How to organize temporary power supply at a construction site? Temporary power supply for a construction site How to calculate the need for electricity for a construction site.

The design of the power supply system is based on the following normative documents:

* "Rules for the installation of electrical installations" (PES);

* "Rules technical operation electrical installations of consumers” (PTE);

* “Safety regulations for the operation of consumer electrical installations” (PTB);

* SNiP 3.05.06-85 Electrical devices.

* SNiP III-4-80 Safety in construction;

Calculation of the need for electricity

Calculation of the need for electricity in the POS

The need for electricity is determined in accordance with the PR part 1.

Need in electrical power is determined depending on the territorial location of construction, the size of the annual volume of construction and installation work and the construction industry according to the formula:

Pp \u003d (S / K) * K1 * P;

Where C is the annual volume of construction and installation works in million rubles;

K - the coefficient of reduction of the estimated cost of construction in a given territorial zone to the estimated cost for the first territorial belt, determined by Appendix. 1 PH part 1;

K1 is a coefficient that takes into account the change in the estimated cost of construction depending on the construction area, the average outdoor temperature and the duration of the heating period, the value of which varies from 0.78 to 1.58 for various territorial belts (see Table 1 PH part 1) ;

P - the need for electricity (kVA) for industries, taking into account the Cosf of electrical consumers (electric motors for driving machines and equipment, electric lighting, electric welding, electric heating of a long loaf, masonry, soil, heating of pipelines), demand factors, as well as losses in networks and for transformation (see Table 2 and Table 3 of the PH Part 1)

Calculation of the need for electricity in the PPR

In the PPR, to determine the design loads on the low-voltage busbars of the supply transformer substation, the method of demand factors is used, giving an error of + 10%.

In accordance with this method, all pantographs are divided into m groups with the same operating mode (passport relative duty cycle Pvp).

For engines of repeated - short-term operation (PV<1), номинальная мощность приводится к длительному режиму (ПВ=1) по формуле:

Where Pn, PBn are, respectively, nameplate power and nameplate duty cycle, indicative data on PB are listed in Table 3.

For welding machines, the rated power (kW) is determined by the formula

Where Sn is the nameplate power (kVA) and the nameplate value cos j n.

The value of the calculated active load Ррn for groups of n receivers homogeneous in mode is determined by the expression

Where: Pn - rated (installed) power of current collectors of construction machines, determined according to passport data or approximately according to table. 1, for outdoor lighting - according to specific power indicators (Table 2);

Kc - demand coefficient for a group of consumers more than two is determined from Table. 3, in the presence of one or two consumers, the demand coefficient must be increased to 0.7 ... 1.

Table 1.

Total installed capacity by types of consumers

Machine name	Installed power of electric motors, kW
Caterpillar diesel-electric and electric cranes of the MKG, RDK, DEK, KG, SKG and other types with a lifting capacity
20 to 50 tons	55.3 to 85
From 60 to 100 tons	88.3 to 118
Over 100 tons	132 to 220
Pneumowheel diesel-electric and electric cranes of the KS, MKP, MKT type, etc. with a lifting capacity
From 13 to 50 tons	34.5 to 165
From 63 to 100 tons
Tower mobile cranes of the MSK series with a load moment
From 1000 to 2000 kNm	40.5 to 62.5
Tower mobile cranes of the KB series with a load moment
Up to 1250 kNm
From 1250 to 2000 kNm	57 to 116.5
From 2400 to 2800 kNm	63.5 to 182
From 3200 to 4000 kNm
Tower attachment cranes type KB with load moment
From 2000 to 3200 kNm	75 to 137.2
Gantry cranes of the KKS, KK, K type with a lifting height of up to 11.5 m with a lifting capacity
10 to 20 tons
30 to 50 tons	81 to 82.5
Gantry cranes type KP, UK, UKP with lifting capacity
From 15 to 50 tons	59 to 66.5
Cargo lifts type GP with load capacity
From 320 to 500 kg
Over 500 kg
Lifts are cargo-passenger type
Overhead cranes
Welding transformers type STE-34 (capacity 408 kVA)
Installation for electric heating 500 kVA

Table 2.

