin of the power line, large dimensions and, as a consequence, the high cost of the insulator. The need to manufacture a durable insulator requires the presence of a solid solid material in the structure, and at the same time, the solid material of the insulator body requires the use of intermediate products for attaching insulators to the pin. This in turn increases the body diameter of the insulator and reduces the electrical characteristics of the insulator itself. Organosilicon rubber is an ideal insulating material, but it cannot bear the bending loads acting on the insulator.

These contradictions are resolved in the proposed insulator.

OBJECTS OF THE INVENTION

The aim of the invention is to increase the operational reliability of insulators, simplifying the design, simplifying installation and reducing the cost of manufacturing the insulator.

Description and implementation example

The design of the insulator allows the use of organosilicon rubber not only as a protective shell, but also to make the supporting body of the insulator out of it. The insulator contains a metal terminator for attaching the insulator to the crosshead pin and an insulating body made of silicone rubber. In contrast to the prototype, where organosilicon rubber performs only the function of protecting the insulating polymer body of the insulator from the action of leakage currents on the surface, weathering, moisture, electric arc, in the proposed design, organosilicon rubber itself is used as the body of the insulator. Mechanical load is carried by the metal pin of the beam through the terminal. The terminal may also be metallic. The terminator can be made in the form of a sleeve with a clamp that is worn on the metal pin of the yoke, or a sleeve with an internal thread for screwing on the pin of the yoke containing the external thread.

The load on the insulator sideways and down carries the metal pin of the traverse of the power line through the terminal. The rubber of the insulator experiences only efforts aimed at compression, which it transfers to the terminal, and that in turn to the pin of the crosshead.

The terminal is preferably made of metal. In this case, it is guaranteed that the place for lateral fastening of the wire will be lower than the upper edge of the terminal and that the lateral force from the tensioned wire will be transmitted to the metal terminal and from it to the traverse pin. A metal terminator eliminates the possibility of errors during installation of the insulator, eliminates the possibility of improper operation of the insulator when the traverse pin is not fully worn on. If the terminator is not metal and the insulator is not fully worn on the cross-arm pin, the place where the wire is fastened will be higher than the upper edge of the cross-arm pin, a bending force will occur that can break the insulator with the end clamp of fragile material.

However, it is possible to use as a tip not a metal tube, but a tube or sleeve made of a fiberglass tube or any other polymer. There are no special requirements for the terminator in the design of this insulator; its main function is to fasten the insulating body of organosilicon rubber to the metal pin of the yoke. If the terminator itself does not have strength properties, this can only lead to improper load distributions during improper installation of the insulator, when the insulator is not completely put on the pin and the place of fastening of the wire on the insulating part is above the upper edge of the crosshead pin.

For the manufacture of the terminal, it is possible to use heat-shrinkable material. The organosilicon rubber insulating body in the manufacture of the insulator at the factory is formed on a sleeve of heat-shrinkable material, for example, radiation-crosslinked polyethylene. In this case, silicone rubber should be on the tip of such a material in a stretched state. The insulator in this case has a terminal of a slightly larger internal diameter than the pin of the support beam. During installation, the insulator is put on the pin on the pin all the way and heats up. The terminator, under the influence of external temperature, decreases in diameter and is firmly fixed to the crosshead pin. Together with the terminal, the entire insulator is firmly fixed on the pin. The fastening of the wire to the insulator is then carried out in the usual way.

The implementation of the invention

At the enterprise, the applicant made samples of insulators with metal terminators and an insulating body made of silicone rubber. The fabricated and tested samples showed sufficient strength for normal operation of the fastening of the insulator with the wire on the yoke pin. With different methods of fastening the wire on the upper and lateral annular groove, the breaking loads down and sideways exceeded those of the compared traditional insulators. In this case, the value of the destructive lateral load was determined not by the strength of the insulator, but by the strength of the metal pin of the crosshead on which it is mounted. The load directed upwards, which may occur when the icing of wires is reset, also exceeded analogues. The body of the insulator became possible to reduce in diameter to almost the diameter of the pin of the traverse of the power line and significantly reduce the consumption of silicone rubber. By reducing the diameter of the insulator significantly increased electrical performance of the insulator. As tests of the samples showed, the voltage increased by 30% before being covered by an electric arc during contamination and wetting, and the voltage maintained by the insulator in the dry state increased by 25%.

Types of tests that the proposed insulators have passed.

1. Heat resistance tests: the number of cycles of different heating and cooling 3, the exposure time when heating, cooling 15 minutes, the temperature drop of hot and cold water 90 degrees, the test time by the action of a continuous stream of sparks 1 min.

2. Test destructive mechanical force in bending: normalized mechanical destructive force of 17-19 kN, while the bent pin of the yoke.

3. Breakdown test: the normalized value of the specific volumetric electrical resistance of the insulating medium is (1-5) 107 Ohm / m, the actual value of the breakdown voltage is 170-200 kV (insulators did not break through).

4. Test withstand voltage of 50 Hz in dry condition and in the rain:

withstand voltage with a frequency of 50 Hz / kV;

in the dry state 74-76.

in the rain 52-56;

atmospheric conditions during testing:

P = 1.014 · 105 Pa, t = 20.2 °.

pollution = 9.5 g / m ² .

The insulators also withstood pulsed voltage tests with a steep wave front.

The thermal resistance of the insulator is limited only by the thermal resistance of organosilicon rubber and metal terminators and can be up to 350 degrees. Such thermal resistance is not characteristic of any known porcelain or glass insulator. The elastic properties of the insulator and the absence of brittle parts make it possible to transport insulators without a fight. The absence of a porcelain part eliminates vandalism against insulators and reduces the risk of guns being shot dead. Reducing the weight of the insulator saves on transportation costs.

The design of the insulator and the method of mounting it on the pin are illustrated by drawings.

In all the drawings, the following notation:

1 - electrical insulating body made of silicone rubber

2 - terminal for attaching to the yoke pin

3 - place for mounting the wire

4 - fins of silicone rubber insulator

5 - terminal made in the form of a sleeve with a female thread

6 - terminal made in the form of a heat-shrink sleeve

The wire in all the drawings is conventionally not shown. The wire is fixed in any traditional way on the upper or side groove of the insulating body.

Figure 1 is a view of a pin insulator containing an electrical insulating body (1) with ribs (4), a wire attachment point (3) and a terminal (2), made in the form of a metal tube for a snug fit on the yoke pin.

Figure 2 is a view of a pin insulator containing an electrical insulating body (1) with ribs (4), a wire attachment point (3) and a termination (5), made in the form of a metal sleeve with an internal thread for screwing onto a metal crosshead pin.

Figure 3 is a view of a pin insulator containing an electrical insulating body (1) with ribs (4), a wire attachment point (3) and a terminal (6) made in the form of a heat-shrink sleeve.

Claims (2)

1. An insulator containing an insulating body with ribs and a place for attaching a wire, characterized in that the insulating body is made of silicone rubber and further comprises a terminal for mounting on the yoke pin. 2. The insulator according to claim 1, characterized in that the terminator is made in the form of a heat-shrinkable sleeve.

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