Power supply construction site.

The supply of electricity to the construction site is one of the decisive factors ensuring the normal course of construction work. Currently, for each worker employed in construction accounts for> 4 thousand square meters per year of electricity consumed for production needs.

Designing a temporary power supply is one of the main tasks in organizing a construction site. General requirements for the design of power supply of a construction object:

1. Ensuring electricity in the required quantity, and the required quality (voltage, current frequency);

2. The flexibility of the electrical circuit - the ability to power consumers in all construction sites;

3. Minimizing the cost of temporary devices and minimal network losses.

The project of temporary power supply is developed in the following order:

- calculate the power sources of electricity needed to meet the needs of construction at its different stages;

- identify sources of electricity generation;

- design the power grid;

- Solve questions about the magnitude of the voltage of high-voltage and low-voltage networks, the number, power, types and location of transformer substations, types and cross-section of wires.

The need for electricity in the development of a PIC, when individual consumers of this energy are not yet known, are determined according to aggregate indicators in kVA per million rubles of the annual CMP program (TsNIIAMT calculation of standards for compiling POS h. I, building 1973).

The required electric power is calculated by the formula: ; where p - the regulatory need for electricity at 1 million per year in the volume of construction and installation work for the industry and industry; С - annual volume of construction and installation works (according to the construction schedule).

K1 - K0 taking into account changes in the estimated cost.

A more accurate calculation of electricity is carried out at the stage of development of the PPR when consumers, the nature and volumes of construction and installation work, the number and capacity of the selected building machines and mechanisms are identified. The power consumption can be determined in this case by the formula:

P - required power source of electricity or transformer KW;

K - K0 taking into account the loss of power in the network (assumed to be 1.05 - 1.1);

Рс - power of individual machines and installations, kW (taken according to the reference book);

Pn - power required for the production of certain types of construction and installation in kW. (according to the directory);

Ditch - power required for indoor lighting, kW;

Ron - power required for outdoor lighting, kW;

- power factor which depends on the nature of the load and the number of consumers (according to the directory);

K1, K2, K3 - the demand factor depending on the number of consumers and the degree of their load (according to the directory).

The value of Kc refers to the group of machines in the presence of 1 - 2 machines Kc should be increased to 0.7 - 0.75.

To calculate the required power of an electrical installation using the above formula, it is necessary to have a calendar schedule of construction, a nomenclature of construction machines and installations, data on the choice of work production and construction plans.

(construction machine schedule and energy demand schedule). The magnitude of the loads of the electric motors of construction machines are taken according to the passports, taking into account the coefficient of simultaneity of their work and the power factor. The required power of incandescent lamps for outdoor lighting and room lighting is calculated on the basis of the illumination standards (CH 81-70), SNiP II - A.8-72 and SNiP II - A.9-71 or in a simplified way according to specific power indicators per illuminated area.

Specific power indicators.

The number of floodlights for construction sites can be calculated by the formula:

- power density (in case of illumination of a live CCD - 35, they take = 0.25 - 0.4 W / m2l; CCD = 45– = 0.2 / 0.3W / m2lk.)

- illumination, lx table above;

- the size of the area to be illuminated M2;

- the power of the searchlight lamp (CCD-35 Rl = 500 and 1000W; CCD-45 Rl = 100 and 1500W).

To illuminate open spaces, projectors in groups (3-4 or more) are installed along the contour of the site at a height depending on the luminous intensity of the lamps (7 m. With 200W lamps, up to 25 m. With 1500W lamps) distance between the projectors 80-250m.

The required power for technological purposes (electric welding, electric heating, artificial drying, etc.) is determined for each type of work based on technological calculations or from reference data.

After identifying consumers and determining the required power, they choose sources of electricity generation, for which they use data on the volumes and order of work deployment, electricity consumption in various construction periods and information on the location of consumers on the construction site. In addition, it is necessary to have data of economic surveys on the existence of the possibility of obtaining electricity in the construction area. The source of electricity generation can serve as the existing high-voltage electrical networks (the most advantageous solution), as well as mobile or temporary container-type transport power plants.

The construction site is supplied with electricity coming from permanent sources through a transformer substation. For this purpose, one-transformer complete transportable or mobile substations with a voltage on the low side of 380 / 220V and a radius of action of 400-700m are usually used. open transformer substations installed on wooden U shaped supports are economical.

