FI95632C - Wiring at a high voltage line for overhead lines with a voltage of about 60 kV or more - Google Patents

Description

1 95632

The present invention relates to a high-voltage line conductor for high-voltage overhead lines of about 60 kV and higher.

Until now, high-voltage overhead lines with a phase conductor voltage exceeding approx. 20 kV consist of clear, i.e. substantially uncoated, conductors. In this case, the conductors 10 must be placed in the column structures so that there is a sufficient distance between the conductors to prevent the conductors from colliding.

On the other hand, 20 kV so-called. The PAS conductor is an air conductor with a simple plastic coating that is used in this voltage range instead of bare conductors. The insulating material is often crosslinked polyethylene XLPE (PEX). The insulation is dimensioned to withstand the voltage stresses caused by the condensation of the conductors, but not to completely insulate the conductor like cables. Often, a PAS cable is an alternative to a much more expensive underground cable solution.

Insulators or coatings are not used in conductors above about 60 kV, and in particular in high voltage conductors of 110 kV and larger, because the insulating layers used in known overhead lines should be very thick to provide adequate insulation. Thus, the column structures, insulators and insulator and conductor accessories currently in use are designed mainly for clear conductors.

Over the last decade, more and more attention has been paid to the electric and magnetic fields generated by power lines and their potential effects on the health of people living nearby. Limit values for magnetic and electric fields have already been set for power lines in some US states and Italy.

35 The electric and magnetic fields generated by overhead lines can be affected by the mutual arrangement of the lines in the transverse plane. The smallest possible fields are obtained when the conductors are placed as close to each other as possible, e.g. at the vertices of an equilateral triangle. For conductors closer to each other, narrower conductor streets are also sufficient, which would result in savings, at least in land acquisition. However, in high-voltage, bare lines, the minimum distances required to avoid short circuits, overexertions, and corona phenomena have effectively prevented a substantial reduction in electric and magnetic fields on and around the line streets.

The object of the present invention is to provide a high-voltage conductor by means of which e.g. overhead lines suitable for narrower conduits and generating smaller electric and magnetic-15 fields. To achieve this, the high voltage conductor according to the invention is characterized in that the conductor is insulated and protected against penetration-induced breakthrough, so that the conductor insulating coating consists of 20 surrounding semiconducting layers and an outermost insulating layer.

With the appropriate choice of the insulating layer of the conductor according to the invention and the considerable investment in various tests to determine the safety and durability of the conductors, a thin and cost-effective high-voltage conductor has surprisingly been obtained which solves most problems of conventional power lines. Using the conductor according to the invention, the conductor streets in the case of 30, e.g. 110 kV, can be reduced from the current width of about 15 meters to about half (vertical placement), and e.g. the magnetic field strengths decrease significantly from the field strengths of existing wires.

Other preferred embodiments of the invention are characterized by what is claimed in the following claims 3,95632.

The invention will now be described in more detail by means of examples with reference to the accompanying figure, which shows a conductor according to the invention.

Figure 1 shows an example of a 110 kV conductor according to the invention with a round aluminum alloy conductor formed of twisted metal wire layers 3 with a diameter of about 20 mm, between the layers of which the passage of water is prevented, e.g. by grease or moisture-swellable powder. The conductor shield 4 is made of a semiconducting plastic or rubber material. The semiconductivity is generally obtained by doping about 30 ... 40% of the carbon black in the crosslinkable insulation material (when using a special carbon black, the semiconductivity can already be achieved by doping about 10%). In a 110 kV insulated conductor, the conductor protection layer is approximately 1 ... 2 mm thick. The purpose of the conductor shield is to smooth the voltage peaks on the surface of the conductor wound from metal wires, to prevent surface surges and to prevent the formation of partial discharge points.

The actual insulating layer 1 surrounding the semiconducting layer 4 is made of high-purity XLPE plastic, the thickness of which in the case of 110 kV is e.g. about 5 mm. Special purity is required to minimize the risk of high voltage breakdowns in the insulation material. Cross-linked polyethylene is used mainly because of the degree of purity, heat resistance, strength and insulation properties it achieves. The outer layer is approx. 1.5 mm thick, eg a weatherproof doped insulation layer. The carbon black content is preferably 2 to 3%, which guarantees sufficient protective properties for the layer, e.g. against UV radiation, without, however, causing too much conductivity to the surface layer of the conductor.

Instead of crosslinkable polyethylene (XLPE CPEX), ethylene propylene rubber, i.e. EP rubber (EDPM or EPR), can also be used as a raw material.

Other information about the 110 kV example conductor according to the invention includes an outer diameter of approx. 39 mm, mass 1730 4 95632

Other data of the 110 kV example conductor according to the invention include an outer diameter of approx. 39 mm, a mass of 1730 kg / km, a breaking load of 108 kN and a load capacity of 660 A. The conductor according to the invention can equally well be used for AC transmission, in which case three phase conductors are replaced by two. with wire (voltage + ground).

