Installation of cable structures. Types of load-bearing structures

Publication date: 09/13/2018

What is cable structures?

Cable structures are load-bearing structures, these include: cable ducts, cable trays, sections, cable racks, consoles, scarves, tees, adapter brackets and other elements designed for laying power and control cables on outdoors, inside buildings and structures of energy facilities, including nuclear power plants in Russian Federation.

What are cable structures made of?

Cable structures are made of bent profiles of increased rigidity. Perforation provides not only ease of installation of structures and fastening of cables, but also their ventilation when heated, as well as rapid detection and elimination of fires on cable routes (including the use of automatic fire extinguishing). Perforation makes it possible to decontaminate cable routes at nuclear power plants and wash off dust from cables in conditions of especially dusty industries (pulverized coal production, woodworking plants, etc.).

Benefits of using

The use of bent profiles of increased rigidity allows, with a low metal consumption, to provide a large load capacity and increased structural strength. Thanks to the zinc coating, these structures can be used in both cold and maritime tropical climates.

A wide range of cable structure elements is provided, which allows:

• install cable routes of any configuration without welding;
• separate cable systems for fire extinguishing, communications, etc. from the main cable flows in compliance with all norms and rules for the joint laying of cables for various purposes on the same cable structures.

View climatic version- U2. Т1 in accordance with GOST 15150. Nominal values ​​of environmental climatic factors in accordance with GOST 15150. Other types of climatic modification are allowed upon agreement with the customer.

The listed products serve primarily for fastening and mounting trays, perforated profiles, boxes and other structures intended for laying cable routes and wires.

Such products create a single structure that makes it possible to simply and with high reliability fasten both elements of electrical structures under the cable, and the cable itself directly on ceilings, walls, floors, load-bearing beams, columns, etc. Examples of installation of load-bearing structures.

Cable shelves and racks are used when laying routes, wires, lines from trays in a horizontal position (on columns, walls, etc.), when designing a route in several tiers.

The GEM stand is attached to the bearing surface (vertical) with brackets. A minimum of two staples are required to secure one element. The shelf is installed in it using the K1156 key and a dovetail.

In the graph below you can see the comparative load characteristics of the models load-bearing structures.

Supporting structure "rack-shelf"

Load characteristics of the supporting structure "rack-shelf"

Types and application of racks

To install shelves, use models K1150-K1155. They differ in length and, accordingly, the number of holes. They are fastened to the wall or column with brackets K 1157. Fastening by welding is allowed to metal structural elements. Perforated holes for fastening shelves are arranged in 50 mm increments.

The analogue of the described models are cable racks S-400 and S-2200.

For installation of cable shelves, perforation has certain differences: there is no fixing tongue.

Cable shelves models K1160-K1164

Shelves have different lengths and different load capacity. Made with perforations. Its pitch is 30 mm, the hole has a size of 10 * 20 mm.

Before laying cables, mark the route of the laying and strengthen the fastening structures. Pipes are placed in places of passages through walls and ceilings. If cable segments, together with couplings and end fittings, are prepared according to measurements centrally in workshops, then instead of pipes, openings are left for the subsequent installation of detachable ones; protective covers.

Paper and plastic insulated cables passing through the walls and ceilings of buildings can contribute to the spread of fire.

To protect against the passage of fire from one room to another, passages through walls and ceilings are sealed after installation with non-combustible materials. So that the passages can be easily released in the event of a cable change, easily punched solutions are used, for example, cement grade 300 - 500 s sand 1:10 by volume, or clay with sand 1:3 by volume, or clay with cement and sand 1.5:1:11 by volume.

Cable entries into buildings are usually part of the cable line, and only in some cases (cramped places) cable entries into buildings are made from the nearest

supports overhead line. Figure 60 shows the head of a reinforced concrete support V L 0.4 kV (terminal), from which cable entry is made. In addition to the cable end mast for a four-wire cable (4 KM), arresters for protection against atmospheric surges (RVN-0.5) and an outdoor lighting lamp (SPO-200) are also installed here.

