Comparison of LED lights with traditional sodium_Lighting Best International Limited

At present, China is creating a resource-saving society, the "green light" environment-friendly concept has gradually popular. With the continuous advancement of technology, the rapid development of semiconductor materials application technology, landscape lighting small power LED light source has been widely used in high-power LED lights are also more and more aroused concerns.

LED light-emitting principle:

LED (Light Emitting Diode), light emitting diode, is made Ⅲ-Ⅳ compound is a solid state semiconductor devices, which can be converted directly into electricity to light. LED's heart is a semiconductor wafer, semiconductor wafer consists of three parts, part of the P-type semiconductor, the hole in it dominates the other end is an N-type semiconductor. When the current through the wire on the chip, the electrons and holes will be pushed to the quantum well, the electron hole recombination, then will be issued in the form of photon energy in the quantum well, which is the principle of LED light. The wavelength of light is the color of the light is determined by the material form a PN junction decision.

HPS light-emitting principle:
After the use of high-pressure sodium lamp is energized an arc is generated between the electrodes at both ends of the arc tube, due to the high temperature of the arc tube so that the mercury and sodium is evaporated into the heated homogeneous mercury vapor and sodium vapor, the electrons emitted by the cathode to the anode during movement, impact discharge of atomic species to obtain ionization or excitation energy, and then return to the ground state from the excited state; or from the ionized state to an excited state and then return to the ground state of an endless loop, at this time, the excess energy is released in the form of optical radiation, will produce the light.
LED street light is a group of light emitting diodes is achieved by a novel low-voltage DC lighting the way lighting needs, with high brightness, good color and other characteristics; In addition, because LED lights for low voltage DC input, with the solar combine to make solar LED lights become a possible future road lighting the way.

1, on the energy efficiency analysis, comparison
Shall achieve the same illuminance (brightness) levels, compare the lighting installation power under near lighting quality standards premise. Because of high pressure sodium lamp power (250 ~ 400W) high luminous efficiency, up to 130 ~ 1401m / W, while the low-power lamp (100 ~ 150W) light efficiency is about 80 ~ 1001m / W, while the active power LED multi 1WLED tube lights, which light effects are similar, so should power lights were on and the low-power lights for analysis.

(1) High-power (≥250W) lights: High-pressure sodium lighting efficiency, consider three factors ballast losses, track lighting efficiency and utilization, overall efficiency if by 0.55 meter, the effective optical efficiency of about sodium 70 ~ 751m / W; and effective luminous efficiency of LED lights, currently in the United States is about 621m / W, the best domestic enterprises has reached 56 ~ 581m / W. Therefore, the town Run King felt for high power street lights, the current LED energy efficiency than sodium lower.

(2) small power (≤150W) lights: effective optical efficiency sodium (included in the overall efficiency of 0.55) is about 45 ~ 551m / W, while LED based upon 56 ~ 581m / W meter, the LED energy saving can be achieved than sodium 10 % ~ 20%, up to 30%. From the analysis, it was found for the branch of small power (≤150W) time, LED lights up to 10% ~ 30% energy savings than sodium, while power is still less than the sodium energy efficiency. Therefore, those who claim that the LED lights in general than high pressure sodium lamp energy saving, energy savings of 50% or even 60% of other phrases, apparently suspected of exaggeration and hype. We should insist on a scientific analysis, the principle of seeking truth from facts, otherwise mislead users and the masses.

2. Analysis of the light source color for road lighting effects

HPS correlated color temperature (Tcp) is about 2100K, warm color temperature genus, its color rendering index (Ra) only 23 to 25, the color is low; and the color temperature of the LED lights are now used much at 5300K, is a cold color temperature, better the product, which can reach 70 to 80 Ra, the color is good. As a vehicle traveling fast-track, main roads, yellowish shade of sodium, to see the front of the 90 ~ 160m distance about road conditions, the effect is slightly better than the white light, especially on foggy, dusty air conditions, sodium more advantages. For sidewalks, pedestrianized street, residential area, such as roads, LED lights color better than sodium, to distinguish the human condition clearer, more advantages.

