**1. Overview**
In recent years, LED lighting products have gained significant popularity due to their energy-saving properties and long lifespan. Consequently, indoor lighting has largely replaced traditional incandescent and fluorescent bulbs. Outdoors, high-quality LED street lamps have proven their worth in road lighting, showcasing advantages like excellent color rendering and extended life. However, their performance in adverse weather conditions, such as rain, snow, and fog, remains suboptimal, which continues to limit their widespread adoption.
**2. Road Lighting Requirements for Penetration**
Street lighting primarily consists of vehicle headlights and street lamps. Currently, yellow light dominates both headlights and streetlights, functioning as indicators to guide, direct, and alert drivers and pedestrians.
**2.1 Headlights**
Heavy fog, rain, or snow poses significant challenges to safe vehicle travel. During such conditions, drivers often activate their fog lights, emitting clusters of bright yellow light. These lights serve not only to illuminate the road ahead but also to mark the vehicle's position, ensuring oncoming drivers and pedestrians can avoid collisions. Scientific research has shown that yellow light is the optimal choice for fog lights.
Mr. Chen, a 28-year-old from Shaoxing, invested heavily in upgrading his car’s headlights to 6000K high-color-temperature xenon lights, which he believed would significantly enhance visibility. He was initially impressed with their brightness, claiming he could barely see anything in good weather once the lights were on. However, when caught in heavy fog, the xenon lights proved ineffective, leaving him disoriented and unable to see beyond a few meters. He narrowly avoided disaster when he realized he was mere centimeters from a cliff.
Experts advise against using high-color-temperature xenon lights in foggy conditions, as their light lacks sufficient penetration. After returning home, Mr. Chen reverted to standard lighting. His dissatisfaction with the wasted expense highlights the limitations of high-color-temperature lights in foggy conditions.
**2.2 Road Lighting**
Historically, low-pressure sodium lamps and high-pressure sodium lamps were the primary choices for road lighting. Low-pressure sodium lamps emit monochromatic yellow light, which is highly efficient and penetrates fog effectively. High-pressure sodium lamps, with their superior color rendering and longevity, offer enhanced visibility while maintaining strong fog penetration.
Wu Chunhai’s study on LED street lamps emphasizes the importance of selecting appropriate color temperatures. Higher color temperatures, such as those of white metal halide lamps, create a foggy visual effect, impairing driver recognition and reaction times. Following public complaints, Shenzhen reverted to using high-pressure sodium lamps with their warmer tones.
**2.3 Traffic Lights**
Yellow lights are commonly used in car fog lights and urban traffic signals. At night, when traffic is sparse, flashing yellow lights alert drivers to slow down and proceed cautiously through intersections.
**3. National Standards for Color Temperature**
According to experts, cool-colored light sources cause discomfort and are unsuitable for public lighting. Additionally, high-color-temperature lights appear excessively white, creating a foggy visual effect.
The Urban Road Lighting Design Standard (CJJ45-2006) was implemented in 2007, focusing primarily on sodium lamps, which have a color temperature of 2500K or below. The updated CJJ45-2015 standard expanded to include LED lights, with a color temperature range of 2300K to 6500K. The standard recommends LED street lamps maintain a color temperature of no more than 5000K, favoring warm or neutral tones.
The Guangxi Zhuang Autonomous Region further specified the use of warm, white, and cool light sources based on geographical and road conditions, discouraging the use of cool light sources on municipal roads.
**4. Factors Affecting Light Penetration**
Light penetration involves bypassing obstacles like dust and water droplets rather than breaking through them. Longer wavelengths scatter less, enhancing penetration. Red light, though theoretically ideal, suffers from low efficiency and is impractical for illumination. The human eye is most sensitive to green light at 555nm, with a luminous efficacy of 683lm/W.
Green light, while effective as a safety indicator, is prone to scattering and lacks versatility for outdoor use. Thus, yellow light emerges as the most suitable for outdoor illumination.
**5. Research on LED Street Lamp Penetration**
Conventional white LEDs emit significant amounts of short-wavelength light, which scatters in fog, reducing visibility. Studies by BobsyAriefKURNIAWAN reveal that red, yellow, and blue light perform best in foggy conditions, with blue light being least visible. In snowy or rainy conditions, yellow light surpasses white due to reduced glare.
Spectral analysis of LEDs shows that 6000K LEDs emit strong blue light, whereas 3000K LEDs emphasize yellow and red wavelengths, offering better penetration but lower overall efficiency.
**6. Achieving Low Color Temperature and High Efficiency**
LED street lamps balance color temperature and efficiency through phosphors and secondary optics. Adjusting the ratio of red, green, and yellow phosphors achieves desired color temperatures. Enhancing efficiency involves using high-efficiency LED chips, phosphors, secondary lenses, and heat-conductive substrates.
