The design of power supply and distribution system should be based on safety, reliability, technical economy and rationality to improve the operation efficiency of the whole power supply and distribution system.
When the total capacity of electrical equipment reaches 250kW or above or the capacity of transformer is 160kVA or above, 10(6)kV should be used for power supply.
The power distribution station should go deep into the load center, and the power supply radius of low voltage (380V/220V) should not exceed 200m·m m. When the total capacity is less than 150KW due to conditions, it can be appropriately relaxed but not more than 250 m. The power supply radius of lighting distribution box branches should not exceed 50 m.
For super-high-rise buildings of 200m and above, it is advisable to set up a power distribution station on the refuge floor of the building.
The design of power supply and distribution system should calculate the power load and reactive power, and reasonably select the load rate, capacity and quantity of transformers to reduce the no-load loss of transformers.
Distribution stations should not be located in the lowest floor of underground buildings. When the power distribution station is located in a building, the power distribution station in a public building should not be located directly above or below an important room, and residential buildings should not be located directly above or below residents and on both sides of adjacent or evacuation exits. When the substation is located outside the residential building, the distance between the outside of the substation and the external wall of the residential building should meet the requirements of fire prevention, noise prevention and electromagnetic radiation prevention, and the substation should avoid the horizontal view of the residents' main windows.
Line.
The selection of distribution transformer should be determined according to the nature, load and environmental conditions of the building, and energy-saving transformer should be selected. In the low-voltage system (IT system) where the power supply system is ungrounded or high-impedance grounded and the exposed conductive part of the electrical device is partially grounded, the lighting system should be equipped with a special transformer.
. When one of the following conditions is met, a special transformer shall be set:
When the seasonal load capacity is large or the impact load seriously affects the power quality1;
2. Some special equipment required by the function;
3. When transformer is used for power and lighting, it will seriously affect the lighting quality and the service life of light source;
4 When the single-phase load capacity is large, and the neutral conductor current exceeds 25% of the rated current of the low-voltage winding of the transformer due to the unbalanced load, or when the single-phase load capacity is not very large, it is appropriate to set up a single-phase transformer.
When the diesel generator is used as emergency power supply and the machine room is set in the building, the unit should be set near the first-class load or distribution station. The diesel generator room can be arranged on the first floor, the first underground floor or the second underground floor of a building, and should not be arranged on the upper floor, the lower floor or adjacent to crowded places on the third and lower underground floors. When arranged underground, measures such as ventilation, moistureproof, smoke exhaust, noise elimination and vibration reduction should be taken to meet the requirements of environmental protection. When the machine room is set in a high-rise building, there should be enough fresh air inlet and reasonable exhaust flue position in the machine room. Smoke exhaust in the computer room should avoid sensitive areas of residents, and smoke exhaust pipes leading to the roof should be built at the smoke exhaust port. When the smoke outlet is located on the roof of the podium, the smoke should be treated before being discharged.
In the low-voltage side of the distribution station or the primary distribution of the low-voltage incoming line, the sub-circuit distribution should be carried out according to the principle of itemized measurement.
The power supply and distribution system should be simple and reliable, and the distribution series from the low voltage side of the transformer to the last terminal distribution box should not exceed three levels.
In the three-phase lighting distribution trunk line of civil buildings, the load of each phase should be balanced, the maximum phase load should not exceed 1 15% of the average load of three phases, and the minimum phase load should not be less than 85% of the average load of three phases.
For three-phase unbalanced or single-phase distribution power supply and distribution system, split-phase reactive power automatic compensation device should be adopted.
For three-phase balanced power supply and distribution system, when hybrid compensation is adopted, the supplementary capacity should not be less than 40% of the total capacity. Reactive power automatic compensation should adopt intelligent maintenance-free complete sets of automatic compensation devices, with zero-crossing automatic switching function, and measures to suppress harmonics and inrush current.
When the civil building is larger than 100kW, reactive power compensation should be carried out, and the power factor on the compensated line should not be less than 0.9.
For the electrical equipment with large harmonic current content in the power supply and distribution system of civil buildings, corresponding harmonic suppression and harmonic control measures should be taken. Such as: large rectification equipment (data center, electronic information room), medical special equipment (hospital), frequency conversion equipment (cold room), silicon controlled dimming equipment (theater). For large and important electrical and electronic systems, intelligent surge protectors and their monitoring systems should be set up.
The cross section of power cables of 20kV and below shall be designed in combination with technical conditions, operating conditions and economic current method, and the selection method of economic current cross section shall comply with the relevant provisions in Appendix B of Code for Cable Design of Electric Power Engineering (GB 502 17-2007).
The power cord in the enclosure shall be made of copper conductor. The exposed cables in high-rise residential buildings should be flame-retardant cables with low smoke and toxicity. Power supply trunk lines and emergency lighting cables of fire control facilities shall comply with relevant regulations.
Buildings should use wires and cables with the same life.
For more information about bid writing and improving the winning rate, click on the bottom customer service for free consultation.