RU2323495C1 - Silicon pin insulator and method for its attachment to cross-piece - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: proposed polymeric high-voltage pin insulator designed for use in overhead power transmission lines, primarily those rated at 6 to 35 kV, has metal cap with wire attachment means and insulating part with head and ribs; novelty is that its insulating part is made of tracking-resistant silicone rubber and its head is clamped during wiring procedure between cross-piece pin and insulator metal cap. Insulating part is composite structure. During installation and wiring nonsplit joint is made between head and pin.

EFFECT: enhanced operating reliability, simplified design, facilitated installation and wiring, reduced manufacturing cost.

4 cl, 6 dwg

Description

Technical field

The invention relates to electrical engineering. In particular, to high-voltage polymer pin insulators of overhead power lines (HVLEDs), designed for a voltage of mainly 6-35 kV.

State of the art

High-voltage insulators are known, consisting of a metal cap firmly connected by means of a cement-sand bond with a tempered glass part, and a dielectric rod in rigid connection with the glass part (SU 1529296, Cl. Н01В 17/20).

Also known is an insulator according to RF patent 2113741, consisting of a metal cap, an insulating part made of tempered glass, and a metal pin rigidly fixed in the insulating part.

A significant drawback of these analogues (SU 1529296, 2113741) is the use of tempered glass as the material of the insulating part as the most mechanically strong of the known commonly used insulating materials. Tempering provides increased heat resistance of the glass part, resistance to compression and bending. But together with hardness and static strength, the insulator acquires the properties characteristic of any glass: brittleness, low impact dynamic strength. In addition, due to the different coefficient of thermal expansion of metal and glass, it is necessary to compensate for different expansion values at the junctions of the glass part with the metal cap and pin. This is done by placing damping pads, grease, etc. Insulators with a glass part are heavy, which creates inconvenience during installation, and also have a large percentage of battle during transportation to the installation site, are subject to vandalism.

The closest prototype is an insulator containing an insulating part in the form of a mechanically strong dielectric rod (JP 2005079044, March 24, 2005), an organosilicon protective shell, and a metal concave shell, which acts as the head of an insulator for attaching a wire to it. The dielectric rod of this insulator is attached to the support beam using a special metal terminator with a threaded connection. The use of a dielectric rod carrying a mechanical load as an insulating part for these analogues complicates the design and leads to a rise in the cost of the entire insulator. Silicone silicone rubber in this insulator is used as a protective sheath and does not carry mechanical stress. In this case, the organosilicon shell does not fully perform electrical insulating functions and is not electrically loaded. This is because the capacity of the organosilicon shell is several orders of magnitude higher than the capacity of the dielectric pin, and therefore all operating voltage will be applied to the pin. In fact, one of the details here is superfluous. But the organosilicon shell in this insulator has the function of protecting the fiberglass rod from weathering, moisture, solar radiation, tracking and other adverse effects. A fiberglass rod provides strength to the insulator during bending loads from wire tension. Typically, the strength of the insulator when applying a bending force should be at least 13 kN. In this insulator, the fiberglass rod is the most short-lived and unreliable element, since fiberglass is destroyed by atmospheric influences, an open electric arc, leakage currents on the surface, etc. and wires to the insulator requires the use of additional terminators, materials (glue, grease) and sealing techniques. In addition, such an insulator can only be used on new lines under construction, since traditionally the traverses of power lines already have metal pins for mounting pin insulators on them.

OBJECTS OF THE INVENTION

The aim of the invention is to increase the operational reliability of the insulators, simplifying the design, simplifying installation and reducing the cost of manufacturing the insulator, with the possibility of use on traditional lines with metal pins on the cross beams.

