On a construction site, electrical energy is needed for various needs. Sample list of consumers electrical energy at the construction site during the construction of the facility is given in Table 1.5.7.
All consumers of electrical energy can be combined into four groups:
Power consumers (P s);
Technological needs (P t);
Internal lighting (R.v.);
External lighting (R o.n.).
Table 1.5.8
Approximate list of electrical energy consumers at a construction site
| No. | Name of consumers |
| I | Power consumers: Electric excavators, mortar units, tower, gantry, bridge cranes, winches, lifts and other small mechanisms, continuous transport mechanisms, compressors, pumps, fans, welding transformers, etc. |
| II | Technological needs: Electric heating of concrete, soil heating, brickwork etc. |
| III | Outdoor lighting: Lighting construction site in the area of work, lighting of main and secondary passages and passages, lighting of work sites: mechanized, earthen; concrete; installation of building structures, masonry, rigging, roofing work, etc., lighting of open warehouses, emergency lighting, security lighting. |
| IV | Interior lighting: Lighting of offices, sanitary and public premises, lighting of places of work: finishing, glass, carpentry, etc., lighting of closed warehouses, emergency lighting. |
The following are used as sources of electrical energy used in the construction process to perform construction and installation work:
Stationary sources of electrical energy;
Mobile transformer substations;
Temporary power plants.
Stationary sources are used to receive electricity, reduce voltage and distribute electricity. For this purpose, transformer substations (TS) are used. Main step-down substations (MSS) receive electricity from power lines, reduce the voltage and distribute it throughout the construction area. GPPs have 220, 110, 35 kV at the input, and 35, 10, 6 kV at the output.
Conventional transformer substations (TS) or distribution TS convert electricity with voltages of 35, 10, 6 kV into 380/220 V or 220/127 V to power most consumers.
Mobile transformer substations They are complete transformer substations (CTS), which are connected via a cable or overhead line to the high voltage source of the power system.
Temporary mobile power stations used in the absence or insufficiency of permanent sources and networks providing construction with electricity. These are, as a rule, mobile power plants of various capacities: low and medium power – up to 100 kW with gasoline engines, and high power up to 1000 kW with diesel engines.
The total demand for electricity for any construction site (i.e., the amount of electrical power required for it) is calculated for the “peak” period - the period of maximum consumption by consumers.
The procedure for designing temporary power supply for a construction site is as follows:
Preparation of initial data;
Calculation of electrical loads for individual consumers;
Constructing a graph of electrical energy consumption by each consumer and a summary diagram of electrical consumption;
Transformer power calculation;
Organization of electric lighting and calculation of the number of spotlights;
Linking temporary power supply networks and conditions for placing electrical energy consumers.
Methods for calculating electrical loads
Estimated value electrical load can be determined in four ways. The first three methods give an approximate result and can be used in PIC development. The fourth method gives the most accurate results and is used in the development of PPR.
1. Calculation of loads based on specific electrical power;
2 Calculation of loads based on specific energy consumption (kW*hour);
3 Calculation of loads based on the installed capacity of electrical receivers and the demand factor without differentiation by type of consumer;
4 Calculation of loads based on the installed capacity of electrical receivers and demand factors with differentiation by types of consumers.
1. Calculation of loads based on specific electrical power
This method is based on the generalization of statistical data on the actual amount of electrical energy (kV*A) consumed during the construction of various objects per enlarged unit estimated cost annual volume of work for the corresponding type of construction. This method is usually used when developing PICs. Thus, the calculated power of the transformer ( R ) can be determined by the formula:
Р =р*С*k
R - specific power, kW*A/million rubles;
WITH - annual volume of construction and installation work in million rubles;
k – coefficient that takes into account the construction area and is accepted according to design standards.