Specific power indicators.

Name of consumers	Average illumination lx	Specific power per 1m² area.
Construction area in the work area
Main roads and passages
Secondary roads and passages
security lighting
Emergency lighting
Places of production of mechanized earthworks and concrete works
Installation of building structures and masonry
Pile work
Finishing work
Concrete, mortar and crushing and screening plants, dryers, compressor and pumping stations, boiler houses, garages, depots
Office and public spaces
Dormitories and apartments

Table3.

The value of the demand factors and power factors of current production.

Electrical receivers.		Power factor.	PV in shares
Electric excavators
Mortar and concrete units.
Mechanisms of continuous transport (conveyors, screws).
Tower cranes.
Drive winches
Electric welding equipment:
Single station welding converters,
welding transformers,
The same types TSP-1, TSP2,
Single station welding rectifiers,
6-gang welding rectifiers.
Equipment used in reinforcement work.
Water reduction installations.
Portable vibrators.
power tool
Drying heating devices.
Boiler rooms.
Installations of electric heating of concrete
Electric lighting interior,
The same outside.
Pumps, fans, compressors

The calculated active load of all m groups of receivers is defined as the sum of the calculated active loads of all groups.

The calculated reactive load Q p (kvar) is determined similarly

The weighted average calculated power factor cos s is determined from tg s from the expression

The total load S (kV * A) for the construction site as a whole (load on the low-voltage buses of the supply substation), taking into account the mismatch in time of the load maxima of individual consumer groups (Крm = 0.8¼0.9), is determined by the formula

The calculation of the total load S can be performed using a simplified formula

where L is a coefficient that takes into account losses in the network, taken equal to 1.05¼1.1;

Pc, Pt, Rov, Ron - respectively, the installed power (kW) of power consumers, for technological needs, lighting, outdoor lighting devices.

Power supply schemes.

Power supply schemes for construction sites should correspond to the expected dynamics of electrical loads and their distribution over the construction site, ensure minimal wire costs and power losses, provide for the widespread use of inventory portable and mobile devices, including integrated transformer substations

Power supply can be carried out from high-rise networks of energy systems, power plants of various departments, as well as own power plants.

Power supply schemes for industrial enterprises and construction sites are divided into external and internal power supply schemes. They are usually depicted in a single line image, three or more wires are depicted in one line, a three-pole knife switch is single-pole, etc.

External power supply schemes

Connections with the power system are determined by a number of factors, the most important of which are:

* the presence of power grids of power systems in the construction area and their remoteness from the latter;

* requirements for the reliability of the power supply of the receivers;

* selected sources of power supply;

* size of power consumption;

* period of providing power supply.

The number and voltage of the supply lines depends on the presence or absence at the construction site. Receivers of the first category, as well as from Locations of construction objects regarding power sources. External power supply can be carried out from the power system at different voltages; from 6 to 1150 kV (depending on the transmission distance and the required power).

Estimated transmitted power and transmission distance of electricity from district high-voltage networks are:

Up to 2000 kW at a voltage of 6 kV -5 - 10 km;

Up to 3000 kW at a voltage of 10 kV - 8 - 15 km;

The use of a power supply scheme along one dead-end line (Fig. 1) is permissible in cases where there are no receivers of the first category at the facility.

A power supply circuit with a branch from one line (Fig. 2) is a type of circuit (Fig. 1). It is used if a line passes near the project and the cross section of its wires is sufficient to connect an additional load to it, there is a power reserve at the power source, and the operating conditions allow such connection.

Internal power supply schemes

(Energy distribution per voltage. up to 1000 V)

The choice of an internal power supply scheme is influenced by a number of factors, the most important of which are:

* required degree of reliability;

* efficiency both in terms of the reduced costs and the costs of the conductive material;

* convenience and reliability of operation;

* location of receivers inside the object;

* schemes of external power supply;

* power of individual receivers;

* reliability of protection against overloads;

* The nature of the environment.

