“LightExpert”: How to choose street LED lamp right?
It’s evident that future of street lighting will form LED light sources. However, LED-technology is not a panacea for the communal service problems. Today a huge number of manufacturers offer to the market their own solutions. But despite the similarity of technologies, the lamps of different brands differ from each other like home appliances or cars of different brands.
But before we will talk about the choice, I would like to say a few words about the importance of innovation in this issue. We are talking not only about many strengths of the light-emitting diodes (there is much info written about) but about the benefits of new technologies generally. Let's consider the following example: you have a task to save an audio recording collection. What will you write it to? Will it be an audio tape (price - 90 rubles), a CD-ROM (price - 31 rubles) or a flash card (price - 1600 rubles)? It’s obviously that most people will choose a memory card despite of its high cost. The first two examples are good except reliability and size. Furthermore, this equipment is obsolete and we have to save a collection for many years. Such attitude is not only fair for saving information devices. New technologies are usually better than old ones. It is the only condition of its birth. This attitude is also fair for LED street lamps. LED lamps differ from each other with its technical characteristics, cost and reliability. It is important to know how to choose them. What are the differences and what turn attention to if technical characteristics specified in documentation or advertising materials don’t give an objective description.
Many manufacturers prefer to specify not actual light flux of a device but the total LEDs flux. They multiply light flux of each light-emitting diode on its quantity instead of measuring an actual light flux of the product. As a result the customer is offered an abstract value obtained by adding the LED manufacturer's data that doesn’t have any relation to reality. LEDs light flux is measured by manufacturers at +25 ºC, and the thermal conditions of the LED depends on many factors in a product (housing design without mentioning an optical system of the lamp). Generally the light flux of a product always low than the amount sum of LEDs light flux. This way you can check the manufacturer on honesty. Just ask for the technical characteristics of the LEDs and their number. Summarize the light flux and you will see has a manufacturer allowed losses or not.
"The reduction factor of light flux depreciation is 0.9 - 0.92 for the 0.35 A current and 0.82 - 0.85 for the 0.7 A current (data for LEDs XP-G, mounted on the aluminum substrate board 1.5 mm thickness) due to the temperature increase of the crystal with the passive heat. Light flux losses work out 0.85-0.9 in the secondary optics. Light flux losses are 0.9-0.92 in the protective glass.
The same abusive manufacturers often declare not actual power consumption of the lamp but the total power of LEDs without losses in the electric power supply. But there are no power supply units of 100% efficiency in nature. It means that the power supply losses are not considered by a manufacturer and consumption figures are not corresponded to reality.
To understand the real consumption, it’s necessary to take the overall power input of the lamp and divide it on the LEDs number. If the power consumption of each LED has a round form (for example, 0.35 W) the manufacturer had got the power consumption by adding. It doesn’t conform to the power of a lamp in practice.
Light intensity curve
Each class of a road matches a specific class of a LED lamp. For example, it’s impossible to use cosine light intensity curve LED lights of D class for road lighting of A class. The class differences affect the lighting uniformity of a road surface. It’s possible to see this uniformity in the program Dialux calculation. If the manufacturer refuses to provide you calculations that were made in this program LED lamp class is a mystery even for the manufacturer.
Protection is a good thing but it’s not always better if the coefficient is always high. For example, if we use street LED lamps the protection class IP65 and above can be a problem. The fact is that the hermetic housings of such devices occur condensate in external temperature falling. It breaks electrical circuits and inevitably leads to premature lamp failure. In many cases, IP54 protection class meaning is more than enough for outdoor use.
Construction and components
Generally, manufacturers of low-cost LED lamps have a big interest in reducing the cost of their products that is achieved in two ways. The first is the using of low-cost LEDs of unknown production. The second is the using of lighting fixture housings which are working on the base of a lamp. It is clear that low-quality LEDs will not be able to work up their full share. In practice, the “innominate” LEDs won’t work up to 10,000 hours while the "branded" sources work more than 50,000 hours. Is it important to say how work can be uncomfortable if the service life of the lamp is unpredictable? There are also some difficulties with the housings. A heat rejection is not critical for the lamp as for the LED which starts degrade very quickly of overheating (the light flux and service life decrease). Place the low-quality LEDs into the lamp housings and you will get a device that quickly burn through a black hole in your budget.
Electrical power unit
There are used two types of electrical power unit in modern LED lamps: pulse and electromagnetic. Many manufacturers use universal pulse electrical power units for depletion of the LED lamp, most manufacturers use ready-made universal switching power supplies, oblivious to the fact that many of them are simply not designed to work in the street environment. For example, conventional pulse electrical power unit badly reacts to lightning and any electrical storm could be the last. There is known a case where only 6 LED lamps were still working after first storm among 15 recently installed ones. The rest LED lamps fell out not having worked a day. Therefore it’s better to give preference to a lamp equipped with electrical power unit specifically designed for it (reliable electrical power units with electromagnetic current stabilizer with less efficiency but absence of doubts about the reliability in a hostile conditions work.
Cheap or expensive
The Hollywood Triangle principle is fully applicable to street LED lamps. Reasonable, fast and reliable! But fulfill all these conditions at once is impossible. We have to wait very long for a reasonable and reliable. Quickly delivered and reasonable one will break just also quickly. Fast and reliable one will be expensive. Obviously the most important characteristic is reliability. The other two conditions are keeping your discretion. The only thing that should be added is cooperate with the manufacturer that is located the same or a neighboring country to you. It’s always easier, faster and more reliable. Obviously, it is also much easier to inquire about its production and easy communicate about warranty.
LED lamp “Altair” is our choice
As for a distributing company of professional sound and lighting equipment all these manufacturer’s tricks are well-known. Over the years in the market we found that to choose a reliable supplier of LED street lights isn’t so simple. Street LED lights is the hot topic today and it is not surprise that so many manufacturers who didn’t understand what is it LED yesterday, strive to enter the market with its "unique" proposition. But really unique propositions are not so much on the market, especially in the medium price range. Therefore LED lights “Altair”, produced by Ukrainian company "REC" (Zhitomir) became a real finding for us.
Company "REC" is 25 years old (the company was founded in 1986). It was developed an electrical power unit of high reliability and secondary optics that is functioning as a protective glass and is used in street and road lighting of RL-01 series by the company "REC".
LED lights "Altair" have unique features: a certificate of European Union, Ukraine and Russia conformity, there are used LEDs CREE, secondary optics is used as a protective glass, the electrical power unit is of own design with an electromagnetic stabilizer. Warranty on the full line of products is 5 years. And the most important, "REC" is a manufacturer that does not need any tricks.
Thus, the right LED street lamp can be selected in two ways. The first way is to become an expert on the unscrupulous manufacturer’s tricks. The second is to address to a reliable and attorney supplier. For example, company "REC".
The article is written by Vladimir Homutinin in a journal “KightExpert”