What might be the tell-tale signs to look out for if a unit is returned? In extreme cases, physical damage can occur. LEDs installed in an environment that is too hot will emit less light than intended and degrade more rapidly than intended both in terms of reduced light output and colour change. What damage might a hot environment cause? The hotter the environment the shorter the LED life. LEDs do not emit the same amount of light of the same colour eternally! The amount of light reduces exponentially and the colour of white LEDs tends to become bluer – both as a function of time and temperature. Installation in an environment that gets too hot What do we mean by LED installation in an environment that gets too hot? However, damage resulting from incorrect drive current and/or voltage may be manifest in many ways ranging from dimly lit but normal-looking LEDs through to severe physical damage. LEDs that have failed catastrophically due to direct mains connection will typically exhibit severe physical damage including breakage and burn marks. If the current and/or voltage is too high the LEDs could either age prematurely (in the case of minor overdrive) or fail catastrophically (in the case of major overdrive) with all scenarios in between being possible. If the current and/or voltage is too low the LEDs will appear too dim, or fail to light at all. If LEDs are powered via a LED Driver or LED Power Supply that supplies incorrect current and/or incorrect voltage several outcomes are possible. If LEDs are connected directly to the UK 230V AC mains supply without any current limiting LED Driver or LED Power Supply they will most likely immediately and catastrophically fail open-circuit, possibly breaking apart explosively in the process. What damage might connecting to a mains supply or using an incorrect LED driver cause? This is in contrast to incandescent lamps that will operate from AC or DC and which generally require no separate current limiting, or fluorescent lamps that operate from AC only but which do require current limiting (i.e. LEDs must be powered from a DC source that limits the current flowing through them. Direct Connection to Mains Supply or Use of an Incorrect LED Driver What does this mean? Consequently they emit no light or only a very small amount of light and if they are connected in a series string the remaining/undamaged LEDs remain lit. High power LEDs that have suffered from failure due to Hot Connect EOS often show no naked-eye/visible signs of damage, but are frequently electrical short-circuits. What might be the tell-tale signs be for LED hot connection if a unit is returned? This kind of LED damage is often categorised under the term Electrical Overstress (EOS). This in turn can result in either immediate damage to LEDs in terms of open-circuits or short-circuits, or latent damage that results in similar LED failure after a potentially long period of time (possibly up to many months). Hot Connecting can result in a short but potentially harmful impulse of electrical energy being discharged from the live LED Driver or LED Power Supply into the LEDs. What damage might an LED hot connection cause? “Hot Connecting” means connecting a circuit comprising one or more bare LEDs to a LED Driver or LED Power Supply that is already powered-up or ‘live’. LED Hot Connection What does LED hot connection mean? Here’s an overview of the main causes of electrical overstress. However, the performance of LEDs can be reduced and even fail if the LED module is used incorrectly: overdriven or the application environment is too hot, and the unit has not been designed to be fit for purpose. LED lighting is incredibly robust and reliable.
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