Internal power supply schemes are a combination of individual elements for which the following definitions are accepted:

¨ Feed lines designed to transmit electricity from a switchgear (shield) to a distribution point (RP) or a separate power receiver;

¨ Trunk lines designed to transmit electricity to several distribution points or power receivers connected to the line at different points;

¨ Branch- lines extending from the mains and intended for the transmission of electricity to one distribution point or power receiver;

¨ Power supply- supply lines, mains and branches from mains;

¨ Distribution network- all lines supplying inputs to electrical receivers;

Schemes of distribution networks of construction sites can be radial, main and mixed. When choosing a circuit, one should strive for the smallest number of intermediate links and steps (in terms of voltage ).

Radial power distribution schemes

Such schemes are used mainly in cases where power receivers (TP) are located in different directions from the power center (GTP or GRP). They can be single-stage or two-stage. Single-stage schemes are used on small construction sites, where the distributed power and areas are small.

Main distribution schemes

backbone called the power supply circuit of several substations from one line, which has a common disconnecting device on the supply side. These schemes are used in cases where: their groups are located in the same direction with respect to the substation,

On fig. 4 shows a main ring open circuit with a required power of more than 500 kVA.

On fig. 5 shows a diagram that can be used for concentrated loads on a small construction site. Jumpers on the low side make it possible to turn off part of the substations with a decrease in loads (night time, day off), and transfer the power to consumers to one transformer.

Figure 6 shows a diagram where the source of power supply is its own power plant, which is built, if possible, in the center of loads.

Power schemes for two parallel lines , connected to different and different sections of the supply switchgear, is used if there are more responsible receivers at the facility. A variation of the main circuit with single or double-sided power supply are the main ring circuits (Fig. 4).

The inexpediency of building a second line depends on the distance and is determined by economic calculation. It may be more beneficial to provide backup power from the facility's own power plants.

Sources of electricity.

For temporary power supply, the following sources of electricity are accepted:

· electrical lines and devices (transformer substations, distribution points) of the state energy system with a voltage of 35.10 and 6 kW;

· — energy systems, nearest industrial enterprises;

— own inventory power plants

The most preferred (economically feasible) source of electricity are permanent (existing or built in the preparatory period) transformer substations located on the construction site or in close proximity to it.

When there are no such transformer substations (networks or distribution points) nearby, the question of the source of electricity (own power plant or tap from the district high-voltage network) is made by economic calculation.

Inventory transformer substations are used to lower the voltage of electricity from 35, 10 and 6 kV to the value of 0.4 / 0.23 kV, which is necessary for powering construction machines and lighting (see Table 4).

Table 4

Inventory transformer substations.

	Power in kVA	Voltage, kV	Dimensions (length, width, height) in mm	Weight, kg
KTPN 62-320/180
(With universal input)				4940x3370x2270
(With universal input)				2695x2520x5120
				2710x1300x1150
				1198x5800x5050
				4710x2050x3500
SKTP-100/6-10				2300x1700x2400
SKTP-160/6-10				2760x1900x2630
SKTP-250/6-10				2760x1900x2630
SKTP-630/6-10				2690x3400x1800
SKTP-750/6-10				2960x3450x1808
SKTP-1000/6-10				2960x3450x1808

In cases where it is not possible to receive electricity from the power system or the nearest power plant at the site, temporary inventory power plants are used as a source of power supply. The parameters of some of them are shown in Table 5.

Table 5

The main indicators of mobile power plants.

Station brand	Power	Place of installation	Dimensions, m	Voltage, V
Small and medium power plants
			Frame with casing
			Frame with casing
			Frame with casing
			Caravan
			Van
			Van
			Van
			Van
			Wagon, Van
Large power plants
			Van, wagon
			Railway carriage	Car length 18.34

Power lines and inventory electrical devices.

The main elements of electrical networks are power lines (TL) and electrical devices used for the input, distribution, metering of electricity and protection of electrical networks from overloads.