2. Calculation of loads based on specific electricity consumption (kW*hour)
to the enlarged meter of the corresponding type of work is carried out according to the following formula:
R= R*V/T *cos
R - specific consumption of electrical energy per enlarged unit of measurement of the corresponding type of work (accepted from reference books);
V – volume of work for the year in natural meters;
T - the accepted annual number of hours depending on the intended intensity of work; when working in one or two shifts, it is taken equal to 2500...5000 hours per year;
3. Calculation of loads based on the installed capacity of electrical receivers and the demand factor without differentiation by type of consumer
Produced according to the formula:
Where: R - installed power of electrical energy consumers, kW;
K- demand coefficient taken from reference books;
cos - power factor, depending on the number and load of power consumers (accepted from reference books).
4. Calculation of loads based on the installed capacity of electrical receivers and demand factors with differentiation by types of consumers.
This method of calculating loads is the most accurate method for determining loads and is recommended to be used when developing PPR and, accordingly, when developing a diploma project.
Load calculations are performed in the following sequence:
Identification of the main consumers of electricity;
For each consumer, normative coefficients demand and cosj t;
The value of the standard power consumption by each consumer is established;
Electrical consumption is calculated for each consumer;
A graph of electricity consumption is drawn up for each of them and then a summary diagram of electrical energy consumption (Figure 1.5.10)
At each moment of time, the total demand for electricity will be determined by the sum of the needs of simultaneously operating consumers according to the following formula:
where: a is a coefficient that takes into account losses in the network depending on the length of the wire cross-section, etc. (assumed equal to - 1.1);
K 1, K 2, K 3, K 4 – demand coefficients, depending on the number of consumers and taking into account the non-simultaneity of their work, incomplete load of electric consumers (accepted from reference books);
cosj c , cosj t – power factors;
P y C– installed power of power current collectors (kW);
P y T– installed capacity of technological consumers (kW);
P at OB– installed power (specific) of indoor lighting fixtures;
P y OH– installed power (specific) of outdoor lighting devices.
A power consumption graph is constructed to identify the dynamics of power consumption at a construction site and establish the period and magnitude of the “peak” load. Based on the value of this load, the power of the transformer or mobile power station is calculated.
For each consumer, a power consumption line is drawn indicating (above the line) the amount of power consumed. The total, final power consumption is plotted in the form of a diagram, the top of which is the “peak” load, i.e. shows the value of the total maximum electrical load of the construction site (P p max).
The required power of the transformer (kV×A) is determined by the value of the calculated total load of the construction site.
,
Where: P r max – the value of the maximum electrical load, taken according to standard diagrams;
K m.s. . – load coincidence coefficient (for construction sites its value is assumed to be 0.75-0.85).
The choice of the type and number of transformers is carried out according to reference books.
Electric lighting at a construction site is divided into working and security. Working lighting must ensure normal work at night on its territory, in places of work. Standardized according to relevant regulatory documents.
Security lighting of the construction site or its boundaries at night must provide, in accordance with building codes, illumination of at least 2 lux at ground level.
To illuminate a construction site (work front, warehouses, roads, etc.), the required number of spotlights and lamps is determined and their total power is calculated. The most widely used method for calculating lighting is based on specific power ( R ud.):
Where: R ud– specific power, W/m2;
To zap– safety factor;
E min – normalized horizontal illumination in Lux, accepted to the standards;
0,16-0,25 – greater value is taken for small areas and illumination.
Number of spotlights (n) determined from the formula:
,
Where: S– illuminated area (m2);
R l– lamp power (W).
Some requirements for laying temporary electrical networks
For temporary power supply, ring, dead-end or mixed circuits for laying electrical networks are used.
Most species construction work requires electricity. This applies not only to power tools, but also to lighting of workplaces, including in a construction trailer for workers in a temporary camp. Thus, it turns out that without preliminary electrical installation work and laying electrical wiring to begin construction of objects makes no sense at all. Capital works power supply at the beginning of construction may require significant changes as work progresses. Therefore, the best option is a temporary power supply to the construction site for the construction period, but taking into account the electrical design in accordance with current requirements for electrical safety and other regulatory documents, including PUE and SNIP.
