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LED light fixture

What are the product features to look for in LEDs used in harsh environments?

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

The LED luminaire is hot to touch. Why is this?

The LED chip, or light engine produces heat. This needs to be dissipated as quickly as possible. This is normally done by with a heat sink, which often has fins. Cool LEDs are more efficient than hot ones. They also have a longer life. Of course, higher power LEDs generally run hotter than low power ones because of the extra heat to remove.

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.

What are the various causes of condensation within LED luminaires?

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

What are common challenges or problems when using LED fixtures in harsh environments?

The LED drivers can fail early due to ingress of moisture or condensation. The driver enclosure needs to be properly sealed to prevent this.LEDs are less resistant to damp than other light sources. This means that particular attention needs to be given to the light fixture seal and cable glands.

What are the different ways in which luminaire design can help reduce glare from LEDs?

Here are few of the ways in which glare can be reduced from LEDs:Use of microprismatic technology to develop special diffusers that disperses light from individual LEDs. This system gives out homogeneous light with optimum levels of contrast avoiding any direct or reflected glare.Design of secondary reflectors systems; where the primary reflector, which will hide the view of the LED and direct the light into the secondary reflector that will distribute the light in the intended way.Use of a combination of TIR (total internal reflection) lenses / collimator lens, which that produce a parallel beam of light, and a facetted lens. This combination will distribute the light beam as intended.

What are the different types of optical systems for LEDs?

The following are types of optical systems of LEDs:Primary systems with integrated lenses - specific beam angles.Secondary optical systems in the form of lenses, reflectors or diffusers.Combinations of primary and secondary optics for specific applications.

What is junction temperature?

Junction temperature is the LED’s active region; the point at which the diode connects to the base. This is where the electrons jump between the two semiconductors to produce photons. A low junction temperature helps LEDs to produce more light also reduces lumen depreciation. Junction temperature is affected by the driver current, the thermal path, and the ambient temperature.

What is the two-phase heat exchange technique of cooling LEDs?

The two-phase heat technique is a cooling technique that uses the advantages of both active and passive cooling methods.It works on the principle of evaporation and condensation. The process requires disposable heat to initiate the process that happens in a hermitically sealed tube that is filled with a minute quantity of liquid. The system has cooling fins around the tube to dissipate heat. This system offers high reliability, zero operation costs and is not orientation dependent.

What are the heat transfer techniques used to cool LEDs?

LEDs are cooled either by passive cooling or active cooling. Passive cooling involves a finned heat exchange system made of cast or extruded metal or a plastic coated metal heat sink that offers a totally silent, robust, heat transfer. Passive cooling is reliant on the surface area of the heat sink material and is orientation dependent. Active cooling may include conventional fans or diaphragm- based forced air cooling. Active cooling using a fan, although more efficient, is noisy, not so reliable, and requires electricity to run. Active cooling places emphasis on forced air flow rate and is not orientation dependent.

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: Reduction in luminous fluxColor shift (change in color appearance)Reduction in life of the LED