In construction, overhead and cable power lines with a voltage of 6.10 and 35 kV are used to power transformer substations and voltages of 380, 220, 127, 36 and 12 V are used to power consumers (electric motors of machines, welding transformers, lighting fixtures, etc.). Reducing the voltage in the network to 12¼36 V is carried out by introducing secondary transformers.

Overhead power lines are widely used due to their lower cost compared to cable, ease of detection of damage sites and ease of repair.

The disadvantages of overhead lines are the possibility of damage to them as a result of external influences of wind, ice, lightning strikes, as well as the danger of electric shock to people in case of damage.

Overhead power lines are made of single-wire or multi-wire uninsulated or insulated (in areas of possible electric shock to people). The smallest cross-section of overhead line wires with a voltage of more than 1 kV: from copper, steel and steel-aluminum - 25 mm, from aluminum and its alloys - 35 mm.

To power electric lighting, power and technological receivers of low power (up to 100-150 kW), four-wire (three-phase) lines with a voltage of 380/220 V are used. ¼18 cm. Seven-meter logs are installed on reinforced concrete bases (stepchildren). The laying depth is usually taken equal to 1/5 of the column length.

The distance between the supports is taken from the condition of the strength of the supports, but not more than 30 m.

Minimum distance from overhead power lines voltage up to 1000 V with the largest sag should be, m:

* - to the surface in populated areas - 6, in uninhabited areas - 5

* - to the head of the railway rail -7.5;

* - to the roadbed - 7;

* - until it is crossed by low-current lines -1.2¼1.5.

Insulated wires must be suspended at a height of at least 2.5 m above the workplace, 3 m above the aisles and 5 m above the aisles, and at a height of up to 2.5 m, the electrical wires are enclosed in pipes or boxes. It is forbidden to lay air networks over buildings (except for non-combustible industrial ones at distances from the lower wire with a voltage of up to 35 kV to the roof of at least 3 m.

Overhead lines crossing Allowed :

* - if the upper line intersects the lower one at a distance of at least 6 m from the support;

* - if the wires of the higher voltage line pass over the lower voltage line;

* - if the distance between the wires of intersecting lines is at least 2 m.

Parallel tracing of overhead lines with voltage up to 1 kV with lines over 1 kV is allowed at a distance of at least 2.5 m for a voltage of 2¼20 kV and 4 m for a voltage of 35 kV.

The smallest horizontal distance from windows, balconies, etc. to the wires of an overhead power line with a voltage of up to 1 kV (with their greatest deviation) is taken equal to 1.5 m from blank walls -1 m.

At a voltage of 2¼20 kV, the distance of wires to the protruding parts of buildings is assumed to be at least 2 m.

The main overhead power lines are laid along the main passages in order to use supports for the installation of lighting fixtures.

cable lines are highly reliable, they do not clutter up the construction site. The issues of laying a cable line are solved using feasibility calculations, taking into account the development of the network, the responsibility and purpose of the line, the nature of the route, the method of laying, cable designs, etc. The route of the cable line is selected taking into account the lowest cable consumption and ensuring its safety from mechanical damage , corrosion, vibration, overheating, etc.

Cables are laid:

* in trenches with a laying depth of 0.7 m from the planning mark, and at the intersection of transport routes - at least 1 m;

* on the surface of the earth (or on low supports) in places where the probability of its damage is excluded;

* on high supports when hanging it from a rope in case of inexpediency of underground laying.

When laying cables, the following minimum horizontal distances (clear) in m between the cable with voltage up to 1000V and structures are accepted:

* - to the foundations and walls of buildings 0.6;

* - to water supply and sewerage 0.5;

* - gas pipeline-1

* - heat pipe-2

* - fences and pillars-0.6

To power mobile mechanisms, flexible

Cables in hermetic PVC or Nenrite (light resistant rubber) with copper wires in rubber insulation.

inventory devices , used for the electrical network of construction sites, can significantly reduce labor costs for temporary networks and increase the electrical safety of their work. Inventory devices include switchgear for networks with a voltage of 6-10 kV, input-distribution and distribution devices for networks with voltage up to 1000 V.