How to supply electricity to the site of proposed work or construction site?
Before starting design in design organization A technical specification is issued in which you must provide:
- composition and power of loads;
- category of connected consumers;
- power source - overhead or cable lines, transformer substation or autonomous source;
- consumer placement plan and lighting fixtures layout.
Based terms of reference And local conditions the design organization considers options for connecting electricity, receives technical instructions (TU) from the electricity supply company, makes the necessary adjustments and proposals, which may relate to the construction of the necessary temporary mobile substations, laying overhead and cable power supply lines, taking into account the uninterrupted supply of electricity. Then a preliminary is performed.
After all the nuances have been agreed upon, a preliminary design, a temporary diagram, and then the design is carried out in in full, a single-line power supply diagram and electrical wiring plan are drawn up and all necessary approvals are carried out. As in the design of power supply for residential and industrial construction projects, a working plan is drawn up, and then executive documentation, which includes all changes made during the construction of temporary power supply devices and equipment.
Only after everything has been done listed actions, you can begin construction in order to connect electricity to the construction site facilities.
It is most rational to design a temporary power supply taking into account the purpose of the work and construction. With this approach, the cost estimate for power supply to the constructed facility is significantly simplified.
Requirements and features of temporary power supply to construction sites
There are some subtleties in the design and construction of temporary power supply:
- the electrical system must be flexible with the ability to quickly redistribute, temporarily connect and connect loads in accordance with the current stages of construction;
- minimal costs;
- Working, emergency and security lighting for construction sites must be present;
- ensuring increased reliability and safety;
- it is required to lay temporary cable power supply lines on supports or suspensions;
- connecting the equipment and turning it on must be carried out only by switching equipment with a dust and moisture protection class IP of at least 54 - 65.
Consumers of the construction site of a residential building or other objects are mainly the following:
- welders;
- asynchronous motors of mechanisms and machines;
- equipment for heating concrete in cold weather.
Consequently, the need to include reactive power compensators in the project cannot be ruled out.
Who can carry out the design
Like the power supply project for a construction site, the calculation and preparation of a temporary power supply project for a construction site must be entrusted to an organization that has the right to carry out the design. Thus, you can get a guarantee of safety, completeness of the developed project, competent organized accounting electricity and save yourself from a lot of hassle of coordinating the project and approving it technical documentation and acceptance of completed work.
The company "Mega.ru" is engaged in the development of all stages of design in Moscow and the Moscow region. The company's specialists also provide assistance in areas adjacent to the Moscow region. At some stages and for individual species work provides for remote collaboration throughout the territory Russian Federation. All prices for work, as well as other necessary information, can be clarified by the coordinates located on the page.
And samples and standard projects You will find other objects in the corresponding articles on our website.
Providing a construction site with electricity is one of the determining factors in the industrialization and mechanization of construction and installation work. Therefore, in order to organize an uninterrupted power supply for construction when designing a construction plan, it is necessary to develop special section project.
The temporary power supply system for construction is designed in the sequence provided by the diagram in Fig. 8.9b.
The calculation of electrical loads is carried out using various methods: by specific electrical power and by the installed power of pantographs.
The first method is to calculate the loads for the development of a site-wide construction plan as part of the PIC. The method is based on statistical data on electricity consumption per 1 million rubles of the annual volume of construction and installation work. It depends on the type of construction and its industry structure.
In housing and civil construction for 1 million rubles. accounts for an average of 70 to 205 kVA of specific electrical power, related to the power of power transformers, with an annual volume of construction and installation work (in 1984 prices) from 3 -5 million to 0.5 million rubles, respectively.
In industrial construction, this figure ranges from 60 kVA to 400 kVA.
The design power of transformers is determined by the formula:
| (8.14.) |
R y = p*S*k t,
where: C is the annual volume of construction and installation work, determined according to the financing schedule during the period of highest intensity of work, million rubles:
p - specific power, kVA/million, rub.:
k t - coefficient taking into account the construction area.
