Abstract: The author recently redesigned the street lights of several roads on the campus of Peking University. During the design process, he had a certain understanding of the overall outdoor lighting of the campus. A brief introduction to the system and control methods of outdoor lighting, the choice of light source type, the grounding of metal poles, the selection of cable sections and types, the layout of street lamps and intelligent lighting control devices. Keywords: campus streetlight renovation design; status quo; intelligent lighting control device; Peking University campus environment elegant, charming scenery. Street lights and courtyard lighting are very important for the campus environment at night. At present, the campus street lights, systems and lamps are relatively old, and the overall campus streetlight renovation is being carried out one after another. Recently, I accepted the commission to renovate the street lights of several roads in Peking University. In the process of design, I have a certain understanding of the current situation of street lamps in the whole school. Below I will introduce some of the problems that I have considered in the design of campus streetlights, the status of campus lights in Peking University and the intelligent lighting control devices. I. Outdoor lighting system and control method The outdoor lighting of Peking University campus includes two systems: building courtyard lighting and street lighting. Some large new buildings have their own courtyard lighting systems. The power supply is usually taken from inside the building, and the opening and closing are controlled by the control box in the respective building. Road lighting is another separate system. Due to the large campus area of ​​Peking University, it is impossible to control the street lights of the whole school with a street light control box. Therefore, the campus is divided into several areas, and several street light control boxes are set up to control the street lights in this area. The power to each control box is taken from a nearby low voltage power supply system. The control method of the street lamp system currently adopts the formula that the central control room uniformly controls the opening and extinguishing. The central control room is located in the control room next to the water tower. It is equipped with a set of brightness time control device, which starts the street lamp system controlled by the room when the outdoor brightness drops to a certain level according to a certain time. At the same time, the light-on signal is transmitted through the control line to the regional street light control box to enable the street lights of the whole school to be simultaneously turned on. At some point in the morning, the central control room has signaled to extinguish the street lights throughout the school. Second, the choice of light source type The main types of light source used in street lighting are: metal halide lamps, high pressure sodium lamps, white flags lamps and energy-saving lamps (compact fluorescent lamps). Among them, the high-pressure sodium lamp has the advantages of high luminous efficiency, energy saving, moderate color temperature, and is widely used in street lamps. Data introduction Through the intelligent lighting control device, the high-pressure sodium lamp and the high-pressure mercury lamp can be operated at the power-saving level during the required period to save power. Therefore, I basically consider the use of high-pressure sodium lamps for the type of light source on the main roads in this retrofit design. The white flag light color is soft and the color rendering is good. The illumination requirements of some branches on the campus are not very high, and at the same time, it is necessary to create a relatively quiet atmosphere. The white banner lights meet these requirements. The white light can not only be operated at the power saving level, but also because it does not require a ballast to match, and the lamp wattage can be replaced at will. Therefore, in some quiet places, I consider choosing a white light. The purpose of this renovation design is that the main roads are relatively bright, and the illumination of some of the branch roads should not be too high, and should be consistent with the surrounding environment. At present, some of the street lamps in our school also use some energy-saving lamps (compact fluorescent lamps). For some reason, the life of the lamps is not ideal, and the replacement is frequent. The energy saving lamp cannot be operated at the power saving level. If the quality of the energy-saving lamps is too high, the energy-saving lamps have high luminous efficiency. In places where no dimming is required, the energy-saving lamps have obvious advantages over the white-flag lamps in terms of energy saving. Third, the metal pole grounding Because the lamp poles we chose for the streetlights are all metal poles, the grounding of the poles is very important. According to the regulations, the metal pole should be grounded. We choose to finally adopt the following grounding method: one for each street lamp, the emergency 9 galvanized round steel standard grounding electrode, and the standard grounding electrode is connected with the metal base of the street lamp by welding with the urgent 0 galvanized round steel. At the same time, the PE wire in the three-core cable is connected to the base of each street lamp of the cable branch. Thereby forming a large grounding system to ensure personal safety. According to the actual measurement, the grounding resistance of a single street lamp is about 7 ohms. After the multi-turn street lamps of the same branch are connected together, the grounding resistance is much less than 4 ohms, and the grounding safety is guaranteed. Fourth, the choice of cable cross-section and type Street lamp system is characterized by a long line, the current on the line is not necessarily large. The requirements for the current carrying capacity when selecting the cable cross section are easily met, and the key consideration is the line voltage drop. The solution to the line voltage drop problem is to increase the cable cross section appropriately. When the