Analysis and Evaluation of LED Street Light Test and Its Application Countermeasures

In recent years, LED street lights have developed very rapidly, and some cities have vigorously promoted them, but more cities are still in a wait-and-see state, and the attitude of the street lighting management department is very cautious. In addition to the overall lamp life, light decay and other indicators have no authoritative data, whether it can save energy is also a lot of different opinions. In order to obtain first-hand data, Shenzhen Lighting Environmental Management Center and Shenzhen Science and Technology and Information Bureau, Shenzhen Electronic Product Quality Testing Center jointly organized LED street light testing, a total of 51 companies signed up, 29 passed the initial review, 27 participated in the test (2 The home failed to provide sample withdrawal). The test began in March and is expected to end in July and announce the results.

This article consists of two parts. The first part is the analysis of the registration information of 51 enterprises. The second part is the road test method and the result. Since the test is not finished yet, the specific data cannot be announced temporarily, but Wu Chunhai, director of the planning and design office of Shenzhen Lighting Environmental Management Center, still A number of important data were selected and analyzed in depth.

The first part of 51 companies registration data analysis

Through the research on the enrollment materials (including business licenses, product testing reports, etc.) of 51 companies, Wu Chunhai, director of the Planning and Design Office of Shenzhen Lighting Environmental Management Center, conducted a detailed analysis of LED street lighting enterprises, testing institutions and technical indicators. Some excellent companies have made great progress, and some models of LED street lamps have energy-saving space compared with existing mainstream lighting such as high-pressure sodium lamps. It is preliminarily believed that the critical point of LED street lamp application has arrived, and on this basis, relevant countermeasures and suggestions are proposed.

I. Analysis of the situation of the company

(1) Geographical distribution

There are 51 enterprises registered, and 29 enterprises have passed the initial examination. The geographical distribution of the enterprises is shown in Table 1-1-1 and Table 1-1-2.

Table 1-1-1 Registered companies

Table 1-1-2 The first instance passed the enterprise

This reflects the fact that the current domestic LED street lamp industry is very regional, and large enterprises across regions have not yet appeared. In this test, although Shenzhen local enterprises enjoy the advantages of information and location, they can still reflect Shenzhen's leading position in the LED street lamp industry. As a result, we have some concerns about the LED streetlight industry. The rise of local protectionism in cities is more important than the technical level and product quality in product procurement. The company's R&D impulses and technological innovations will suffocate, and low-level repetitive investment is inevitable. At present, this situation is very serious in China!

(2) Establishment time, registered capital, capital type

Table 1-1-3 Established time

Note: The information of the two companies is incomplete. The sample of the sample in Table 1-1-x (x=3-5) is 49.

It can be seen from Table 1-1-3 that although the development time of domestic LED street lamps is not long, the establishment time of enterprises is not concentrated in recent years, but is distributed. The shortest period of establishment was less than half a year, in January 2009; the longest was more than 17 years, in December 1991. Obviously, enterprises mainly come through transformation. There are some traditional lighting companies, but the number is limited, and more are the original electronics manufacturers. At the same time, there are not many enterprises that mainly focus on LED street lamps. More enterprises only regard LED street lamps as a possible development direction, paving the way for future development, and do not rule out that some enterprises blindly enter the market enthusiasm.

Table 1-1-4 Registered funds

Table 1-1-5 Capital Type

From Tables 1-1-4 and 1-1-5, LED street light enterprises are mainly small and medium-sized domestic enterprises, with a registered capital of at least 100,000 yuan, but there are also many large enterprises with a registered capital of up to 2.3 billion yuan. Considering the mixed business of various companies, LED street lights are only a part of them, and the proportion is difficult to determine. Therefore, the amount of registered capital does not represent the strength of the company in LED street lights. From the point of view of market promotion, in order to improve user confidence, certain registered capital is also necessary. We think that more than 10 million yuan is more suitable, and the capital type has little relationship, but listed companies will have certain advantages.

Second, the analysis of testing institutions

Table 1-2-1 Type of organization

Note: There are 44 third-party test reports provided by 44 companies. The sample of this study is 44.

