Section 4. Switchgears and substations

Switchgears and substations with voltages above 1 kV. General requirements

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

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4.2.17. Electrical equipment, current-carrying parts, insulators, fastenings, fences, load-bearing structures, insulating and other distances must be selected and installed in such a way that:

1) the forces caused by the normal operating conditions of the electrical installation, heating, electric arc or other phenomena accompanying its operation (sparking, emission of gases, etc.) could not harm the operating personnel, as well as lead to damage to the equipment and the occurrence of a short circuit (short circuit) or ground fault;

2) in case of violation of the normal operating conditions of the electrical installation, the necessary localization of damage caused by the short circuit was ensured;

3) when the voltage is removed from any circuit, the devices, current-carrying parts and structures related to it could be subjected to safe maintenance and repair without disrupting the normal operation of adjacent circuits;

4) the possibility of convenient transportation of equipment was provided.

4.2.18. When using disconnectors and separators for their external and internal installation for switching off and on no-load currents of power transformers, charging currents of overhead and cable power lines and busbar systems, the following requirements must be met:

1) disconnectors and separators with a voltage of 110-500 kV, regardless of climatic conditions and the degree of industrial pollution of the atmosphere, when installed outdoors, it is allowed to turn off and turn on the no-load current of power transformers and the charging currents of overhead and cable lines, busbar systems and connections that do not exceed the values, indicated in the table. 4.2.1;

2) disconnectors and separators with a voltage of 110, 150, 220 kV when installed internally with standard distances between the axes of the poles, respectively, 2; 2,5 and 3,5 m, it is allowed to turn off and turn on no-load currents of power (auto) transformers with a dead-earthed neutral, respectively, no more than 4, 2 and 2 A, as well as charging currents of connections no more than 1,5 A;

3) indicated in fig. 4.2.1 horizontal distances a, b, c from the columns and ends of the horizontal-swivel (HP) moving contacts in the off position to the grounded and current-carrying parts of adjacent connections must not be less than the distance between the axes of the poles d specified in Table. 4.2.1 and 4.2.2. These requirements for distances a, b, c according to fig. 4.2.1 are also applicable to disconnectors and separators with a voltage of 110-220 kV when installed internally according to clause 2.

Vertical distances r from the ends of vertically cutting (VR) and GP moving contacts to grounded and current-carrying parts should be 0,5 m more than distances d;

4) with 6-35 kV disconnectors and separators, when installed outdoors and indoors, it is allowed to turn off and turn on no-load currents of power transformers, charging currents of overhead and cable power lines, as well as ground fault currents that do not exceed the values ​​\u4.2.2b\u4.2.1bspecified in Table. 4.2.3. (see Fig. 4.2.2) and Table. XNUMX (Fig. XNUMX, a and b).

Dimensions of insulating partitions for standard three-pole disconnectors are given in table. 4.2.4 in accordance with fig. 4.2.2, a and b;

5) for disconnectors and separators installed horizontally, the descents from the flexible wire should be laid hollow to avoid transferring the arc to them, avoiding an arrangement close to vertical. The angle between the horizontal and the straight line connecting the descent suspension point and the linear clamp of the pole must be no more than 65º.

Busbars made of rigid tires should be carried out so that at a distance 'c' (see Fig. 4.2.1) the tires approach the disconnectors (separators) with a rise or horizontally. Inadmissible convergence of busbars with moving contacts for horizontal rotary disconnectors and separators is shown by a dotted line;

6) to ensure the safety of personnel and protect them from the light and heat effects of the arc, install roofs or canopies made of non-combustible material over the manual drives of separators and disconnectors. The construction of peaks is not required for disconnectors and separators with a voltage of 6-35 kV, if the disconnected no-load current does not exceed 3 A, and the disconnected charging current does not exceed 2 A;

7) drives of three-pole disconnectors 6-35 kV when installed internally, if they are not separated from the disconnectors by a wall or ceiling, to be provided with a blind shield located between the drive and the disconnector;

8) in electrical installations with a voltage of 35, 110, 150 and 220 kV with disconnectors and separators in the same circuit, disconnect an unloaded transformer, autotransformer, bus system, power lines remotely with a separator, and switch on with a disconnector.

