Because the LED interests?
The LED is the acronym for Light Emitting Diode (light emitting diode), have the characteristics of a diode, or consists essentially of a PN junction which, if biased, emits a light radiation due to the effect of electroluminescence of the junction, ie that phenomenon, discovered in 1923 by Lossew, for which, following a recombination between a gap and an electron is the formation of an electromagnetic radiation, due to the energy released during this phenomenon.
This phenomenon was then perfected and applied to the LED technology in 1962, through the use of particular semiconductors, such as gallium gallium (GaAs), by Nick Holonyak Jr.
The first LEDs were only available in red.
Were used as indicators in electronic circuits and seven segment display,
later were developed LED that emitted yellow and green light and were built devices that incorporate two LEDs, one red and one green generally, in the same container allowing you to view four states (off, green, red, red + green = yellow) with the same device.
one green and one blue) In the nineties, LEDs were realized with more and more high and in a greater range of colors with efficiency until the realization of blue-light LED was possible to realize devices that, by integrating three LEDs (one red,, they could generate any color.
The main advantages of this technology currently are:
High reliability and efficiency
The LEDs are gradually becoming part of the lighting components and, as seen before, are obtained using the characteristics of semiconductors as seen before.
We have said that they have the ability to generate various colors of light according to their construction and the values of voltage and current supply.
The color of the LED lighting is classified in Warm White, Natural White and Cold White.
The “Cold White” LEDs emit a very light indicated with typical color temperature of 5600 K for external applications.
The “Warm White” LEDs emit a much warmer light, with an average color temperature of 3250 K with a CRI value of 80. This leads them to be very suitable for interior applications and wherever there is a need to highlight the colors in a vivid and brilliant.
The LEDs “Natural White”, trade-off between brightness, color temperature and color rendering factor, are the new frontier and are the best choice for light sources combinations already present in the landscape.
The mixing of such technologies comes the Dynamic White, which allows for range of white from a 3100 K color temperature up to 6500 K, this instrument is ideal for commercial environments seeking enhancement of merchandise.
The luminous efficiency of this technology is very high and is between 50-100 lm / W with a service life that is around 50,000 hours.
Advantages and disadvantages
From what is written above it can be deduced that the LEDs are an excellent light source and here comes the idea of using this technology for the private and public lighting.
Given the reduced consumption (explained in more detail later), it has, during use, an energy savings compared to other light sources, also given the high durability life, require less maintenance, thus reducing the costs still .
Another advantage, in addition to the reduced dimensions that allow to direct the luminous flux directly where desired without the use of special reflectors or optical, is the fact that turn out to be a technology with reduced heat emission and can therefore also be used in places with other technologies may be problematic.
The small angle of illumination can be a benefit but at the same time also a disadvantage as there is need more luminaires to achieve effective illumination, and also the emitted light is not uniformly distributed but concentrated in a particular area.
Such lamps were found to have a higher purchase price compared to those incandescent or fluorescent and, given that most of them work in low tension, optimal arrangement for a combination with production plants of photovoltaic energy, have the need to be fed by means of the use of power supplies that further raise the cost and bulk.
Other LED lighting advantage is the endless color variations that allow the RGB lamps, optimal for creating special atmospheres useful for decorative lighting in public places.
Then evaluated the advantages and disadvantages of this technology, we can not say with certainty whether the LED lamps are more affordable than those traditionally used until now, but each individual case must be taken into account by making a careful analysis of the conditions and installation and affected plant operation. Below is a summary table of all the electrical and lighting characteristics of lamps typically used in domestic (bulb lamps).
The lamps are taken into account such as to be put in comparison, ie they have more or less the same luminous flux.
We must make special considerations on fluorescent lamps:
the life span is calculated until the break, but the light output is reduced significantly with the passage of the hours:
average life to 50% luminous flux: 12000 h
luminous flux after 2000 h: 85%
luminous flux after 5000 h: 80%
From the table you can make the following considerations:
1. The LED lamps were found to have a lower rated power and therefore a saving in terms of energy absorption;
2. The duration of the lamps have a big time jump when compared incandescent and halogen to fluorescent and LED;
3. Despite the higher luminous flux turns out to be that of compact fluorescent lamps, LED lamps are having the most luminous efficiency.
4. The LED pattern is immediate as that of incandescent lamps and halogen lamps, while for fluorescent lamps have to wait a few minutes to obtain 100% of the luminous flux.
The economic comparison between the various types of lamps is carried out taking into account the duration of the lamps themselves, an interest rate of 5% per annum and to a constant cost of energy in all time slots.
Also starting from the idea of using a lamp in a commercial environment, we assume a use of 8 hours per day.