Through the analysis of the test report, the current level of various institutions is uneven, and the methods and standards are different, which seriously affects the credibility of the test report. In addition, the testing standards of various agencies are different, and the contents of the report are different, which is not conducive to the bidding work in various places. Therefore, we believe that the unified measurement method is more important than the product standard. There is no unified evaluation project and measurement method. The test reports of different organizations lack comparability, and the product standards will not be implemented.

Testing institutions are the key to product evaluation, the last level of industry integrity, and even the cornerstone of the entire industry, must be paid enough attention in the industry. At present, the "Measurement Method for Integrated LED Street Lights" has been officially released. Relevant departments should unify the testing standards as soon as possible and standardize the testing industry. Otherwise, it will seriously affect the promotion and application of LED street lights.

Third, technical indicators analysis

(1) Overall technical situation

This test is for input power, single chip power, chip light efficiency, overall lighting efficiency, color temperature, color rendering index, light distribution curve, power factor, electromagnetic compatibility, protection level, electrical insulation level, heat dissipation performance, and lamp life. The technical parameters are proposed to be specific indicators. Due to the tight registration time, many enterprises have not covered the above technical parameters. Of the 44 test reports in Table 1-2-1, 3 were missing relevant parameters, 41 were relatively complete, so the study sample was 41. The analysis parameters included light distribution curve, overall lighting efficiency, color temperature, color rendering index, and power. Factor.

Table 1-3-1 Light distribution curve

Note: 41 test reports were relatively complete, with 41 samples of 1-3-x (x=1-5).

For road lighting, light efficiency and light distribution curves are two important parameters. LED light efficiency has no advantage over high-pressure sodium lamps, and energy saving depends mainly on the light distribution design of the lamps. At the same time, LED street lamp enterprises have been transformed from electronic product manufacturers, and they neither understand nor value the light distribution. In view of this situation, this paper regards the light distribution curve as the most important evaluation index. As can be seen from Table 1-3-1, 15 reports are batwings. Although the proportion still needs to be improved, it has made significant progress compared with the previous two years, indicating that the problem of light distribution has been valued by enterprises. From the technical route, the single 1-5W chip with lens is easier to obtain the batwing shape distribution curve, indicating that the technology has a promising future. However, with a single polycrystalline chip (30-120W), the maximum intensity of the longitudinal section of the road tends to appear in the 0o direction instead of 60o, and it is difficult to obtain the batwing-shaped light distribution curve. The glare problem is more difficult to solve.

Table 1-3-2 Overall lighting effect

As can be seen from Table 1-3-2, with the advancement of LED chip technology, the overall lighting efficiency is improved rapidly. Even if you remove several super-high-efficiency data that may be problematic, the overall situation is ideal, and the overall lighting efficiency is mostly over 50Lm/W. Compared with high-pressure sodium lamps, 150W or less products have energy-saving space, 250W is gradually approaching, and the product gap of 400W or above is large.

Table 1-3-3 Color temperature

From Table 1-3-3, the color temperature is still concentrated in the higher range. There is no report less than 4500K. Enterprises still need to continue to work hard to produce products with different color temperatures to meet the different needs of the market. However, through physical observation, LED street lights with lower color temperature are still not ideal. Except for low light efficiency, the light color is more serious. The lower color temperature products are prone to yellowish green (as shown in Figure 1). It feels very unnatural.

Figure 1 Lower color temperature products are prone to yellowish greenish

Table 1-3-4 Color rendering index

Table 1-3-5 Power factor

From Tables 1-3-4 and 1-3-5, although the color rendering index and power factor are not detected, the detected results are very good. In particular, the power factor data indirectly confirms the origin of many LED street lamp manufacturers.

(2) Advanced technology

In view of the importance of the light distribution curve and the overall lighting effect, the two indicators are used to determine whether the LED street lamp technology is advanced. In 14 reports of batwing wings (as shown in Table 1-3-6), the overall lighting efficiency is 45.6 Lm/W, the highest is 70.31 Lm/W, and the mainstream level is 50 to 60 Lm/W. , basically in line with the normal distribution.

