China Aviation Industry Planning and Design Institute Ren Yuanhui
LEDs have a new look after the advent of white light, making it possible for LEDs to enter the field of illumination as a new source of light. For more than ten years, LED technology and products have developed rapidly. The emergence of high-power LED chips, packaging, heat dissipation and other issues have been continuously advanced. In recent years, various road lighting fixtures have been developed and started in townships, villages, and residential areas. Community roads, urban branch road applications, and further urban road trials. Because LED is different from the widely used high-efficiency light source, due to the characteristics of LED, such as directionality of light, dimming, long life, shock resistance, weather resistance, etc., as well as obvious problems and deficiencies in his application, in lighting It is understandable that the community and even the community have different reactions.
Here are a few application questions for LED streetlights and high-pressure sodium lamps that are now widely used.
1. About energy efficiency analysis and comparison
The lighting installation power of both should be compared in accordance with the same illumination (brightness) level and close lighting quality standards. Because high-pressure sodium lamp high-power lamp (250~400W) has high luminous efficiency, it can reach 130~140 1m/W, while low-power lamp (100~150W) has about 40~100 1m/W, but it is now large. Power LED street lights use 1W LED tubes, and their light effects are similar. Therefore, it is necessary to analyze high-power street lamps and low-power street lamps separately.
(1) High-power (≥250W) street light: high-pressure sodium light effect, considering ballast loss, lamp efficiency and track utilization, etc. If the overall efficiency is 0.55, the effective light efficiency of the sodium lamp is about 70~75 1m/W; and the effective light efficiency of LED street lamps is currently about 62 1m/W in the US, and the best domestic enterprises have reached 56~58 1m/W. Therefore, for high-power street lamps, LEDs are currently less energy efficient than sodium lamps.
(2) Low power (≤150W) street light. The effective light efficiency of the sodium lamp (included in the overall efficiency of 0.55) is about 45~55 1m/W, while the LED is still calculated according to 56~58 1m/W, the LED can achieve energy saving 10%~20% than the sodium lamp, up to 30 %.
From the above analysis, it can be seen that the LED street lamp can save 10%~30% energy compared to the sodium lamp when the power is small (≤150W) for the branch, and the high power is still not comparable to the energy efficiency of the sodium lamp. Therefore, those who generally claim that LED street lamps are more energy efficient than high-pressure sodium lamps, and even save 50%, 60%, etc., are obviously exaggerated and speculative. We should adhere to the scientific analysis and the principle of seeking truth from facts, otherwise it will easily mislead users and the masses.
2. Analysis of the effect of light source color on road lighting
The color temperature (Tcp) of the high pressure sodium lamp is about 2100K, which is a warm color temperature. The color rendering index (Ra) is only 23~25, and the color rendering is low. The color temperature of the LED street lamp is more than 5300K, which is a cool color temperature. The product has a Ra of 70~80 and good color rendering.
As a fast track, main road, and yellow light of the motor vehicle, it is better to see the road surface at a distance of about 90~160m in front, which is better than white light, especially for foggy and dusty air conditions. More advantage.
For roads such as sidewalks, commercial pedestrian streets, residential quarters, etc., the color rendering of LEDs is better than that of sodium lamps, which distinguishes people's conditions more clearly and has advantages.
3. Economic analysis and comparison
High-pressure sodium lamps, each set is about 1200~1500 yuan; currently LED street lights, according to the size of the power, the price difference is large, about 4000~8000 yuan. As far as the status quo is concerned, LED street lights are obviously too expensive, and the price is as high as 3 to 5 times. For example, LEDs with less than 150W can save 10%~30% energy, and each lamp saves about 50~150KWh per year. It is impossible to recover the cost of purchasing lamps. It can only be expected that in the next few years, the LED development trend will see its price gradually decline, energy efficiency will be further improved, and then its economic performance will be compared.
4, life analysis, comparison
The service life should be based on the life of the lamp. High-pressure sodium lamps include light sources, electrical accessories (mainly ballasts, triggers) and lamps, sodium lamps for street lamps with an average life of 3 to 5 years, energy-saving magnetic ballasts for no less than 20 years, and lamps. However, there is no experience in the service life of LED street lamps. The existing enterprises claim to be 50,000 or 60,000 hours, and there is no reliable basis. The requirements set by the US Energy Star are divided into two grades of no less than 35000h and 25000h, mainly because the LED chip has a long life, but it has a great relationship with many factors such as temperature and heat dissipation after packaging, and there are also electronic circuits for driving circuit devices. Component life issues, such as capacitors are often only 8000h to 10000h. Therefore, as a whole, the service life of LED street lamps cannot be compared with that of sodium lamps.
5, maintain performance comparison
Users represented by the urban street lamp management department are more concerned about the maintenance performance of street lamps. According to the analysis, the maintenance performance of the sodium lamp is good, the lamp only needs to be scrubbed, there is no need to replace it, the ballast is rarely replaced, and the light source is replaced once every 3 to 5 years, which is also very convenient. LED street lights, LED tubes, modules (including lenses, etc.), power supply devices, etc., are more likely to cause damage to components and components, and maintenance and replacement are also difficult. It is likely to be replaced as a whole, and the cost is high. solve. LED street lights have no standard to follow, which is unfavorable for bidding, ordering, and use and maintenance.
In summary, we believe that LED street lights are new things that have emerged in recent years. With the development of the LED industry, there will be greater development and broad prospects. However, there are still many problems in the current application status. Although there are a few companies engaged in the research, development and production of LED street lamps, they have made great efforts to solve some technical problems and promote the advancement of this product. They are not the elite of the industry; But as a whole, the level, quality, unevenness and difference of LED street lamp products are very large. There are no standards to standardize. Some have quick success, some products are not efficient, the heat dissipation problem is not handled well, the light decay is very large, and the service life is not long. There is no reasonable lighting for the lamps and lanterns, and the promotion and use requirements cannot be met.
We hope that scientific research, teaching, design units, use units and production enterprises work together to solve various technical problems, improve product levels, formulate and improve a series of standards, and prepare for the promotion and application. In the promotion and application, we should adhere to the step-by-step approach, starting from the pilot, summing up the experience, and continuously improving; from the application of small power LED street lamps to the branch roads, residential roads, and then to the main roads, high-power street lights, and gradually advance.
No matter what kind of light source or lamp is used, it should meet the requirements of “City Road Lighting Design Standards†(CJJ45-2006), including brightness, illumination, uniformity and other quality indicators. Adhere to seeking truth from facts, avoid excessive exaggeration, compare bogey to raise yourself, and avoid pressing down on others, adhere to lighting quality, photo (light) level, adhere to the combination of technology and economy, apply energy and environmental protection, prevent excessive hype, for users Service, responsible for the user, do not mislead the user, but also a real face of the user. Do not lightly replace any light source. It should be improved after several years or years, in order to become a high-quality, high-efficiency new light source and lamp in road lighting for users to choose. Let the user speak and let the effect be evaluated.
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