Prospects for LED street lights
The application of LEDs in the field of lighting is a technology that has emerged and developed rapidly in recent years. China is a fast-growing country, and the demand for urban lighting is growing. Therefore, how to reduce energy consumption and use energy-saving systems has become a major hot issue that the Chinese government attaches to and considers. The high efficiency, energy saving and low pollution characteristics of LED lighting systems have become a good way to save energy and reduce emissions worldwide.
At present, there are about 120 million to 130 million street lamps in the world. According to the statistics of the national street lamp industry in 2006, there are about 15 million street lamps in China's urban lighting. With the development of national infrastructure, the growth rate of street lamps in recent years is about 20%. the above. Under the trend of global energy conservation and emission reduction, the demand for LED street lamps has increased rapidly. The survey data of the Taiwan Industrial Research Institute shows that the penetration rate of global LED street lamps in 2007 is only 0.23%, but it is expected that LED street lamps in 2009 will be The penetration rate will exceed 1%, reaching 4% in 2011. Statistics from StrategiesUnlimited predict that when the LED street lamp market penetration rate exceeds 5%, it is estimated that the global LED street lamp output value will exceed 4 billion US dollars. During 2007-2013, the composite growth rate of LED street lamp production value is as high as 87%. Based on this estimation, the annual market size of lighting street lamps in the country should be no less than 5 billion yuan. Compared with traditional lighting systems, LED lighting systems involve complex work in many different fields, and the current price is higher than traditional street lamps, but with the advancement of technology and the rapid growth of market demand, the price of LED lighting systems will be very high. Falling fast. Therefore, in the long-term energy-saving benefits, the advantages of LED lighting systems will not be replaced.
Energy efficiency considerations for LED street lights
Compared with the traditional street lamp system, the LED street lamps have the following characteristics: 1. The light source and the illumination mechanism are different; 2. The integration characteristics and extension of the system are different; 3. The key factors affecting the system performance are different; 4. The system composition requirements are different. . For LED streetlights, the factors that affect the performance of the system include the optical efficiency of the system, the efficiency of the power supply, and the thermal management scheme of the system.
At present, LED street lamps usually use lenses and reflectors as components of secondary optical design, and their optical efficiency can reach about 90%. Most of the current LED street lamps use polycarbonate (PC) or acrylic (PMMA) rubber sheet material as a protective cover for the light-emitting surface to obtain higher light transmittance and reduce the weight of the lamp. When the rubber sheet material is exposed to sunlight for a long time, it will be aging due to the action of ultraviolet light in sunlight, resulting in a decrease in the output luminous flux of the lamp. In addition, because the material of the rubber sheet is soft and easy to generate static electricity, it is easy to appear surface dust and scratching when it is hit by sand and dust, which seriously affects its light transmittance. However, the current technical standards or specifications do not stipulate related issues, so there is still room for discussion and improvement. Due to the waterproof and dustproof in the outdoor environment (generally required to be above IP65), effective anti-aging and safety considerations, the high light transmittance (~94%) of the tempered glass on the light-emitting surface of the LED street light system should be applicable. For the alternative, the security certification can still be tested using the GB7000.5 standard. Considering the role of tempered glass, the overall optical efficiency of the LED street light system is around 85%.
A thermal management solution that is one of the factors that affects its system performance is also important. It is well known that the heat dissipation function in an LED lighting system directly determines the performance and life of the system. At present, the LED street lamp market in the United States mostly uses the US Cree LED device for system integration of lamps. When Cree's high-power LED device is heated to 80 degrees Celsius at 25 degrees Celsius, its white light output efficiency is reduced by 10%. When driving at 350mA driving current under the same temperature rise condition, the LED life will be shortened by about 30%, so LED The heat dissipation of the lighting system becomes a critical and problem to be solved.
Based on the current technical parameters of LED street lights, we compare the system energy efficiency with traditional high-pressure sodium (HPS) street lights, as shown in Figure 1. The HPS street lamp with transformer/ballast applied to urban road lighting has a system power consumption between 70W and 400W. In the calculation, we use a general quality HPS power supply, and the system has a power efficiency of 83%. At present, the efficiency of the driving power of the LED street lamp is generally in the range of 83% to 90%. As shown in Figure 1, the efficacy of the HPS luminaire increases as the system's power consumption increases. This characteristic is determined by its luminescence characteristics. When the luminaire's optical efficiency is 75%, the 70W to 400W HPS luminaires have a luminous efficacy of 45 lm/W to 76 lm/W. For the LED street lamps currently on the market, the efficacy of some high-end LED devices is about 100lm/W (the normal working temperature), and the overall luminous efficacy of these LED streetlight systems is 72lm/W.
Compared with HPS street lamps with a system power consumption of less than 250W, the current LED street light has certain advantages. Take the 8m high HPS street lamp as an example, the lamp source power is 100W~150W, the system power is 120W~180W, and the average illuminance of the road surface is about 30lx~40lx. If the average illumination requirement of 15lx~20lx is met, the HPS must use a low-power light source, but the efficiency of the lamp is significantly reduced (from 60lm/W at 150W to 42lm/W at 70W). For the road surface average illumination of 20lx, if the double-sided cross arrangement is adopted, the system power 80W LED street lamp system can effectively realize the function of adjusting the system power output and adjusting the light and dark without reducing the efficiency of the lamp (72lm/W), saving energy compared with HPS. 40%.