With a large distance from the construction of power lines for energy supply using temporary power plants, transportable or mobile. From transportable power plants, diesel automated power plants with a capacity of 2 × 100kW are used, as well as mobile power stations mounted in vans. The distributor of low-voltage temporary grid on construction sites arrange for radial, ring or mixed circuits. The radial scheme is based on the unilateral powering of each consumer from the transformer substation or distribution point. The most reliable ring trunk circuits with two-way power.

The power supply of the construction site from external sources is, as a rule, carried by overhead power lines. If under the terms of work and the requirement of TB it is not possible to construct temporary overhead lines, lay an electrical cable. When constructing and operating temporary power supply networks to reduce labor costs and reduce the cost of work, it is advisable to use various inventory devices and devices, inventory elements of electrical networks, portable supports, collapsible risers, etc.

(The range of one shield SGP-50m)

The proposed scheme SCHRSP

Analysis of electrical injuries in construction suggests that electrical injuries most often occur during the operation of temporary electrical grids, both wired and cable, built for the period of construction of various facilities (industrial enterprises, residential houses, etc.). On such networks, for various reasons, insulation is often damaged, causing indirect contact with live parts, and the latter leads to accidents.

One of the measures of protection against electrical shock is the mandatory use of protective shutdown devices (RCDs), which is required by the Electrical Installation Rules (ПУЭ) ed. 7, ch.1.1.49; 1.7.50; 1.7.51.

To solve the problem of increasing electrical safety when working with hand-held electric machines, power tools, and other electrical equipment in the construction process, the development of the Spektr-Elektro-Shchit company - distribution boards for construction sites (ShchRSP) is intended.

In addition to improving electrical safety, switchboards are also distinguished by other positive qualities:
• mobility, low weight, which allows, if necessary, easily transfer them to another workplace;
• the ability to monitor the health of outgoing power lines, each line separately;
• the ability to connect panels to any electrical network, such as: T-NS or TN-C, etc., which allows you to turn on any consumer on the construction site in accordance with the requirements of the ПУЭ;
• ability to monitor the state of insulation resistance of outgoing lines;
• prevention and prevention of fire, which may occur due to malfunction of the electrical network and electrical equipment;
• standard components of modular type, which allows you to quickly repair if necessary;
• separate power supply to each outgoing line (if it is impossible to promptly repair one of the outgoing lines), which allows you to disconnect the faulty line and continue working on the others.

Models contain wiring accessories (circuit breakers, RCD, power connectors, etc.).
The ShchRSP complete set meets the requirements of GOST 51327299 (IEC-1008) and GOST 52327200 (IEC-1009), put into effect since 2001. The boards are certified by the bodies of the State Standard of the Russian Federation.
The proposed SCRSPs are protected by a patent of the Russian Federation (No. 35043 of December 20, 2003) and recommended for use in the construction industry in order to increase electrical safety, protect people from electric shock and fire safety equipment.

The proposed scheme SCHRSP

1. Introduction to distribution device (I LIE-006 SESCH-630-43).
It is intended for input, distribution and metering of three-phase alternating current electrical voltage of 380V of 50 Hz frequency and ensuring protection of outgoing lines during overloads and short circuits. The proposed VRU has two independent inputs, an electrical energy metering station and up to six outgoing lines. Its rated current can be up to 630 A.

2. Distribution switchboard for building sites (SCHRSP SESCH-04-250-40).
Designed for the transmission of electrical energy to the terminal SCHRSP (SCHRSP SESCH-03-063-24). The rated current of the proposed ShchRSP can be up to 250 A. The board consists of four circuit breakers, four power sockets with mating plugs, a bus bridge. The degree of protection of the shell to IP54.

3. Distribution switchboard for construction sites (SSCPRSP SESCH-02-250-32).
Designed to transfer electrical energy between floors in buildings under construction. The shield includes: a bus bridge, two power sockets with mating plugs for 63A, one power socket with a mating plug for 32A, two sockets for powering hand-held power tools.

4. Switchboard for construction sites (SCHRSP SESHCH-03-063-24).
Designed to power electrical devices with a voltage of 380 V and a hand-held power tool with a voltage of 220 V. The panel includes: a load switch, protective cut-off devices, automatic switches, power sockets with 32A plugs, power sockets for hand-held power tools.

The connection of the products included in the package is carried out with the help of quick-disconnecting power connectors and cables, which makes it possible to assemble the necessary primary power supply circuit quickly and at low cost.