Starting the construction of a house, you definitely need to worry about the electrification of the construction site, since there is practically nothing to do at a modern construction site without the help of power tools. Concrete mixers, jackhammers, perforators, cutting machines, drills, welding machines are powered by electricity and greatly facilitate and speed up the construction stages, so temporary power supply of the construction site is the first stage of any construction.

Electrical network requirements

First of all, we provide the requirements for temporary power supply of the site where construction work is carried out:

1. Reliability. Uninterrupted power supply during the construction period.
2. Quality. Frequency and voltage must guarantee the operation of electrical devices.
3. Security. Maximum protection for personnel and operators on the construction site.

To do this, it is necessary to document the organizational issues associated with connecting to existing highways of sufficient capacity.

Organizational events

Depending on the location of the site on which the construction takes place, the choice of a method for supplying temporary power is carried out. The following points influence the choice of cable laying type:

• Distance from power lines.
• Type of object: residential building, warehouse or production workshop.
• Estimated power consumption.
• Choice of network: single-phase or three-phase.
• Condition of the nearest overhead power line.

Based on these options, the best way to install temporary power supply at the construction site is selected. This may be a connection to existing networks or the installation of an autonomous power generator. When connecting to the power grid, it is better to individually find out in the power grid and in the energy sales organization the calculation procedure and other conditions.

Features of connection to existing electrical networks

The first situation that we will consider is that construction is carried out in the immediate vicinity of one's own housing. The method of electrification from an already registered input is considered less expensive and more preferable. For the duration of the construction work, electricity is consumed, which is already present at the facility and payment for it occurs in accordance with the previously concluded contract. This option is suitable for temporary power supply of a private house.

After the construction of a new facility and, possibly, the dismantling of old buildings, it will be necessary to re-register the contract with the supply organization.

For this you need:

1. Specify the estimated power consumption.
2. Have an organization and a connection point for input.
3. Order project documentation.
4. Coordinate the project with the state technical supervision.
5. Carry out electrical work.
6. Call an electrical laboratory to evaluate and draw up a test report.
7. Conclude an agreement with the energy sales company, put the facility into operation.

All documents are provided in the photo:

Please note that in order to make temporary electrical wiring, you will also need to issue this package of documents.

In cases where the construction site is located far from power lines, it will be necessary to build a new overhead line (or lay a cable). To do this, you need to contact the power grid organization and write an application for a technological connection, after which you should be given a technical specification. After completing the documents, you must fulfill the conditions of the technical specifications and re-apply to the network organization to connect the shield to and seal the metering devices. For more information about connecting, see the video:

Input at the facility should be done as for permanent operation. To do this, you need to install an external vandal-proof shield with an IP54 protection class. The box is set in such dimensions that it is possible to install a meter and protection devices, sockets and grounding buses. You also need to provide a place for backup power supply.

During construction within a non-profit partnership, the cost of services for collective connections is much cheaper than dacha, horticultural and garage cooperatives. They have a transformer substation to which it is possible to connect. Many teams have already settled down and formed. Repair and modernization of equipment was carried out at their expense, transformers, laying of overhead lines. Newly appeared developers can be presented with monetary compensation from the work already carried out and the modernization of some equipment.

Another situation that I would like to consider is the temporary power supply of a private house from neighbors. If, due to reasons beyond your control, electrification is being debugged, and the deadlines are running out, then it is worth negotiating with the neighbors. If such a kind person was found, through an additional metering device, the power supply is connected for the period of repair and construction. The amount of output power is agreed in advance (control by metering device) and the installation of a protective restrictive device. In this way, it is easiest to make temporary wiring to the site.

Separately, it is necessary to consider such a method of supplying electricity as. From a technical point of view, generator sets provide high-quality electricity. Builders use them at their own discretion and do not depend on anyone. The disadvantage is the high cost of the generated electricity. This type of supply is mainly resorted to at the beginning of construction, when there was a hitch with temporary supply at the stage of paperwork.

