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, and as energy-saving products, they are increasingly used in road lighting. Can high-power LED street lights really replace traditional light sources (mainly high-pressure sodium lamps) at present? The following is my opinion on the application of high-power LED street lights:

1. Regarding the power-saving effect of LED street lights, in many cases where practical LED street lights replace high-pressure sodium lamps, power saving is an important factor, 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 light-emitting and the efficiency of lamps is higher than that of high-pressure sodium lamps, due to the low luminous efficiency, the comprehensive energy efficiency of LED street lamps is still lower than that of high-pressure sodium lamps.

In some cases that prove that LED street lights replace high-pressure sodium lamps to achieve power-saving effects, according to analysis, these cases are often the original street lamps with high power (severely exceeding the brightness standard) or low lamp efficiency, and the light source is seriously attenuated. It is not scientific to use this as the basis for saving power for LED street lights.

Second, the color of LED street lamps. At present, high-power LED street lamps 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, so daylight-colored LED street lamps are not suitable for practical street lamps.

Third, 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 4,000 yuan to 8,000 yuan, or even higher. The price of a set of imported 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 attenuation of the lamps 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 with the actual application of 3 to 4 years. In comparison, the life of high-pressure sodium lamps and supporting electrical appliances is more problematic.

For the maintenance of light sources, high-pressure sodium lamps are much easier, and the light source electrical appliances can be directly replaced on site, and the cost is also low. As for LED street lamps, I think the manufacturers may think that they are maintenance-free, so on-site maintenance cannot be carried out.

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 secondary light distribution systems instead of simply relying on chip arrangement for light distribution. However, on the whole, the light distribution cannot be 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 that have developed secondary light distribution systems, 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 no unified technical standard for LED street lamp production. Each manufacturer produces its own products according to its own standards, which is difficult to be universal. In addition, the characteristics of LED street lamp multi-chip assembly make the chip and lamp bundled together, which is difficult to maintain. The original product must be used

for maintenance. However, due to the unified technical standards, high-pressure sodium lamps have strong versatility in lamps, light sources, and electrical appliances. Products from different manufacturers can be used interchangeably. From the perspective of maintenance, this is very important, and maintenance is the top priority for street lamp management units. Only in this way can the extinguished street lamps be maintained in time to ensure a high lighting rate (the most important content in the assessment of street lamp management by the superior department), and at the same time greatly reduce maintenance costs.

It can be said that in the current development situation, LED street lamps cannot be maintained. Once a fault 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 unfavorable 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.