Analysis of the advantages and disadvantages of LED street lights and high pressure sodium lamps

In recent years, the application of domestic LED lighting has developed rapidly. Many manufacturers have launched high-power LED street lights , which are increasingly used in road lighting as energy-saving products. Can high-power LED street lights really replace traditional light sources (mainly high-pressure sodium lamps)? Here are some of my views on the application of high-power LED street lights:

1. Regarding the power saving effect of LED street lights , power saving is an important factor in many cases where LED street lights replace high-pressure sodium lamps, but in reality, LED street lights are not more power-saving than high-pressure sodium lamps. From the comparison of luminous efficiency , the luminous efficiency of high-power LED street lights currently in practical use (80lm/W) is much lower than that of high-pressure sodium lamps (100~138lm/W). Although LEDs are directional and have higher lamp efficiency than high-pressure sodium lamps, due to their low luminous efficiency, the overall energy efficiency of LED street lights is still lower than that of high-pressure sodium lamps.

In some cases that prove that LED street lamps can save energy by replacing high-pressure sodium lamps, according to analysis, these cases are often due to the original street lamps with high power ( severely exceeding the brightness standard) or low lamp efficiency and serious light source attenuation. It is not scientific to use this as a basis for LED street lamps to save energy.

Second, the color of LED street lights. Currently, high-power LED street lights basically use white light with a color temperature of 5000K~6000K. As a road lighting source, it is too cold in visual perception, and the observation ability of the eyes will decrease when farsighted. Some studies in this regard have proved that yellow light or warm white light below 3000K is more suitable for road lighting. Therefore, daylight-colored LED street lights are not suitable for practical use as street lights.

3. The current cost of LED street lamps is far lower than that of high-pressure sodium lamps. The current price of an LED street lamp is between 4,000 yuan and 8,000 yuan, or even higher. The price of an imported brand of high-pressure sodium lamps (including lamps and complete sets of electrical light sources) does not exceed 1,500 yuan, and the average price is less than a quarter of that of LED street lamps.

Fourth, the nominal service life of LED street lamps is more than 50,000 hours, which is the ideal life of the chip. The chip packaging, lamp heat dissipation and other factors may cause light attenuation, and the life of the drive circuit (mainly electronic components) obviously cannot reach 50,000 hours. In some LED street lamps that have been tried, it was found that the lamp attenuation was very obvious in less than half a month.

The nominal life of high-pressure sodium lamps has now exceeded 28,000 hours, and there is no problem in actual use for 3 to 4 years. In comparison, the life of high-pressure sodium lamps and supporting electrical appliances is more problematic.

The maintenance of high-pressure sodium lamps is much easier, and the light source appliances can be directly replaced on site, and the cost is also low. As for LED street lights, I think the manufacturers may think they are maintenance-free, so on-site maintenance is not possible.

5. The light distribution problem of LED street lamps. At present, the light distribution technology of LED street lamps has made great progress. Some manufacturers have developed a secondary light distribution system instead of relying solely on chip arrangement for light distribution. However, on the whole, the light distribution is not completely reasonable. I have observed a lamp. The light distribution on the road side is brighter and the uniformity meets the requirements, but the brightness on the sidewalk side is obviously insufficient and the SR value obviously does not meet the requirements.

At present, there are not many products with secondary light distribution systems developed, and there are not many good LED street lamps to choose from in applications.

6. LED street lamps lack unified technical standards in terms of product specifications. There is currently no unified technical standard for the production of LED street lamps. Each manufacturer produces its own products according to its own standards, which makes it difficult for them to be interchangeable. In addition, the characteristics of the multi-chip assembly of LED street lamps bundle the chips and lamps together, making them difficult to maintain. Original products must be used for maintenance.

High-pressure sodium lamps have unified technical standards, and their lamps, light sources, and electrical appliances are highly versatile. Products from different manufacturers can be interoperable, which is very important from a maintenance perspective. Maintenance is of utmost importance to street lamp management units. Only in this way can they maintain extinguished street lamps in a timely manner to ensure a high lighting rate (the most important item in the superior department's assessment of street lamp management), while greatly reducing maintenance costs.

It can be said that under the current development situation, LED street lights are impossible to maintain. Once a failure occurs, the entire lamp can only be replaced. In addition to the high cost, the maintenance time will also be greatly extended, which is very disadvantageous for the user unit.

LED lighting is a developing technology, its lighting effect is constantly improving and its cost is constantly decreasing, but it is not yet time to replace traditional high-pressure sodium lamps as street lighting. Therefore, in the "Eleventh Five-Year Plan for Urban Green Lighting Project Planning Outline" issued by the Ministry of Construction and the "Implementation Rules for the Implementation of the "Eleventh Five-Year Plan for Urban Green Lighting Project Planning Outline" issued by the Urban Road Lighting Professional Committee, it is clearly stated that high-pressure sodium lamps are still the main energy-saving light source for street lamps, and LEDs are recommended for use in urban landscape lighting.