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LED Street Light Contrast With Traditional Sodium Lamps

LONGT Lighting Group Co.,Ltd | Updated: Sep 04, 2017

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

LED light light principle:

LED light-emitting diodes, is made of III-IV compounds, is a solid-state semiconductor devices, it can be directly converted into light. LED heart is a semiconductor chip, semiconductor chip consists of three parts, part of the P-type semiconductor, in which the dominant hole inside, the other end is the N-type semiconductor. When the current through the wire on the role of the chip, electrons and holes will be pushed to the quantum wells, electrons in the quantum wells with holes, and then will be in the form of photon energy, which is the principle of LED light. And the wavelength of light is the color of light, which is determined by the material that forms the P-N junction.

High-pressure sodium lamp light principle:

High-pressure sodium lamp is the use of power, the arc tube between the electrodes at both ends of the arc, due to the high temperature of the arc so that the tube of sodium amalgam heat evaporation into mercury vapor and sodium vapor, cathode electrons in the process of moving to the anode, The atoms of the material, so that the energy generated by ionization or excitation, and then from the excited state to the ground state; or from the ionization state into the excited state, and then return to the ground state infinite cycle, this time, the excess energy in the form of optical radiation, It produces light.

High-power LED street lamp is a kind of new lighting method which realizes the lighting demand through the DC low-voltage light-emitting diode group. It has the characteristics of high brightness and good color rendering. In addition, because the input of LED street lamp is low-voltage direct current, Solar energy together, making solar LED lights become a way of future road lighting possible.

1, on energy efficiency analysis, comparison

Should be in accordance with the same illumination (brightness) level, close to the lighting quality standards under the premise of both the lighting installation power. High-power lamp (100 ~ 150W) light efficiency of about 80 ~ 1001m / W, and the use of high-power LED (250 ~ 400W) high efficiency, up to 130 ~ 1401m / W, Street lights with 1WLED tube, the light effect are similar, it is appropriate for high-power street lamps and low-power street lights for analysis.

(1) high-power (≥ 250W) lights: high-pressure sodium lamp high efficiency, consider the ballast loss, lamp efficiency and track utilization and other three factors, the overall efficiency of 0.55 dollars, the effective light effect of sodium 70 ~ 751m / W; and LED lights effective light effect, the current in the United States is about 621m / W, the best domestic enterprises have reached 56 ~ 581m / W. Therefore, the ancient town of Runjing lights feel for high-power street lamps, the current LED energy efficiency than the sodium lamp is lower.

(2) low power (≤ 150W) street light: the effective light efficiency of sodium lamp (included in the comprehensive efficiency of 0.55) is about 45 ~ 551m / W, while the LED is still 56 ~ 581m / W dollars, the LED than the lamp can achieve energy saving 10 % ~ 20%, up to 30%. From the analysis, we can see for the branch of the small power (≤ 150W), LED lights than the sodium lamp can save 10% to 30%, while the high power is still less than the energy efficiency of sodium lamps. Therefore, those generally claimed that LED lights than high-pressure sodium lamp energy-saving, and even energy-saving 50%, 60% and other claims, apparently exaggerated and speculation suspected. We should adhere to the scientific analysis, the principle of seeking truth from facts, or easy to mislead the users and the masses.

2, light source light color on the road lighting effect analysis

The relative color temperature (Tcp) of the high pressure sodium lamp is about 2100K, which is warm color temperature, its color rendering index (Ra) is only 23 ~ 25, the color is low; and LED street lamp now use the color temperature is more than 5300K, Of the products, the Ra up to 70 to 80, good color rendering. As a motor vehicle driving the fast track, the main road, partial yellow light of the sodium lamp, to see the front 90 ~ 160m distance from the road conditions, the effect is slightly lighter than the white light, especially for fog, dusty air conditions, sodium More advantage. For sidewalks, commercial pedestrian street, residential area and other roads, LED color is better than sodium lamp, to distinguish the situation is more clear, more advantages.