However, when compared with HPW street lamps from 250W to 400W, this advantage no longer exists. The 400W HPS luminaire can achieve a luminous efficiency of 76lm/W. In other words, at this time, the HPS street lamp has better energy saving effect than the LED street lamp system. Based on the above data, it can be clearly concluded that from the perspective of energy saving and emission reduction, in order to better highlight the characteristics and advantages of LEDs, LED street lamps are suitable for scheduling on secondary roads under the existing technical conditions. On the road. LED street lights are not recommended for use on major roads or main roads. Recently, some companies have noticed that 120lm/W high-power LED devices have been introduced. With these LED devices, the luminous efficacy of the lamps can theoretically reach 86lm/W. It is estimated that the finished products of street lamps will be available soon. It is expected to use 120lm/W. LED streetlights for high-power devices will be competitive in the 10m and 12m high streetlight markets, but there are some difficulties in completely replacing the traditional streetlight market. The overall efficacy of the luminaire is in addition to the price and the life of the drive power, it is the key to determine whether the LED street lamp can completely replace the traditional street lamp, that is, only improve the light efficiency of the LED device itself, and ensure good optical efficiency, power efficiency and system heat dissipation performance. In order to make LED street lights truly occupy the market.
Institutional safety issues with LED street lights
In the new specification "Semiconductor Lighting Pilot Demonstration Project - Technical Specifications for LED Road Lighting Products" (LB/T002-2009), the road lighting for the current semiconductor lighting "Ten Cities and Ten Thousand Cities" demonstration project has been made for LED street lighting products. The relevant functional requirements include: specification classification, initial luminous flux, initial luminous efficacy, and lumen maintenance rate and other basic optical performance parameters. The technical specifications also specify electrical safety requirements and radio disturbance characteristics. However, the specification does not take into account the impact of the safety and stability of the LED street lamp itself on the safety certification of the product. Among the national standards for road lighting fixtures in China, GB7000.1-2007 and GB7000.5-2005 respectively stipulate the electrical safety, mechanism safety, waterproof and dustproof requirements and some basic requirements for road lighting lamps. Among them, GB7000.5-2005 specifically proposes the use of static load test to detect the safety and stability of the street lamp system and the safety test method of the glass cover of the lamp.
Compared with the static load test, the Taiwan region proposed a wind pressure test scheme for the application of the streetlight entity in the "Draft Standard for Illuminated Diode Road Lighting Fixtures" in 2008. This scheme uses low-speed wind tunnels for LED street lights. The institutional part is tested for safety. The difference between static and dynamic testing is that static testing is mainly for testing the load resistance of the external mechanism of the luminaire. In addition to the additional wind load generated by the exposed components inside the lamp body, the dynamic test will also focus on testing the overall luminaire. During the vibration process, whether the external structure and internal small parts and the joints of the parts are deformed, loosened, peeled off, cracked, etc., so the two test methods still have considerable differences. For LED street lamps with a large number of heat dissipation mechanisms, Due to the complexity of the heat dissipation mechanism and the fact that some of them are located outside the LED street light, the products that are tested according to the static test requirements may not be able to ensure dynamic testing and ensure the strength of the lamp body in practical applications.
Since the current technical specifications do not provide guidance for the mechanical safety testing of LED lamps, the safety of the LED street lamps used in the “Ten Cities and Ten Thousand†demonstration projects has caused some degree of concern, especially for some. This kind of worry is even more serious in the coastal project with a typhoon threat. The LED streetlight products have entered the market and are widely accepted to create cost and time barriers. Therefore, it is also important to incorporate institutional safety assessment methods and relevant documentation guidelines. If the safety of the system organization is strictly considered, dynamic testing is also necessary and should be included in the standard as the basis for evaluating the safety of the lamp body!
In recent years, many LED key technologies have been broken, and the global LED market has risen rapidly. In 2009, the Chinese government proposed the “Ten Cities and Ten Thousand Cities†program to promote the development of various technologies in China's LED industry chain. With the introduction of "Semiconductor Lighting Pilot Demonstration Project - Technical Specification for LED Road Lighting Products" (LB/T002-2009), this specification has established a clear development direction for the development of LED street lighting technology, but there are still some calibration and practical application processes. The difference is still to be resolved.
LED lighting has become an industry that has developed rapidly in China in recent years. With the support of the government, many practical products and demonstration projects have emerged. While seeing the bright future of LED lighting, we must also face up to the problems in the current technological development and more effectively improve the light efficiency of the lighting system. And constantly improve and revise the existing normative standards, and ultimately the lighting products developed by LED technology will bring the substantial benefits of energy saving and emission reduction to the society, and drive the independent development of China's high-tech industry.
High efficient charging speed for Acer laptop, stable current outlet can offer power for the laptop at the same time charge the laptop battery. The best choice for your replacement adapter. The DC connector is 5.5*1.7mm or 3.3*1.0mm. We can meet your specific requirement of the products, like label design. The plug type is US/UK/AU/EU. The material of this product is PC+ABS. All condition of our product is 100% brand new.
Our products built with input/output overvoltage protection, input/output overcurrent protection, over temperature protection, over power protection and short circuit protection. You can send more details of this product, so that we can offer best service to you!
Laptop Adapter For Acer,Charger For Acer,Acer Laptop Adapter ,Ac Adapter For Acer
Shenzhen Waweis Technology Co., Ltd. , https://www.waweis.com