Frequently Asked Questions About LEDs

What does LED stand for?
What is an LED?
What applications can an LED be used for?
Can LEDs be used for general illumination lighting?
How do LED lights differ from traditional light sources such as incandescent bulbs, fluorescent lights and high intensity discharge (HID) lights?
What are the advantages and challenges of using LED's for general illumination?
What are the environmental advantages of using LED luminaries?
Why doesn't U-Tron produce lights with ratings higher than 110 watts?
Why don't U-Tron LED lamps use lenses?
How does ambient temperature affect LED efficiency?
What is junction temperature?
How is junction temperature managed?
How long will LEDs last?
Why is the life span of an LED measured as lumen depreciation?
How many years use is 50,000 hours?
How Much Energy Do LED Lights Save?

What does LED stand for?

Light Emitting Diode.

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What is an LED?

An LED is a semiconductor diode that emits light when a voltage is applied to it.

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What applications can an LED be used for?
LEDs have been used for more than 30 years as indicator lights and for alphabetic and numeric displays. Now the technology has progressed and LEDs can be used for a wide range of lighting applications.

LEDs are commonly used for special lighting applications. Most traffic lights and exit signs, for example, now use red, green or blue LEDs. They are also used to highlight architectural features of buildings.

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Can LEDs be used for general illumination lighting?
Yes. Although the first attempts to apply LEDs in general illumination lighting generally gave poor results, because they could not meet the requirements for lumen-per-watt output and because of the limited color range of early LEDs, modern LEDs are suitable for use in general illumination applications.

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How do LED lights differ from traditional light sources such as incandescent bulbs, fluorescent lights and high intensity discharge (HID) lights?
Unlike other sources of light, LEDs covert electricity directly to visible light and do not produce heat or other forms of radiation such as ultra-violet light.

Traditional illumination sources radiate light evenly through 360˚. LEDs radiate light in a fixed arc. This has advantages in some applications and presents some challenges when designing lighting fixtures to use LEDs.

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What are the advantages and challenges of using LED's for general illumination?
LEDs have the advantages of high efficiency and durability. These result in energy savings, maintenance savings and overall cost savings over their lifespan.

Since an LED radiates light in a fixed arc none of the light generated is lost by being absorbed by light fittings or by being radiated in directions in which it serves no useful purpose (often referred to as "light pollution"). On the other hand the fixed arc presents a challenge when LEDs are used for area illumination. Care has to be taken in the design of luminaries that use LEDs for area illumination to ensure that the light generated illuminates the area evenly.

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What are the environmental advantages of using LED luminaries?
LED luminaries contain no mercury or toxic gasses, last longer and produce less waste. In addition they are made from fully recyclable materials so they have a much smaller impact on the environment. When used for applications such as street lighting the directional property of LED luminaries eliminates light pollution, bringing back the night sky and reducing the impact of street lighting on wildlife.

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Why doesn't U-Tron produce lights with ratings higher than 110 watts?
It is technically feasible to produce higher-powered LED lamps. However U-Tron's philosophy is to use LED technology to reduce energy consumption. For many applications a 110 watt LED lamp can effectively replace a higher-powered traditional light. As LED technology advances even more lumens per watt will be possible. U-Tron will then take advantage of this to produce even more energy-efficient lamps.

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Why don't U-Tron LED lamps use lenses?
Other manufacturers of LED lamps use lenses to direct the LED light output over the area to be illuminated. However lenses have a number of disadvantages: lenses are expensive to produce, a lens absorbs up to 20% of the light output by an LED and lenses get dirty, thus further reducing the usable light.

U-Tron uses its patented "reflective cup" technology to produce an even distribution of light from the LEDs in a luminary. Reflective cups are cheaper to produce than lenses, they do not absorb light and produce an even light distribution as effectively, or more effectively, than lenses.

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How does ambient temperature affect LED efficiency?
LED fixtures must be designed with junction temperature thermal management as a key component and must use the correct LEDs. These products will then be robust enough to operate in most ambient temperature applications. Unlike fluorescent sources, cold temperatures do not impact the performance of LEDs.

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What is junction temperature?
Junction temperature is the temperature at the point where an individual diode connects to its base. Maintaining a low junction temperature increases output and slows LED lumen depreciation. Junction temperature is a key metric for evaluating an LED product's quality and ability to deliver long life.

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How is junction temperature managed?
U-Tron LED lights use aluminum heat sinks that are specifically designed to keep the junction temperature as low as possible.

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How long will LEDs last?
An LED does not burn out in the same way as traditional light sources do. Instead, the diodes gradually produces lower output levels over a very long period of time (lumen depreciation). Generally LED life spans are 50,000 hours or longer. If one LED fails, it does not stop the lamp from continuing to work.

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Why is the life span of an LED measured as lumen depreciation?
The life span of an LED is vastly longer than that of incandescent, fluorescent or HID light sources. LED are generally rated to last 50,000 hours or 100,000 hours. Although an LED never completely burns out the brightness of the light output by an LED diminishes over time. This diminution is known as "lumen depreciation" and the useable life span of an LED (in hours of operation) is measured by its  lumen depreciation.

The industry norm for calculating the life span of an LED is the point at which the LED reaches 30 percent lumen depreciation.

A 100,000-hour rating is not equivalent to a lamp life rating. LED life is rated to a point where it has reached 30 percent lumen depreciation. At over 100,000 hours an LED would still be operating, but at a decreased lumen output.

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How many years use is 50,000 hours?
The life span in years for an LED lamp will depend on how many hours the lamp is in operation each day.

Hours per day            50,000 hours is equivalent to         100,000 hours is equivalent to
24 hours a day                  5.7 years                                     11.4 years
18 hours per day               7.4 years                                     14.8 years
12 hours per day             11.4 years                                      22.8 years
8 hours per day               17.1 years                                      34.2 years

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How Much Energy Do LED Lights Save?
To calculate how much energy LED lights save and how you can reduce your costs you can download the following calculators.

Savings from LED streetlights.

Savings from replacing conventional light bulbs with LED bulbs.

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