Building electrical includes: power supply and distribution systems; lighting systems; disaster mitigation systems (including safe use of electricity, lightning protection, grounding, fire prevention, anti-theft, air defense and explosion-proof); information systems (including television, radio and audio, network, computer management systems) , building automation, etc.).
Strong electricity: power supply, distribution, lighting, control systems, lightning protection grounding, line laying, etc.
Weak electricity: automatic fire alarm and fire linkage, security system, communication network system, information network system, integrated wiring system, TV and building automation.
Supply and distribution system
First, the power system
1. The rated voltage levels of power transmission lines are divided into: AC 500, 330, 220, 110, 66, 35, 10 (6) KV and 380/220V and DC 500KV.
2. 1000V is the dividing line between high and low voltage. The common voltages in industrial and civil buildings are 10 KV and 380/220V.
Second, the power load grading, according to its power supply reliability requirements and interrupted power supply in the political and economic losses or impacts are divided into three levels.
1. The primary load should be powered by two independent circuits (or more than two circuits). The two power supplies should come from different power points or bus sections of different transformers in the same city substation.
2. The special first-class load should be powered by two independent circuits, and an emergency power supply must be set up.
Commonly used as emergency power supply: generator set independent of normal power supply; dedicated feeder line independent of normal power supply in power supply network; battery; dry battery.
3. The secondary load should be powered by two circuits.
4. The power supply of the telephone room is the primary load; the passenger ladder, the living water pump and the drainage pump of the high-rise building are the primary load.
Third, the electrical load is generally divided into lighting load and power load, but in civil buildings, air conditioning, electric heating equipment is classified into lighting load; power load refers to elevators, water pump fans, washing machines, etc.
Fourth, voltage selection, power factor and reactive power compensation: the installation capacity of the electrical equipment is 250KW or the transformer capacity is below 160KVA, and the power should be supplied in low voltage mode. For power supply units with high voltage supply, the power factor should be above 0.9, and the power factor of low voltage power supply should be above 0.85.
Substation and self-supplied power supply
1. Power distribution equipment and emergency generator sets: Transformers are classified into oil-immersed and dry-type according to cooling methods. Most of the emergency standby generator sets currently use diesel generator sets.
Second, the choice of the site of the substation:
1. It should not be located in places with severe vibration or high temperature;
2, should not be located in dusty, water mist (such as large cooling towers) or places with corrosive gases, can not be far away, should not be placed in the wind direction of the prevailing wind direction of the pollution source;
3, should not be located directly below the toilet, bathroom or other places where water is often accumulated, and should not be adjacent to the above places;
4. When the substation is located in the basement of a high-rise building, it should not be located at the lowest level. When there is only one floor under the local area, water-proof measures such as raising the ground should be taken.
5. The substation of high-rise buildings should be located in the basement or first floor. When the building height exceeds 100 meters, substations can also be set up in the refuge or upper technical layer of the high-rise area.
6. In multi-storey buildings without special fire protection requirements, substations with flammable oil electrical equipment may be located on the bottom part of the outer wall, but should not be located above, below, attached or evacuated in densely populated places. Exit both sides.
7. When arranging electrical equipment with flammable oil on the bottom layer of the multi-storey and high-rise main building, a fire-proof provocation with a width of not less than 1.0 m should be placed above the opening part i of the outer wall of the bottom layer.
Third, the substation's requirements for the building and equipment layout
1. The fire resistance rating of the fuel-immersible power transformer room should be one level.
The fire resistance rating of the power transformer room, high voltage power distribution equipment room, high voltage capacitor room and underground cable laying storage layer of non-combustible (or flame retardant) medium shall not be lower than the second grade.
The fuel-free equipment room such as the low-voltage power distribution unit and the low-voltage capacitor room shall have a fire resistance rating of not less than three.
2, high-voltage power distribution room and capacitor room, should be set to open natural light window, the height of the window below the outdoor ground should not be less than 1.8 meters, the side of the street should not open the window, the low-voltage power distribution room can be set to open natural light window .