Rice. 4.2.1. The boundaries of the location of open moving contacts of the disconnector (separator) in relation to grounded and current-carrying parts

Table 4.2.1. The highest no-load currents and charging currents switched off and on by disconnectors and separators 110-500 kV 12

1. VR - vertically chopping, GP - horizontally rotary, PN - suspended, PNZ - suspended with advanced shutdown and lagging switching on of the phase B pole.

2. The resulting no-load currents are given taking into account the mutual compensation of inductive currents of unloaded transformers by charging currents of their connections and charging currents of overhead or cable connections by inductive currents of unloaded transformers.

Table 4.2.2. The highest no-load and charging currents, earth fault currents switched off and on by disconnectors and separators 6-35 kV

a - vertical; b - inclined; 1 - insulating partitions

Rice. 4.2.2. Installing the disconnector (separator):

Table 4.2.3. The highest no-load and charging currents, earth fault currents switched off and on by disconnectors and separators 6-35 kV *

* With insulating partitions between the poles, the switched-off and switched-on currents are 1,5 times greater than the values ​​\u4.2.3b\uXNUMXbspecified in Table. XNUMX.

Table 4.2.4. Dimensions of insulating partitions

4.2.19. The choice of devices, conductors and insulators according to the conditions of short circuit. must be carried out in accordance with 1.4.

4.2.20. Structures on which electrical equipment, devices, current-carrying parts and insulators are installed must withstand loads from their weight, tension, switching operations, exposure to wind, ice and short circuit, as well as seismic effects.

Building structures accessible to the touch of personnel should not be heated by electric current above 50 ºС; inaccessible to touch - above 70 ºС.

Designs for heating may not be checked if an alternating current of 1000 A or less passes through the current-carrying parts.

4.2.21. In all circuits of the switchgear, it must be provided for the installation of disconnecting devices with a visible break, providing the possibility of disconnecting all devices (switches, fuses, current transformers, voltage transformers, etc.) of each circuit from all its sides, from where voltage can be applied.

A visible gap may be absent in prefabricated switchgears (including those filled with SFXNUMX gas - KRUE) with withdrawable elements and / or in the presence of a reliable mechanical indicator of the guaranteed position of the contacts.

This requirement does not apply to high-frequency arresters and coupling capacitors, voltage transformers installed on outgoing lines, as well as capacitive-type voltage transformers connected to busbar systems, arresters and surge arresters installed at the terminals of transformers and shunt reactors and on outgoing lines, as well as for power transformers with cable glands.

In some cases, due to circuit or design solutions, current transformers may be installed before the disconnecting devices.

4.2.22. When the switchgear and substations are located in places where the air may contain substances that worsen the operation of the insulation or have a destructive effect on equipment and buses, measures must be taken to ensure reliable operation of the installation:

• the use of closed substations and switchgear, protected from the penetration of dust, harmful gases or vapors into the room;
• the use of reinforced insulation and busbars made of a material resistant to the environment, or painting them with a protective coating;
• location of the substation and switchgear from the side of the prevailing wind direction;
• the use of a minimum amount of openly installed equipment.

When constructing substations and switchgears near sea coasts, salt lakes, chemical plants, as well as in places where long-term operating experience has established the destruction of aluminum from corrosion, special aluminum and steel-aluminum wires protected from corrosion, including polymer coating, or wires from copper and its alloys.

4.2.23. When the switchgear and substation are located in seismic areas, in order to ensure the required seismic resistance, along with the use of the available seismic-resistant equipment, special measures should be taken to increase the seismic resistance of the electrical installation.

4.2.24. In outdoor switchgear, switchgear, switchgear and unheated indoor switchgear, where the ambient temperature may be lower than the permissible temperature for the equipment, heating must be provided in accordance with the current equipment standards.

