Design of the electrical distribution network for workplaces in the office
We have developed project documentation for the electrical network, connecting workstations in an office building.
Full system name: Electrical Network .
The short name of the system: ERS. ERS is designed to distribute electricity from uninterruptible power and general power switchboards to cross-users, security system equipment, computer equipment and residential consumers of automated workplaces (AWP) of the designed building. The main purpose of creating an EDS is to provide an automated banking system, communications and telecommunications in the building of an open joint-stock company with high-quality electricity with acceptable reliability indicators (in accordance with GOST R 54149-2010).The requirements for ERS for categorizing this group of consumers, the autonomous operation time of the system, are taken into account when developing the distribution network of uninterrupted power to the building and are not considered in this section of the working documentation.
The initial data for the design are:
- Special technical conditions for the design of fire protection of the administrative-banking complex;
- Technological tasks for office premises, IT rooms, MMS, etc .;
- Architectural and technological planning of the building.
When creating an EDS ARM, only technologies and hardware and software permitted for use on the territory of the Russian Federation should be used.
The documentation has been developed in accordance with the requirements of environmental, sanitary and hygienic, fire prevention and other standards in force in the territory of the Russian Federation and ensuring thesafe operation of the system for human life and health, while observing the measures provided for in the design and regulatory documents.
The boundaries of design and construction
The upper boundary of the design begins:
- output terminal group circuit breakers electricity distribution boards, and uninterrupted power supply in common, for connecting cables electricity network AWS
- output terminal group circuit breakers electricity distribution boards uninterruptible power supply (UPS installed in the rooms and electric panel board) and server rooms Cross
The lower boundaries of the design are:
- input terminals of the process equipment of the cross-rooms (GKK, KKE), multimedia systems and rooms of the server rooms (SK-1, SK-2);
- computer and household sockets that are part of the AWP;
The connection of power supply panels for security systems equipment, control panels for ventilation and air conditioning systems, fire automatics and alarm panels is not taken into account in this section of the project.
2. TECHNICAL SOLUTIONS
2.1 Basic requirements
All equipment and materials provided for in the working documentation must have certificates and technical certificates in accordance with the law of the Russian Federation “On certification of products and services”. When developing a project, apply modern electrical equipment that ensures reliability, minimal operating costs, a high level of comfort and safety of people working in the building, as well as reliable and convenient operation of the building. The design, construction, installation method, insulation class and degree of electrical equipment protection must comply with the rated mains voltage and environmental conditions.
The equipment selected on the basis of a technical and economic comparison is agreed with the Customer.
The following consumers are included in the EDS:
- technological equipment of server and floor cross;
- in-line climate systems serving the server and floor cross equipment
- automated workplaces (AWP);
- multimedia equipment negotiation;
- IT infrastructure monitoring systems ;
Calculation of electrical loads should be made according to the parameters of loads, taking into account the demand factors specified in the TOR, according to the calculation method presented in SP 31-110-2003.The calculation of the electrical loads connected to the floor-standing UPSs, based on the number of workstations given below, on the floors of the designed building:
1st floor - 91 AWP;
2nd floor - 235 AWP;
3rd floor - 223 AWP;
4th floor - 214 AWP;
5th floor - 202 AWP;
6th floor - 193 AWP;
7th floor - 166 AWP;
8th floor - 96 AWP.
Estimated capacities of the rest of the equipment (televisions, information boards, printers, MMS intercoms) connected to the automated work station are determined by the passport data of this equipment.Equipment with an installed capacity of more than 2 kW is connected to a separate group line. Determine the demand factor for equipment that is not part of the AWP at the stage of development of working documentation in accordance with a separate technical task. For cross rooms (GKK, KKE), server rooms (SK-1, SK-2), the estimated power consumed by the equipment in each telecommutation cabinet is calculated from the passport data of the installed equipment with Кс = 1.
