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Re: Anyone moved to LED Lighting?



How can the efficiency of a white LED be higher than it's constituent LEDs?
Is this due to phosphour screens used?

"Don Klipstein" <don@xxxxxxxxxxxxxx> wrote in message
news:slrnhgpdda.mt7.don@xxxxxxxxxxxxxxxxx
> In article <MYSOm.49165$Zu5.42027@xxxxxxxxxxxx>, Josepi wrote:
>
>>The incandescents lasted forever (well at least 4-10 years) until they
>>were
>>turned off.
>>
>>I believe I have the supplier mixed up. It wasn't OSRAM but another
>>supplier
>>with similiar type name???. OMRON or something..Been awhile now. These lED
>>indicators were all crap and we tried many different styles and many
>>different current levels. When run at their rated current (I think about
>>20mA) they all went up in smoke after a few years, anyway. The main
>>(130vdc)
>>ballast resistors were mounted elsewhere so they weren't a problem. The
>>problem, as I saw it were they were designed as a 24v bulb with 24vdc
>>worth
>>of ballast in a miniature bulb....that's a no..no and did them in from
>>localized heat. Finally, after about 15 years of experimenting with them
>>and
>>different breeds, the Engineering department decided to ignore the
>>manufacturer's advice, went back to incandescents and replace the bulbs
>>every few years when the device was de-enrgized, basically.
>>
>>As  I stated, the LED units are back without any diffusion. LEDs just
>>don't
>>put out enough light to make them look like incandescents with diffusion
>>and
>>still be visible with bright lighting. The red and yellow ones were never
>>a
>>problem, only the green, other than being short lived.
>
>  My experience of red, yellow and green LEDs at 20 mA, for ones
> characterized at 20 mA:
>
>  Red - my champion experience here so far is around 1.8 lumens at 20 mA.
> They appear to me to achieve about .8 lumen at 10 mA.  (Nichia NSPR510CS)
>
>  Yellow - I got about .6-.7 lumen at 20 mA several years ago, likely now
> at least a little better.  My experiece is generally 60% of red - so I
> expect Osram to have something delivering around a lumen at 20 mA
> nowadays.
>
>  Green - my champion experience so far here is 3.7-4.4 lumens at 20 mA,
> more than half of this at 10 mA, averaging .94 lumen at 3 mA and around
> .58 lumen at 1.7 mA, at which their efficiency is close to peak and much
> improved over that at 20 mA.  Part number - Nichia NSPG520AS.
>
> http://members.misty.com/don/led.html
>
> - Don Klipstein (don@xxxxxxxxx)
>
>>"Don Klipstein" <don@xxxxxxxxxxxxxx> wrote in message
>>news:slrnhgmgss.30.don@xxxxxxxxxxxxxxxxx
>>> In article <lrCOm.78212$Wf2.529@xxxxxxxxxxxx>, Josepi wrote:
>>>>As some of the articles point out LED testing may be done unfairly, is
>>>>many
>>>>cases. The manufactures show lumen output for bare elements and then add
>>>>the
>>>>reflectors, lenses and other external parts later.
>>>>
>>>>The ballast in not usually included in the efficiency testing, either.
>>>>
>>>>Are these the white phosphour screen based LEDs, you refer too?
>>>>
>>>>As a side note our company put in hundreds of OSRAM indicator pilot
>>>>lamps
>>>>on
>>>>electrical control panels. After 10-15 years of replacing bulbs,
>>>>burnout,
>>>>sock melting, changing ballast current limiters, lenses and filters,
>>>
>>>  Due to someone not knowing how to implement the LEDs properly, though
>>> 15
>>> years ago efficiency of LEDs was a lot less and maybe they could not
>>> have
>>> been implemented properly.
>>>
>>>> we changed them all back and retrofitted them to incandescent bulbs.
>>>>
>>>>Certain colours, green especially, could not be dicerned, when
>>>>illuminated,
>>>>if there was any windows with sunlight entering into the buildings. If
>>>>we
>>>>put a similar green pilot lamp  with a lime green filter in it (unlit)
>>>>beside a normal green illuminated unit, no difference could be detected.
>>>
>>>  This problem is very easy to avoid with the green LEDs that are
>>> available nowadays, not too hard to avoid with green LEDs that have been
>>> available since about 2000-2001 or so.
>>>
>>>>When we increased the drive current, the bulbs only lasted a month or so
>>>>(at
>>>>a cost of about $5 per bulb). These were very tiny LED segments with
>>>>about
>>>>9
>>>>elements in each bulb. The ballast resistor dropped the current from a
>>>>130vdc battery bank and was a burn hazard for humans.
>>>
>>>  Have a look at what just one modern good InGaN green LED can do with
>>> 5-10 mA now, or what one made by Nichia in 2001 can do.
>>>
>>>> Inverter technology
>>>>was a much better proposition but too expensive a retrofit for so many
>>>>bulbs. They spent tens of thousands of dollars trying all of OSRAM's
>>>>tehnologies they had availble for about 10 years and finally went back
>>>>to
>>>>incandecent bulbs with low current supplies (less than the LEDs) and the
>>>>bulbs last about 10-15 years (or until your turn them off, after a few
>>>>years
>>>>of usage...LOL).
>>>
>>>  Did you run controlled tests?  I have heard of testing showing that
>>> most
>>> incandescents do not lose much life to cold starts.  They do become
>>> unable
>>> to survive a cold start before they become unable to survive continuous
>>> operation, but not by a lot.  The usual incandescent failure is from a
>>> hot
>>> thin spot in the filament, prone to temperature overshoot beyond its
>>> already-excessive temperature when a cold start is imposed upon it.
>>> This
>>> bad condition of an aging filament accelerates worse than exponentially,
>>> and an aging filament that cannot survive a cold start will kick the
>>> bucket soon no matter what.
>>>
>>> - Don Klipstein (don@xxxxxxxxx)
>>>
>>>>In the last few years the pilot lamps got smarter and went to a
>>>>non-filtered
>>>>LED holder, so the area of illumination decreased and the LED elements
>>>>were
>>>>now visible. This made the LEDs visible and workable but the whole thing
>>>>dazzled the eyes like a Christmas tree.
>>
>>
>>




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