Section 2. Sewerage of electricity

Overhead power lines with voltage above 1 kV. The location of wires and cables and the distance between them

Encyclopedia of radio electronics and electrical engineering / Rules for the installation of electrical installations (PUE)

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2.5.86. On an overhead line, any arrangement of wires on the support can be used: horizontal, vertical, mixed. On overhead lines of 35 kV and above with wires arranged in several tiers, the preferred scheme is to shift the wires of adjacent tiers horizontally; In areas with ice conditions of IV or more, it is recommended to use a horizontal arrangement of wires.

2.5.87. The distances between overhead line wires, as well as between wires and cables, must be selected:

1) according to the operating conditions of wires (cables) in spans in accordance with 2.5.88 - 2.5.94;

2) according to permissible insulation distances: between wires in accordance with 2.5.126; between wires and support elements in accordance with 2.5.125;

3) according to the conditions of protection against lightning surges in accordance with 2.5.120 and 2.5.121;

4) according to corona conditions and permissible levels of radio interference and acoustic noise in accordance with Ch. 1.3, 2.5.81, state standards, building codes and regulations.

The distances between wires, as well as between wires and cables, are selected according to the sag corresponding to the overall span; in this case, the sag of the cable should be no more than the sag of the wire.

In individual spans (no more than 10% of the total), obtained by arranging supports and exceeding the overall spans by no more than 25%, an increase in the distances calculated for the overall span is not required.

For spans exceeding the overall dimensions by more than 25%, the distances between wires and between wires and cables should be checked in accordance with instructions 2.5.88 - 2.5.90, 2.5.92 - 2.5.95, 2.5.120 and 2.5.121, while it is allowed to ignore the requirements of the application tables.

If there are differences in sag, wire designs and insulator strings in different phases of overhead lines, the distances between the wires (cables) in the span must be additionally checked. The check is carried out under the most unfavorable static deviations at standard wind pressure W0 directed perpendicular to the span axis of a given overhead line. In this case, the clear distances between wires or wires and cables for the conditions of the highest operating voltage must be no less than those specified in 2.5.125 and 2.5.126.

2.5.88. On overhead lines with supporting garlands of insulators with horizontal wires, the minimum distance between wires in a span is determined by the formula

where dgor is the horizontal distance between undeviated wires (for split wires - between the nearest wires of different phases), m;

del - distance according to 2.5.126 for internal overvoltage conditions, m;

Kv - coefficient, the value of which is taken from the table. 2.5.12;

f - the greatest sag at the highest temperature or with ice without wind, corresponding to the actual span, m;

λ - length of the supporting string of insulators, m:

for a span limited by anchor supports λ = 0; for spans with combined strings of insulators λ is taken to be equal to its projection onto the vertical plane;

for spans with different designs of insulator strings, λ is taken equal to half the sum of the lengths of the insulator strings of adjacent supports;

δ - correction for the distance between wires, m, is taken equal to 0,25 on 35 kV overhead lines and 0,5 on 110 kV and higher overhead lines in spans limited by anchor supports, in other cases δ = 0.

Table 2.5.12. Kv coefficient value^{1), 2), 3)}

1. Рwп - design wind load on the wire according to 2.5.54, N;

2. PI - design load from the weight of the wire, N.

3. For intermediate values ​​of Pwp/PI indicated in table. 2.5.12, Kв is determined by linear interpolation.

2.5.89. On overhead lines with supporting garlands of insulators with vertical wires, the minimum distance between undeviated wires in the middle of the span is determined by the formula

where dvert is the vertical distance between undeviated wires (for split wires - between the nearest wires of opposite phases) vertically, m;

del, f, λ, δ - the same as in 2.5.88;

Kg - coefficient, the value of which is taken from the table. 2.5.13;

Θ - angle of inclination of the straight line connecting the points of attachment of wires (cables) to the horizontal; at angles of inclination up to 10º it is allowed to take cos Θ = 1.

Table 2.5.13. The value of the coefficient Kg^{1), 2), 3)}

1. Рг.п - calculated ice load on the wire, N/m, determined according to 2.5.55;

2. PI - the same as in 2.5.88.

3. For intermediate values ​​of Pr.p/PI indicated in Table 2.5.13, Kg is determined by linear interpolation.

2.5.90. On an overhead line with supporting garlands of insulators with a mixed arrangement of wires (there are displacements of the wires relative to each other both horizontally and vertically), the minimum horizontal displacement dhor (for a given vertical distance between the wires) or the minimum vertical distance dvert (for a given displacement horizontally) is determined in the middle of the span depending on the shortest distances between the overhead line wires dhorizontal and dvert, calculated in accordance with 2.5.88 and 2.5.89 for actual conditions, and is accepted in accordance with table. 2.5.14 (for dhor < dvert) or table. 2.5.15 (at dhor > dvert).

Intermediate offsets and distances are determined by linear interpolation.

Distances determined according to 2.5.88, 2.5.89, 2.5.90 may be rounded to 0,1 m for booms with a sag of up to 4 m, to 0,25 m for booms with a sag of 4-12 m and up to 0,5 m for booms more than 12 m.

