LED Bulb Analysis. Start Up Project 23

1AOne of my LED Bulbs showed some unusual behaviour during the Peak hours. Unusual dimming, flickering, lighting faintly after switch off etc. It is a 15 watts LED bulb purchased for Rs.300. Checked its specifications. It is 980 Lm and 6500 K . That showed that there is something related to Watts, Lm and the K. The manufactures say that, instead of Watts, look the Lm before purchasing the LED bulb because “Watts” is an obsolete term for the LED bulb. Then what are the Lm and K? Lm is the short form of “Lumen” which is the measure of total amount of light from a source. As a general rule, a 100 watts ordinary bulb gives 1500 lumen light. K is the short form of “Kelvin” which is the measure of “Colour Temperature “of light. For example, the day light has 5000 K and a White LED Bulb gives around 6000 K . As the Colour temperature value increases, the light turns more and more white then turns to blue. Lower values of K shows Yellow to Red light. So as per the specification, the LED bulb should give 980 Lumens and 6500 K light. Ideal its specifications. Then what is happening in it. Analysed thoroughly.
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Why CFL gives bluish white light? Fact File 17

Compact Fluorescent Lamp was developed with aim of energy conservation. CFL requires a start up time to attain full brightness. The light colour is slightly greenish at power on which changes to blue white after the warm up period of a few minutes. This bluish white colour is due to the presence of Ultraviolet rays from the  excited mercury vapour. The CFL has a resonant converter to generate high frequency AC to excite the mercury vapour filled inside the tube. The excited mercury atoms generate UV rays that produces fluorescence in the Phosphor coating of the tube. The phosphor coating then emits visible light with some UV fraction that gives bluish white colour to the light.

Unlike ordinary bulb, CFL generates secondary light. The light is not directly from the filament, but from the phosphor coating. Actually this secondary light is not friendly for the eyes since the human eye is adapted for natural direct lights such as sunlight and light from flame. UV ray is also not good for the eyes. Low quality CFL generates large amount of UV rays. This can cause eye strain if the light is viewed long time.

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Compact Fluorescent Lamp

Compact Fluorescent Lamp or CFL is the energy saving lamp designed to provide adequate light at the expense of low current.CFL uses less power around one fifth of an ordinary bulb and has long life.CFL is designed to emit Soft white light using the phosphor formulations.CFL comes in two forms like integrated and non integrated CFLs. In integrated type, the tube combines with an electronic ballast as a single unit while in non integrated type, ballast and tube are separate units so that the tube can be replaced.AC and DC CFLs are available.CFL generally has a life span of 6000 to 20000 hours.

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