Table 1-3-6 Overall lighting effect of batwing light distribution lamps

Note: 15 reports are batwing, 1 of which has no overall lighting effect, and 14 samples in this study.

Table 1-3-7 Proportion of outstanding enterprises

Note: This table has a calculation base of 51.

Considering the light distribution curve and the overall lighting effect, the batwing shape and the overall lighting effect is more than 50 Lm/W, among which 50 to 60 Lm/W is a good level, and 60 to 70 Lm/W is an advanced level, which is greater than 70 Lm/W is the leading level, accounting for 51 of the total number of companies registered, see Table 1-3-7. However, if we consider the indicators such as the life of the whole lamp, the light decay, and the quality difference between the products to be inspected and the mass-produced products, the excellent ratio will be significantly reduced.

Fourth, countermeasures and recommendations

Despite the mixed LED street lamp industry in China, some excellent enterprises have come to the fore. Some models have energy-saving space compared with the existing mainstream street lamps, and have obvious promotion and application value. Initially, the critical point of LED street light application has arrived. Of course, whether this conclusion is true or not remains to be verified, and we will publish a series of papers.

Although the critical point is up, whether it can ignite immediately or continue to be in a critical state depends on technological progress and the efforts of colleagues in the industry. To this end, this paper proposes the following countermeasures and recommendations:

(1) Breaking local protectionism at the national level, encouraging advanced enterprises to compete freely across regions and promoting technological innovation.

(2) Strengthening self-discipline in the industry and restoring the confidence of the street lighting management department with the strength of the enterprise (core technology, demonstration projects, registered capital, etc.) and integrity.

(3) Unified testing standards, standardize the testing industry, strengthen the neutrality and credibility of third-party testing organizations, and make testing reports a key component of bidding.

(4) Recognize the particularity of road lighting, pay attention to optical design, and have reasonable energy-saving LED street lights. Personally, LED streetlights need a second revolution, and domestic companies must seize opportunities.

(5) Based on the power of 150W or less, take root and non-main roads, and then gradually penetrate into the main road after gaining advantages.

(6) Pay attention to the research of color temperature of LED to solve the problem of current low color temperature products. Starting from people's needs, looking for the best color temperature range corresponding to different nature and different levels of roads, this will be an opportunity for China to catch up with international companies.

(7) Comprehensively look at the parameters of the whole lighting effect, light distribution curve, color temperature, lamp life and light decay, and the products with good comprehensive indicators are competitive.

(8) Establishing common evaluation indicators for LED and existing mainstream lighting, which is more intuitive and convenient, and meets product comparison and bidding needs. At the laboratory level, based on the existing iso-illuminance curve, the evaluation factors such as road application area, uniformity and environmental ratio should be introduced to establish a new indicator-application area illumination curve. The pavement test should be evaluated by applying light efficiency, uniformity, and longitudinal uniformity.

The second part of the road test method and results

First, the test method

organization:
Shenzhen Lighting Center and Shenzhen Science and Technology Bureau, Shenzhen Electric Inspection Center

Participating companies:
51 companies signed up, 29 passed the initial review, and 27 participated in the test (2 failed to provide sample withdrawal).

Test material:
Each unit provides 3-4 sets of lamps, one of which is sent to the laboratory for testing, and two to three sets are used for road testing in high-tech.

Comparison material:
3 sets of 100W, 150W high pressure sodium lamps and 140W warm white lamps of an international famous brand.

Test Methods:
The formal test is divided into pavement test and laboratory test: laboratory test includes optical performance, electrical performance and 2000 hours aging; pavement test is selected in Shenzhen Gaoxin Zhongyi and Technology Zhongsan Road (as shown in Figure 2, Figure 3) It is divided into objective test and subjective evaluation.

Figure 2 The street light is 10 meters high, the road width is 12 meters, and the double side lights are on, and the one side lights up during the test.

Figure 3 Pavement test including brightness, illumination, subjective evaluation, etc.

(1) Objective test:

Objective test indicators include application of light efficiency, uniformity, and longitudinal uniformity. The key factor to consider is to scientifically set the application area.