line voltage drop meets the requirements, the current carrying capacity of the cable has greatly exceeded the requirements. Therefore, we choose the cable section to be appropriately thickened, which not only satisfies the requirement of reducing the pressure drop, but also leaves a margin for increasing the number of street lamps. At the same time, because the voltage drop is small, the line loss is small, the system stability is high, and the whole system is extended. The longevity, while also saving energy, makes a lot of sense. In addition, we know that there are two main types of power cables buried outdoors: one is YJV and the other is VV. Cables of the same cross-section have the same effect on voltage drop, while YJV-type cables of the same cross-section are more expensive than VV-type cables. When the current carrying capacity is satisfied and has the same effect in terms of pressure drop, we consider the VV type to be more economical in terms of economics. VV type is currently used in outdoor VV23 type and VV22 type cable. The performance and price of these two types of cables are different. The price of VV23 type cable is relatively high, and the waterproof performance is relatively good. VV22 cable is relatively weak in waterproof performance, VV23 but the price is relatively cheaper. According to the above characteristics, I chose to use the VV23 cable with better waterproof performance in the damp place near the lake. It is more economical to choose the VV22 cable in other places. In order to facilitate the control, the street lamp system is designed to use a three-core cable for each phase ~220V. The cable includes phase, neutral and protective grounding wires. Thus each single phase branch can be individually disconnected. 5. Whether the layout of the streetlights of the street lamps is appropriate is directly related to the lighting effect. For most of the roads in this renovation, I chose a single side lighting according to the road conditions. Only on the main road of the South Gate, the way of double-sided lighting was adopted. There are two ways to double-sided cloth lamps: one is a symmetrical arrangement, and the other is a staggered arrangement, each with its own advantages and disadvantages. The advantage of the symmetrical arrangement is that it is more beautiful, but the disadvantage is that the illumination is not uniform enough for a wide road. The staggered arrangement is not as beautiful as the symmetrical cloth, but the illumination is relatively uniform. Since the road inside the school is not very wide even if it is a trunk road, the shortcomings of uneven illumination will be more prominent. Through the discussion, the staggered arrangement is finally adopted. To determine the location of the street light, first of all, you must look at the scene. After understanding the scene, mark the preliminary points on the topographic map, draw a sketch, and then form a formal map after discussion. Before the construction, press the official map to the site to gradually determine the specific lamp position. After appropriate adjustment according to the situation, nail the small wooden stake on the lamp position to implement the exact position. Sixth, intelligent lighting control devices to improve the overall level of school street lighting system is the direction of transformation. It includes the replacement of cables, replacement of lamps, re-distribution, replacement of control systems and other aspects, including the promotion of a smart lighting control device. In addition to the timing control, this intelligent lighting control device has the following outstanding features: the output voltage is not ~220V but ~200V when starting at the program timing, and slowly rises to the standard voltage of ~220V after a while. When the late night road illumination requirements are reduced, the controller can be slowly reduced to different low voltages according to the type of the lamp to achieve energy saving and extend the life of the lamp. Then, at the time set before dawn, the voltage is slowly raised to the standard voltage of ~220V, and the light is turned off at the specified time, and the cycle is repeated. The first phase of this new intelligent lighting controller requires a certain amount of investment, but it can greatly extend the life of the lamp, and has obvious power saving effect. Long-term benefits are far greater than one-time inputs. Therefore, I advocate the active promotion of the use of intelligent lighting control devices. Peking University has a large campus with mountains and waters and different functional areas. The environment is both beautiful and complex. There are many aspects to consider when designing outdoor lighting. At the same time, many places in the school are under construction or planning to be expanded and expanded, and there are many uncertain factors. The scope of the retrofit design must also be in accordance with the planning requirements of the school management department. Therefore, this time only the street lighting renovation design of a part of the campus. And some of the roads that will be formed in the planning are still to be demolished, so the order of construction is also one of the considerations in design. In addition, it is necessary to consider that the new system of this design should be well connected with the system that has been modified last time and the next time it will be modified, so as to make the street lamps reconstructed at different stages coordinated, and finally form a unified overall to lay a large scale. There are many factors in the design of street lighting in complex environments. It is necessary to seriously study and seriously think about it. At the same time, we must listen to opinions in many aspects, conduct many discussions, and coordinate and comprehensively consider various requirements. At the same time, it is necessary to run the site more and solve specific construction problems according to the actual situation. We believe that through the efforts of everyone, the new system will be more advanced in technology and energy-saving. The night view of the campus is sure to be more beautiful.
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