When designing PPR, loads are calculated based on the installed power of electrical receivers - electricity consumers. The most accurate method is to calculate the power required to ensure the operation of construction machines - R s, the performance of construction and installation work - R t, lighting of the external construction site - R on and internal premises - Rov.
Loads are calculated using the formula
where: K s, K t, Ko - demand coefficients depending on the number of consumers table. 8.6.
cos φ - power factor, depending on the number and load of power consumers - 0.65-0.75.
1.1 is a coefficient that takes into account network losses.
The power of electricity consumers (kW) is determined:
power plants R with and for technological processes R t - according to reference books and catalogues; lighting devices; Rov, R on - according to specific power indicators per illuminated area (Table 8.6., 8.7.).
Conversion of power in kVA to installed power in is carried out using the formula:
(8.16)
Values of demand coefficients Ks and power Table 8.6.
Table 8.7.
Specific indicators power
The sources of power supply at the construction site are stationary or mobile transformer substations. Stationary transformer substations are constructed during the preparatory period of construction and are designed for power from 10 to 1800 kVA. Mobile transformer substations are used at facilities that are not provided with a constant power supply. They are connected to high voltage sources of the power system (operating stationary transformer substation) via cable or overhead line. Characteristics of some types of mobile transformer substations are given in Table. 8.8
Table 8.8.
Characteristics of complete stationary transformer substations.
| No. pp. | Name (type) | Power, kVA |
| 1. | SKTP-1SO-10/6/0.4 | 20-100 |
| 2. | SKTP-180-10/6/0.4 | |
| 3. | ZhTP-560 | |
| 4. | SKTP-750 |
When building in undeveloped areas or in rural areas, and also in the absence of sources and power supply networks during the preparatory period of construction, temporary mobile power plants of low and medium power (up to 1 (0) kW) as well as large power plants with diesel engines with a power of up to 1000 kW are also used.
Not a single one engineering system, which is responsible for the stable energy supply of any facility or construction site, cannot be put into operation relying on “maybe”. This rule is relevant for any cases: both when a new residential property is put into operation, and when a temporary power supply to a construction site on a site allocated for future development. Along with this, it is currently also not accepted to begin construction of a facility in an area not connected to a centralized energy supply system.
Taking into account all of the above, two more issues of primary importance are added to the list of tasks facing the developer planning to begin construction work on his site in the near future:
- The first question is the need to obtain permits for the electrification of a construction site.
- The second is the need to develop and agree on a temporary power supply project for the construction site, which will be needed to provide the construction site with a sufficient amount of electrical power.
The role of temporary power supply in the construction of modern facilities
Why is electricity needed on a construction site? In fact, there are a great many problems that can be solved at a construction site using electricity:
- lighting of the construction site area at night;
- provision of electricity to main and auxiliary electrical equipment (lifting mechanisms, drills, concrete mixers, etc.);
- heating of construction cabins and much more.
More generally speaking, then design of power supply systems construction sites aims to make the construction site more functional and completely independent of autonomous power sources (diesel generators, welding generators, and so on).
Installing energy-receiving equipment at a construction site is, in principle, not difficult. It is much more difficult to obtain the necessary permits and settle numerous formalities associated with the development and execution of documentation. First, the developer’s representative (or the developer himself) must determine the amount of electrical power that his facility will need during the construction period. Secondly, the customer must visit the nearest representative office of the local power grid company, where they will issue a permit for temporary power supply and develop technical specifications.
The technical specifications specify the requirements that the customer must ensure compliance with before making technical connections. The technical specifications also contain information that is used in their activities by designers involved in the development of a project for the temporary power supply of a facility. The design of temporary power supply, as well as the installation features of power-receiving equipment, directly depend on the requirements specified in the technical specifications. Without technical conditions, specialized specialists do not start designing a system, in principle.