The comparison is done by reporting the costs to one year “type” and so the purchase cost of the various lamps is updated to “Today” through the use of the discount factor, which takes into account the annual interest rate and length of life lamp, referring to the hours of annual use.
The result is:
It has, therefore, that, despite a first impression that the LED technology seems to be the most expensive, as you can easily infer from the graph of the cost per Watt, it has that a more careful analysis of the costs it turns out to be some of the cheapest , ranking immediately after the fluorescent lamps.
An analysis of the costs and hourly consumption, above graphic, one can easily see that the incandescent lamps and halogen lamps, are much more expensive than LED lamps or the most common compact fluorescent.
At first glance it can reach the conclusion that the fluorescent lamps turn out to be the most convenient in terms of cost, but remember that they pose a significant decay of the luminous flux with the passing of the hours of operation.
We can therefore conclude that the incandescent lamps and halogen lamps are definitely the most expensive in terms of fuel consumption and at the same time the less convenient also in terms of lighting. It has in fact that the costs per lumen of these two technologies are far superior to the other two taken into consideration.
And ‘interesting to note that, for compact fluorescent lamps at the beginning of life, the cost / lumen ratio is definitely the most convenient, taking into account, however, the decrease in luminous efficiency, we have that with the passing of the hours, this ratio be higher than that of the LEDs.
In the calculations we note that the meeting point between the two technology we have that after about three years and a half a long enough time in domestic applications, but comparing it to life, the LED turns out to be the most convenient for the lumen maintenance .
PRACTICAL APPLICATION OF LED TECHNOLOGY
Although LED technology is not yet advanced, there are common Italians starting to consider it as a viable alternative to conventional lamps.
the example of the first “LED is following city” in the world that despite our country is among the most backward in Europe compared to the spread for low-energy light bulbs and environmentally friendly, it is located in Italy.
Torraca fact is a small town in the province of Salerno, a town of about 1,300 inhabitants, where, in 2007, the town council decided to switch to LED technology for public lighting, installing about 700 light points throughout the city, with an investment of around 280 thousand Euros planning to recover in about six years.
The plant was built by the Electronic Gelbison, local firm, under the supervision of engineer Luciano Fraietta, professor at the University of Naples Federico II.
Since Torraca also owns three solar power plants it has received several awards, among them the “reward local authorities for Kyoto in 2007”.
On the actual efficiency of ‘plant there are mixed opinions. The plant has actually led to a net energy saving according to the mayor of about 60% and in addition, given that the installed lamps operating at 48V security has received a high benefit, on the other hand, however, there are citizens who complain of not entirely efficient yield of the installed lighting lanterns.
The LEDs are certainly the future of lighting, it is public or private. Attention to the environment and the continuous research of energy saving presently make them the best light source in these fields also, being still a very young technology than the other, have enormous room for growth and development.
There is in addition to the efficiency of the light source, also other aspects that are important in the design and choice of one source over another. color temperature, color rendering index, lifetime and consequent maintenance costs, safety, would be as fundamental terms for choice.
Analyzed how far the LEDs turn out to be the best technology considering all its technical and lighting features, as well as assessments useful in the design, especially considering the cost is in this field that the LEDs considering new possibilities climbing places in standings because more and constantly updated.
So we can argue that LED lamps are to be affordable when compared to obsolete incandescent or halogen lamps that have a very low luminous efficiency due to the type of light generation, in fact they have a strong heat generation bound to their operation, as opposed to other types of lamps.
Despite a relatively higher investment cost than other technologies, LED lamps, however, they have a lifespan and a better lumen maintenance than direct rivals, and that makes them a competitive alternative to fluorescent lamps in plants wherein the usage time proves quite high. If we consider also the possibility to change the color and to easily direzionarne the luminous flux, this type of lamps is better in case you want to use for a furniture illumination and for the creation of specific atmospheres.
As just mentioned, it makes the LEDs have a very good technology for private lighting, especially for use in commercial activities where the hours of use are higher, and if you think that the scope for improvement of this source are very broad, it can be concluded that they definitely represent the future of lighting private.
Even in this case, if one thinks of the electrical characteristics of the various types of lamps, LEDs are surely be among the best. In fact, they do not present substances dangerous for the environment, have a high duration of life, a good color rendering index, and also the possibility to be supplied at low voltage, which makes them optimal for coupling with photovoltaic panels, thus reducing the reduces operating costs and environmental impact.
The light produced by metal halide lamps is to be white and therefore of excellent quality and the hourly consumption turns out to be equal with respect to all the others, but in front of a shorter shelf life, and thus to higher maintenance costs.
If you wanted to, thinking mainly environmental, LED technology would still the best