It is a unit of luminous flux and a measure of the total amount of visible light emitted by a source.
It is a measure of how efficiently a lighting source produces visible light per unit of input wattage. LEDs have high efficacy > 150 lm/W as compared to GLS 10 lm/W or CFL 60 lm/W.
It is the unit of illuminance and measure of luminous flux per unit area. Each application has its standard lux requirements. The task-oriented areas like kitchen or sewing will require a high lux values as compared to non-task areas like corridor or lobbies.
Correlated Colour Temperature (K)
It is the method of describing the colour characteristics of light, either warm (yellowish), neutral (off white) or cool (white), and is measured in degrees of Kelvin (°K).
Colour Rendering Index (CRI)
It is the ability of a light source to produce natural colours. For example an object seen in sunlight will show its natural colours (high CRI) whereas if the object is shown under a blue or green light it shows a different colour (low CRI).
It indicates the spread of light from the light source. A narrow beam gives a concentrated light, which is better for accent lighting. A wide beam gives a softer light, suitable for ambience lighting applications.
What is an LED?
LED stands for Light Emitting Diode. It emits light when a current is passed through it.
What are the benefits of LED Lighting?
LEDs have numerous benefits over conventional lighting technologies –
What is the lifespan of an LED (L70)?
Unlike conventional lamps that fail abruptly, LEDs depreciate slowly over time. The life of an LED is defined as when its lumen output depreciates to 70%. It is also called L70.
What is the comparison of an LED’s lifespan as compared to conventional lamps?
|GLS||: 1,000 hours|
|Halogen||: 2,000 hours|
|CFL||: 5,000 hours|
|FTL||: 6,000 hours|
|LED||: 50,000 hours|
What is the physical significance of 50,000 hours life?
|4 hours daily operation||: 34 years|
|8 hours daily operation||: 17 years|
|12 hours daily operation||: 11 years|
|24 hours daily operation||: 05 years|
Are there any standards that determine the quality of LEDs?
Yes, there is a LM-80 standard that helps users to evaluate LEDs.
What is LM80 standard?
It is the standard for measuring lumen maintenance of an LED light sources. This standard is approved by the Illuminating Engineering Society of North America (IESNA). Under this test the luminous flux for a given current (over a 6,000 hours period with interval measurements) is measured. Luminous flux will be measure for 3 different LED case temperatures: 55ºC, 85ºC and a third temperature that is selected by the manufacturer. The results are then extrapolated for 50,000 hours as per TM-21 standard to determine the life of LEDs.
How much lumen depreciates after 6,000 hours testing?
Normally for a good LED the amount is <5-6%.
What are the challenges with LED Lighting?
LEDs are very sensitive to temperature and also produce a lot of heat. This heat should be removed from the system to maintain the junction temperature within the prescribed limits. LED are also point sources, hence they are prone to cause glare if the optics are not properly designed.
What is junction temperature?
It is the temperature of the PN junction in the LED chip.
What happens if the junction temperature increases?
An increase in junction temperature may drastically reduce the performance of the LED by;
What is the role of a heat sink?
A heat sink is required to dissipate heat generated by LEDs during operation. Since ambient temperature in India varies from – 50C to + 550C, the heat sink design ensures effective thermal management under all circumstances. The heat sink is made of high grade aluminium (either aluminium pressure die-cast or aluminium extrusion).
What is the role of optics?
LEDs are directional point sources and they are prone to glare. The role of optics is to reduce this glare and distribute light as per the application. The different kinds of optical material that are used for this purpose are diffusers, lenses, reflectors and light guide plates (LGP).
What kind of optical material is used in the Wipro Garnet LED Bulb?
Wipro Garnet LEDs use lens/reflector optics for spot lighting and diffuser/LGP for ambient lighting applications. The optical material used in the lens, diffuser and LGP have high translucency and are of a non-yellowing grade.
What is a driver?
A driver is an electrical device that regulates the power to an LED. It converts 230V AC input into DC voltage, which powers the LED.
What makes Garnet drivers reliable and robust?
With the dynamic power conditions in India, a robust power supply with protection is required for good performance. Garnet drivers incorporate the below features to ensure a reliable performance,
There are lot of parameters to be considered while designing the lighting for home/office/establishment. Each application has its own lighting requirements, for example:
1 Lux requirements
Lux requirement varies with size and area of the space. A study room would require 300 lux whereas a corridor would require 100 lux.
2 Beam Angle
Narrow and focused beam angles are required for accent or spot lighting, whereas wide beam angles are required for general ambience lighting.
3 Colour Temperature
Colour Temperature is a matter of preference. Cool white is ideal for task-orientated areas like kitchens and areas that have a warmer climate, the lighting will help to make the rooms feel cooler. Warm white helps to create a more intimate atmosphere. Warm whites are suited for bedrooms and living rooms, these colour temperatures create a more relaxing and comfortable environment. A tip is to stick to just one colour throughout an open plan living area; otherwise the mixing of colours will be distracting to the eye.
4 Colour Rendering Index (CRI)
High CRI > 90 are required for applications like in museum lighting, jewellery showroom or places where the actual colour of an object is very important.
5 Efficacy (lm/W)
Two LED downlights may have the same beam angle and wattage, but different lumen outputs. The one with more lumen output will have better efficacy as compared to the other. So if we design a room with standard lux levels (say 300 lux) then we require fewer high efficacy downlights to achieve the same lux values as compared to the poor efficacy downlights.