3. The door of the transformer room, power distribution unit, and capacitor room should be opened outward.
4. There should be two outlets for the power distribution unit with a length greater than 7 meters.
5. The transformer room should be naturally ventilated, and the temperature difference between the inlet and outlet should not exceed 15 degrees.
6. The transformer room, capacitor room, power distribution unit, and control room should not have a pipeline that is unrelated to it.
7. Some people who are on duty should have water and sewage facilities.
8. The power distribution cabinets arranged in rows shall have a length of more than 6 meters. The passages behind the cabinet shall be provided with two outlets, and shall be arranged at both ends of the passage. When the distance between the two outlets exceeds 15 meters, Increase exports.
9. The indoor floor of the power distribution room should be 0.15-0.30 meters higher than the outdoor floor.
Fourth, diesel generator room
1. The unit should be placed close to the primary load or substation.
2. When the oil storage room is connected to the machine room, a Class A fire door shall be provided on the wall and opened to the generator room.
3. The trenches and cables in the equipment room should have a slope of 0.3% and drainage measures, and the edge of the trench should be treated with oil.
4, the fire compartment risk category and fire rating of the machine room work room:
Generator room level one
Control and distribution room
Oil storage room
Distribution system for civil buildings
First, the grounding method of the distribution system: radial, trunk, and ring.
Second, the distribution system:
1) High-voltage power distribution system: Generally, a 10KV power distribution station is set up at 2KM2 per land or 4x105 total construction area. When there are more than 6 substation, 10KV power distribution station can also be set.
2) Low-voltage power distribution system: grounding method - TT TN IT three forms.
Ultra-low voltage distribution: Distribution with a rated voltage of 50v or less. There are two safety voltage limits: 50V in normal environment and 25V in humid environment. In China, the portable street lamp voltage used in normal environment is 36V.
Indoor and outdoor electrical wiring
First, outdoor wiring:
1) Overhead line: An overhead line between the high and low voltage lines and the first support point of the building is called an overhead line. The distance from the power receiving end of the high voltage receiving line shall not be less than 4 meters; the distance from the receiving end of the low voltage receiving line to the ground shall not be less than 2.5 meters.
Dual power lines that supply primary load should not be erected on the same pole.
2) Cable route: Cables laid in cable trenches and cable tunnels should be bare-armored cables, bare lead-clad cables or plastic-sheathed cables.
a Cable buried directly: When the number of outdoor cables laid along the same path is 8 or less, the buried depth should not be less than 0.7m. Dual power cables that supply the same path to the primary load should not be routed in the same trench.
b Cables are laid in cable trenches or tunnels: if there are more than 8 cables in the same path, less than or equal to 18, it is suitable for cable trenching. If there are more than 18 cables, cable tunneling can be used. The cable tunnel height should not be less than 1.9 meters. When the length of the cable tunnel is greater than 7 meters, the outlet shall be provided at both ends. When the distance between the two outlets exceeds 75 meters, the exit shall also be increased.
c Cables are laid in the pipes: asbestos cement pipes or concrete pipes are generally used.
Second, the indoor line: direct wiring - the construction of the ceiling is strictly prohibited.
Metal pipe wiring - should be used in the ceiling of the building.
Hard plastic pipe wiring - suitable for indoor locations and places with acid-alkaline corrosive media.
Inter-electrical wiring—The well wall should be a non-combustion body with a fire endurance of not less than 1 hour. The electrical room should be provided with maintenance access doors on each floor and should be opened to the public corridor. The fire resistance limit should not be lower than the third level. Fire seal isolation should be done. Micro-signal training is worth your attention!
The electrical lines of the high voltage, low voltage and emergency power supply in the electrical room shall be kept at a distance of 0.3 m or more from each other or isolation measures shall be adopted.
The power line that supplies power to the elevator should not be laid in the elevator shaft.
Electrical lighting
Lighting methods can be divided into: general lighting, district general lighting, local lighting and hybrid lighting.
The types of lighting can be divided into: normal lighting, emergency lighting, duty lighting, security lighting, landscape lighting and obstacle sign lights, etc., including emergency lighting, evacuation lighting, and safety lighting.
First, the quality of lighting: general illumination uniformity, should not be lower than 0.7, the color rendering index of the lighting source should not be less than 80.