The grounding conductor of the cable box is connected to the upper grounding terminal of the support (strut and strut), and the lower grounding terminals of the support - to the grounding conductor mounted in the ground. The cable is lowered into the ground along the strut, strengthened

Rice. 60. Installation of a cable box on the end reinforced concrete support of a 0.4 kV overhead line: 1 - support post; 2 - ground conductor; 3 - arrester RVN-0.5; 4 - branch clamp; b - cable box 4KM; 6 - loop ram clamp.

brackets and protected at an accessible height with a steel pipe.

Cable entries into buildings from trenches can have different designs depending on local conditions (Fig. 61). If significant soil subsidence is not expected at the cable entry points, then the cable stock can be left either in a horizontal or vertical plane.

The cable stock (approximately 1 m) is laid in an incomplete loop. The bending radius must not be lower than that allowed for this brand of cable. The value of the temporary elevation of the backfill above the planning mark, the cable reserve, the thickness of the backfill are taken based on local conditions and depending on the possible amount of soil subsidence. The depth of the cable at the entry points to the buildings must be at least 500 mm.

The diameter of the pipe is chosen depending on the thickness of the cable, and the length of the pipe is determined by the thickness of the wall.

To protect against strong subsidence of the soil, they lay
reinforced concrete slab (Fig. 61, b). Hole width in
wall (dimension A): 500 mm for one cable and 650 mm for
two cables. Plate width 500 and 650 mm respectively
(the size).

Rice. 61. Entering cables from trenches into the building:

a - with small expected plantings of soil; b - with significant subsidence of the soil; 1- power cable; 2- slabs or bricks (cable protection); 3- fine earth or sand; 4- sand without admixture of clay and stones; 5 - pipe seal; 6- - concrete grade 100; 7 - waterproofing 8 - pipe; 9 - reinforced concrete slab; A - the width of the hole in the foundation; B - plate width.

When mounting a cable entry to a shield or shield installed directly on the wall of the building through which the input is made, the cable is passed through a curved pipe. Figure 62 shows the designs of such inputs to buildings with wooden block and chopped walls. For buildings with brick and reinforced concrete, as well as with frame-backfill walls, the input device differs only in the way it is attached to the walls (brackets on dowels or wood screws).

The diameter and length of the pipes are determined by the thickness of the cable, the thickness of the walls, the height of the floor. The smallest bending radius of the pipes is selected according to the brand of cable with the expectation that the cable pulled into the pipe has a bending steepness within the allowable range (Fig. 55). For example, for the passage of unarmored cables with rubber insulation, the pipe must be bent with a radius equal to at least six pipe diameters, and for cables with plastic or paper normally impregnated core insulation, armored or unarmoured, with a radius equal to fifteen diameters. For a cable up to 20 mm thick, lay a pipe with an inner diameter of 25-30 mm; and for a cable up to 30, 40 mm, respectively, pipes with a diameter of 50, 70 mm.

Rice. 62. Options for cable entry from trenches into buildings

at the location of the input shield in the building on outer wall:

1 - power cable; 2 - cable protection (plates or bricks); 3 - seal, pipes; 4 - fine soil or sand; 5 - bushing; 6 - bracket; 7 - protective pipe 1.3 m long; 8 - coupling with a grounding nut; 9 - input pipe; A - size from the floor, equal to 1500 mm for wall-mounted shields or 150 mm for floor-mounted shields.

The places where the cable exits the pipe are sealed with cable yarn soaked in oil. If there is no cable yarn, then steel pipes can be sealed with cement. If asbestos-cement pipes are used to pass through the walls, they can be sealed with tow impregnated with bitumen. Pipe ends are sealed with yarn over a length of 300 mm, with cement over a length of 60 mm, and with tow over a length. 150 mm. At a low level ground water for wetting yarn (cable or hemp), you can use clay. -

The wall at the outlet of the pipe to the outside is covered with coating waterproofing or covered with hydrophobic sand or hydrophobic clay. In dry soils, the hydrophobic layer can be replaced by a layer of clean, doughy clay mashed with water.