The power of IT equipment to take:
- SK-1 (Server room - 1) - 263.4 kW;
- SK-2 (Server room - 2) - 23.2 kW;
- SCC (Main Cross Room) - 187.5 kW
- ГКВ-1 (Main cable input-1) - 1 kW;
- ГКВ-2 (Main cable input-2) - 1 kW;
- KKE (Cross Room Floor) - 4.4 kW
Equip the premises with uninterruptible power supply and general power supply sockets in accordance with Table 1 of the CTZ. Sockets should be placed in wall electrical boxes with a partition. Power supply of IT-equipment in telecommunications cabinets and racks to perform on a two-beam scheme from different UPS. To do this, in the room, mount two mutually reserved electrical panels. Mount two interconnected PDUs in each telecommunication cabinet , and mount at least one 19 ” socket box in racks . To connect the in-line air conditioners to the EDS for each device, mount two industrial connectors Е N60309, connected to inter-reserved electrical boards. The layout and composition of the UPS equipment, type, redundancy scheme, is not considered in this section of the project. Connecting equipment GKK and SK-1, SK-2, KKE, to perform in accordance with the "Uniform requirements for providing units with uninterrupted power supply of communications and computing equipment"
2.3 Power supply AWP
Connecting the group lines from the nearest floor switchboards installed in the premises of the UPS and switchboard, and designed to power the equipment of the respective areas of the building. Group lines to form, taking into account their technological purpose and the category of reliability of power supply, by groups of electrical receivers:
- a socket network to power computers and computer equipment of an automated workplace connected to uninterruptible power supply boards;
- a socket network for power supply of office equipment, residential consumers of automated workplaces connected to general electric power supply boards;
- group power lines for equipment and equipment for low-voltage systems and communication facilities of IT premises connected to uninterruptible power supply boards.
Autonomous sources, for power supply of automation equipment, dispatching, as well as fire alarm and warning, burglar alarm systems, access systems, television surveillance, communications and other low-current equipment, are considered (if necessary) in the relevant technological sections of the working documentation of the designed building. In the group lines of the socket network, to connect the PC to use automatic switches, in other, normatively justified cases, to connect other electrical receivers, use differential automatic switches with a leakage current of 30 mA. In each switchboard, provide backup circuit breakers on outgoing lines at the rate of 20% of the total number of circuit breakers in the switchboard (but not less than three).When connecting group lines, a balance of current loading of the power supply cable phases must be ensured. The difference of loads of the most and least loaded phases should not be more than 15%. To provide for automatic disconnection of power supply to group EDS panels, when fire extinguishing systems are turned on. ERS perform 5-wire for three-phase and 3-wire with single-phase network, voltage of 0.38 / 0.23 kV. Grounding system - TN-S. The connection to the network of uninterrupted power supply of technological consumers should be performed in accordance with the requirements specified in the technological tasks from the developers of the relevant sections of the working documentation.
2.4 Device distribution and group network
Installation of electrical sockets ARM should be performed in accordance with the equipment placement plan and in accordance with Table 1 of the CTZ . The composition of workplaces with an individual set of electrical sockets can be specified at the stage of RD development.
Electrical outlets of workplaces can be placed:
- hidden in the walls;
- in floor hatches;
- complete in furniture.
For the power supply of the automated workplace, to provide for the arrangement of uninterrupted and general power sockets in close proximity to the SCS connection modules The main way to install AWS sockets in office premises are: - a socket block with an extension cord connected to the distribution block of consolidation points. Metal box made by OBO “Bettermann” with GST 18i connectors should be used as a distribution block .Installation of electrical outlet blocks on the wall (partition) should be carried out taking into account the layout of the SCS and MMC sockets. The height and method of installation of the socket blocks should be determined at the stage of development of working documentation taking into account the design of the project. When placing outlets, jobs in furniture, outlet blocks and necessary extension cords are provided by furniture suppliers. Distribution and group networks to perform cable in the performance of PPGng-HF low flammability. For emergency power networks, provide a PPGng-FRHF cable.Design of electrical networks to perform with the rest of the engineering networks and communications facility. Installation of cable traces of power and information cables should be performed taking into account the fulfillment of the requirements of the information cable manufacturer for compliance with electromagnetic compatibility conditions (control of the minimum allowable distances between parallel cables, the intersection of power and information cables at right angles).