Second, emergency lighting: evacuation lighting includes safety exit sign lights, evacuation indicator lights, evacuation lights. The standby lighting has a continuous working time of more than 2 hours.
6 electrical safety and building lightning protection
1. Safe use of electricity: When the AC is below 15-20 mA or below 50 mA, it is safe for the human body.
A voltage above 36V becomes a dangerous voltage. The rating of the safe voltage rating is: 42, 36, 24, 12, 6V
Protection against electric shock: Indirect contact protection - protection by automatic cut-off power supply (including leakage current action protection), supplemented by total equipotential bonding.
The total equipotential bonding is to electrically connect the mains, grounding mains, water mains, heating and air conditioning pipes, and metal components of the building to each other at the building's power line.
The distribution lines of the following equipment should be equipped with leakage current action protection: the incoming switch or the outlet dedicated circuit of each household in the residential building. Electrical equipment powered by the TT system.
Second, building lightning protection
Buildings should be classified into three categories according to their importance, the nature of their use, the likelihood and consequences of a lightning accident, and lightning protection requirements:-
1. Lightning protection measures for the first type of lightning protection buildings
A. Anti-direct lightning strike: an independent lightning rod or overhead lightning protection line (net) should be installed. The grid size of the overhead lightning protection net should not exceed 5mx5m or 6mx4m. The lightning protection net is easy to strike along the corners, ridges, eaves and corners. Laying.
B. Measures for lightning protection: Metal objects such as equipment, pipes and air ducts in buildings should be connected to the grounding device for lightning protection. Every 18-24 meters around the metal roof should be grounded once by the down conductor.
C. Measures to prevent lightning wave intrusion: The low-voltage line should be directly grounded by cable. The metal sheath and steel pipe of the cable should be connected to the grounding device of lightning protection at the household end.
D. When the trees are higher than the building and are not within the protection range of the lightning receptor, the clear distance between the trees and the lightning receptor should not be less than 5 meters.
2. Lightning protection measures for the second type of lightning protection buildings
A. Anti-direct lightning strike: It is advisable to use a lightning rod or lightning protection line (net) installed on the building or a combination of the lightning receptors. The grid size of the aerial lightning protection net should not exceed 10mx10m or 12mx8m. Lay, ridges, eaves and horns are easily laid.
B Measures to prevent the intrusion of lightning waves:
3. Lightning protection measures for the third type of lightning protection buildings
A. Anti-direct lightning strike: It is advisable to use a lightning rod or lightning protection line (net) installed on the building or a lightning receptor composed of a mixture. The grid size of the aerial lightning protection net should not exceed 20mx20m or 24mx16m. Lay, ridges, eaves and horns are easily laid.
B. Measures to prevent lightning wave intrusion:
4, lightning protection device
The lightning protection device outside the building consists of three parts: the lightning receptor, the down conductor and the grounding device.
The lightning protection inside the building includes equipotential bonding facilities, shielding facilities, installation of lightning arresters, and reasonable wiring and good grounding.
5, lightning protection electromagnetic pulse: especially for buildings with information systems. The main practice is to equipotentially connect and install a surge protector that matches the power system.
Fire alarm and fire linkage
First, the protection object of the fire automatic alarm system should be divided into special grade, first grade and second grade according to the nature of its use, fire hazard, evacuation and difficulty of fighting.
Second, the setting of the fire detector
In super high-rise buildings, fire detectors should be fully installed except for parts that are not suitable for installing fire detectors (such as toilets and bathrooms).
Third, the form of automatic fire alarm system: regional alarm system; centralized alarm system; control center alarm system;
Fourth, fire emergency broadcast and special telephone
1. Fire emergency broadcast: The centralized alarm system and the control center alarm system should be equipped with fire emergency broadcast. Ensure that the distance from any part of a fire zone to the nearest speaker is no more than 25 meters. The distance from the last speaker in the aisle to the end of the aisle should not be greater than 12.5 meters. The rated power of each speaker should not be less than 3 watts.
The fire emergency broadcast feed voltage should not be greater than 100 watts.