Instead of pipes, profile metal can be used to protect the cable when it is pulled out of the trench to the wall,

Rice. 63. The output of the cable from the trench to. building wall with channel protection:

1- power cable; 2 - protection of bricks or slabs; 3 - channel; 4 - bracket.

for example, a channel (Fig. 63). Distance between cables (size BUT) 60 mm should be taken for cable thickness up to 20 mm, 70 mm for cable thickness up to 30 mm and 100 mm for cable thickness over 30 mm. The channel can be bent from 3 mm thick sheet steel. The following are the dimensions of the channel, depending on the thickness of the cable:

Cable thickness, mm Channel dimensions (channel width shelf width) for one cable, mm. Channel dimensions. and for two cables, mm

Up to 20 - Over 20 Over 30 32X32 50X50 60x60

80x32 120x50 160x60

When reconstructing air inlets of 0.4 kV overhead lines into buildings and replacing them with cable ones using existing passages in the walls of buildings, the input structure shown in Figure 64 is used.

Cable glands, if they are well made and properly maintained, are more reliable than air ones, since they are not affected by wind and ice, they cannot be closed by a wire throw, damaged when snow is thrown from the roof. They are safer, since all current-carrying parts are hidden under the shell.

Figure 64. Cable entry into the building when replacing the air entry, using existing passages in the walls of buildings:

1- power cable; 2 - bracket; 3 - funnel; 4 - sleeve

But it must be remembered that the cable insulation must always be high, and the metal sheaths and protective coatings- securely grounded.

Inside the building, cables are laid both openly (at a height of at least 2 m) and in the floors - in specially laid pipes, as well as in special trays or channels when in large numbers cables. Between the walls and columns of buildings, as well as under canopies, cables can be suspended on cables.

Cables laid horizontally in the building are rigidly fixed at the turns of the route and at the couplings. Cables laid vertically are fixed in such a way that there is no deformation of the sheath and connections under the influence of weight on the cable.

The cables protect against heat radiation from various heat sources and from the direct action of sunlight, with the exception of the northern regions (geographic, latitude more than 65 degrees), where protection from solar radiation is not required. The bare sheaths of the cable are protected at the attachment points by elastic pads. If a cable with a jute cover is laid in a trench and brought into the building, then the jute cover is removed on the cable section inside the building.

The pipes through which the cable is led out of the building must be sloped towards the trench and sealed to prevent water from entering the building.

In order to fire safety inside buildings, cables are used without external combustible sheaths or covers (for example, jute).

By wooden structures cables are laid with a gap from the bases to the cable of at least 50 mm. There must be gaps between cables in a bare aluminum sheath and concrete and brick plastered walls. If such walls are painted oil paint, the cables can be laid without gaps. If there is a danger of mechanical damage during operation, then armored cables or protection with boxes, angular steel, pipes are used. With a laying height of unarmored cables of less than 2 m, such protection is always required.

Dismantling the cable line:

Remove the fertile layer in a separate place. Remove barren soil. Remove brick. Remove sand pad. Remove the cable from the trench and the sleeve in the wall.

Routing

Installation of cable structures

1. General requirements. 4
2. The procedure for the production of works. 5
3. The need for machines and mechanisms, technological equipment and materials. 7
4. The composition of the brigade by profession.. 7
5. Solutions for labor protection, industrial and fire safety. eight
6. Scheme of operational quality control. 13
7. Work production schemes. fifteen
8. Reference list. 17

1. General requirements

The technological map was developed to perform a set of works on the installation of cable structures (racks, shelves, boxes, trays, pipes) for electrical installation work during the construction of the facility

The technological map has been developed in accordance with the requirements of the following regulatory and technical documentation:

• SNiP 12-03-2001. Labor safety in construction. Part 1 General requirements;
• SNiP 12-04-2002. Labor safety in construction. Part 2 Building production;
• SP 12-136-2002. Labor safety in construction. Solutions for labor protection and industrial safety in projects for the organization of construction and projects for the production of works;
• SP 126.13330.2012 Geodetic works in construction. Updated edition of SNiP 3.01.03-84;
• SP 45.13330.2012 Earthworks, bases and foundations. Updated edition of SNiP 3.02.01-87;
• SP 48.13330.2011 Organization of construction. Updated edition
  SNiP 12-01-2004;
• OR-91.200.00-KTN-108-16 "Procedure for the implementation of construction control of the customer when performing construction and installation works at the facilities of organizations of the Transneft system."
• OR-91.040.00-KTN-109-16 “Requirements for quality services of construction contractors at the facilities of organizations of the Transneft system”.
• OR-91.010.30-KTN-111-12 "Procedure for the development of projects for the production of work for the construction, technical re-equipment and reconstruction of objects of main oil pipelines and oil product pipelines."
• RD-93.010.00-KTN-011-15 Main pipeline transportation of oil and oil products. Construction and installation work performed on the linear part of the main pipelines
• OR-91.200.00-KTN-201-14 Main pipeline transport of oil and oil products. The procedure for organizing and exercising construction control over compliance with design decisions and the quality of construction of underwater crossings MN and MNPP
• RD-35.240.00-KTN-178-16 Equipment installation requirements automated systems process control