Features of the electrical project
IN project documentation The temporary power supply system contains information on the total power consumption, the performance characteristics of power receiving and distribution equipment, as well as technological recommendations for its installation. The electrical diagrams also contain detailed information about the point of connection, the protection systems and the performance characteristics of the protective equipment.
This information is of paramount importance for building the safest electrical installation possible. And ensuring safety is a key task for both electricians and designers. In this regard, the design of power supply networks for construction sites should be carried out exclusively by specialized specialists who have the appropriate permits.
The MasterEnergoService company provides services for obtaining and arranging temporary power supply in Moscow and the Moscow region. Often this service is a necessity for construction needs. Our company, having accumulated many years of experience in the field of power supply, can confidently say - we will solve the most difficult questions related to the connection of temporary power supply and we will do this as soon as possible.
When constructing or reconstructing facilities in Moscow, one of the most important issues is power supply. Often, power grid organizations do not have enough power to provide permanent power supply, and even more so for temporary power supply. But what to do? It is built on diesel generator sets (DGS) - expensive, and for energy-intensive construction work it is simply not possible.
MasterEnergoService knows the answer to the question posed - it is necessary to find existing power owners in the same area and negotiate with them about a temporary supply of electricity.
Having successfully connected several hundred large facilities in Moscow, we have accumulated an invaluable base of capacity owners who have become our partners and today it is not difficult for us to temporarily connect a new facility to the power supply.
Temporary power supply for construction site
The MasterEnergoService company provides services for the construction and design of temporary power supply to construction sites in Moscow and the Moscow region.
The construction of houses and other objects requires a huge amount of resources and technical support, but not a single object can be started to be built without providing the construction site with electricity. The most effective solution to this problem is temporary power supply for construction needs, the design and implementation of which must be entrusted to qualified specialists who will take into account all factors in order to ensure that the construction site is provided with power supply properly, having completed all the necessary documents
We will be happy to help you at the very beginning of construction.
Why is temporary power supply to a construction site necessary? In order to provide electric power to power tools, mechanics, which are used to build a house or other building, for this it is actually necessary temporary power supply to a construction site.
What are the advantages of temporary power supply to a construction site? The main advantage is autonomy and independence from anyone in matters of electricity consumption for the entire long-term period of the construction robot.
The company providing electricity in your region will provide you with a power line connection point.
In order to supply electricity to a construction site, you need to carry out a number of preparatory operations.
You will need to contact an organization that is licensed to perform electrical load calculations. After receiving the calculations, you contact directly the company that owns the power line closest to the construction site to receive technical recommendations and conditions from them. Having received the technical specifications, you can contact specialized organizations for the design of power supply for a construction site, which have the appropriate licenses.
Next, it is necessary to coordinate the construction site power supply project with RosTechNadzor and the owner company electrical network, however, we will be able to do this work after receiving technical specifications from you. As a result, you will receive from us the final documentation for installation and temporary power supply to the construction site.
Then, in accordance with the project, it is possible to carry out installation and obtain power supply to the construction site. When the installation is completed, it will need to be shown to RosTechNadzor for inspection, after which you will become an independent consumer of electricity, having temporary power supply for your construction site.
In order for the temporary power supply project for a construction site to include these and many similar factors, its development should be entrusted only to qualified specialists. The company professionally designs and installs power supply systems. By concluding an agreement with us to provide permanent power supply to the facility and temporary power supply to the construction site, you will save yourself from the need to obtain missing permits for the power supply of your facility and the need to coordinate the adopted design decisions. All this will be handled by our company’s specialists.
We are ready to offer our services to resolve the entire range of issues related to the power supply of your facility: design, construction and installation work on external and internal power supply to ensure a permanent and temporary power supply scheme for the facility, with obtaining all the necessary permits and full support until the signing of the corresponding temporary power supply agreement construction site or permanent power supply agreement finished object with an energy sales organization.
Tell us what needs to be done, and we will tell you how much it costs!