Overhead power lines with voltage above 1 kV. Insulators and fittings

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Section 2. Sewerage of electricity

Overhead power lines with voltage above 1 kV. Insulators and fittings

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

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2.5.97. On overhead lines of 110 kV and above, suspension insulators should be used, the use of rod and support-rod insulators is allowed.

On 35 kV overhead lines, suspension or rod insulators should be used. Use of pin insulators is allowed.

On overhead lines of 20 kV and below, the following should be applied:

1) on intermediate supports - any types of insulators;

2) on anchor-type supports - suspension insulators, it is allowed to use pin insulators in the area on ice I and in uninhabited areas.

2.5.98. The choice of type and material (glass, porcelain, polymer materials) of insulators is made taking into account climatic conditions (temperature and humidity) and pollution conditions.

On overhead lines of 330 kV and above, it is recommended to use, as a rule, glass insulators; on overhead lines 35 - 220 kV - glass, polymer and porcelain, preference should be given to glass or polymer insulators.

On overhead lines passing in especially difficult conditions for operation (mountains, swamps, regions of the Far North, etc.), on overhead lines constructed on double-circuit and multi-circuit supports, on overhead lines feeding traction substations of electrified railways, and on large crossings independently against voltage, glass insulators or, if justified, polymer insulators should be used.

2.5.99. The choice of the number of insulators in garlands is made in accordance with Ch. 1.9.

2.5.100. Insulators and fittings are selected according to the loads in normal and emergency modes of operation of overhead lines under the climatic conditions specified in 2.5.71 and 2.5.72, respectively.

The horizontal load in emergency modes of supporting strings of insulators is determined in accordance with 2.5.141, 2.5.142 and 2.5.143.

The design forces in insulators and fittings should not exceed the values of breaking loads (mechanical or electromechanical for insulators and mechanical for fittings) established by state standards and specifications, divided by the safety factor for the material γm.

For overhead lines passing in areas with an average annual temperature of minus 10 ºС and below or in areas with the lowest temperature of minus 50 ºС and below, the design forces in insulators and fittings are multiplied by the coefficient of working conditions γd = 1,4, for the rest of the overhead lines γd = 1,0, XNUMX.

2.5.101. The safety factors for the material γm for insulators and fittings must be at least:

1) in normal mode:

at the highest loads - 2,5
at average operating loads for insulators:
for supporting garlands - 5,0
for tension garlands - 6,0

2) in emergency mode:

for 500 kV and 750 kV overhead lines - 2,0
for overhead lines 330 kV and below - 1,8

3) in normal and emergency modes:

for hooks and pins - 1,1

2.5.102. As a design emergency mode of operation of double- and multi-circuit supporting and tension insulator strings with a mechanical connection between insulator circuits (2.5.111), one circuit break should be taken. In this case, the design loads from wires and cables are accepted for the climatic conditions specified in 2.5.71 in the modes that give the highest load values, and the design forces in the insulator circuits remaining in operation should not exceed 90% of the mechanical (electromechanical) breaking load of the insulators.

2.5.103. The design of the supporting and tension strings of insulators should provide the possibility of convenient construction, installation and repair work.

2.5.104. Fastening of wires to suspension insulators and fastening of cables should be carried out using deaf supporting or tension clamps.

Fastening wires to pin insulators should be done with wire ties or special clamps.

2.5.105. Radio interference created by garlands of insulators and fittings at the highest operating voltage of the overhead line should not exceed the values normalized by state standards.

2.5.106. Supporting garlands of insulators of 750 kV overhead lines must be double-circuit with separate fastening to the support.

2.5.107. Supporting garlands of insulators for intermediate-corner supports of 330 kV overhead lines and above must be double-circuit.

2.5.108. On overhead lines of 110 kV and above in hard-to-reach areas, it is recommended to use double-circuit supporting and tension insulator garlands with separate fastening to the support.

2.5.109. In double-circuit supporting garlands of insulators, the circuits should be located along the axis of the overhead line.

2.5.110. To protect the wires of the loops (loops) from damage when they collide with the fittings of the tension garlands of the overhead line insulators with phases split into three or more wires, safety couplings must be installed on them at the points where the loop wires approach the fittings of the garland.

2.5.111. Two- and three-circuit tension garlands of insulators should be provided with separate fastening to the support. Tension garlands with more than three chains are allowed to be attached to the support at least at two points.

The structures of tension garlands of split-phase insulators and their attachment to the support must ensure separate installation and dismantling of each wire included in the split phase.

2.5.112. On overhead lines of 330 kV and above, in the tension garlands of insulators with separate fastening of circuits to the support, a mechanical connection between all circuits of the garland, installed from the side of the wires, must be provided.

2.5.113. In the tension garlands of insulators of 330 kV and higher overhead lines, screen protective fittings must be installed on the side of the span.

2.5.114. In one span of overhead lines, no more than one connection is allowed for each wire and cable.

In the spans of the intersection of overhead lines with streets (drives), engineering structures listed in 2.5.231 - 2.5.268, 2.5.279, water spaces, one connection per wire (cable) is allowed:

with steel-aluminum wires with a cross-sectional area for aluminum of 240 mm2 or more, regardless of the steel content;
with steel-aluminum wires with A / C ratios ≤1,49 for any aluminum cross-sectional area;
with steel cables with a cross-sectional area of 120 mm2 or more;
when splitting the phase into three steel-aluminum wires with a cross-sectional area for aluminum of 150 mm2 or more.

It is not allowed to connect wires (cables) in the spans of the intersection of overhead lines with each other on the crossing (upper) overhead lines, as well as in the spans of the intersection of overhead lines with overhead and ground pipelines for the transport of flammable liquids and gases.

2.5.115. The strength of the termination of wires and cables in connecting and tension clamps must be at least 90% of the breaking force of wires and cables in tension.

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

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