Technical measures

After all organizational issues have been resolved and a temporary power supply scheme has been selected at the construction site, a place is determined for installing the input shield on a rack or support. An additional support is also installed if the site is more than 25 meters away from the power line (see, paragraph 2.4.12.). But this value may also differ downwards according to the EIC Chapter 2.4. clause 2.4.19. According to the rules, the input shield is installed at the border or territory of the applicant. From the introductory box, the marking of cable routes or power transmission poles to the place of work, power and lighting networks is already being done. For optimal distribution of power over the construction site, power wires are led to lifting mechanisms, to the concrete preparation area, to the woodworking area, to the place of welding work.

At the beginning of construction, the temporary lighting system may consist of several spotlights, and will be divided into main and emergency, local or general. You can learn more about it in our separate article.

Consumer connection diagrams

During the construction of the building, cable laying routes appear, the type and length of the cable, the characteristics of the loads are indicated, and a scheme for their inclusion is created. The connection scheme can be radial, ring, mixed wiring. Radial power is produced from one input, from which it is distributed by cables to power posts and lighting installations. If the developer has a backup generator, then the temporary power supply scheme will be ring or mixed type. The radial scheme is duplicated by the connection scheme from the generator set. This type of supply allows you to continue building in case of possible power failures.

Input design

One of our articles has already talked about self-reliance on a personal plot. The assembly technology of this shield is not much different, we recall the important points.

The meter and protection devices, such as, must be in a sealed box that prevents the ingress of moisture and foreign objects. It is also necessary to organize a grounding device, ground the shield and re-ground zero from the overhead power line (clause 1.7.61.), Organize the system (PUE chapter 7.1. clause 7.1.13). Do not forget to take all safety measures for the production of work.

Cable laying is possible both in trenches, in places where it will not experience loads from vehicles passing through it, and by hanging on a cable at a safe height. We recommend to study the technology in the country.

Security measures

Construction is always movement and movement, as a result of which unforeseen risks may arise. Therefore, there are special requirements for temporary power supply, since there is such a factor as the adverse effect of the atmosphere on the elements of electrical installations and their parts. Allied workers with a low tolerance group, or without qualifications, the presence of combustible and caustic materials at the construction site, the lack of grounding and potential equalization elements for electrical appliances.

When working in conditions of high humidity, it is necessary to follow the current rules of PUE 1.7.50-53, which prescribe protection, with indirect contact in cases where the voltage exceeds 50 volts AC and 120 DC. Also, to increase the safety of personnel working with power tools, it is necessary to use isolation transformers with a potential equalization system that combines all open cases using protective connectors in the socket.

When illuminating an object, the luminaires are selected with an IP54 protection class, for outdoor installation. By following our recommendations and current rules, you will minimize the risk of injury. Take care of yourself. Finally, we recommend watching a video that shows a shield for temporarily supplying the site with electricity:

That's all I wanted to tell you about what constitutes a temporary power supply for a construction site and what requirements are placed on it. We hope you found these basics useful and interesting!

To create normal lighting in the dark hours of the day or in darkened rooms, lamps with incandescent lamps or fluorescent lamps are used.

Calculation of the annual need for electricity for lighting is carried out using the method of specific installed power, applied when the size of the premises is more than 10 m 2.

Electricity consumption for lighting is determined by the formula:

W osv =	P · F · TO cn · T slave	, kWh,(3.7)

where P - specific power for lighting, W / m 2;

F - area of ​​​​the premises (site), m 2;

K cn - demand coefficient, taking into account the non-simultaneity of the operation of all lamps at once and losses in the network;

T slave - the operating time of the lamps per year, h.

The number of hours of lamp operation per year depends on the geographic latitude of the area, and is generally determined based on the average lamp burning time per day. For all sections of the drying section, except for the control corridor, laboratory and traverse corridor, 3285 hours should be taken, since during two-shift operation the average lamp burning time per day is 9 hours. For the control corridor, the traverse corridor and the laboratory, 4745 hours, since during three-shift operation, the average duration of the lamps is 18 hours.

