Recently I have heard the views of many experts and scholars that the LED lights to replace the high-pressure sodium lamp as a technically premature. The main reasons are the following:
1. LED luminous efficiency and high-pressure sodium lamp can not be compared to
2. LED exposure is too concentrated, their exposure to poor uniformity of
3. LED street light decline of serious, life expectancy is not long
4. LED street lamp itself is too heavy a weight is not conducive to the installation, wind
5. LED lights cost is too high, can not be widely
Our point of view one by one according to the above analysis:
1. LED light decline problems
Now, some businesses, in order to reduce costs, φ5 on the use of several hundred low-power LED. However, such a low-power LED light is a very serious decline, and its optical decline to 80% life span of only 1,000 hours. Therefore, as a long-term use of the street need never be allowed to adopt this low-power LED's. As a high-power LED, the light should decline much better.
2. LED lights of the weight problem
LED street lamps, and high pressure sodium lamp in the replacement process, in order to prevent the LED street lamp too heavy, a number of LED lamps manufacturers as much as possible to reduce the weight LED lamp. From the original single lamp about 30 kg, down to the present more than 10 kilograms. Weight reduction there is further decline.
3. LED lights cost is too high, can not be widely
LED street lamp is composed of many parts, of which the most effective components are light-emitting chips, the price is also the most expensive part of the chip. Luminous efficiency of the chip is now in the 65 ~ 75lm / w, but the major chip manufacturers have a greater light efficiency in the development of chips. Imagine, with the advancement of technology, optical efficiency, once developed to a very high level, then the number of chips used will be less than it is now, and the price of chips will be fallen. By that time, LED lights overall price will fall.
4. Luminous efficiency
At present, LED light-emitting efficiency of Looking at the figures certainly not as good as high-pressure sodium lamp. LED light efficiency is generally 65 ~ 75lm / w, and along with technology, LED light effect increased each year, while the high-pressure sodium lamp can reach 125lm / w. However, the high-pressure sodium lamp spectrum are relatively concentrated in the yellow, and its color temperature is relatively low, only 2000 ~ 2500K, while the LED color temperature higher than 3500 ~ 4500K can be achieved. Another high-pressure sodium light is to launch four, there are a large part of light can not reach the road. Also, the high-pressure sodium lamps of color-rendering index is poor, only 23 or so, feeling the dark; and LED-high color-rendering index can reach 75 ~ 80. The road bright and comfortable. So from a practical view of the glow, LED but can be much higher than the high-pressure sodium lamp. The LED can replace 135W high pressure sodium lamp 250W, or 300W for mercury lamp. 135W of LED, its output is only about 7020 lumens luminous flux (after the second optical design, will be lost), to reach the road when the number is still 6500 lumens lumens, while the average intensity of the road can reach 16Lux (12m high pole). 250W high pressure sodium lamp luminous flux output of 20,000 lumens. But the road to reach the number of lumens only 7000 lumens. The illumination of the road is about 30 ~ 40Lux, because of the color difference coefficient, LED illumination correction factor of 2.35 times, high pressure sodium lamp of the correction factor of 0.94 times. So, after a revised 135W of LED illumination for the ground 37.6Lux, while the high-pressure sodium lamp illumination of the revised 28.2 ~ 37.6. Both quite. Therefore, 135W of LED can replace 250W high pressure sodium lamp, LED can be 1.85 times more energy-saving, energy efficiency is about 50%.
5. Irradiation uniformity problems
Indeed, without a second optical design, LED exposure is relatively concentrated, they must be a second optical design, so that light intensity distribution was bat-shaped.
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