The conductor according to the invention is thus coated with an insulating layer considerably thinner than the normal cable structure, which is specifically dimensioned to withstand the collisions between the phase conductors in the tendon. Thus, the insulating layer does not even aim to completely insulate the conductor, but there are leakage currents of the mA class on the surface of the outer layer, so for example, touching the 110 kV conductor 15 with bare hands is life-threatening.

In experiments in which the two conductors were subjected to a voltage of 120 kV, the conductors were knocked together 540,000 times without breakdown. In addition, 17 days were performed with the same conductors. a durable leaning test in which the wires rested on each other, 20 without any breakthrough. Thus, the conductors according to the invention are allowed to strike each other, e.g. under the influence of wind and short-circuit forces. The required minimum conductor distances must therefore be calculated on the basis of relevant criteria other than the short-circuit case criteria. It has proved possible to reduce the spacing of 110 kV phase conductors from the current about 2 meters to about half.

In any case, it has thus been found that the coated conductors according to the invention make it possible to considerably reduce the phase intervals and to narrow the conductor streets. As a result, the field strengths of the electric and magnetic fields generated by the wire formed of the coated conductors are small compared to conventional wires.

Il 95632 maximum value CABLE B___ HWX 0.1 uT 0.2 μΤ Clear horizontal 1 33 23 Clear vertical 0.68 33 21 Clear triangle 0.45 25 16 On. triangle 0.39 21 13 Top. horizontal 0.33 16 10 On. vertical 0.32 18 11 On. delta 0.21 13 6 Bmax = magnetic field flux density S 'Ο, ΙμΤ and 0.2μΤ = flux density decreases level at the distance of the number of meters indicated in the table from the center line of the line TABLE 1

Table 1 shows the magnetic flux densities of the high voltage overhead line on the ground for different types of lines. The comparison includes a standard uninsulated wire with horizontal, triangular and vertical configurations at normal 2 m phase intervals, as well as a coated wire according to the invention with horizontal, vertical, triangular and delta configurations and 1.15 m phase intervals. The initial data values for the measurement results shown in Table 1 are as follows:

- U = 123 kV

- Load current 100 A, P = 18 MW

- coated conductor: SAX 355, σ0 = 40 N / mm2 - Exposed conductor: Duck, σ0 = 40 N / mm2 •. 2 - Lightning conductor: Sustrong, σ0 = 60 N / mm

- Power cord temperature + 15 ° C

- Lightning conductor temperature + 5 ° C

- Height of the lowest power cable from the ground 5.9 m at a temperature of +70 C (minimum permitted height) - Tension ae = a = 200 m

With regard to the magnetic field, the following observations can be made from Table 1: - when the conductors have a horizontal position, the maximum value of the flux density decreases by about one third with the PAS line compared to the corresponding uninsulated conductor line 6 95632. The flux density decreases to the level of background radiation (= 0.1 μΤ) at distances of 33 m resp. 16 m from the center line of the line.

- when the conductors have a vertical position, the maximum value of the flux density of the PAS conductor drops by about half compared to a normal conductor. The flux density decreases to the level of background radiation at distances of 33 m resp. 18 m from the center line of the line.

- when the conductors have a three-position, the maximum value of the flux density of the conductor does not differ much from the value of a normal conductor. However, the flux density decreases with PAS conductors to the level of background radiation at a distance of 21 m from the centerline of the conductor, while in the case of a corresponding uninsulated conductor it is 25 m. free air gap, determine the location of the conductors. Thus, the structure on both wires is approximately the same. However, in the electric field strength measurements, it was found that the PAS lines achieve a halving of the peak value of the field strength.

- The delta location (equilateral triangle) of the PAS line is clearly the best solution for the fields. Compared to a standard uninsulated portal horizontal line, the maximum value of the flux density is only about one-fifth and to the level of background radiation, the flux density decreases already at a distance of 13 m from the line.

The conductor according to the invention can be manufactured in a known manner without major changes, e.g. in the insulation lines of the underground cable. With the triple compression technique, all the coating layers of the conductor can be obtained in one operation.

It will be clear to a person skilled in the art that the various embodiments of the invention are not limited to the examples given above, but that they can vary freely within the scope of the claims below.

Claims (5)

95632 High-voltage conductor for high-voltage overhead lines of approx. 60 kV and higher, characterized in that the conductor (3) is insulated and protected against breakthrough caused by contact with the second conductor, so that the conductive coating of the conductor (3) consists of a surrounding semiconducting layer (4). ) and the outermost weatherproof surface insulation layer (2), as well as 10 intermediate insulation layers (1) between them. Conductor according to Claim 1, characterized in that cross-linked polyethylene (XLPE) is used as the insulating material. Conductor according to Claim 1, characterized in that an EP rubber material (EPDM or EPR) is used as the insulating material. Conductor according to Claim 1, characterized in that the weather-resistant surface insulation layer (2) 20 is obtained by adding about 2 to 3% of carbon black to the insulation material. Use of a conductor (3) with an insulating coating and protected against penetration by a second conductor, the insulating coating of which consists of a surrounding semiconducting layer (4) and an outer surface insulating layer (2), and an actual insulating layer (1) therebetween. 60 kV and higher in AC and DC power lines. δ 95632