1.Development of LED light.

At the end of the 20th century, LED lamps made their debut, injecting new vitality into the lighting field. Entering the 21st century, LED street lamps have “advanced by leaps and bounds” with a series of outstanding advantages—such as high efficiency, energy saving, environmental friendliness and no pollution, long service life, directional light emission, good starting performance, fast response speed and strong shock resistance. They have gradually replaced traditional lighting equipment and become the undisputed first choice for street lamp light sources.

2.Advantages of LED Lamps

Currently, China is building a resource-conserving and environment-friendly society, and the concept of “green lighting” is gradually taking root in people’s minds. With the continuous development of lighting technology, street lamps have transitioned from the previous high-pressure sodium lamps to LED street lamps.

From a technical perspective, LED lamps are comparable to and even outperform high-pressure sodium lamps. For instance, in terms of the luminous efficacy of the entire lamp, LED street lamps can reach over 100 lm/W. Even when high-pressure sodium lamps are equipped with lamps and ballasts, their luminous efficacy can only reach a maximum of 60-70 lm/W. Clearly, the luminous efficacy of LEDs has surpassed that of high-pressure sodium lamps. Moreover, in terms of price and cost, LEDs are not much more expensive than high-pressure sodium lamps.

3.Feature Comparison Between High-Pressure Sodium Lamps and LED Lamps

High-pressure sodium lamps emit yellow light, with relatively low color temperature and color rendering index (CRI). The CRI of sunlight is 100, while that of high-pressure sodium lamps is only around 20 (for yellow light).

The color temperature of LED street lamp light sources can be flexibly adjusted between 4000K and 7000K, and the CRI can reach over 80 at most. The light color of the lamps is closer to natural light.

The bulb structure of sodium lamps results in low light source utilization rate, only about 40%. The luminous angle of the tube is 360°, so most of the light must be reflected by a reflector to reach the designated area.

LED lamps have a high light source utilization rate of approximately 90%. The luminous angle of LED diodes can be consistent with that of the lamps. Therefore, most of the light from the lamps is directly emitted to the designated area, and only a small part is reflected, leading to high light source utilization.

High-pressure sodium lamps require a long startup time, and a certain time interval is needed for restarting. It takes about 5-10 minutes for a high-pressure sodium lamp to reach normal brightness after being powered on, and the interval for restarting is generally more than 5 minutes.

LED lamps have no startup delay issue. They can be turned on and operate at any time, making it very convenient to realize intelligent energy-saving control.

For sodium lamps, the temperature difference between when the lamp is on and off is significant. If the lamp body is not equipped with a breathing system, the reflector is prone to corrosion by harmful gases, resulting in large light loss.

LED lamps do not require an additional breathing system.