introduction
Street lamps are an important component of urban lighting. Traditional street lamps often use high-pressure sodium lamps, and the low-efficiency of high-pressure sodium lamps as a whole has caused huge waste of energy. Therefore, the development of new street lamps with high efficiency, energy saving, long life, high color rendering index and environmental protection is of great significance for urban lighting energy conservation. In recent years, LED street lamps have developed rapidly in China, and the market scale has been expanding. However, the initial investment cost is much higher than that of traditional street lamps. This paper proposes to build LED street lighting with BOT investment.
1 LED street light features
High-power LED street light source uses low-voltage DC power supply, high-efficiency white light diode synthesized by GaN-based power blue LED and yellow phosphor. It has the unique advantages of high efficiency, safety, energy saving, environmental protection, long life, fast response and high color rendering index. Can be widely used in urban road lighting.
2 LED street light advantages
(1) The characteristics of the LED street lamp itself—the unidirectionality of light, without the diffusion of light, to ensure the illumination efficiency;
(2) The LED street lamp has a unique secondary optical design, which illuminates the area of ​​the LED street lamp to the required illumination area, further improving the illumination efficiency to achieve energy saving purposes;
(3) The light source efficiency of LED has reached 90~110 lm/W, and there is still a lot of room for development. The theoretical value is 250 lm/W. The luminous efficiency of the high-pressure sodium lamp increases with the increase of power. Therefore, the overall luminous efficacy LED street lamp is stronger than the high-pressure sodium lamp;
(4) The color rendering of LED street lamps is much higher than that of high-pressure sodium lamps. The color rendering index of high-pressure sodium lamps is only about 23, while the color rendering index of LED street lamps reaches 75 or more. From the perspective of visual psychology, the same brightness is achieved, and the illumination of LED street lamps is average. Can be reduced by more than 20% than high pressure sodium lamps (refer to British road lighting standards);
(5) The light decay of LED street lamps is small, the light decay of less than 7% in one year, and the illuminance requirement for road use is still achieved after 10 years of use, while the high-pressure sodium light decays, which is more than 30% in a year or so, so LED street lights are The power used can be designed to be lower than the high pressure sodium lamp;
(6) LED street lights have automatic control energy-saving devices, which can achieve the maximum possible power reduction and save energy when meeting the lighting requirements of different time periods;
(7) LED is a low-voltage device that drives the voltage of a single LED to be a safe voltage. The power of a single LED in a series is 1W, so it is a safer power source than a high-voltage power supply. It is especially suitable for public places (such as street lamps). Lighting, factory lighting, automotive lighting, civil lighting, etc.);
(8) Each unit LED chip is small in size, so it can be fabricated into various shapes of devices and is suitable for a variable environment;
(9) Long life: can use more than 50,000 hours;
(10) High light efficiency: using chips above ≥100 lm, it can save more than 75% energy compared with traditional high-pressure sodium lamps;
(11) Easy installation: directly install the lamp head on the lamp post or nest the light source in the original lamp housing;
(12) Reliable quality: All circuit power supplies use high-quality components, and each LED has a separate overcurrent protection, so there is no need to worry about damage. Based on the above principle, the energy-saving effect of high-power LED street lamps is remarkable, and the high-pressure sodium lamp can save more than 60% of electricity. Compared with traditional street lamps, the maintenance cost of LED street lamps is extremely low. After comparison, the total input cost can be recovered in less than 6 years.
3 LED street light shortcomings
(1) The power of a single LED is low. In order to obtain high power, multiple simultaneous uses are required;
(2) Spots. Due to defects in the manufacturing process of the white LED itself and the coordination error with the reflective cup or lens, the "yellow circle" problem is easily caused;
(3) Heat dissipation. Street lamps use high-power LEDs. High-power LEDs need to be equipped with suitable heat sinks to ensure the normal use of LEDs. 80% of the cost is used on heat sinks. The largest LED street lamp currently on the market is 250W, and the price is very high;
(4) The power supply life cannot be guaranteed.
4 Technical indicators
At present, LED lighting technology is becoming more and more mature, and the efficacy of high-power LED light source has reached more than 100 lm/W, which makes energy-saving renovation of urban street lighting possible. LED street lights, especially high-power LED street lights, are hitting the traditional street light market at a rapid rate.
(1) LED luminous efficiency ≥ 80 lm / W. LED light source used in LED street light can not be lower than this value;
(2) Lens transmittance ≥93%, temperature resistance - 38 to +90 °C. Mainly used for LED street light lens, the spot is rectangular, the material is PMMA optical material, or it can be borax glass, which can guarantee the service life of the lens;
(3) The uniformity of road illumination is ≥0.4 than the average illumination. The spot ratio is 1:2;
(4) Meet the road illumination requirements. The actual 1/2 center spot reaches 25 LUX, the 1/4 center light intensity reaches 15 LUX, the lowest light intensity 4 LUX at 16 meters, and the overlapping light intensity is about 6 LUX;
(5) Input voltage: AC90V ~ 280V / 50Hz;
(6) Power consumption: the ratio of actual power consumption to total lamp power consumption is ≥80%;
(7) Power factor ≥ 0.9;
(8) Adapt to humidity ≤ 95%;
(9) The external temperature of the lamp is ≤60°C. Despite the rapid development of LED street lamps, the standards for LED street lamps are relatively lagging. The standards for LED street lamps vary from region to region.
5 LED street light and traditional street light use comparison
For example, a city road in a city needs to construct 2km of road lighting, the height of the street lamp is 10m, the street lamp interval is 40m, and the two sides are symmetrically arranged, and 102 street lamps are required. There are two options to choose from. The first is to use high-pressure sodium lamps as the light source, and the second is to use LED street lamps as the light source. The cost is compared with a 250W sodium lamp.