4.2.25. The busbars of the switchgear and substations, as a rule, should be made of aluminum and steel-aluminum wires, strips, pipes and busbars made of aluminum profiles and aluminum alloys for electrical purposes (for exceptions, see 4.2.22).

In this case, when deformations of the busbar, caused by temperature changes, can cause dangerous mechanical stresses in the wires or insulators, measures should be taken to exclude the occurrence of such stresses.

The design of a rigid busbar should include devices for damping tire vibrations and compensating devices to prevent the transfer of mechanical forces to the contact terminals of the devices and support insulators from temperature deformations and uneven settlement of support structures.

Conductors should be carried out in accordance with the requirements of Ch. 2.2.

4.2.26. The designation of the phases of electrical equipment and busbars of the switchgear and substations must be carried out in accordance with the requirements of Ch. 1.1.

4.2.27. Switchgears must be equipped with operational interlocking of incorrect actions during switching in electrical installations (abbreviated as operational interlocking), designed to prevent incorrect operations with disconnectors, earthing knives *, separators and short circuiters.

Operational blocking should exclude:

• voltage supply by a disconnector to the section of the electrical circuit grounded by the switched on grounding switch, as well as to the section of the electrical circuit separated from the switched on grounding switches only by a switch;
• the inclusion of a grounding switch in a section of the circuit that is not separated by a disconnector from other sections, which can be both energized and without voltage;
• opening and closing by load current disconnectors.

Operational interlocking should ensure in the circuit with a series connection of a disconnector with a separator, the switching on of an unloaded transformer by the disconnector, and disconnection - by the separator.

On the earthing switches of the line disconnectors on the line side, it is allowed to have only a mechanical interlock with the disconnector drive.

* In the following text of this chapter, instead of the words "grounding knife", the word "grounding switch" is used, which means both an element of the apparatus and a separately installed apparatus.

4.2.28. Switchgears and substations, as a rule, must be equipped with stationary grounding switches, which ensure the grounding of devices and busbars in accordance with safety requirements.

In a switchgear of 3 kV and above, stationary grounding switches must be placed so that portable grounding is not needed and that personnel working on live parts of any connection sections and busbars are protected by grounding switches on all sides from which voltage can be applied.

In case of disconnection during the repair process of the disconnector with earthing switches or only the earthing switch of this disconnector, earthing switches must be provided for other disconnectors in this section of the circuit, located on the side of the possible voltage supply. The last requirement does not apply to grounding switches on the side of linear disconnectors (in the absence of a bypass bus system or a repair jumper on the side of the overhead line), as well as to grounding switches in the sectional communication circuit of the switchgear.

On the grounding switches of linear disconnectors on the line side, as a rule, they should have a remote-controlled drive to prevent injury to personnel if they are turned on by mistake and there is voltage on the line; in GIS cells, these grounding switches, in addition, are recommended to have high-speed ones.

Each section (system) of busbars of 35 kV switchgear and above should, as a rule, have two sets of grounding switches. In the presence of voltage transformers, earthing of busbars should be carried out, as a rule, by earthing switches of voltage transformers.

The use of portable protective grounding is provided in the following cases:

• when working on linear disconnectors and on equipment located from the side of the overhead line to the linear disconnector;
• in sections of the circuit where grounding switches are installed separately from disconnectors, for the period of repair of grounding switches;
• for protection against induced voltage.

4.2.29. Mesh and mixed fencing of current-carrying parts and electrical equipment must have a height above the planning level for outdoor switchgear and openly installed transformers of 2 or 1,6 m (taking into account the requirements of 4.2.57 and 4.2.58), and above the floor level for switchgear and transformers installed inside buildings, 1,9 m; nets must have openings no larger than 25x25 mm, as well as devices for locking them. The lower edge of these fences in the outdoor switchgear should be located at a height of 0,1-0,2 m, and in the indoor switchgear - at floor level.