3. Comparison of Economic Analysis
High-pressure sodium lamps, each about 1200 ~ 1500 yuan; the current LED lights, according to the power of different sizes, the price difference between the larger, about 4,000 to 8,000 yuan. Their current state, LED lights clearly too expensive, up to 3 to 5 times the price of the giant. As before? Less than 150W of LED can save 10% to 30% per year per lamp saving about 50 ~ 150KWh, simply can not buy the lamp recycling costs more than it takes. Can only hope that in the coming years, LED development trend, the price will gradually decline, to further improve energy efficiency, and then compare their economic performance.

4, life analysis
Compare life should be based on the whole lamp life. HPS includes a light source, electrical accessories (mainly ballast, flip-flops) and lamps, sodium lamps for street lights average life of 3 to 5 years, energy-saving ballast not less than 20 years, the lighting as well. The service life of LED lights no experience, existing enterprise known as 50000, 60000 hours, there is no reliable basis. US Energy Star requirements formulated, is divided into two tranches of not less than 35000h and 25000h, mainly LED chip life is very long, but the relationship between temperature and packaged, heat and other factors greatly, in addition to an electronic circuit device driver Component life issues, such as capacitors often only 8000h to 10000h. So overall, said, LED lamp life and sodium lamps can not match.

5, to maintain the performance comparison
In the city street department, represented by the user, are more concerned about street maintenance performance. According to the analysis, the maintenance of good performance sodium lamps as long as the scrub, do not replace, little ballast replacement, lighting replaced every three to five years, is also very convenient. The LED lights, LED tubes involved, modules (including lenses, etc.), power devices, components occurs, the larger the possibility of component damage, and repair and replacement also have difficulties, it is likely to be replaced as a whole, the higher the cost, the future remains to be resolved. LED lights have no standard to follow, for bidding, ordering, use, maintenance are detrimental. In summary, we believe that LED lights are new things in recent years, with the development of LED industry is bound to have greater development prospects. But the current application status, there are still many problems, although there are a few in the LED lights research, development and production enterprises, has made great efforts to solve some technical problems, and promote the advancement of the product, they are worthy of the industry's elite; but overall, said horizontal LED lamp products, quality, uneven, varies greatly, there is no standard to regulate them, and some quick success, energy efficiency is not high, the heat did not deal with the problem, the light fades great, life is not long no reasonable lamps with light, can not achieve promotion requirements.We hope that research, teaching, design units, using units and production companies to work together to address a variety of technical problems, improve product standards, develop and perfect a series of standards for the promotion and application of make all the preparations. On the application, you should insist on orderly and gradual, beginning from the pilot experiences, and continuous improvement; small power LED lights should be applied to the branch, district roads began, then developed into roads, power streetlights, a gradual manner. No matter what the source, lighting, should be consistent with "urban road lighting design standards" (CJJ45-2006) provisions, including brightness, illumination, uniformity and other quality indicators. Seek truth from facts, avoid over-exaggeration, contrast bogey raise their own, more bogey down the other, insist on lighting quality, according to the (bright) degree level, adhere to technological and economic integration, application and energy saving combination, to prevent excessive speculation, for users service, the user is responsible, do not mislead the user, but also the user a true face. Do not give "instead of" what sources should be after a few years or a few years efforts to constantly improve themselves in order to become a high quality, efficient new light in road lighting, lamps, for users to choose. Allowing users to speak, so use of effects to evaluate. Luminous efficiency: units of lumens per watt Lm / w. That electric light energy into light energy capacity, the luminous flux emitted divided by the power consumption to be represented.

6, the luminous efficiency
Luminous efficiency of LED light source, the current foreign States, Japan about 75Lm / w or so, the domestic production of LED about 65Lm / w or so. High pressure sodium light emitting efficiency is 100Lm / w or so, the luminous flux emitted per w higher than the LED 25 ~ 35Lm / w. 400w high pressure sodium lamp luminous efficiency of up to 120Lm / w.

7, through the fog
In road lighting for LED lights for the fog penetrating understanding of a great misunderstanding. Most people have always thought that the penetration of LED lights sodium than traditional lighting penetration is low, this is a wrong understanding. Most people are seeing some of the information from the network, or to see some of the sensory experience on the road, and did not do a scientific evaluation and analysis, which considers penetrating LED street light is poor. In this paper, this situation will make a scientific analysis.