Application light efficiency = average illumination × application area area ÷ input power

Table 2-1-1 Comparison of luminous efficacy and uniformity between LED street lamps and other light sources

Note: Due to the end of the test, the specific data will not be announced.

It can be seen from Table 2-1-1 that when the road width is changed from 12 meters to 9 meters, the application light effect of LED street lamps decreases less than that of warm white light and sodium lamps, and the increase of uniformity is greater than that of warm white light and sodium light. In addition, due to the difference in the light control capability of the lamps of different light sources in the lateral direction of the road, the narrower the road, the more obvious the comparative advantage of the LED street lamps.

Applied light effect limit = lower limit of luminous flux in the application area 输入 upper limit of input power in the application area = (maintaining illuminance ÷ maintenance coefficient × application area) ÷ (power density value × application area) = maintenance illuminance ÷ maintenance coefficient ÷ power The density value is calculated by taking the secondary road with the number of two-way lanes ≥ 4 and maintaining the illumination to take 15 Lx as an example: the application of the luminous efficacy limit = 15 ÷ 0.7 ÷ 0.7 = 31 Lm / W

Significance: The application of street lights with a luminous efficacy of less than 31 Lm/W is comparable to the secondary road design standards, or the average illuminance is not up to standard, or the power density is exceeded, or both.

Table 2-1-2 Applicable luminous efficacy limits for different grades of roads in CJJ45-2006 (maintenance factor is 0.7)

As can be seen from Table 2-1-2, the application light efficiency limit required by the road lighting design standard is not high. The highest grade road only needs 41Lx/W, and the lowest grade road only needs 23Lx/W. However, it is not the application of street lamps with luminous efficacy above the limit that meets the design standards, because the application of light efficiency is necessary, not sufficient, to meet design standards. However, it is very certain that a street light with a luminous efficacy below the limit must not meet the design criteria.

From the preliminary test data, the average application efficiency of 27 LED street lamps is greater than 31Lm/W when the road width is 12 meters and 9 meters, indicating that the application space of LED street lamps is expanding.

Table 2-1-3 Comparison of reflection performance of LED street lamps and other light sources on the road surface

From Table 2-1-3, the following conclusions can be drawn:

1. Evaluate the ratio of illuminance to brightness at a certain point with the same conditions.
2. The lower the color temperature, the smaller the ratio and the better the reflection performance.
3. The low color temperature has a large proportion of red spectrum, a long wavelength, and strong reflection on the road surface; the blue color spectrum with high color temperature has a large proportion, the wavelength is short, and the reflection ability to the road surface is poor.
4. It may also be related to the color characteristics of the road surface. Cement and asphalt roads have the same regularity and need further study.
5. Under the same illumination, the brightness of the LED street light is lower than that of the low color temperature light source, so the LED street light should be more illuminating than the brightness.

(II) Subjective evaluation: score 30 street lights on site

Content: Whether the color of light is natural, the type of light color, whether the color of light is green, the brightness of the main lane, the uniformity of the roadway, the brightness of the sidewalk, the glare, and the overall feeling.
Group: professional, semi-professional, non-professional.
Personal information: name, gender, age, preferences for light color.

Through subjective assessment, we have the following conclusions: Demonstration projects rely on leadership and scale to promote the public. Because LED street lights can be transferred from demonstration projects to scale promotion, the color problem is crucial. If the LED street lights completely replace the high-pressure sodium lamps, the city night will "change the sky", the main color changes from yellow to white, the public accepts, need to study as early as possible.

summary

1. Existing street lighting such as LED street lamps and high-pressure sodium lamps have their own advantages and disadvantages. LED street lamps must be developed to avoid weaknesses and maintain differentiated development with existing mainstream lighting.

2. Find the best match between road lighting needs and LED characteristics to produce more efficient, more reasonable, more pleasant and reliable products.

3. Conduct application research from three levels: engineering application, road lighting demand, and human needs.

The above content is provided by WOSEN. WOSEN is a professional manufacturer and supplier of Led Flood Light, Led Street Light, Led Solar Light, etc. For more information, please visit https://www.wosenled.com/ or contact admin@wosenled.com or WhatsApp +86-13425434349