2. The procedure for the production of works

General technical requirements.

Prior to installation, it is necessary to carry out a set of organizational and technical measures and preparatory work:

1) organization of a team of workers;

2) appointment of a person responsible for the quality and safe performance of work (foreman, foreman);

3) providing workers with the necessary equipment, tools, inventory, fixtures, overalls and footwear in accordance with established standards;

4) providing jobs with the means of the first medical care, drinking water, fire fighting equipment;

5) inspection and testing of power tools;

6) delivery of equipment to the construction site.

All materials must comply with the requirements of regulatory documents and specifications.

The progress of work during the installation of cable structures (racks, shelves, boxes, trays):

1) according to the project, the installation sites of cable structures are marked;

2) drilling is carried out according to the marking;

3) installation of racks to the flyover / wall of the room;

4) installation of shelves to cable racks;

5) installation of boxes, trays on shelves with fastening with M8 bolts. With the help of connecting elements, the boxes are docked, the fastening of which is carried out with M6 bolts.

Works on the installation of cable ducts, trays are carried out in accordance with the requirements of SNiP 12-03-2001, SNiP 12-04-2002, PUE ed. 7, SP 76.13330.2016.

At the end of the installation work, the line of boxes should be straightened with the final tightening of all fasteners.

The progress of work during the installation of cable structures (pipes):

1) A section for laying pipes is marked;

2) a trench is being developed for laying pipes (on the marked area, a trench is dug with a depth of 0.9 m and a width of 200 mm to 1000 mm, depending on the number, brand and cross section of the cable cores in the trench);

3) temporary plugs are removed from the pipes;

4) plastic bushings are inserted into the ends of the pipes so as not to damage the insulation of wires, cables are also used when pulling into protective pipes; lubricants are also used;

Cables are pulled only into fully assembled pipelines. The open ends of the laid and fixed protective pipes before pulling cables and wires into them are closed with wooden or plastic plugs so that dirt does not get into the pipes.

When laying a cable in pipes, the pipes used must also have an inner surface that excludes damage to the insulation of the wires when they are pulled into the pipe and an anti-corrosion coating outer surface. In the places where the wires exit the pipes, heat-shrinkable insulating tubes are used.

Wires are fastened with clamps in junction boxes or at the ends of pipes. Wires and cables in pipes must lie freely, without tension.

The pipe diameter is taken in accordance with the instructions in the working drawings.

Monitoring the compliance of the work production process, the quality of work and identifying deviations and inconsistencies with the requirements of working and regulatory documentation, checking compliance with the sequence and composition of technological operations during construction is carried out at each stage of all work by the body of the Customer's IC and the Contractor's QC.

It is forbidden to start a new stage of work without a corresponding examination of the previous one by the Customer's IC body and the Contractor's CCM.

3. The need for machines and mechanisms, technological equipment and materials

Table 3.1

Equipment specified in Table 3.1 and hereinafter in this technological map can be replaced by the Contractor with a similar one available at the time of work, based on the required performance and technical characteristics.