Description and implementation example

The purpose of the invention is achieved in that the change in the design of the insulator eliminates the contradiction that exists in the design of the prototype: the dielectric rod must be able to withstand the bending load, and should not be, since it duplicates the electrical insulation functions of the silicone shell and is the weakest link in the insulator. The high-voltage insulator of the proposed design contains only two parts: a metal head with wire fastening means and an electrical insulating part with a head and ring ribs. The insulator is mounted on existing metal pins of the traverse of the VLEP supports. The design of the insulator has no parts that resist bending loads. All mechanical loads on the insulator from the wire are absorbed by the traverse pin through compression of the insulator body. The insulator is characterized in that the insulating part is not made of mechanically strong material, but, on the contrary, from elastic. Inside the insulator during operation there is no effort directed towards bending; only compression forces and pressure arise in the direction of the crosshead pin. Therefore, theoretically, the strength of the insulator of this design is equal to the bending strength of the pin of the support beam. The electrical insulating part is made of tracking resistant silicone rubber, and the head of the electrical insulating part during installation is pressed between the crosshead pin and the metal head of the insulator. The installation process consists in putting the insulator on the VLEP traverse pin, compressing the outer metal head of the insulator or compressing its part, as a result of which the head of the insulating organosilicon component is pressed onto the traverse pin and the entire insulator is fixed on this pin. Compression in the diameter of the head or part of the head of the insulator can be carried out in several ways: compression from the outside with a hand press with round dies, tightening the clamp, if the head is made in the form of a clamp or walls have slots for compression and the head contains a clamp, tightening with a screw, etc. After installation, the insulator and the yoke pin is a single body, wherein the metal head of the insulator is electrically isolated from the metal yoke pin. After that, wires are fastened to the insulator head in any known manner. There may be ring grooves on the head, and the wire is tied to these grooves with knitting wire.

The highly stressed, compressed (compressed) state of the rubber under the metal tip provides the necessary solid mechanical properties of the insulating body of the insulator. The mechanical load from the metal head down and bending to the sides is perceived by the metal pin through a layer of compressed rubber. Compression is achieved during installation of the insulator using one of the methods mentioned above.

The insulator can be made by combining a metal head and an electrical insulating silicone (silicone) part in the factory. Subsequently, the installation of the insulator directly to the power transmission tower or traverse is made as a single integral unit. It is possible to manufacture and deliver to installation on a high-voltage transmission line an insulator complete with an organosilicon insulating part and a head with wire fastening elements as two insulator parts, with their subsequent connection on a pin together by compressing the head on the insulating part.

In a compressed state, organosilicon rubber transfers loads from the weight of the wire downward and lateral bending loads from wire tension directly to the metal pin of the crosshead, since these loads are directed inside the organosilicon insulating part for compression. Long-term efforts on the insulator directed vertically upwards are not encountered in practice. Accidental loads from dancing wires after ice discharge are small and are compensated by shear stresses in the pressed rubber. Compression of rubber in the cap creates a sufficiently strong seal of the insulator head and the wires attached to it on the metal pin and eliminates the need for additional devices.

The insulating part made of organosilicon rubber is an excellent dielectric between the metal head of the insulator with the wires attached and the grounded pin of the yoke. The thermal resistance of such an insulator is more than 350 degrees and is limited only by the heat resistance of silicone rubber and the melting point of the metal of the head and pin. The electrical insulating part itself becomes a damping pad, compensating for the possible different coefficients of the thermal intrinsic expansion, as well as the expansion of the insulator head material and the metal of the VLEP traverse pin. As a result, the insulator can withstand sudden changes in temperature up to 300 degrees (thermal shock), which is an order of magnitude more than all existing insulators. 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 glass part eliminates vandalism against insulators and reduces the risk of guns being shot dead. Reducing the weight of the insulator saves on transportation costs. Ring ribs (concentric plates), which are part of the electrical insulating part, which are located on the pin below the cap, increase the length of the current leakage path over the surface of the insulator.

The use of organosilicon rubber as a tracking-resistant coating or sheath is used in many insulators to reduce leakage currents, impart hydrophobicity to the surface, but in this insulator this material is used as the main sole material of the insulating part, including mechanical stresses.