The use of barriers is allowed at the entrance to the chambers of switches, transformers and other devices for their inspection in the presence of voltage on current-carrying parts. Barriers should be installed at a height of 1,2 m and be removable. If the floor height of the cells above ground level is more than 0,3 m, it is necessary to leave a distance of at least 0,5 m between the door and the barrier or provide a platform in front of the door for inspection.

The use of barriers as the only type of fencing of live parts is unacceptable.

4.2.30. Oil level and temperature indicators of oil-filled transformers and apparatuses and other indicators characterizing the condition of the equipment must be located in such a way that convenient and safe conditions are provided for access to them and monitoring them without removing voltage (for example, from the side of the passage to the chamber) .

For oil sampling, the distance from the floor level or the ground surface to the crane of the transformer or apparatus must be at least 0,2 m, or an appropriate pit must be provided.

4.2.31. Wiring of protection circuits for automation, measurement, signaling and lighting, laid along electrical devices with oil filling, must be made with wires with oil-resistant insulation.

4.2.32. The calculated level of high (flood) waters is accepted with a probability of 2% (recurrence 1 time in 50 years) for SS 330 kV and below and 1% (recurrence 1 time in 100 years) for SS 500 kV and above.

4.2.33. Distribution devices and substations must be equipped with electric lighting. Light fittings must be installed in such a way that their safe maintenance is ensured.

4.2.34. Distribution devices and substations must be provided with telephone and other types of communication in accordance with the accepted service system.

4.2.35. Location of switchgear and substations, master plan and engineering preparation of the territory and their protection from flooding, landslides, avalanches, etc. must be carried out in accordance with the requirements of the SNiP Gosstroy of Russia.

4.2.36. The layout and design of the outdoor switchgear and indoor switchgear should provide for the possibility of using mechanisms, including special ones, for installation and repair work.

4.2.37. The distances between the switchgear (PS) and trees with a height of more than 4 m should be such that damage to the equipment and busbars when a tree falls (taking into account the growth of trees over 25 years) is excluded.

4.2.38. For switchgear and substations located in the area of ​​residential and industrial development, measures should be taken to reduce the noise generated by operating electrical equipment (transformers, synchronous compensators, etc.) to values ​​permissible by sanitary standards.

4.2.39. Substations with constant duty of personnel, as well as in the presence of residential buildings near them, must be provided with drinking water by installing a drinking water supply system, constructing artesian wells or wells.

4.2.40. For switchgear and substations with constant duty of personnel with water supply, insulated latrines with sewerage should be arranged. If there are no sewer mains near the substation, local sewer devices (sumps, filters) may be installed. For substations without constant duty of personnel, it is allowed to install non-insulated latrines with waterproof cesspools.

When a substation of 110 kV and above is located without constant duty of personnel near the existing water supply and sewerage systems (at a distance of up to 0,5 km), sanitary sewer units should be provided in the building of the control room.

4.2.41. The territory of the substation must be enclosed by an external fence in accordance with the requirements of the technological design standards of the substation.

On the territory of the substation, outdoor switchgear and power transformers should be enclosed with an internal fence 1,6 m high (see also 4.2.58).

Outdoor switchgear of different voltages and power transformers may have a common fence.

When outdoor switchgear (PS) is located on the territory of power plants, these outdoor switchgear (PS) must be enclosed by an internal fence 1,6 m high.

Fences may not be provided for closed substations, as well as for pole, mast and packaged substations of outdoor installation with higher voltage up to 35 kV, subject to the requirements of 4.2.132.

4.2.42. On the territory of outdoor switchgear, substations and power plants, devices should be provided for collecting and removing oil (in the presence of oil-filled equipment) in order to exclude the possibility of its spreading over the territory and getting into water bodies.

4.2.43. Distances from electrical equipment to explosive zones and premises should be taken according to Ch. 7.3.

4.2.44. On the substation, direct and alternating operating currents are used.

Alternating current should be used whenever possible and leads to the simplification and reduction in cost of electrical installations while ensuring the necessary reliability of their operation.

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

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