4. The composition of the team by profession

The composition of the brigade is shown in table 4.1

Table 4.1

5. Solutions for labor protection, industrial and fire safety

When performing work, the following requirements must be observed:

– SNiP 12-03-2001 “Labor safety in construction. Part 1. General requirements”;

– SNiP 12-04-2002 “Labor safety in construction. Part 2. Construction production”;

- VSN 31-81. Production instruction construction works in protected areas of main pipelines of the Ministry of Oil Industry;

- SP 12-136-2002. Solutions for labor protection and industrial safety in projects for the organization of construction and projects for the production of works;

– GOST R 12.4.026-2015 System of labor safety standards. Signal colors, safety signs and signal markings. Purpose and rules of application. General technical requirements and characteristics. Test methods;

- SP 36.13330.2012 Code of Rules "Main pipelines"

- SP 52.13330.2011 Code of Practice "Natural and artificial lighting"

– Safety regulations for the construction of main steel pipelines;

– Rules for labor protection during construction (Order of the Ministry of Labor and social protection RF dated June 1, 2015 N 336n);

- Rules for labor protection when working with tools and devices (Order of the Ministry of Labor and Social Protection of the Russian Federation of August 17, 2015 N 552n);

– RD-13.110.00-KTN-260-14 “Main pipeline transportation of oil and oil products. Safety rules for the operation of the facilities of OAO AK Transneft”;

Persons not younger than 18 years of age, who do not have medical contraindications for performing this type of work, who have the appropriate qualifications, are allowed to work. independent work in accordance with the established procedure, having an electrical safety group not lower than II. The person responsible for carrying out the work must have an electrical safety group no lower than that of subordinate operational personnel.

Before starting work, the personnel must put on overalls and safety shoes, PPE appropriate for the weather conditions, in accordance with approved standards, a helmet with a chin strap. Overalls, safety shoes and PPE must be in good condition, fastened with all buttons and fasteners. It is not allowed to perform work in overalls and PPE contaminated with combustible or toxic materials that have expired.

Personnel operating the means of mechanization, equipment, fixtures and manual machines, before starting work, must be trained in safe methods and techniques of work with their application in accordance with the requirements of the manufacturer's instructions and labor protection instructions.

Being in the territory of work, all employees are obliged to comply with the internal labor regulations adopted in this organization.

Admission to the production area of ​​unauthorized persons, as well as workers in a state of intoxication or not employed at work in this area, is prohibited.

Cable laying workers must be provided with sanitary facilities (dressing rooms, dryers for clothes and shoes, rooms for eating, resting and heating, etc.) in accordance with the relevant building codes and rules and the collective agreement or tariff agreement.

Preparation for the operation of sanitary facilities and devices must be completed before the start of work.

At workplaces, workers must be provided with drinking water, the quality of which must comply with sanitary requirements.

In the sanitary facilities there should be a first aid kit with medicines, stretchers, fixing splints and other means of providing first aid to the injured.

Construction machines, mechanisms and equipment must be in good working order and adapted for their safe use, provided technical documentation for operation.

It is forbidden to operate construction machines without enclosing devices, interlocks, alarm systems provided for by their design.

Manual electric machines must comply with the relevant national standards.

The device and operation of electrical installations are carried out in accordance with the requirements of the Rules for the Arrangement of Electrical Installations (PUE), the Safety Rules for the Operation of Consumer Electrical Installations (PTB), the Rules for the Operation of Consumer Electrical Installations.

Workplace lighting

At dusk, a temporary lighting tower is installed on the site to illuminate the place of construction and installation work. Electricity is supplied from a mobile diesel or gasoline generator Contractor (diesel station). Norm of illumination of the construction site - 10 lux

On the basis of GOST 12.1.046-2014, electric lighting of construction sites and sites is divided into working, emergency, evacuation and security. At nightfall, work sites, workplaces, driveways and passages to them must be illuminated: at least 10 lux when performing earthworks; at least 100lux at the workplace when performing installation and insulation work; at least 2 lux on driveways within the working site; at least 5lux in the aisles to the place of work.

At night, lighting of the working pit should be carried out by searchlights or lamps in an explosion-proof design.

Fire safety

When performing work, it is necessary to strictly comply with the fire safety requirements aimed at preventing the impact of fire hazards, as set out in the following normative documents:

– RD 13.220.00-KTN-148-15 Main pipeline transport of oil and oil products. Fire safety rules at the facilities of the organizations of the Transneft system.

– Typical instruction on the procedure for conducting welding and other hot work at explosive, explosive and fire hazardous objects of the oil industry.

