1 lamp selection Road lighting fixtures can be divided into three categories according to the light intensity distribution. 1. 1 cut light fixture For cut-off lamps, the maximum light intensity is in the range of 0° to 65°, the maximum allowable light intensity in the 90° direction is 10 cd/ 1 000 lm, and the maximum allowable light intensity in the 80° direction is 30 cd/1 000. Lm, can obtain higher road surface brightness and brightness uniformity, glare is lighter, but the area around the road is dark, mainly used for fast road regular road lighting. 1. 2 half cut light fixture For half-cut light fixtures, the maximum light intensity is in the range of 0° to 75°, the maximum allowable light intensity in the 90° direction is 50 cd/ 1 000 lm, and the maximum allowable light intensity in the 80° direction is 100 cd/1000. Lm, which has a certain degree of limitation on horizontal light, and lateral light also has a certain degree of extension, glare but not too serious, mainly used for urban roads, secondary trunk roads and branch roads. 1. 3 non-cutting lamps For non-truncated luminaires, the maximum allowable light intensity in the 90° direction is 1 000 cd/ 1 000 lm. It is glare, but it looks bright and is used in low-speed streets, parks, scenic roads. illumination. In actual engineering design, according to the grade and nature of the road, the requirements for use should be met to ensure safety. For roads with strict requirements for glare, cut-off or half-cutting lamps are used to reduce the glare hazard and ensure the safety of the vehicle. For the glare requirements, the parks and scenic spots with high lighting requirements are designed to be non-cut. Light fixtures for bright lighting. 2 light source selection At present, the most widely used electric light sources for road lighting in China are incandescent lamps, high-pressure mercury lamps and high-pressure sodium lamps. Incandescent lamps are cheap and easy to use, but their lifespan is too short, and the light efficiency is too low. A large number of uses will cause great waste of energy, and the number of lamp replacements will increase greatly. The road illumination is not easy to meet the standard requirements, so road lighting should not use incandescent lamps, incandescent Lights are also being phased out in road lighting design. High-pressure sodium lamps are most commonly used in road lighting in China. This is because high-pressure sodium lamps and high-pressure mercury lamps have the characteristics of high luminous efficiency and long service life, but the advantages of high-pressure sodium lamps are more prominent, life is longer, and light efficiency is higher. The national requirements for road lighting energy conservation have also reduced the maintenance of daily street lighting facilities, and the high-pressure sodium lamp has strong fog-transparent performance. Therefore, although high-pressure sodium lamps have the disadvantage of poor color rendering, they are not the main evaluation indicators for urban road lighting. In view of the characteristics of the above various light sources, comprehensive comparison and measurement, it is recommended to use high-pressure sodium lamps in urban road lighting. 3 street light configuration The arrangement of urban conventional road lighting street lamps is single-sided, double-sided staggered, bilaterally symmetric, and centrally symmetric. The selection of the street lamp layout method should be determined according to the road section form. In order to make the road surface brightness distribution uniform, the ratio of the installation height (H), the pole spacing (s), and the road width (Weff) is limited to a certain range for different types of light distribution lamps, that is, It can meet the requirements of uniformity of road illumination (see 1). 1 luminaire type of light distribution, installation method and installation height, spacing relationship <1> luminaire light distribution type cut-off type non-light-cut type cloth installation height H (m) spacing s (m) installation height H (m) The spacing s (m) installation height H (m) spacing s (m) one-sided arrangement H ≥ W eff s ≤ 3H H ≥ 1. 2 W eff s ≤ 3. 5H H ≥ 1. 4 W eff s ≤ 4H interlaced 5 W eff s ≤ 3H H ≥ 0. 6 W eff s ≤ ≤ 3H H ≥ 0. 8 W ​​eff s ≤ 3. 5H H ≥ 0. 9 W eff s ≤ 4H symmetric arrangement H ≥ 0. 5 W eff s ≤ 3H H ≥ 0. 6 W Eff s ≤ 3. 5H H ≥ 0. 7 W eff s ≤ 4H where Weff is the effective width of the road surface. When the luminaire adopts a one-sided arrangement, the effective width of the road is the actual road width minus one cantilever length; When adopting the double-sided arrangement, the effective width of the road is the actual road width minus the two cantilever lengths; when the luminaire is arranged in the central symmetrical arrangement with the central symmetrical arrangement, the effective width of the road is the actual width of the road. H is the installation height, that is, the vertical distance from the center point of the electric light source to the ground. After determining the arrangement of the luminaires, the illuminance calculation is performed, and the calculation of the average illuminance by the coefficient method is usually adopted. Calculation formula: E average = (n × φ × U × k × N) Π(W × s) where: n - the number of light sources in each street lamp; φ - - single source light flux; U - - The