China Aviation Industry Planning and Design Institute Ren Yuanhui
LEDs have a new look after the advent of white light, making it possible for LEDs to enter the field of illumination as a new source of light. For more than ten years, LED technology and products have developed rapidly. The emergence of high-power LED chips, packaging, heat dissipation and other issues have been continuously advanced. In recent years, various road lighting fixtures have been developed and started in townships, villages, and residential areas. Community roads, urban branch road applications, and further urban road trials. Because LED is different from the widely used high-efficiency light source, due to the characteristics of LED, such as directionality of light, dimming, long life, shock resistance, weather resistance, etc., as well as obvious problems and deficiencies in his application, in lighting It is understandable that the community and even the community have different reactions.
Here are a few application questions for LED streetlights and high-pressure sodium lamps that are now widely used.
1. About energy efficiency analysis and comparison
The lighting installation power of both should be compared in accordance with the same illumination (brightness) level and close lighting quality standards. Because high-pressure sodium lamp high-power lamp (250~400W) has high luminous efficiency, it can reach 130~140 1m/W, while low-power lamp (100~150W) has about 40~100 1m/W, but it is now large. Power LED street lights use 1W LED tubes, and their light effects are similar. Therefore, it is necessary to analyze high-power street lamps and low-power street lamps separately.
(1) High-power (≥250W) street light: high-pressure sodium light effect, considering ballast loss, lamp efficiency and track utilization, etc. If the overall efficiency is 0.55, the effective light efficiency of the sodium lamp is about 70~75 1m/W; and the effective light efficiency of LED street lamps is currently about 62 1m/W in the US, and the best domestic enterprises have reached 56~58 1m/W. Therefore, for high-power street lamps, LEDs are currently less energy efficient than sodium lamps.
(2) Low power (≤150W) street light. The effective light efficiency of the sodium lamp (included in the overall efficiency of 0.55) is about 45~55 1m/W, while the LED is still calculated according to 56~58 1m/W, the LED can achieve energy saving 10%~20% than the sodium lamp, up to 30 %.
From the above analysis, it can be seen that the LED street lamp can save 10%~30% energy compared to the sodium lamp when the power is small (≤150W) for the branch, and the high power is still not comparable to the energy efficiency of the sodium lamp. Therefore, those who generally claim that LED street lamps are more energy efficient than high-pressure sodium lamps, and even save 50%, 60%, etc., are obviously exaggerated and speculative. We should adhere to the scientific analysis and the principle of seeking truth from facts, otherwise it will easily mislead users and the masses.
2. Analysis of the effect of light source color on road lighting
The color temperature (Tcp) of the high pressure sodium lamp is about 2100K, which is a warm color temperature. The color rendering index (Ra) is only 23~25, and the color rendering is low. The color temperature of the LED street lamp is more than 5300K, which is a cool color temperature. The product has a Ra of 70~80 and good color rendering.
As a fast track, main road, and yellow light of the motor vehicle, it is better to see the road surface at a distance of about 90~160m in front, which is better than white light, especially for foggy and dusty air conditions. More advantage.
For roads such as sidewalks, commercial pedestrian streets, residential quarters, etc., the color rendering of LEDs is better than that of sodium lamps, which distinguishes people's conditions more clearly and has advantages.
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