GOST 12.1.004-91. SSBT. "Fire safety. General requirements";

GOST 12.1.010-76. SSBT. “Explosive safety. General requirements";

Fire safety rules in the forests of the Russian Federation. Decree of the Government of the Russian Federation No. 417 dated June 30, 2007;

Rules of the fire regime in the Russian Federation. Decree of the Government of the Russian Federation
from 25.04.2012 №390

All employees engaged in work must be trained in PTM (fire-technical minimum), undergo fire safety briefings. Primary briefing at the workplace and targeted briefing before starting work should be carried out by the immediate supervisor of the work (foreman, site manager, etc.). Introductory briefing on fire safety should be carried out by a fire safety engineer, fire safety instructor.

Engineers of organizations responsible for carrying out the work must be trained in a specialized organization under the fire-technical minimum program. This requirement for the contractor should be included in special conditions contractor agreement, in accordance with clause 7.1.7 of RD-13.220.00-KTN-148-15.

The work foreman must check the implementation of fire safety measures within the work site. It is allowed to start work only after all measures to ensure fire safety have been completed.

The contractor's work supervisors are responsible for compliance by subordinate personnel with the fire safety rules in force at the facility and for the occurrence of fires that occurred through their fault, in accordance with clause 7.1.17 of RD-13.220.00-KTN-148-15.

The completion of work sites with primary fire extinguishing equipment, depending on the type and scope of work, must be carried out by the contractor in accordance with clause 7.1.18 of RD-13.220.00-KTN-148-15.

Roads and entrances to sources of fire-fighting water supply should provide access fire fighting equipment to them at any time of the day, at any time of the year.

When placing and arranging temporary (cars), be guided by the requirements of section 6.5.9 of RD-13.220.00-KTN-148-15.

It is necessary to establish a fire regime at the work site in accordance with the Rules for the fire regime in the Russian Federation (approved by Decree of the Government of the Russian Federation dated April 25, 2012 No. 390) and
RD-13.220.00-KTN-148-15.

Actions in case of fire

Actions of workers in the event of a fire

Each employee upon detection of a fire or signs of burning (smoke, burning smell, temperature increase, etc.) must:

a) immediately inform the fire brigade about this by phone; in this case, it is necessary to give the address of the object, the place of the fire, and also give your last name;

b) take measures to evacuate people and, if possible, preserve material assets, fire suppression by primary and stationary fire extinguishing means;

c) inform the dispatcher (operator) of the facility or the manager of the facility (senior official of the facility) about the fire.

Managers and officials of the facilities, persons duly appointed responsible for ensuring fire safety, upon arrival at the fire site, must:

a) report a fire to the fire brigade, notify the management and duty services of the facility;

b) in case of a threat to people's lives, immediately organize their rescue, using the available forces and means for this;

c) check the activation of automatic BPDs, if any, (fire extinguishing, cooling (irrigation), smoke protection, warning and evacuation control systems in case of fire);

d) if necessary, turn off the electricity (with the exception of the CCD), stop the operation of transporting devices, units, apparatus, take other measures that help prevent the development of fire hazards;

e) stop all work (if it is permissible according to the technological process of production), except for work related to fire extinguishing measures;

f) remove all employees who are not involved in extinguishing the fire outside the danger zone;

g) to carry out a general fire extinguishing guidance (taking into account the specific features of the facility) before the arrival of the fire department;

i) ensure compliance with safety requirements by employees participating in fire extinguishing;

j) simultaneously with extinguishing the fire, organize the evacuation and protection of material assets;

k) organize a meeting of fire departments and assist in choosing the shortest path to get to the fire;

l) inform the fire departments involved in extinguishing fires and conducting related emergency rescue operations with information about hazardous (explosive), explosive, highly toxic substances processed or stored at the facility, necessary to ensure the safety of personnel.

Upon the arrival of the fire department, the head or the person replacing him informs the fire extinguishing head of the constructive and technological features of the object, adjacent buildings and structures, the quantity and fire hazard properties of the stored and used substances, materials, products and other information necessary for the successful elimination of the fire, the operation of the fire protection system, emergency response systems, also organizes the involvement of the forces and means of the object to carry out the necessary measures related to the elimination fire and prevention of its development.