luminaire utilization coefficient can be used to check the luminaire utilization coefficient curve, and the k--maintenance coefficient is generally in the range of 0.6 to 0.8; N--the street lamp arrangement mode, single row, staggered arrangement, N = 1; Arranged on both sides, N = 2; s - the distance between the poles; W - the width of the road. According to the requirements of the average illuminance of different grades of roads, combined with the choice of road section and the selection of lamps, the above formula can be used to determine the power (wattage) of the light source in the luminaire. For wider roads, if the sidewalk is also wide, you can use two-arm streetlights. In addition to the lamps on the side of the lane, the sidewalk side should also be equipped with lamps. The sidewalk side lamps are installed at about 1/2 pole height. It is made into an elevation angle of 15°, which is more beautiful, and the lighting utilization on the lane side is higher. For non-wide roads, if the sidewalk is narrow, single-arm street lights can be used. The lights on the lane side, in addition to the lighting lanes, also take into account the sidewalks. At this time, the lamps should be installed horizontally as much as possible, or the elevation angle of the street lamp arms should be controlled within 5°. To make the lanes and sidewalks have better illumination. 4 street light supply and line Due to the three-phase power supply, the transformer is easy to use and it is easy to achieve three-phase load balance. In the case of the same load and power supply distance, the cable cross section is smaller than the single-phase power supply, so the new urban road lighting generally adopts three-phase power supply. The safety of overhead power supply is poor, affecting the city's appearance. It is often used for temporary projects, borrowing electricity cement streetlights and projects with more underground conditions. Most of the newly built road lighting projects in China are powered by cables. The lines are laid in high-voltage nylon plastic pipes with VV - 1KV cables, which are safe, convenient and flexible. 5 street lamp grounding Because there are no specifications and procedures specific to the grounding of street lamps. Seeking, the actual engineering design and implementation of street lamp grounding practices are varied. Some projects use TT grounding systems, some use TN-C systems, some use TN-C-S systems, and some use TN-S systems. The following compares several grounding forms and proposes a safe, reliable, and easy to use grounding form. 5. 1 TT system The TT system refers to a protection system that directly grounds the metal casing of an electrical device. The exposed portion of the load device and the metal conductive portion not connected to the charged body are directly connected to the ground, and are not directly related to the grounding of the power system. Grounding indication 2. In this system, when the metal casing of the electrical equipment is energized, the risk of electric shock can be greatly reduced due to the grounding protection. However, this system requires that the exposed part of each load device and the metal conductive part not connected to the charged body be directly grounded. For the distributed multi-point load of the street lamp, it is required to ground separately at each base lamp. And every grounding must meet the requirements of grounding resistance. This makes construction and maintenance cumbersome, increasing engineering investment and engineering difficulty. 5. 2 TN - C system The TN-C system uses the working zero line as the zero-protection line, and the grounding indicates. 3. Because the three-phase load of the street light distribution system is difficult to balance, there is unbalanced current on the working zero line, there is voltage on the ground, so the protection line The metal casing of the connected electrical equipment has a certain voltage, which may cause electric shock to people. The more unbalanced the load, the greater the voltage deviation of the pole housing from the ground, and the greater the risk of electric shock to people. If the working neutral line is broken, the housing of the leakage device that protects the zero is charged, which is extremely dangerous. When the leakage protector is used on the trunk line of the TN-C system, all repeated grounding behind the working neutral line must be removed. Otherwise, the leakage switch cannot be closed, and the working neutral line must not be disconnected under any circumstances. Therefore, work in practice The neutral line can only have repeated grounding on the upper side of the leakage protector. This system is poorly secured. 5. 3 TN - C - S system In the distribution line, if the front part is the TN-C mode power supply, and the latter part is the TN-S mode power supply, the PE line can be separated from the total distribution box in the back part of the system. This system is called TN-C- S system. Grounding instructions 4. The TN-C-S system is a workaround on the TN-C system. The TN-C-S system also has a load imbalance due to load imbalance, which causes the voltage of the lamp post to be grounded, which is safe for the person. Therefore, the system is less secure. 5. 