Table 3.2 - Electricity consumption for lighting the drying area

Name of premises (sections)	The area of ​​the premises (plot),	Specific power,	Demand factor	Number of hours of lamp burning per year, h	Annual electricity consumption for lighting, kWh
Corridor of governance
Cooling platform
Disbandment area
Laboratory
Women's wardrobe
Men's wardrobe
The dining room
household corridor

3.1.3 Calculation of energy consumption for ventilation

Due to the fact that drying plants have increased heat and moisture emissions, supply and exhaust ventilation of the drying areas is necessary. The air exchange rate must be at least 1.5. On average, you can take the specific power of electric motors for supply and exhaust ventilation P = 2-3 kW per 1000 m 3 of the building.

The energy consumption for ventilation is determined by the formula.

The calculation consists in determining the power of the step-down transformer substation 380 / 220 W. Power consumption will include the operation of the engines of all machines (cranes, hoists, welding machines, etc.), all technological processes associated with the consumption of electricity (electric heating of concrete, soil, etc.) and lighting (external and internal). Power consumption is determined taking into account the unevenness and heterogeneity of consumption.

In each passage to the building, a distribution board is installed and electricity is supplied to it. Illumination of the entire construction site is carried out with the help of floodlights, which stand along the perimeter of the site at a distance of 20-30 m from each other.

The initial data for the organization of power supply are the types, volumes and terms of construction and installation works, types of construction machines and mechanisms, the area of ​​the construction site and the shift of work.

Estimated transformer power, kVA, with simultaneous consumption of electricity by all sources and is determined by the formula:

where 1.1 is the coefficient taking into account power losses in the network; R c is the power output of the machine or installation, kW; R c - power consumption for technological needs, kW; R ov - power consumption. Required for outdoor lighting, kW; R he - power consumption required for outdoor lighting, kW; k 1 , k 2 , k 3 , k 4 - demand coefficients depending on the number of consumers; cos φ - power factor, depending on the nature, number and load of consumers with power energy.

The calculation of the need for temporary power supply is given in the table below.

Table "Calculation of the need for temporary power supply"

Name of consumers	Unit rev.	Qty	Specific power per unit. meas., kW	Demand coefficient, Ks	Power factor, CosCh	Transformer power, kVA
Power electricity
tower crane	PCS.			0,5	0,7	35,71
Electric welding machines	PCS.			0,5	0,4	75,00
Total	110,71
Interior lighting
Foreman, household premises	M 2	220,65	0,015	0,8		2,65
Showers and latrines	M 2		0,003	0,8		0,13
Warehouses closed	M 2		0,015	0,35		0,14
Sheds	M 2	55,0	0,003	0,35		0,05
Total	2,97
Outdoor Lighting
Construction areas	100 m2	127,5	0,015			1,91
Emergency lighting	km		3,5
Total	141,91
Total 255.59

2.5. Construction site water supply

The initial data for determining the need for water are the accepted methods of production and organization of construction and installation works, their volumes and deadlines.

Water at the construction site is used for industrial, household needs, as well as in case of fire extinguishing.

Water supply networks pass outside the site, water is taken from the nearest well and pulled up to the entrance to the site. Hydrants with a diameter of 50 mm are installed every 40–50 m.

The calculation of the need for temporary water supply is completed by finding the diameter of the input of a temporary water supply to the construction site.

Sources of water supply for construction sites can be city networks or networks of industrial enterprises.