On the floors, the laying of cable lines and electrical wiring to perform hidden, replaceable:
- for under-ceiling ceilings made of non-combustible materials - when the number of cables is three or more in solid metal trays with a lid, single cables in PVC pipes directly on the structures of the ceiling beam and also in PVC pipes on building structures;
- in voids of walls and partitions of fireproof materials - on a metal frame, cable in PVC pipes;
- in brick and block walls - with a cable in pipes, in wall punches with their subsequent puttying;
- under the raised floor plates - when the number of cables is three or more in solid metal trays with a lid, as well as in PVC pipes for single cables (up to three);
- in concrete preparation of the floor - in metal cable trays with installation lingering drawers, as well as in HDPE pipes.
In technical rooms, laying of cable lines and electrical wiring should be performed openly on cable structures. Passages of wires and cables through walls and interfloor overlappings should be made in sections of steel pipes with a fireproof, easily removable material. Sections of wires and cables are selected according to the condition of heating, long-term rated current in normal and post-emergency modes and checked for voltage loss, compliance with the selected protection apparatus and environmental conditions. The cross-section of cable lines of the distribution network should be selected taking into account the development prospects, with a margin of at least 15% in cable capacity. For group networks - with a margin of at least 10%.The capacity of trays and channels must be calculated taking into account 20% of the reserve.For all cable lines of ERS ARM, a reserve of cable structures (pipes, technological holes) in the amount of 15% should be provided for the needs of operation.
Interconnecting cables for power supply of technological consumers should be laid in different trays or one by one, but divided by a partition with a fire resistance rating of at least EI45. Other ways of laying electrical wiring to determine the working documentation in accordance with applicable regulations. All components of the power network are subject to labeling. Marking should be performed using standard tags, plates, be uniform, neat, legible and serve the entire life of the equipment.
Technological grounding
Perform technological grounding in the designed building in accordance with the requirements of the developers of technological sections of the working documentation.
Installation of the main conductor of the technological grounding, from the main grounding bus (GZSH) of the electrical installation of the building, to the level of the 8th floor, should be performed with a PuGVng-LS wirewith a cross section of 50 mm². Tire technological grounding Server (CK-1, CK-2), floor cross (CKE), connected to the main conductor of the technological grounding, wire PuGVng-LS with a cross section of 35 mm², using crimping. Tires of technological grounding to place taking into account providing the minimum lengths of the grounding conductors. Technological grounding of telecommunication cabinets should be performed according to the “star” scheme without formation of contours , with a wire of 16 mm cross section . 2. Connect the protective neutral conductors inside the racks and telecommunication cabinets, perform in accordance with the factory installation instructions.
2.6 Grounding and electrical safety measures
In accordance with the PUE ed. 7th clause 1.7.76 , all metal non-current-carrying parts of electrical installations , which are normally not energized, but which may be energized due to insulation damage to the supply conductors, must be grounded (protective earth) using a neutral protective conductor “PE”. The development of the main and additional systems of equalizing electrical potentials in accordance with clauses 1.7.82, 1.7.83, 7.1.87-88 PUE (ed. 7) is not provided for in this section of the project. Ground the metal coating of raised floor slabs in accordance with the manufacturer's recommendations and the requirements of the electrical installation code.Conductive cable structures should ensure the continuity of the electrical circuit and the necessary conductivity along the entire length. To ensure the reliability of the contact connections of individual elements of cable structures, make connecting jumpers with a 6 mm² conductor. As an additional protection measure, provide for the use of differential protection devices with a leakage current of 30 mA in group networks of a household electrical outlet network, as well as in other normatively justified cases. In the event of a fire, provide for the possibility of automatic disconnection of sockets installed in floor decorative hatches, including those intended for uninterrupted power supply of computers.