3, economic analysis and comparison

High pressure sodium lamps, each set about 1200 ~ 1500 yuan; current LED lights, according to the power of different sizes, the price difference between the larger, about 4000 ~ 8000 yuan. On the status quo, LED lights are too expensive, the price of up to 3 to 5 times the giant If less than 150W before the LED can save 10% to 30%, each annual energy saving about 50 ~ 150KWh, simply can not recover more cost of the purchase of lights. Can only expect in the next few years, LED development trend to see its price will gradually decline, further improve energy efficiency, and then compare its economic performance.

4, the life of the analysis

Comparison of service life should be based on the life of the whole lamp. High pressure sodium lamp, including light source, electrical accessories (mainly ballasts, triggers) and lamps, sodium lamps for the average life expectancy of 3 to 5 years, energy-saving ballasts will not be less than 20 years, the same is true. The LED lights have no experience in the use of life, the existing enterprises known as 50,000, 60,000 hours, there is no reliable basis. US Energy Star requirements, divided into not less than 35000h and 25000h two stalls, mainly LED chip life is very long, but with the package after the temperature, heat and many other factors, in addition to the drive circuit device electronics Component life problems, such as capacitors are often only 8000h to 10000h. So the whole said, LED lamp life and sodium lamp can not be compared.

5, to maintain performance comparison

To the city lights management department as the representative of the user, more concerned about the maintenance of street lamps. According to the analysis, sodium lamp maintenance performance is good, as long as the scrubbing lamps, do not have to replace the ballast rarely replaced, light 3 to 5 years replacement time, is also very convenient. The LED lights, involving LED tubes, modules (including lenses, etc.), power supply devices, the occurrence of components, components, the possibility of damage, maintenance and replacement is also difficult, it is necessary to replace the whole, the higher cost, yet to be the future solve. LED lights have no standard to follow, the tender, order, use, maintenance are unfavorable. To sum up, we believe that LED lights in recent years there are new things, with the development of LED industry will have a greater development, broad prospects. But the current application of the status quo, there are still many problems, although a small number of LED lights in the research and development and production enterprises, made great efforts to solve a number of technical problems, to promote the product forward, they deserve the industry elite; But the overall said, LED street lamp product level, quality, uneven, very different, there is no standard to be standardized, and some quick success, product energy efficiency is not high, the heat problem is not handled well, great light failure, long life , There is no reasonable light distribution, can not meet the promotion requirements. We hope that scientific research, teaching, design units, the use of units and production enterprises to work together to solve various technical problems, improve product levels, develop and improve a series of standards for the promotion and application of the preparation. In the promotion and application, should adhere to step by step, starting from the pilot, sum up experience, continuous improvement; should be applied from the small power LED street lights, residential roads, and then to the main road, high power lights, and gradually advance. No matter what light source, lamps, should meet the "urban road lighting design standards" (CJJ45-2006) requirements, including brightness, illumination, uniformity and other quality indicators. Adhere to the principle of seeking truth from facts, should not be exaggerated, compared to avoid their own bogey, bogey down the other, adhere to the lighting quality, according to (light) level, adhere to the combination of technology and economy, combined with energy saving and environmental protection to prevent excessive speculation for the user Service, the user is responsible, do not mislead the user, but also the user a real face. Do not lightly "replace" what light source, should be years or years of efforts to constantly improve themselves, in order to become a road lighting in a high quality and efficient new light source, for the user to choose. Let the user speak, so that the use of results to evaluate. Luminous efficiency: unit per lumen lm / w. That is, the ability of the electric light source to convert electrical energy into light energy, expressed by the amount of luminous flux emitted by the power consumption divided by the power consumption.

6, luminous efficiency

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

7, through the fog

In the road lighting for LED lights for the penetration of fog awareness of a great misunderstanding. Most people have always believed that the penetration of LED lights than the traditional light source of sodium lamp penetration is low, this is a wrong understanding. Most people are from the network to see some of the information or to see some of the senses on the road feel, and did not do a scientific assessment and analysis, so that LED lights light penetration is poor. In this paper, this situation will be a scientific analysis.