Table "Calculation of the need for temporary water supply"

Types of water consumption	Unit rev.	Qty	Specific water consumption, l	Coefficient of uneven consumption	Duration of water consumption	Water consumption, l/s
Production needs
Plaster work	M 2	7,89		1,5		0,002
Painting works	M 2	14,78	0,5	1,5		0,000
Tree planting	1 PC.	10,00		1,5		0,521
concrete preparation	M 3	45,03		1,5		0,586
Total	1,11
Household needs
Household and drinking needs	Pers.					0,19
Shower installations	Pers.				0,75	1,75
Total	1,94
fire fighting targets
Construction site area, up to 50 ha	ha
Total
Total	22,79

The water consumption for a permanent supply to the building is calculated according to the following formula:

The water consumption for a temporary supply to the building is calculated according to the following formula:

The diameter of the constant pressure water supply network, mm, is determined by the formula:

V- jet speed equal to 2 l / s

The diameter of the temporary pressure water supply network, mm, is determined by the formula:

V- jet speed equal to 1 l / s

The calculation of the construction site's need for electricity begins after the design of the construction plan.

Electricity at the construction site is used to power power plants, technological needs, internal lighting of sanitary and other temporary buildings, and external lighting of the construction site and work front.

The calculation of the temporary power supply of the construction site is reduced to determining the power of the transformer according to the formula:

P \u003d α (∑K 1s P s / cosφ + ∑K 2 c P t / cosφ + ∑K 3s. P ov + ∑P he), (21)

where cosφ is the power factor (accepted according to Table 22);

α - coefficient taking into account power losses in the network (assumed 1.05-1.1);

K 1s, K 2s, K 3s - demand coefficients depending on the number of consumers

(K 3s - taken equal to 0.8, and the values ​​​​of K 1s and K 2s according to Table 22)

P s - power of power consumers (accepted according to the schedule of electrical load in Table 23);

P t - power for technological needs (accepted according to the schedule of electrical load, table 23);

P ov - the power of indoor lighting devices. Determined from expression

P s =S N (22)

where S is the area of ​​household premises and closed warehouses (Tables 16,18);

N - specific power - is taken according to table. 76 textbook A.F. Gaeva, S.A. Usyk "Course and diploma design";

R he - the power of outdoor lighting devices, the sum of the power for lighting the territory (R str.on) and for lighting the work front in the second and third shifts (R fr.on).

To determine the period of maximum electricity consumption, based on the schedule of machines and mechanisms, the calendar plan, a schedule of electrical loads is built (see Table 23).

Table 22. Values ​​of demand factors (Kc) and power factors (cos φ)

Having determined the power of the transformer according to the above formula, we select the brand of the transformer according to table 83 of the A.F. Gaeva, S.A. Usyk "Course and diploma design" or other reference data.

Table 23. Electrical load schedule

Name of consumers	Unit rev.	Qty	Installed power of electric motors, illumination rate, kW	Total power, kW	Months
June	July	August	September
1 Power consumers
1.1 tower crane KB-100 0A	PCS
1.2 plastering station SPSh-4B	PCS		17,5	17,5			17,5
etc.
total: P c \u003d 57.5 kW							57,5 17,5
2 Technological needs 2.1 electric heating of concrete	m³	-	95-140
total: R t
3 Interior lighting
3.1 office	100m²	0,18	1-1,5	0,18	0,18	0,18	0,18	0,18
3.2 wardrobe	100m²	0,52	1-1,5	0,52	0,52	0, 52	0,52	0,52
etc.
total: Р ov = 0.7					0,7	0,7	0,7	0,7
4 Outdoor lighting
4.1 open warehouses	1000m²	0,8	8-1,2	0,64	0,64	0,64	0,64	0,64
4.2 security lighting	1000m²	0,706	1-1,5	0,706	0,706	0,706	0,706	0,706
4.3 installation work	1000m²	0,5	2,4	1,2		1,2
etc
total: P he \u003d 2.546					1,346	2,546	1,346	1,346

Note:

1. The installed capacity for power consumers should be taken according to reference data.

2. Technological needs in this example are not taken into account, because construction of our building is carried out during the summer period.

3. See tables 16, 18 for indoor lighting areas.

4. According to the schedule of electrical loads, the period of maximum electricity consumption is determined.

In the example, P c \u003d 57.5 kW, P ov \u003d 0.7 kW, P he \u003d 2.546 kW.

5. The maximum consumption is not determined by column 4, but by the graphic part.