Re: Anyone moved to LED Lighting?

[don@xxxxxxxxxxxxxx (Don Klipstein)]

In article <Ge3Pm.11182$cX4.10981@xxxxxxxxxxxx>, Josepi wrote:
>How can the efficiency of a white LED be higher than it's constituent LEDs?
>Is this due to phosphour screens used?

  Yes.  The usual white LEDs have blue-emitting chips coated by a phosphor
that absorbs some-most of the blue light and converts it to a
yellow/yellowish broad band whose spectral content typically covers
mid-green to mid-red.  Some of the blue light is not absorbed but passes
through the phosphor, to mix with the yellow/yellowish light so that you
get white light.

  Nowadays, some of these blue chips used for white LEDs are achieving
around 40-50% efficiency.  The most efficient white LED on the market that
I am aware of, Nichia NSPWR70CSS-K1 at 20 mA, is a goodly 40% efficient
even after losses of the phosphor.  At 20 mA, it is supposed to typically
achieve 150 lumens/watt.

 - Don Klipstein (don@xxxxxxxxx)

>"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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