4 TN - S system The TN-S system is a power supply system that strictly separates the working neutral line N from the dedicated protection line PE. Grounding is indicated. When the system is in normal operation, the dedicated protection line does not have current, but there is an unbalanced current on the working zero line. There is no voltage on the PE line to the ground, so the zero protection of the metal casing of the electrical equipment is connected to the special protection line PE, which is safe and reliable. The leakage protector is used on the main line. The working neutral line must not have repeated grounding. The PE line has repeated grounding, but it does not pass through the leakage protector. Therefore, the leakage protector can also be installed on the TN-S system power supply main line. This system is more secure. Comprehensive comparison of the above several grounding system forms, to determine the TN-S system is the best security, the most standardized, so it should be preferred in urban road lighting grounding system. 5TN-S grounding system is different in the design and engineering of PE wire. Some use the metal sheath of armored cable as PE protection wire; some use galvanized round steel as PE protection wire; some use cable One core is used as a special PE protection line. The engineering practice proves that the anti-corrosion problem of cable metal sheath and galvanized round steel is difficult to meet the requirements. When it is just built, the safety is no problem. After a long time, due to corrosion, the PE wire may be broken, so that the grounding protection loses its effect. Security risks. The corrosion problem of the metal sheath of the cable is more prominent. By using a core cable as a special PE protection line, the above problems can be overcome, and the life of the PE protection line is close to the line life. Therefore, it is recommended to use three-phase five-wire or single-phase three-wire power supply in the grounding system, and use a core cable as a dedicated PE wire to make the protection run through the line from beginning to end. According to the actual experience of the project, in order to prevent the street lamp PE protection line from being broken due to mechanical or human damage, some street lamp protection grounding failures and endangering personal safety, a set of grounding can be made at every 3 intervals of the base lamp at the starting point, the end point and the middle of the street lamp line. Extremely, the grounding resistance of each group is less than 4Ω, which can greatly improve the safety of street lamp protection. 6 street light control There are many ways to control street lamps. The traditional control methods include light control and time control. With the popularization of computer application technology, the street lamp microcomputer monitoring system has been adopted in some major city road lighting systems. The traditional light control system is simple, easy to install and maintain, and inexpensive, but the control accuracy is poor, and it is easy to malfunction in bad weather conditions. The time control system is simple, easy to install and maintain, and inexpensive, but the control is not flexible, the opening and extinguishing time is relatively dead, and it cannot adapt to the requirements of different seasons. On the basis of the traditional time control, a programmable warp and weft time control system has emerged. This system overcomes the shortcomings of the traditional time control system, which can be adjusted according to the latitude and longitude of different regions. The time to turn the street lights on and off. Since the programmable warp and weft time control system is more flexible and smarter than the traditional light control and time control, and has the advantages of simple system, convenient installation and maintenance, and low price, some road lighting systems are small and the control requirements are not high. The application of small and medium-sized cities with limited funds is very common. The street lamp microcomputer monitoring system is based on the network monitoring and management system under the window98 environment, which is mainly composed of three parts: the control center end (main station), the substation end and the terminal. Remote monitoring and control of the operation of road lighting facilities can be realized, and the operation of road lighting facilities can be seen at a glance in the control center, which reduces the workload of maintenance. Although the advantages of the streetlight microcomputer monitoring system are outstanding, there are also some complicated systems and high investment defects. Therefore, it can only be used in large cities with large road lighting systems, high control requirements and strong capital. 7 Conclusion In order to make the road lighting design reasonable, the six design priorities should be grasped and applied in combination with the actual project, so that the road lighting brightness, uniformity and glare meet the specification requirements, the layout is reasonable, and the investment is low, the power consumption is small, and the operation is safe and reliable. It is easy to maintain and manage, and adopt advanced technology and products as much as possible in combination with the project situation, continuously improve the technical level of road lighting and better serve the municipal municipal construction. 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