6. Scheme of operational quality control

Construction control should be carried out by the construction control units of the CCM at all stages of the implementation of all types of construction and installation work. It is prohibited to carry out construction and installation works without the participation of the JCC. Responsibility for the organization and quality of construction control is assigned to the contractor.

The CCM must carry out construction control during each technological stage of work. The results of the construction control are recorded daily in the construction control log of the contractor at the work site, the general work log and the notes and suggestions log. The construction control journal of the contractor is drawn up in accordance with Appendix B OR-91.200.00-KTN-108-16.

The following measures should be observed:

Written notification from the head of the section (flow) of the construction contractor to the responsible representatives of the customer and the IC body at the work site for the time sufficient to mobilize the customer's IC specialists, but not less than 1 calendar day, about the start of new stages and types of construction and installation works, about changing the number of brigades (columns) performing work, shifts of work performed, about the need to conduct an examination hidden works, as well as other cases requiring a change in the numerical and / or qualification composition of the customer's IC specialists, indicating the responsible representatives of the building contractor's body and representatives of the quality control service of the construction contractor.

Notification of the customer and the IC body of the need to carry out control measures for the acceptance of work performed 3 working days in advance if it is necessary to submit work that requires specialized control and measuring equipment.

Presentation of completed technological operations to representatives of the customer's IC authority and obtaining written permission in the form of Appendix B in the cases specified in clause 7.2.16 OR-91.200.00-KTN-108-16. In other cases, execution and signing of the AOSR (if it is provided for by the design / working documentation).

Execution of technological operations of the subsequent technological stage, only after obtaining the appropriate permission in the form of Appendix B in the cases specified in clause 7.2.16 OR-91.200.00-KTN-108-16, issued by the customer's IC specialist. In other cases - after the execution and signing of the AOSR (if it is provided for by the design / working documentation), indicating the permission to perform the next stage of work.

7. Acquaintance sheet

How power cables are arranged

Power cables consist of the following basic elements: conductive cores, insulation, sheaths and protective covers. In addition to the main elements, the cable design may include screens, protective earth conductors and fillers.

Power cables distinguish: according to the type of metal of the conductive conductors - cables with aluminum and copper conductors, according to the type of materials with which the current-carrying conductors are insulated, cables with paper, plastic and rubber insulation, according to the type of protection of the insulation of the cable cores from the influence of the external environment - cables in metal, plastic and rubber sheath, according to the method of protection against mechanical damage - armored and unarmored, according to the number of cores - one-, two-, three-, four- and five-core.

Each cable design has its own designation and brand. The brand of the cable is made up of the initial letters of the words describing the design of the cable.

Rice. 1. Cross-sections of power cables: a - two-core cables with round and segmented cores, b - three-core cables with belt insulation and separate sheaths, c - four-core cables with a zero core of round, sector and triangular shape, 1 - conductive core, 2 - zero core , 3 - core insulation, 4 - screen on conductive core, 5 - belt insulation, 6 - filler, 7 - screen on core insulation, 8 - sheath, 9 - armored cover, 10 - outer protective cover

Structural elements of power cables and their purpose.

Conductive conductors are conductors of electric current. Power cables have main and neutral conductors. Main conductors are used for transmission electrical energy, and zero - for the passage of the phase current difference at and uneven load.

The current-carrying cores of power cables are made of aluminum and copper, single-wire and multi-wire. The shape of the core is made round, sector or segmented (see Fig. 1).

Aluminum conductors of cables up to 35 mm2 inclusive are made single-wire, 50-240 mm2 - single-wire or stranded, 300-800 mm2 - stranded.

Copper conductors up to 16 mm2 inclusive are made single-wire, 25 - 95 mm2 - single-wire or stranded, 120 - 800 mm2 - stranded.

The neutral conductor or the protective earth conductor, as a rule, has a section that is reduced compared to the main conductors. It can be round, sector or triangular in shape and is located in the center of the cable or between its main cores (see Fig. 1).

The protective earth conductor is used to connect non-live metal parts of the electrical installation to the protective earth loop.

Insulation provides the necessary electrical strength of the current-carrying conductors in relation to each other and to the grounded sheath (ground). Paper, rubber and plastic (polyvinyl chloride and polyethylene) insulation is used.