Table 2.5.14. Relationships between horizontal and vertical mixing of wires at dhor

Table 2.5.15. Relationship between horizontal and vertical displacements of wires at dhor>dvert

2.5.91. The distances between the wires selected in accordance with 2.5.89, 2.5.90 must also be checked for dancing conditions (see Tables P1 - P8 of the appendix). The larger of the two distances should be taken.

2.5.92. On overhead lines of 35 kV and above with suspended insulators with non-parallel arrangement of wires, the minimum distances between them should be determined:

1) in the middle of the span - in accordance with 2.5.88 - 2.5.91;

2) on the support: horizontal distances dhor - according to 2.5.88 with the wire sag f/16, the length of the supporting garland of insulators l/16 and Kv = 1; vertical distances dvert - according to 2.5.89 with sag f = 0 and Kg = 1.

The distances between the wires of overhead lines with metal and reinforced concrete supports must also meet the requirements: on single-circuit supports - 2.5.125, 2.5.126, on double-circuit supports - 2.5.95, and on overhead lines with wooden supports - requirements 2.5.123;

3) at a distance from the support of 0,25 span lengths: horizontal distances dhorizontal are determined by interpolating the distance at the support and in the middle of the span; vertical distances dvert are taken as for the middle of the span.

When the relative position of the wires in the span changes, the smallest distance between the wires is determined by linear interpolation of the minimum distances dhor or dvert, calculated at the points limiting the first or second quarter of the span from the support at which there is an intersection.

2.5.93. The distances between wires and cables are determined according to 2.5.88 - 2.5.90 twice: according to the parameters of the wire and the parameters of the cable, and the largest of the two distances is selected. In this case, it is possible to determine distances based on the phase voltage of the overhead line.

The choice of distances between wires and cables according to the dancing conditions is made according to the arrows of the wire sag at the average annual temperature (see appendix).

When there are two or more cables on an overhead line, the distances between them are selected according to the parameters of the cables.

2.5.94. On overhead lines of 35 kV and below with pin and rod insulators, for any arrangement of wires, the distance between them, according to the conditions of their approach in the span, must be no less than the values ​​​​determined by the formula, m,

d = del + 0,6f,

where del is the same as in 2.5.88;

f - sag at the highest temperature after drawing the wire in the actual span, m.

For f > 2 m, distance d can be determined in accordance with 2.5.88 and 2.5.89 for d = 0.

The distance between the wires on the support and in the span of the overhead line, regardless of the location of the wires on the support and the area on ice, must be at least 0,4 m.

2.5.95. On double-circuit supports, the distance between the nearest wires of different circuits, according to the operating conditions of the wires in the span, must satisfy the requirements of 2.5.88 - 2.5.91, 2.5.96; in this case, the indicated distances must be at least: 2 m - for overhead lines up to 20 kV with pin insulators and 2,5 m with pendant insulators; 2,5 m - for 35 kV overhead lines with pin and 3 m with pendant insulators; 4 m - for 110 kV overhead line; 5 m - for 150 kV overhead line; 6 m - for 220 kV overhead line; 7 m - for 330 kV overhead line; 8,5 m for 500 kV overhead lines and 10 m for 750 kV overhead lines.

On double-circuit supports of an overhead line, the distance between the nearest wires of different circuits must be at least 0,6 m for an overhead line with pin insulators and 1,5 m with pendant insulators.

2.5.96. Overhead line wires of different voltages above 1 kV can be suspended on common supports.

It is allowed to hang wires of overhead lines up to 10 kV and overhead lines up to 1 kV on common supports, subject to the following conditions:

1) Overhead lines up to 1 kV must be carried out according to the design conditions of high voltage overhead lines;

2) overhead line wires up to 10 kV should be located above overhead line wires up to 1 kV, and the distance between the nearest overhead line wires of different voltages on a support, as well as in the middle of the span at an ambient temperature of plus 15 ºC without wind, should be at least 2 m;

3) fastening of high voltage wires to pin insulators must be double.

In networks up to 35 kV with an isolated neutral, having areas of joint suspension with overhead lines of higher voltage, the electromagnetic and electrostatic influence of the latter should not cause a displacement of the neutral under normal network conditions of more than 15% of the phase voltage.

For networks with a grounded neutral exposed to higher voltage overhead lines, there are no special requirements regarding the induced voltage.

Overhead line wires can be suspended on common supports with overhead line wires 6-20 kV, as well as with overhead line and overhead line wires* up to 1 kV.

The vertical distance between the nearest wires of overhead lines and 6-20 kV overhead lines on a common support and in the span at a temperature of plus 15 ºС without wind should be at least 1,5 m.

When hanging on common supports wires of overhead lines 6-20 kV and overhead lines up to 1 kV or overhead lines, the following requirements must be met:

1) VL up to 1 kV or VLI must be carried out according to the design conditions of VLZ;

2) wires VLZ 6-20 kV should be located above the wires of overhead lines up to 1 kV or VLI;

3) the vertical distance between the nearest wires of overhead lines 6-20 kV and wires of overhead lines up to 1 kV or overhead lines on a common support and in the span at a temperature of plus 15 ºС without wind should be at least 0,4 m for overhead lines and 1,5 m for VL;

4) the fastening of 6-20 kV overhead line wires on pin and suspension insulators must be reinforced.

* Hereinafter, VLI is an overhead power line with self-supporting insulated wires.

See other articles Section Rules for the installation of electrical installations (PUE).

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