2. The fire-fighting telephone network should be an independent fire communication system.
Each refuge floor of the special protection object shall be provided with a fire-only telephone extension or telephone jack every 20 meters.
An external telephone with direct alarm should be set up in the fire control room, fire duty room or enterprise fire station.
5. Fire control room and fire duty room
1. Fire duty room: only when there is a fire alarm and there is no fire linkage control function. It should be located near the main entrance of the first floor.
2. Fire control room: It is equipped with automatic fire alarm and automatic fire extinguishing or building with fire linkage control facilities.
The fire control room attached to the building should be located in the first floor or underground floor of the building, and be separated from other parts and set up a safety exit directly to the outside and should not be more than 20 meters from the entrance and exit.
The door should be opened in the direction of evacuation. There is a clear sign at the entrance. The fire resistance of the partition wall is not less than 3 hours, and the fire resistance of the floor is not less than 2 hours.
Sixth, fire-fighting linkage objects: fire-fighting facilities, smoke control facilities, elevators.
7. Power distribution system for fire-fighting equipment
Fire-fighting linkage, automatic fire-fighting control, communication, emergency lighting and emergency broadcasting should be laid in a dark manner, and the thickness of the protective layer should not be less than 3cm.
The cable shafts of weak current lines shall be separately set up with the cable shafts of the strong electric lines. When they are used together, they shall be respectively placed on both sides of the shaft.
Telephone, cable broadcasting and sound reinforcement, simultaneous interpretation
First, the setting of the telephone station: the number of telephone users is 50 or more, generally set up a telephone station, but the residential, apartment, and rental office buildings are not set, and the telephone users directly enter the local telephone network.
Second, the choice of telephone station site: When building with other buildings, it should be set up in the first floor or above of the 4th floor, and should be facing south and have windows. In wet areas, the first floor should not be equipped with a telephone exchange room.
Third, the requirements of the telephone station for the building: the fire resistance rating of the building should be two-level, and the seismic design should be considered according to the intensity of the area specified in the site. The technical room of the telephone station, the minimum height of the room should generally be 3 meters below the beam. The floor of the technical room should be made of anti-static raised floor or plastic floor.
4. Cable broadcasting: Cable broadcasting of public buildings can be generally divided into: commercial broadcasting systems, service broadcasting systems, and fire accident broadcasting systems. Wired broadcast power amplifier equipment should use a constant voltage output.
5. Sound reinforcement and simultaneous interpretation
The position of the sound reinforcement control room should be located at:
1. Theatres and auditorium buildings should be located at the back of the auditorium.
2. Stadiums and pavilions should be located on the side of the podium or facing the site to observe the location of the audience.
3. The conference hall and lecture hall should be located at the back of the hall.
Shared antenna television system and closed circuit application television system
1. Shared Antenna Television System (CATV): The system consists of four parts: the receiving antenna, the front-end equipment, the signal distribution network and the user terminal.
Second, closed-circuit application television system (CCTV): camera installation height - indoor 2.5-5 meters is appropriate; outdoor 3.5-10 meters is appropriate, not less than 3.5 meters.
10 echo (call) signal and public display device
Hospitals, hotels, echo (call) signal devices should use a safe working voltage below 50V, generally 24V.
11 building integrated wiring system
The definition of intelligent building: building as a platform, compatible with building equipment, office automation and communication network system, integrating structure, system, service, management and the optimal combination between them to provide people with a safe, efficient, comfortable and convenient Building environment. Including construction equipment automation systems, communication network systems, office automation systems, integrated wiring systems, and system integration.
The length of the integrated wiring horizontal cable must not exceed 90 meters.
The trunk channel vertical channel has cable holes, pipes and cable shafts to choose from. It is recommended to use cable shaft method, and the horizontal channel can be selected as pre-buried concealed pipe or cable tray.
Electricity unit: kW. When, also known as electricity, referred to as degree. It is the unit of electric energy, and the instrument for measuring electric energy is called electric energy.Indoor Outdoor Fiber Optic Cable,Indoor Outdoor Fiber,Indoor Fiber Cable,Indoor Fiber Optic Cable Types
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