Insulation applied to a cable core is called core insulation, and applied over insulated twisted or parallel conductors of a multi-core cable is called belt insulation.

It is impregnated with viscous impregnating compounds (oil rosin or electrical insulating synthetic).

The disadvantage of cables with a viscous impregnation composition is extremely limited opportunity laying them along inclined routes, namely, the height difference between their end terminations should not exceed: for cables with viscous impregnation up to 3 kV, armored and unarmored in an aluminum sheath - 25 m, unarmored in a lead sheath - 20 m, armored in a lead sheath - 25 m, for cables with viscous impregnation 6 kV armored and unarmored in lead sheath - 15 m, in aluminum - 20 m, for cables with viscous impregnation 10 kV armored and unarmored in lead and aluminum sheath - 15 m.

Cables with a viscous impregnating composition, the free part of which is removed, are called cables with lean impregnated insulation. They are used when laying on vertical and inclined routes without limiting the level difference, if these are unarmoured and armored cables in an aluminum sheath for voltages up to 3 kV, and with a level difference of up to 100 m - for any other cables with depleted impregnated insulation.

For laying along vertical and steep routes without limiting the level difference, cables are made with paper insulation impregnated with a special composition based on ceresin or polyisobutylene. This composition has an increased viscosity, as a result of which, when a cable laid vertically or along a steeply inclined route is heated, it does not flow down. Therefore, cables with such insulation can be laid to any height, just like cables with plastic and rubber insulation.

Rubber insulation is made from a continuous layer of rubber or from rubber bands, followed by vulcanization. Power cables with rubber insulation are used in AC networks up to 1 kV and direct current up to 10 kV.

They have isolation from polyvinylchloride plastic compound in the form of a continuous layer or from compositions of polyethylene. Cables with self-extinguishing (non-combustible) and vulcanized polyethylene insulation are also used.

Screens are used to protect external circuits from the influence of electromagnetic fields of currents passing through the cable, and to ensure the symmetry of the electric field around the cable cores. Screens are made of semi-conductive paper and aluminum or copper foil.

Fillers are needed to eliminate the free spaces between structural elements cable for the purpose of sealing, giving the necessary shape and mechanical stability of the cable structure. As fillers, bundles of paper tapes or cable yarn, plastic or rubber threads are used.

Power cable sheaths. Aluminum, lead, corrugated steel, plastic and rubber non-combustible (nayrite) cable sheaths protect the internal elements of the cable from destruction by moisture, acids, gases, etc.

The aluminum sheath of power cables for voltages up to 1 kV may be used as the fourth (zero) core in four-wire AC networks with a solidly grounded neutral, with the exception of installations with an explosive environment and installations in which the current is neutral wire under normal conditions is more than 75% of the current in the phase conductor.

Protective covers for power cables. Since cable sheaths can be damaged and even destroyed by chemical and mechanical influences, they are covered with protective covers.

Protective covers protect cable sheaths from external influences (corrosion, mechanical damage). These include the cushion, armor cover, and outer cover. Depending on the design of the cable, one, two or three protective covers are used.

The cushion is applied to the screen or shell to protect it from corrosion and damage by armor tapes or wires. The pillow is made from layers of impregnated cable yarn, PVC, polyamide and other equivalent tapes, crepe paper, bituminous composition or bitumen.

To protect against mechanical damage, the cable sheaths are wrapped depending on the operating conditions. steel belt or wire armor. Wire armor is made of round or flat wires.

Armor made of flat steel tapes protects cables only from mechanical damage. Armor made of steel wires, in addition to this, also perceives tensile forces. These forces occur in cables when cables are laid vertically at great heights or along steeply inclined routes.

To protect the armor of cables from corrosion, it is covered with an outer cover made of a layer of cable or glass yarn impregnated with bituminous composition, and in some designs, a pressed PVC or polyethylene hose is applied over the layers of yarn and bitumen.

In mines, explosive and fire hazardous rooms, it is not allowed to use armored cables of a conventional design due to the presence of a “cushion” containing combustible bitumen between the sheath and armor of the cable. In these cases, cables with a non-combustible "cushion" and an outer cover made from glass yarn from glass staple must be used.