The electrical insulating part may be integral. With this option, there are several silicone rings (ribs) as separate elements, in the manufacture they are glued together or cured together and form an integral one insulating body.

The implementation of the invention

At the enterprise, the applicant manufactured the proposed insulators. The insulator was mounted on the pin of the support beam. The insulator head was a cap and was made of galvanized steel. Installation was carried out as follows:

- an insulating body of an organosilicon rubber was put on the crosshead pin;

- on the insulating body, on its head was worn a cap (cap) with side grooves for securing the wire;

- the metal cap was pressed on the insulating body with round dies with a diameter of 5 mm less than the initial diameter of the cap;

- AC70 wire was fastened to the side grooves of the cap using a knitting wire in accordance with the Electrical Installation Rules (PUE).

Installation of the wire took less than 2 minutes. A traditional installation using meerk soaked tow takes an average of more than 10 minutes. Reduce installation time by more than 5 times. The insulator along with the mounted piece of wire was placed on a testing machine. The following indicators were tested: breaking load, device behavior during vibration and dancing of wires, alternating fatigue loads, wire termination force, imitation of icing discharge from the wire. All tests showed good results and satisfactory operation of the device. All properties make it possible to effectively use the proposed device for fastening wires to pin insulators, especially for high-voltage power lines of 6-35 kV.

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

In all the drawings, the following notation:

1 - metal head of the insulator

2 - electrical insulating part of the silicone rubber insulator

3 - side groove on the cap for attaching the wire

4 - place of compression of the cap for fixing the insulator on the pin of the yoke

5 - a pin of a support beam

6 - the head of the insulating part of the insulator

7 - a collar

P - radial application of force when compressing the cap of the insulator

The wire in all the drawings is conventionally not shown. The wire is fixed in any traditional way.

Figure 1 - View of the pin insulator prior to installation. Compression will be performed along the side grooves on the cap of the insulator.

Figure 2 - View of the pin insulator after installing on the pin of the traverse and radial compression of the cap. Compression is done by round dies with a hand or mobile press (press not shown). The compression was made along the side grooves on the cap in the place of the subsequent fastening of the wire. The connection is one-piece and one-piece.

Figure 3 - View of the pin insulator prior to installation. Compression will be performed in a special place below the side grooves on the cap of the insulator.

Figure 4 - View of the pin insulator after installing on the pin of the traverse and radial compression of the cap. Compression is done by round dies with a hand or mobile press (press not shown). Compressed below the side grooves on the cap, the place of compression does not affect the fastening of the wire. The connection of the insulator with the pin is one-piece and one-piece.

Figure 5 - View of the pin insulator prior to installation. Compression will be done with a clamp. On the cap of the insulator, slots are made in the lower part to allow compression with small efforts from the clamp.

6 is a view of the pin insulator after installing on the pin of the traverse and radial compression of the cap. Compression is done by tightening the clamp at the bottom of the hood. Compressed below the side grooves on the cap, the place of compression does not affect the fastening of the wire. After installation, it is possible to dismantle the insulator by simply loosening the clamp.

Claims (4)

1. A pin insulator containing a metal head with wire fastening means and an electrical insulating part with a head and ribs, characterized in that the electrical insulating part is made of tracking resistant silicone rubber, and its head is clamped between the crosshead pin and the metal head of the insulator during installation of the insulator. 2. The insulator according to claim 1, characterized in that the electrical insulating part is made integral - its head and annular ribs are separate elements connected together. 3. The insulator according to claim 1 or 2, characterized in that during installation by radial crimping by a press, the walls of the metal tip are deformed and inseparably connected to the power line traverse pin through an organosilicon electrical insulating part. 4. The insulator according to claim 1 or 2, characterized in that the metal head of the insulator is made in the form of a clamp or contains a clamp with the possibility of reducing the diameter and, during installation, the insulator is fixed on the crosshead pin of the power transmission line by crimping by tightening the clamp through the insulating part.

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