FAQ

FAQ

QUESTIONS&ANSWERS ABOUT TECHNICAL AND APPLICATIONS

WHAT DOES “FUTURE-PROOFING” OF LED PRODUCTS MEAN?

LED technology is constantly changing. Rapid innovation continues to improve the performance of LED on an almost daily basis. Future-proofing of LED modules allows luminaire manufacturers to switch from one generation to the next improved generation without major retooling or changes in luminaire design, offering backward compatibility with drivers.

WHAT IS ZHAGA?

Zhaga is an industry-wide consortium aiming to standardize specifications for interfaces between LED luminaires and light engines. The aim is to permit interchangeability between products made by different manufacturers. Zhaga defines test procedures for luminaires and LED light engines so that the luminaire will accept the LED engine.

What IS CELMA?

CELMA is the Federation of National Manufacturers Associations for Luminaires and Electrotechnical components in the European Union. CELMA along with ELC, - (European Lamp Companies Federation) provides standards and guides for LED lighting in Europe.

HOW DO I KNOW THAT A LIGHT FITTING IS SAFE?

In Europe, every light fitting must have a CE label. This tells you that the seller claims that the fitting conforms to all the relevant European safety standards. The most important of these is EN 60598 which covers electrical, thermal and mechanical safety.

IS IT TRUE THAT LEDS DO NOT PRODUCE HEAT?

No. It is true that there is no heat, IR, in the beam. However, the LED fixture itself, does produce heat. However it may become warm, or hot, to the touch.

WHY IS THE HEAT SINK DESIGN CRITICAL FOR THE PERFORMANCE OF AN LED FITTING?
Heat management is critical for the performance of LEDs. Increasing heat in LEDs has the following effects in performance characters:

1. Reduction in luminous flux
2. Color shift (change in color appearance)
3. Reduction in life of the LED

HOW DO LEDS KEEP FOOD FRESHER THAN CONVENTIONAL LIGHT SOURCES?

LEDs do not emit ultra-violet light and do not carry heat in the beam, unlike their conventional counterparts. This helps keep food fresher in refrigerators and cold stores.

WHAT ASPECTS NEED TO BE TAKEN CONSIDERATION IN A RETROFIT PROJECT WITH LED?

1. The lamp base / holder screw fixing position.
2. he physical dimension of the LED lamp and how it fits into the existing housing.
3. The electrical characteristics of LEDs compared to the existing system. (mains voltage, low voltage, 4. control methods).
4. The location and size of the light emitting surface in relation to the luminaire reflector and in comparison to the original light source.
5. The light distribution, lumen output and other photometric properties like color temperature in 6/ comparison to the original light source.
6. The heat generated by the LED during operation and the maximum operating temperature.

CAN LINEAR LEDS BE USED AS A SUBSTITUTE FOR T8 OR T5 FLUORESCENT LAMPS?

Most LED tubes, although they have the same size, lamp base as a linear fluorescent, and possibly a similar lumenoutput, do not have the same omni directional light distribution. Many luminaires emit 20%-30% less light output with narrower beam spreads when fitted with LEDs. This is especially true of troffers with reflectors that offer batwing (wide-spread) light distribution with fluorescents. This needs to be taken into account when considering the overall 30-50% less power usage by LEDs with increased system efficiencies.
It is likely that the luminaire will need some rewiring and this should be done in conformance with the local electrical installation standards.

HOW DOES THE WIDE TEMPERATURE TOLERANCE OF LED EXPAND THEIR APPLICATION?

LEDs work more efficiently in cold temperatures and their lifecycle is extended since the cold air offers a passive heat absorption mechanism. This gives LEDs an advantage in various applications like ice-skating rings / tracks, refrigeration applications, and lighting public places in colder countries.

WHAT ARE THE VARIOUS CAUSES OF CONDENSATION WITHIN LED LUMINAIRES?

1. Heat build up occurs as the luminaire is turned on, and as it cools down when it is switched off.
2. Pressure changes caused by a change in altitude and environmental conditions during transportation in cargo holds or in planes.
3. Thermal shock due to rain, snow or washing cycles.

WHAT PRODUCT FEATURES SHOULD I LOOK FOR WHEN SEEKING LEDS FOR USE IN HARSH ENVIRONMENTS?

1. More rugged O rings and gaskets for more robust seals.
2. Thicker enclosures to prevent movement around seals to prevent breakage of seals.
3. Additional bolting around gaskets and seals to prevent snapping of seals.
4. A vent made of two-way permeable membrane. This allows water vapor and gas to pass through but not liquid water.

HOW ARE LEDS DIMMED?

LEDs are dimmed either by Pulse Width Modulation PWM, or by Constant Current Reduction CCR. PWM dimming involves switching current at a high frequency from zero to the rated output current. CCR dimming: The lighting level required is proportional to the current flowing through the LED. Current flows through the LED continuously and is reduced or increased based on whether the LED is to be dimmed further or made brighter.

WHY DO SOME LEDS FLICKER WHEN DIMMED OR TURNED OFF?

This is usually due to incompatibility between the driver and the control system. When purchasing an LED product, it is important to use the correct driver type as specified by the manufacturer. It is also important to check that the LED is dimmable. Some retrofits are not.

WHY ARE LENSES PREFERRED OVER REFLECTORS FOR MANY LED LUMINAIRES?

LEDs are directional sources of light as opposed to the traditional luminaires, which are omni-directional. When LEDsare fitted with reflectors, much of the light at the center of the beam passes out of the system without even touching the reflector. This reduces the scope of modulation of the beam of light and can cause of glare. Lenses, however, help guide virtually every ray of light emitted by the LED.

DOES INCREASING THE WATTAGE OF LEDS INCREASE THEIR OUTPUT?

This may occur if you are using the same product from the same brand, with the same optics and hardware. However, in general, the nature of the components (like the optical system, the heat sink, the LED chip, and the driver) affects the output more than the wattage does.

A 3watt LED luminaire from one manufacturer will have a different output to a 3watt LED luminaire from another manufacturer, even if the same LED chip is used. Hence, using a high quality chip alone does not guarantee better performance. Note that as the wattage increases, the efficiency drops slightly. An LEDdriven at 3W will emit slightly less than three times the output of one driven at 1W.

WHAT ARE THE FACTORS THAT AFFECT THE LIFESPAN OF THE LEDS?

The thermal management of the LEDs. If LEDs come on a standalone chip, appropriate heat sinks have to be designed to prevent premature failure of LEDs.

The electrical stress: Running LEDs at currents higher than specified make the LED run hot. This can happen with wrongly matched drivers. For example, if the driver produces 700mA but the LED needs 350mA, this will put stress onLED and reduce its lifespan.

Higher ambient temperatures than the ones that the LED is rated for will reduce its expected life.

WHAT IS THE NEW DEVELOPMENT OF “LI-FI” THAT HAS BEEN RECENTLY PUBLISHED?

Research is being conducted into the development of LEDs that can not only provide light, but also offer internet connectivity through “Li-fi” technology. By increasing the flicker rate of LEDs, data can be transmitted to specially adapted laptops and electronic devices via the visible spectrum, instead of via the currently used radio and microwaves.

HOW ARE LEDS DISPOSED RECYCLED?

LEDs are primarily made of electronic components like PCBs, diodes, semiconductors etc. Therefore, they must be treated in the same way that traditional electronics are treated. They collected separately from household wastes and must be treated the same as standard electronic equipment.


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