Industry trends reflect these advancements, with color temperatures decreasing annually while overall lighting improves.
**7. Conclusion**
Improving fog penetration is crucial for road safety. LED street lamps combine energy efficiency, long life, and excellent color rendering, offering clear advantages over traditional lamps. By controlling color temperature within the range of high-pressure sodium and incandescent lamps, LED street lamps continue to evolve, enhancing their suitability for outdoor applications.
References:
[1] Urban Road Lighting Design Standards (CJJ45-2006)
[2] Urban Road Lighting Design Standards (CJJ45-2015)
[3] Guangxi Zhuang Autonomous Region Housing and Construction Department “Urban Lighting and Construction Management Work Plan (2015-2016)â€
[4] Wu Chunhai, "Thinking and Choosing the Color Temperature of LED Street Lights"
[5] International Lighting Commission Color System (CIE Color System)
Intern Editor: Yang Zhiwei
Digital Timer Switch Socket
Instruction Manual
1. Features
Clock display, 10 sets of adjustable timed power control, randomized power control, manual switch and optional DST setup.
2. First time charging
This timer contains a rechargeable battery. It is normal that the new/old model runs out of battery if it wasn`t being charged for a long period of time. In this case, the screen will not turn on.
To charge : simply plug the timer to a power outlet. The charging time should take at least 15 minutes.
If the screen doesn`t light up or displays garbled characters, simply reboot the system by pressing the [RESET" button.
3. Set clock
Hold [CLOCK" button and [WEEK" button to adjust week.
Hold [CLOCK" button and [HOUR" button to adjust hour.
Hold [CLOCK" button and [MINUTE" button to adjust minute.
Hold [CLOCK" button and [TIMER" button to select 12 hour/24 hour display.
Hold [CLOCK" button and [ON/AUTO/OFF" button to enable/disable DST (daylight-saving-time).
4. Set timer
Press [TIMER" button, select and set timer. Setting rotation : 1on, 1off, 2on, 2off, ...... , 10on, 10off.
Press [HOUR" button to set hour for timer.
Press [MIN" button to set minute for timer.
Press [WEEK" button to set weekday for timer. Multiple weekdays can be selected. ex: if selected [MO", the timer will only apply on every Monday; if selected [ MO, WE, FR", the timer will apply on every Monday, Wednesday and Friday.
Press [RES/RCL" button to cancel the selected on or off timer. The screen will show "-- -- : -- --" , the timer is canceled.
Press [RES/RCL" button again to reactivate the timer.
When timers are set, press [CLOCK" to quit timer setting and return to clock.
5. Random function
Press [RANDOM" button to activate random function, press again to cancel function.
System only runs random function when [AUTO" is on.
Random function will automatically start the timer from 2 to 32 minutes after the setting.
ex : if timer 1on was set to 19:30 with the random function on, the timer will activate randomly between 19:33 to 20:03.
if timer 1off was set to 23:00 with the random function on, the timer will activate randomly between 23:02 to 23:32.
To avoid overlapping, make sure to leave a minimum of 31 minutes gap between different sets of timer.
6. Manual control
Displayed features:
ON : socket turns on.
OFF : socket turns off.
AUTO : socket turns on/off automatically via timer.
Manual ON setting
Press [ON/AUTO/OFF" button to switch from [AUTO" to [ON".
This mode allows socket of the device to power up. Power indicator will light up.
Manual OFF setting
Press [ON/AUTO/OFF" button to switch from [AUTO" to [OFF".
This mode turns socket of the device off. Power indicators will turn off.
7. Electrical parameters
Operating voltage : 230VAC
Battery : NiMh 1.2V
Power consumption : < 0.9W
Response time : 1 minute
Power output : 230VAC/16A/3680W
Q&A
Q: Why won`t my timer turn on?
A: It`s out of battery, you can charge the timer by plugging onto any power outlet. Charge the device for at least 15 minutes. Then press [RESET " button to reset the device.
Q: Can I set seconds of the timer?
A: No, the smallest time unit is minute.
Q: Does my timer keeps old settings without being plugged onto a power outlet?
A: Yes, the timer has an internal battery, it allows the timer to save settings without a power outlet.
Q: Is the battery rechargeable?
A: Yes, the battery is rechargeable. We recommend to charge it for 4 hours so the battery is fully charged.
Q: Does the timer needs internet connection?
A: The timer does not need internet.
Q: Does the screen have back light function?
A: It doesn`t support back light.
Digital Timer Socket, Timing Switch Socket, Electronic Timer Socket, Timer Socket
NINGBO COWELL ELECTRONICS & TECHNOLOGY CO., LTD , https://www.cowellsockets.com