We all know that the range of visible light is between 380nm and 780nm, in this range of light can be accepted and recognized by the human eye. Guzhen Runjing street that all the lamps only in this band within the light of the use of value, out of this range of human eye is not recognized. In this paper, the analysis of penetration is only within this range. Spectrum can be seen in the spectrum of the LED than the full number of sodium lamps, the two peaks are at 580nm, LED blue part of the total light flux only about 6%, while the sodium lamp is almost no. LED red light distribution than the high-pressure sodium lamp more widely.

High pressure sodium lamp and LED light source lighting performance comparison

1, the life of the comparison

LED lamp is a kind of semiconductor diode, its light source theory life is very long (provided that meet the required temperature range, L70 light failure standard), but the overall life of a lamp is not simply light source life, the lamp also includes the lens Part of the impact. So the life of the final lamp should be the life of all lighting components in the minimum limit. When the luminous flux decays to 30%, its life reached 50,000 hours, while the metal halide lamp life of 6000-12000 hours, high pressure sodium lamp life is 20,000 hours.

2, light lighting effects on the comparison

(1) Color rendering index LED white light

LED color temperature in 3500-7000K; color rendering index of 80 to 93. Traditional high pressure sodium lamp: high pressure sodium lamp color temperature in 2000-2500K; color rendering index in 20 to 30.

Through the above comparison results can be seen high pressure sodium lamp color rendering index is low, poor color rendering, the object itself, the reduction of color is not conducive to the depth of the surrounding environment to determine; LED light color rendering index is high, good color, can be very good The actual color of the object is restored, but the white light is cold. Look at high pressure sodium lamps, closer to natural light. LED lighting at this stage of the light effect is slightly better than the sodium lamp, with the development of LED technology and mature, lighting efficiency will be greatly improved.

(2) dimming function

LED lights have a more perfect dimming function. LED light output and operating current is proportional to, so you can reduce the current method to dim. In addition, because the LED lights for frequent switching on it is not much damage, LED lights can also use the pulse width adjustment method to dim, by adjusting the voltage duty cycle and operating frequency, can effectively adjust the LED light intensity. 3, light utilization, luminous rate

LED light source of the smallest loss of luminous flux, and the traditional light source is different, LED light is half-space light source. High-pressure sodium lamp is a full-space light source, the need to change the direction of a half-space light to the other half of the space reflector reflection at the same time, the inevitable absorption of light and light source of their own light. The use of LED lights as a light source, there will be no loss in this area, the light utilization ratio is higher than the high pressure satisfied lamp. The current LED lights in 65-100 lumens / watt, while the high pressure sodium lamp can reach 140 lumens / watt. High pressure sodium lamp spectrum is concentrated in the yellow, color temperature 2000-2500K wear fog strong. Sodium lamp has a very big problem is the sodium lamp lighting is very bad. Sodium lamp in the working state, the lamp cavity temperature should be more than 150 degrees, and LED lamp temperature is 30% of high pressure sodium lamp, in the non-working state because of negative pressure sucked into a lot of dust and insects, greatly affect the sodium light Effect and life. While the LED is relatively stable.

4, energy saving and environmental comparison

LED lights efficient energy, ultra-low power consumption. White LED energy consumption is only 1/10 of incandescent, energy-saving lamps 1/4. And the LED light source does not contain harmful metal mercury. High pressure sodium lamp light source containing metal mercury, metal sodium (after the change into mercury vapor and sodium vapor), short life (relative to the LED), follow-up waste disposal on environmental pollution. LED lights are good weather resistance and convenient transportation. Solid-state package, belonging to cold light source type. So it is easy to transport and install.

5, structure and cost comparison

LED lamps generally grainy are more obvious, and its luminous position is more concentrated. So the LED need to do better in the light above the design, the point light source as far as possible to expand into the surface light source, improve eye comfort. Then there are many products will do LED dimming design to save energy. At present, the town of Runjing street lights and most manufacturers design and manufacture of LED lights, like lamps, their weight is very heavy, often more than 10 kg. Such a large self-weight tend to make pole pole overload, reducing its wind resistance. Most of the LED lighting manufacturers, LED lamps will be designed to replace the way, that is directly replace the existing lamps. And the LED current is large to maintain the brightness unchanged in the case of reducing the number of wicks to save costs, or compress the PCB area, or reduce the safety device.